TNRD WNv Final Report 2006 - CivicWeb

Final Report of the Thompson-Nicola Regional District

West Nile Virus Prevention Program, 2006

Report prepared October, 2006

By Cheryl Phippen, RN, BSc,

BWP Consulting Inc.

Thompson-Nicola Regional District West Nile Virus Program, 2006

BWP Consulting Inc Page ii

TABLE OF CONTENTS List of Tables ..................................................................................................................... vi List of Figures .................................................................................................................. viii Executive Summary ............................................................................................................ 1 1.0 Introduction................................................................................................................... 3

1.1. History of West Nile Virus in North America ......................................................... 3 1.2. West Nile Virus Life Cycle...................................................................................... 4 1.3. Surveillance in British Columbia............................................................................. 5 1.4. Overview of Grant Funding and Completed Activities ........................................... 5

2.0 Public Education ........................................................................................................... 6 2.1. Personal Protection .................................................................................................. 6 2.2. Reduction of Mosquito Larval development Sites................................................... 7 2.3. The Disease and Its Effects on Humans .................................................................. 7 2.4. West Nile virus Information Booth.......................................................................... 7 2.5. Radio and Television Advertising ........................................................................... 8 2.6. Public Education Events .......................................................................................... 8

2.6.1. Ashcroft & District: Fall Fair, Sept 9th ............................................................. 9 2.6.2. Cache Creek: Council Meeting, July 17th ......................................................... 9 2.6.3. Clinton Jamboree : August 19th ........................................................................ 9 2.6.4. Logan Lake: Council Board Meeting, July 11th............................................. 10 2.6.5. Lytton: Farmer’s Market, September 1st ......................................................... 10 2.6.6. Kamloops: Kamloops Spring Home and Garden Show, March 10th-12th ...... 10 2.6.7. Kamloops: Farmer’s Market, July 20th ........................................................... 10 2.6.8. Kamloops: Merchant’s Market, July 21st........................................................ 10 2.6.9. Kamloops: River Family Fun Day at Riverside Park, July 23th...................... 10 2.6.10. Rural TNRD: 70 Mile House, May 20th ....................................................... 11 2.6.11. Rural TNRD: Blue River, September 25th .................................................... 11 2.6.12. Rural TNRD: Barriere Post Office, September 12th ..................................... 11 2.6.13. Rural TNRD: Clearwater Post Office, September 13th................................. 11 2.6.14. Rural TNRD: Merritt Home and Garden Show, April 21st – 23rd ................ 11 2.6.15. Rural TNRD: Westwold General Store: Oct 3, 2006 ................................... 11 2.6.16. Adams Lake Indian Band.............................................................................. 12 2.6.17. Ashcroft First Nations: July 7th ..................................................................... 12 2.6.18. Bonaparte Indian Band: ................................................................................ 12 2.6.19. Coldwater Indian Band: ................................................................................ 12 2.6.20. Cook’s Ferry Indian Band: August 12th ........................................................ 12 2.6.21. High Bar First Nations .................................................................................. 12 2.6.22. Kamloops First Nation: August 5th ............................................................... 12 2.6.23. Kanaka Bar Indian Band: July 19th & Oct 24th ............................................. 12 2.6.24. Lower Nicola Indian Band............................................................................ 13 2.6.25. Lytton First Nation: September 1st and July 19th .......................................... 13 2.6.26. Neskonlith Indian Band: July 27th ................................................................ 13 2.6.27. Nicomen Indian Band: July 19th and October 18th........................................ 13 2.6.28. Nooaitch Indian Band, July 18th ................................................................... 13 2.6.29. Oregon Jack Creek Band .............................................................................. 14 2.6.30. Shackan Indian Band: October 6th ................................................................ 14


BWP Consulting Inc Page iii

2.6.31. Simpcw First Nations: August 15th ............................................................... 14 2.6.32. Siska Indian Band: July 19th and October 24th.............................................. 14 2.6.33. Skeetchestn Indian Band: August 24th .......................................................... 14 2.6.34. Skuppah Indian Band: July 19th ................................................................... 14 2.6.35. Upper Nicola Indian Band ............................................................................ 14 2.6.36. Whispering Pines/Clinton Indian Band ........................................................ 15

3.0 Mosquito Surveillance ................................................................................................ 15 3.1. Method of Adult Surveillance................................................................................ 15 3.2. Results of Mosquito Surveillance in the North Thompson Valley ........................ 17

3.2.1. Blue River @ David Hannah’s Residence Behind the Blue River Esso ........ 20 3.2.2. Clearwater @ the Residence of Chris Fleury on Archibald Street ................. 21 3.2.3. Blackpool next the Roundtop Road Wildlife Sanctuary................................. 22 3.2.4. East Blackpool, Auldgirth Road ..................................................................... 23 3.2.5. MacColl Road, Darfield, BC .......................................................................... 24 3.2.6. Simpcw First Nation ....................................................................................... 25 3.2.7. Barriere @ DJ’s Campground ........................................................................ 26 3.2.8. McLure @ Bob Hearn’s residence on Glenacres Road .................................. 27 3.2.9. Whispering Pines@ Indian Band Office......................................................... 27 3.2.10. Noble Creek @ Edward Babcock’s Residence............................................. 28

3.3. Summary of WNv Vectors in the North Thompson Valley .................................. 29 3.4. Results of Mosquito Surveillance in the City of Kamloops .................................. 30

3.4.1. Kamloops: 129 Beachview Drive, Rayleigh................................................... 32 3.4.2. Kamloops: Dunes Golf Course, Westsyde...................................................... 33 3.4.3. Kamloops: Cinnamon Ridge near Tranquille Wildlife Sanctuary.................. 34 3.4.4. Kamloops: Mission Flats, Waste Water Treatment Plant ............................... 36 3.4.5. Kamloops: Brocklehurst, McArthur Island Park ............................................ 37 3.4.6. Kamloops: Kamloops First Nation Reservation ............................................. 38 3.4.7. Kamloops: Peter Rd, Valleyview.................................................................... 39 3.4.8. Kamloops: Lamar Drive, Barnhartvale........................................................... 40 3.4.9. Kamloops: Hillside Drive, Dufferin ............................................................... 41

3.5. Summary of WNv Vectors in the City of Kamloops............................................. 41 3.6. Results of Mosquito Surveillance in the South Thompson River VAlley ............. 42

3.6.1. Adams Lake Indian Band................................................................................ 44 3.6.2. Veterans Road, Chase, BC.............................................................................. 45 3.6.3. Neskonlith Indian Band .................................................................................. 46 3.6.4. Community of Pritchard ................................................................................. 47

3.7. Summary of WNv Vectors in the South Thompson River Valley......................... 48 3.8. Results of Mosquito Surveillance in the Thompson Valley .................................. 48

3.8.1. Skeetchestn Indian Band................................................................................. 50 3.8.2. Bonaparte Indian Band ................................................................................... 51 3.8.3. Village of Cache Creek................................................................................... 52 3.8.4. Village of Ashcroft ......................................................................................... 53 3.8.5. Ashcroft First Nations..................................................................................... 54 3.8.6. Spences Bridge................................................................................................ 55 3.8.7. Cook’s Ferry Indian Band............................................................................... 57 3.8.8. Nicomen Indian Band ..................................................................................... 58


BWP Consulting Inc Page iv

3.9. Summary of WNv Vectors in the Thompson River Valley................................... 58 3.10. Results of Mosquito Surveillance in the Nicola Valley....................................... 59

3.10.1. TNRD: Nicola Valley ................................................................................... 60 3.10.2. Upper Nicola Indian Band ............................................................................ 62 3.10.3. Lower Nicola Indian Band............................................................................ 63 3.10.4. Nooaitch Indian Band ................................................................................... 64 3.10.5. Shackan Indian Band .................................................................................... 65

3.11. Summary of WNv Vectors in the Nicola Valley ................................................. 66 3.12. Results of Mosquito Surveillance in the Fraser River Valley.............................. 66

3.12.1. High Bar First Nation.................................................................................... 68 3.12.2. Lytton First Nation........................................................................................ 69 3.12.3. Village of Lytton........................................................................................... 70 3.12.4. Skuppah Indian Band.................................................................................... 71 3.12.5. Siska Indian Band ......................................................................................... 71 3.12.6. Kanaka Bar Indian Band............................................................................... 72

3.13. Summary of WNv Vectors in the Fraser River Valley ........................................ 73 3.14. Results of Mosquito Surveillance in the Southern Cariboo................................. 73

3.14.1. Village of Clinton ......................................................................................... 74 3.14.2. TNRD: 70 Mile House.................................................................................. 75

3.15. Summary of WNv Vectors in the Southern Cariboo ........................................... 76 3.16. Results of Mosquito Surveillance In Four Trapping Sites Situated Outside of the Primary Valleys of the TNRD. ..................................................................................... 76

3.16.1. Logan Lake ................................................................................................... 77 3.16.2. TNRD: Brookmere........................................................................................ 78 3.16.3. Coldwater Indian Band ................................................................................. 79 3.16.4. TNRD: Monte Creek at Duck Meadow (Duck’s Unlimited Site) ................ 80

3.17. Summary of Results of All Adult Sampling ........................................................ 81 4.0 Summary of West Nile Virus Vector Competency for BC Mosquito Species ........... 86 5.0 Biology of Major Mosquito Species Collected in the TNRD in 2006........................ 87

5.1. Anopheles Species.................................................................................................. 87 5.1.1. Anopheles earlei.............................................................................................. 88 5.1.2. Anopheles freeborni ........................................................................................ 88 5.1.3. Anopheles punctipennis .................................................................................. 88

5.2. Aedes and Ochlerotatus Species ............................................................................ 88 5.2.1. Aedes cinereus ................................................................................................ 89 5.2.2. Aedes vexans ................................................................................................... 90 5.2.3. Ochlerotatus campestris ................................................................................. 90 5.2.4. Ochlerotatus communis .................................................................................. 91 5.2.5. Ochlerotatus dorsalis...................................................................................... 91 5.2.6. Ochlerotatus excrucians ................................................................................. 91 5.2.7. Ochlerotatus fitchii ......................................................................................... 92 5.2.8. Ochlerotatus implicatus .................................................................................. 92 5.2.9. Ochlerotatus increpitus................................................................................... 92 5.2.10. Ochlerotatus melanimon ............................................................................... 92 5.2.11. Ochlerotatus spencerii (both variants).......................................................... 93 5.2.12. Ochlerotatus sticticus.................................................................................... 93


BWP Consulting Inc Page v

5.3. Coquillettidia Species ............................................................................................ 93 5.3.1. Coquillettidia perturbans................................................................................ 93

5.4. Culex species.......................................................................................................... 94 5.4.1. Culex pipiens................................................................................................... 94 5.4.2. Culex tarsalis .................................................................................................. 95

5.5. Culiseta Species ..................................................................................................... 96 5.5.1. Culiseta alaskaensis........................................................................................ 96 5.5.2. Culiseta incidens ............................................................................................. 96 5.5.3. Culiseta inornata ............................................................................................ 97 5.5.4. Culiseta impatiens........................................................................................... 97 5.5.5. Culiseta morsitans .......................................................................................... 98

6.0 Prevention of West Nile Virus Through Mosquito Abatement .................................. 98 7.0 Habitat Mapping and Equipment Purchase................................................................. 99 8.0 Monitoring and Larviciding for WNv Vectors ......................................................... 100 9.0 Larval Surveillance and Treatment........................................................................... 100

9.1. Overview of Helicopter Applications .................................................................. 101 9.2. Overview of Hand Applications .......................................................................... 102

10.0 Conclusions............................................................................................................. 104 11.0 Recommendations................................................................................................... 105 References....................................................................................................................... 107


BWP Consulting Inc Page vi

LIST OF TABLES Table 1. Location of mosquito trapping sites in the North Thompson River Valley, 2006.

................................................................................................................................... 18 Table 2. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

the residence of Mr Hannah in Blue River, BC. ....................................................... 20 Table 3. Numbers of adult mosquitoes captured each week in a New Jersey black-light

trap at the residence of Chris Fleury on Archibald Rd in Clearwater, B.C. ............. 21 Table 4. Numbers of adult mosquitoes captured each week in a New Jersey black light

trap near the Roundtop Road Wildlife Sanctuary in Blackpool, BC. ....................... 22 Table 5. Numbers of adult mosquitoes captured each week in a New Jersey black-light

trap set on Auldgirth Road in East Blackpool, BC. .................................................. 23 Table 6. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

MacColl Road in Darfield, BC. ................................................................................ 24 Table 7. Numbers of adult mosquitoes captured each week in a CDC black-light trap set

once per week on the Simpcw First Nation reservation, BC. ................................... 25 Table 8. Numbers of adult mosquitoes captured each week in a CDC black-light trap, at

DJ’s Campground in Barriere, BC............................................................................ 26 Table 9. Numbers of adult mosquitoes captured each week in a New Jersey light trap at

McLure, BC. ............................................................................................................. 27 Table 10. Numbers of adult mosquitoes captured each week in a New Jersey light trap at

the residence of Edward Babcock in Noble Creek, BC. ........................................... 28 Table 11. Location of Trapping Sites within the City of Kamloops, 2006....................... 30 Table 12. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

129 Beachview Drive, Rayleigh in Kamloops, BC. ................................................. 32 Table 13. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

the Dunes Golf Course, Kamloops, BC. ................................................................... 33 Table 14. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

Cinnamon Ridge, Kamloops, BC. ............................................................................ 35 Table 15. Numbers of adult mosquitoes captured each week in a New Jersey black-light

trap at the Waste Water Treatment Plant in Kamloops, BC. .................................... 36 Table 16. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

the McArthur Park Golf Course in Kamloops, BC................................................... 37 Table 17. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

the Kamloops First Nation reservation in Kamloops, BC. ....................................... 38 Table 18. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

Peter Road in Valleyview, Kamloops, BC................................................................ 39 Table 19. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

1399 Lamar Drive, Kamloops, BC. .......................................................................... 40 Table 20. Numbers of adult mosquitoes captured each week in a CDC black-light trap set

at #23-1940 Hillside Drive, Dufferin, Kamloops, BC. ............................................. 41 Table 21. Locations of trapping sites along the South Thompson River Valley, 2006. ... 42 Table 22. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located at the Adams Lake Indian Band office, near Chase, BC.............................. 44 Table 23. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located at Veteran’s Road, in Chase, BC.................................................................. 45


BWP Consulting Inc Page vii

Table 24. Numbers of adult mosquitoes captured each week in a CDC black-light trap on the Neskonlith Indian Band reservation, BC. ........................................................... 46

Table 25. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at 1249 DeCamillis Road, in Pritchard, BC. .............................................. 47

Table 26. Locations of trapping sites along the Thompson River Valley, 2006. ............ 48 Table 27. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located at #55- 909 Deadman-Vidette Road on the Skeetchestn Indian Band Reserve, BC. ............................................................................................................. 50

Table 28. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Bonaparte Indian Band office, BC. .......................................................... 51

Table 29. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Sage and Sands Trailer Park in the Village of Cache Creek, BC............. 52

Table 30. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on Old Cariboo Road in the Village of Ashcroft, BC. ................................. 53

Table 31. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at 705 Dick Street on the Ashcroft First Nations Reservation, BC.............. 54

Table 32. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Acacia Grove RV Park in Spences Bridge, BC........................................ 56

Table 33. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at the Cook’s Ferry Indian Band office, BC................................................. 57

Table 34. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at 2946 Nicomen Place on the Nicomen Indian Band reservation near Spence Bridge, BC.................................................................................................... 58

Table 35. Locations of trapping sites along the Nicola Valley, 2006.............................. 59 Table 36. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on Guichon Ranch in the Nicola Valley, BC. .............................................. 61 Table 37. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Upper Nicola Indian Band reservation, BC....................................... 62 Table 38. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Lower Nicola Indian Band reservation, BC. ..................................... 63 Table 39. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Nooaitch Indian Band reservation, BC.............................................. 64 Table 40. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Shackan Indian Band reservation, BC............................................... 65 Table 41. Locations of trapping sites along the Fraser River Valley, 2006..................... 66 Table 42. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located at the Big Bar Ferry, just north of the High Bar First Nation....................... 68 Table 43. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Lytton First Nation reservation, BC. ................................................. 69 Table 44. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located in the Village of Lytton, BC......................................................................... 70 Table 45. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Skuppah Indian Reserve, BC............................................................. 71 Table 46. Numbers of adult mosquitoes captured each week in a CDC black-light trap

located on the Siska Indian Band reservation, BC.................................................... 71


BWP Consulting Inc Page viii

Table 47. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Kanaka Bar Indian Band reservation, BC. ........................................ 72

Table 48. Locations of mosquito trapping sites in the South Cariboo Region. ................ 73 Table 49. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

Waste Water Treatment area in Clinton, BC. ........................................................... 74 Table 50. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

70 Mile House, BC. .................................................................................................. 75 Table 51. Locations of mosquito trapping sites Logan Lake, Brookmere, Coldwater

Indian Band and Westwold....................................................................................... 76 Table 52. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

the Highland Bed and Breakfast in Logan Lake, BC................................................ 77 Table 53. Numbers of adult mosquitoes captured each week in a CDC black-light trap in

the community of Brookmere, BC............................................................................ 78 Table 54. Numbers of adult mosquitoes captured each week in a CDC black-light trap at

the Coldwater Indian Band reservation, BC. ............................................................ 79 Table 55. Numbers of adult mosquitoes captured each week in a CDC black-light trap in

Duck Meadow, Monte Creek, BC............................................................................. 80 Table 56. Distributions of mosquito species found in the TNRD in 2006. ..................... 83 Table 57. Summary of compositions of each of the mosquito light traps employed in the

TNRD during the summer of 2006. .......................................................................... 84 Table 58. Mosquito species in British Columbia identified as potential human West Nile

Virus Vectors (Belton, 2004).................................................................................... 87 Table 59. Breakdown of Larvicide Applications for WNv Vector Control* within the

TNRD in 2006......................................................................................................... 103

LIST OF FIGURES Figure 1. Photograph of the West Nile Virus information booth at the Kamloops

Children’s Festival, September 18th, 2005.................................................................. 9 Figure 2. CDC mosquito black-light trap with octenol and dry ice canister. .................. 16 Figure 3. Map of North Thompson Valley Mosquito Sampling Sites, 2006.................... 19 Figure 4. Locations of Mosquito Trapping Sites within the City of Kamloops, 2006. ... 31 Figure 5. Locations of Mosquito Trapping Sites along the South Thompson River Valley,

2006........................................................................................................................... 43 Figure 6. Locations of Mosquito Trapping Sites along the Thompson River Valley, 2006.

................................................................................................................................... 49 Figure 7. Locations of Mosquito Trapping Sites along the Nicola Valley, 2006. ........... 60 Figure 8. Map of mosquito trapping locations along the Fraser River Valley (excluding

High Bar to the north). .............................................................................................. 67


BWP Consulting Inc Page 1

EXECUTIVE SUMMARY Public education , mosquito surveillance, and vector mosquito mapping and

control were carried out with grant funding from the Union of British Columbia

municipalities under the Provincial West Nile Virus Risk Reduction Initiative and

the West Nile Virus Crown Lands Initiative. The funding was provided to the

Thompson-Nicola Regional District (TNRD) and to the municipalities of Ashcroft,

Cache Creek, Chase, Clinton, Kamloops, Lytton, and Logan Lake. Funding was

also provided for 21 participating First Nations within the TNRD. BWP Consulting

Inc. was contracted to conduct all West Nile virus (WNv) activities under this grant

funding.

Last year the TNRD allotted funding to the creation of a WNv information

booth. This booth was used extensively this year. It was displayed at public events

throughout the TNRD and attendees were invited to ask questions and view live

mosquito larvae. In addition, a number of local governments and community

groups requested presentations of between 15 minutes and 1.5 hours in length.

Radio and television advertising was also purchased during the summer. The

focuses of the public education campaign were “personal protection from West Nile

virus” and “mosquito control around the home.”

CDC black-light mosquito traps were purchased, and 48 trapping sites were

selected within the TNRD. Traps were operated for 10-14 weeks, during which time

the contents of the traps were identified to determine species distribution at each

trapping site. A total of 13494 mosquitoes were captured; the two primary vectors

of WNv, Culex pipiens and Culex tarsalis, were found throughout the TNRD, in most

of the trapping locations.

Mosquito habitat mapping was conducted throughout the TNRD as

necessary. All new sites were mapped and entered into the TNRD online database.

New equipment was purchased that will allow for the creation of GIS shape files for

larval development sites throughout the Regional District.

Vector mosquito control was conducted throughout the TNRD, including all

participating municipalities and First Nations. A total of 1913.1 kg of Aquabac and

1450.5 kg of Vectobac (Bacillus thuringiensis var israelensis) was applied to 334.9 ha



of standing water via hand and helicopter application. 36.0 kg of the long-acting

larvicide, Altosid (methoprene), was applied to standing water near the City of

Kamloops and the community of Pritchard. A further 0.28 kg of this larvicide was

used to treat 40 catch basins in the Westsyde area of Kamloops. VectoLex pouches

(Bacillus sphaericus) were applied to 2562 catch basins in Kamloops, Chase, Cache

Creek, Ashcroft and Clinton.

Predictions were made regarding the areas of the TNRD that are more likely

to see cases of WNv when the virus arrives in British Columbia. These predictions

were based on the mosquito surveillance and habitat mapping that occurred this

year and in the previous two years. It is important to note that mosquito

populations can be affected by weather, temperature, and habitat, and therefore

predictions can change from year to year, so no area of the TNRD should be

completely discounted as having the potential for WNv cases.



1.0 INTRODUCTION 1.1. HISTORY OF WEST NILE VIRUS IN NORTH AMERICA

West Nile Virus (WNv) is considered a new and emerging disease in North

America. It was first detected in New York City in the summer of 1999 with the deaths

of countless American Crows (Corvus brachyrhynchos). That summer, 62 cases of WNv

were identified in New York and seven human deaths occurred (CDC, 2004). At that

time, it was unknown if the outbreak would be an isolated event, and there were

questions surrounding the ability of the virus to survive North America’s winters. The

following spring, these questions were answered as the virus reappeared and rapidly

started its “migration” across the continent.

In 2000 and 2001, the virus appeared in most of the eastern United States (US) as

well as in parts of Eastern Canada. In 2002, the WNv made its greatest advancement

across the continent: viral activity was detected in all Canadian provinces except in New

Brunswick, Newfoundland, and British Columbia (BC), and was detected in all but five

of the contiguous United States. In that year, there were 284 deaths in the US and nine

deaths in Canada. In 2003, there were large outbreaks in the Canadian prairies (Alberta,

Saskatchewan and Manitoba), and cases in Washington and Idaho (BC’s neighboring US

states) (CDC, 2004; Health Canada, 2003). In 2004, British Columbia expected the virus

to arrive from the infected birds traveling from both the prairies and Washington, but a

relatively cool summer throughout North America stunted the advancement of the virus,

despite significant outbreaks in California and Oregon. In 2005, British Columbians

braced themselves once again for an early spring arrival of the virus via migrating birds

in the Pacific Flyway. Although WNv did make its way as far north as Washington and

as far west as Alberta by early-September, it was once again not detected in British

Columbia. This year, excessive precipitation in May followed by high temperatures in

July and August created ideal conditions for Culex tarsalis larvae. This resulted in an

incredible outbreak in Idaho where a “state of emergency” was declared in numerous

counties. It was predicted that BC would see its first case by late September, 2006 in the

Kootenay north of Idaho, but as of October 12, 2006, no virus has been detected.



1.2. WEST NILE VIRUS LIFE CYCLE

WNv is primarily a disease of birds, especially those of the Corvid Family (crows,

ravens, jays, and magpies). It is transmitted from host to host through the bite of

particular species of mosquitoes. While a number of mosquito species are considered

potential vectors, as you will read later in Section 4.0 , it is widely accepted that the two

primary species for concern in Western Canada are Culex tarsalis and Culex pipiens.

These species play different roles in the transmission of the virus, but both should be

considered equally important.

When a bird is bitten by an infected mosquito, the mosquito injects the virus into

the bird. The immune systems of some bird species are able to fight the virus and do not

allow the virus to replicate significantly. Members of the Corvid family, however, are

especially susceptible to the virus; inside of these birds, the virus replicates rapidly and is

soon present in high concentrations in the blood. When other mosquitoes bite the

infected bird, they contract the virus and become infected themselves; approximately 9-

12 days later, the newly infected mosquitoes are able to transmit the virus when they next

bite.

In British Columbia, as in most of western Canada and the United States, the

species of mosquito known as Culex pipiens is responsible for “amplifying” the virus in

the bird population. This species of mosquito feeds almost exclusively on birds, and will

take numerous blood meals in a summer, so it has a number of opportunities and thus an

increased probability of biting an infected bird and subsequently transmitting the virus to

a new host. Each time a female feeds, she then develops a brood of eggs and lays them

on stagnant water. With each successive generation, the number of individual

mosquitoes grows exponentially, simultaneously increasing the chance of a Culex pipiens

feeding on an infected bird and communicating the virus. Populations of this insect peak

in mid- to late- August, as do the number of cases of WNv in both birds and humans.

Culex pipiens are common in urban settings and will readily breed in common water-

holding containers such as bird-baths, old tires, eaves troughs, wheelbarrows, etc. This

species can also breed in exceptionally large numbers in urban catch basins.

Once the virus has increased, or “amplified,” in the bird populations, the risk of

“spill-over” into other hosts increases. A second species of mosquito, Culex tarsalis, is



most often implicated in this “bridging” of the virus from bird populations to mammals.

This species of mosquito also has multiple generations each summer and takes numerous

blood meals. In the early summer, Culex tarsalis plays a significant role alongside Culex

pipiens in the amplification of the virus, and later in the summer becomes a significant

vector of WNv to humans. What is different about this species is its willingness to take

blood meals from bird hosts as well as mammal hosts, especially later in the summer.

Therefore, if an individual of this species takes a meal from an infected bird, it may –

during a subsequent feeding – transmit the virus to a human, horse, or other non-avian

host. In humans, the virus rarely causes serious illness; however, in approximately 20%

of infections, humans can experience flu-like symptoms. In less than 1% of human cases,

WNv can cause inflammation of the brain and/or spinal chord (meningioencephalitis),

which can occasionally result in death.

1.3. SURVEILLANCE IN BRITISH COLUMBIA

The British Columbia Centre for Disease Control (BCCDC) and health authorities

have been anticipating cases of WNv in British Columbia since the summer of 2003. In

the summer of 2003, the province started to collect and submit dead corvids (crows, jays,

ravens, and magpies) for WNv testing. It also started to use CDC light traps and gravid

traps to attract and collect mosquitoes which were ground up and tested for the presence

of the virus. In the last four years, 5285 corvids have been collected and tested, and

582,182 mosquitoes have been trapped, from which number the females have been

separated and tested (BCCDC, 2006). To date, there has not been a single corvid or

mosquito found to positively carry WNv. There were a small number of human WNv

cases found in BC in 2003; however, in each of the cases, the infected person acquired

the illness while traveling outside of the province.

1.4. OVERVIEW OF GRANT FUNDING AND COMPLETED ACTIVITIES

This spring the Ministry of Health Services offered grant funding to

Municipalities, First Nations bands, and Regional Districts for WNv education, mosquito

control, and mosquito surveillance. This funding was administered through the Union of

British Columbia Municipalities (UBCM). The Thompson-Nicola Regional District

(TNRD) applied for and received grant funding under this program for all Electoral

Areas, and the municipalities of Cache Creek, Clinton, Ashcroft, Logan Lake, Kamloops,



Lytton, and Chase. All First Nations bands within the Regional District were also

contacted and invited to participate, and funding was obtained on behalf of the following

bands: Adams Lake Indian Band, Ashcroft Indian Band, Bonaparte Indian Band,

Coldwater Indian Band, Cook’s Ferry Indian Band, High Bar Indian Band, Kamloops

First Nation, Kanaka Bar Indian Band, Lower Nicola Indian Band, Lytton First Nation,

Neskonlith Indian Band, Nicomen Indian Band, Nooaitch Indian Band, Oregon Jack

Creek Indian Band, Shackan Indian Band, Simpcw First Nation, Siska Indian Band,

Skeetchestn Indian Band, Skuppah Indian Band, Upper Nicola Indian Band, and

Whispering Pines/Clinton Indian Band. This funding was used to hire BWP Consulting

Inc. to conduct an extensive public education, mosquito habitat mapping, mosquito

control, and mosquito surveillance program in the TNRD. This is the Final Report of all

activities completed under this contract in 2006, including a list of recommendations for

future and further work at the conclusion of this report.

2.0 PUBLIC EDUCATION

There are numerous strategies that individuals can employ to protect themselves

from WNv. Grant funding was used to present an information booth at various events,

and to sponsor television and radio commercials to convey personal protective measures.

2.1. PERSONAL PROTECTION

An important part of WNv prevention includes educating the public on how to

avoid being bitten by mosquitoes. Culex mosquitoes usually bite at dawn and at dusk,

and so special precautions should be taken at these times to avoid being bitten.

Individuals should wear long-sleeved, tight-knitted shirts and long pants during these

prime biting times; also, active movement such as jogging or cycling rather than

standing, sitting, or walking will reduce one’s chance of being bitten. People should

ensure that the screens on their windows and doors are in good repair as Culex species

will find the tiniest holes through which they can enter dwellings. When people are

active outside during periods of high mosquito activity, repellents containing DEET or

lemon oil of eucalyptus should be applied to skin and clothing according to the label

(generally, lemon oil of eucalyptus requires more frequent re-application than does

DEET).



2.2. REDUCTION OF MOSQUITO LARVAL DEVELOPMENT SITES

Since Culex and Culiseta mosquitoes will both readily breed in containers,

homeowners are encouraged to reduce standing water around their homes. Water-

holding items such as plastic containers, wheelbarrows, and swimming pool covers

should be emptied or turned upside-down. Eaves troughs should be cleared of debris to

ensure that they are draining properly. Bird baths and children’s wading pools should be

dumped and filled with fresh water twice per week. Pumps should be used in ornamental

ponds to circulate water (thus drowning larvae), or ponds should be stocked with goldfish

(which consume larvae). Attempts should be made to educate the public and enable it to

identify mosquitoes in their larval stage so people will recognize larvae and subsequently

remove them from whatever container or pond in which they may occupy (many people

mistake mosquito larvae for worms, tadpoles, or minnows).

2.3. THE DISEASE AND ITS EFFECTS ON HUMANS

There are a number of misconceptions about WNv and its effects on humans.

Extensive media coverage has served to induce undue levels of fear in a significant

portion of the public. It is important for the public to be properly informed about the

actual risks associated with WNv. While many people think of the extreme cases of

human illness such as paralysis or death when they hear the words “West Nile Virus”, the

reality is that the majority of people who contract the disease – an estimated eighty

percent – do not develop any symptoms, and unless tested, would probably never know

that they had ever contracted the virus. Of the remaining twenty percent, most will

develop “West Nile Fever,” which is characterized by mild flu-like symptoms; only about

0.1% of people infected with WNv develop serious infections of the central nervous

system which could lead to long term health effects or even death.

2.4. WEST NILE VIRUS INFORMATION BOOTH

The TNRD West Nile virus information booth is comprised of 5 poster boards,

live larvae, toys for children, DEET samples and information brochures. The public is

invited to ask questions and take brochures.



2.5. RADIO AND TELEVISION ADVERTISING

As part of our education program, we developed various thirty second radio

advertisements to encourage homeowners to look for and eliminate standing water on

their properties. Other commercials encouraged personal protection and promoted the

use of insect repellent. Radio advertising was carried out on Radio NL, the River

97.5FM, CIFM, B-100, and Country 101. Advertising began in June and ran into

September.

Television advertisements were aired June through August on CFJC TV 7. The

advertisements contained a similar message to those aired on the radio, with an emphasis

on “backyard cleanup” and elimination of mosquito larval development sites.

2.6. PUBLIC EDUCATION EVENTS

Throughout the summer, our senior staff members set up and tended West Nile

Virus Education Booth, or delivered PowerPoint presentations at twenty-six events

within the TNRD this summer (Figure 1). Along with the poster boards, live larvae were

displayed, and insect repellent samples were distributed. Literature including the Interior

Health Authority WNv pamphlet “Put the Bite on West Nile Virus”, an information sheet

concerning DEET, and numerous handouts describing the illness in horses were made

available at each of these booths and presentations. To help attract the public, we offered

a “bug zapper” or “mosquito puzzle” as a prize for a free draw; we also had a bug stamp

or stickers for children at most events. Finally, the Interior Health Corvid Collection

Program was promoted, and the public was asked to report sightings of dead corvids to

help in the surveillance of WNv. The following sub-sections contain brief descriptions of

each of the events at which we provided public education throughout the summer. An

attempt was made to attend at least one event in each participating municipality and First

Nations band.



Figure 1. Photograph of the West Nile Virus information booth at the Kamloops

Children’s Festival, September 18th, 2005.

2.6.1. Ashcroft & District: Fall Fair, Sept 9th

The booth was displayed at the Ashcroft and District Fall fair which took place at

the Drylands Arena on September 9th, 2006. The event was busy and many individuals

stopped by to ask questions and to pick up brochures.

2.6.2. Cache Creek: Council Meeting, July 17th

Cheryl Phippen attended the Cache Creek Council Meeting and gave a 20 minute

PowerPoint presentation. The mayor and councilors seemed interested and asked many

questions.

2.6.3. Clinton Jamboree : August 19th

This was an outdoor event; the booth was set up in the park at this “fair-like”

event. This was an exceptionally busy event and many local residents stopped by to ask

questions and pick up brochures.



2.6.4. Logan Lake: Council Board Meeting, July 11th

Cheryl Phippen gave a 20 minute PowerPoint seminar, explaining the TNRD’s

nuisance and WNv mosquito control programs. Board members received accurate and

immediate answers and responses to all of their questions and concerns about mosquitoes

and mosquito control in the area. A new area of larval habitat was described and will be

looked at next spring. The District of Logan Lake has invited us to attend an event in

April of 2007 and we will be happy to attend with the booth.

2.6.5. Lytton: Farmer’s Market, September 1st

A number of local residents attended the Lytton Farmer’s Market. Insect

repellent samples and brochures were handed out to all in attendance.

2.6.6. Kamloops: Kamloops Spring Home and Garden Show, March 10th-

12th

The Kamloops Spring Home and Garden Show was busier this spring than it has

been for the past couple of years. During this three-day trade show, our staff continually

answered questions, offered literature, and discussed mosquitoes, WNv, and mosquito

control. It is estimated that over 8000 people attend the Home and Garden Show from all

areas of the TNRD and beyond. This was one of our busiest events of the year.

2.6.7. Kamloops: Farmer’s Market, July 20th

Our staff set up a fantastic booth with a basin full of larvae for children to dip

mosquito larvae. This was an incredibly busy event with many attendees from the

Kamloops and surrounding areas.

2.6.8. Kamloops: Merchant’s Market, July 21st

The Kamloops Merchant’s Market is an annual event occurring in downtown

Kamloops. Our staff produced an interactive booth with a basin of larvae for children

(and adults) to dip larvae. This event was well attended and enjoyed by both staff and

attendees.

2.6.9. Kamloops: River Family Fun Day at Riverside Park, July 23th

River Family Fun Day is hosted by Radio NL and The River annually at Riverside

Park. These radio stations launched an extensive radio advertising campaign leading up



to the event, and many residents of Kamloops and the neighbouring communities attend

this activity-filled event. The booth was set up in the center of the action and our staff

was kept busy with questions and concerns from the event participants.

2.6.10. Rural TNRD: 70 Mile House, May 20th

On May long weekend the 70 Mile House Access Center hosts a community

garage sale. This year a higher than usual number of locals attended the garage sale and

picked up brochures.

2.6.11. Rural TNRD: Blue River, September 25th

Our staff gave a 20 minute PowerPoint presentation for the Blue River

Community Association. This event was well attended and the participants seemed to

have many questions.

2.6.12. Rural TNRD: Barriere Post Office, September 12th

Staff set up our WNv booth outside the Barriere Post Office and handed out

brochures to many of the local residents. Many questions were asked about mosquito

control and West Nile virus.

2.6.13. Rural TNRD: Clearwater Post Office, September 13th

Staff set up our WNv booth outside the Clearwater Post Office and handed out

brochures to many of the local residents. Very few people stopped by to ask questions

since the weather was cold and rainy.

2.6.14. Rural TNRD: Merritt Home and Garden Show, April 21st – 23rd

Staff attended the Merritt Home and Garden Show over the weekend of April 21st

to 23rd. This was a busy event for the City of Merritt, and people also attended from the

surrounding Electoral Areas. Many questions were asked about mosquito control and

WNv.

2.6.15. Rural TNRD: Westwold General Store: Oct 3, 2006

Staff set up the information booth outside the Westwold General Store and a

small number of local residents stopped by to ask questions and pick up brochures.



2.6.16. Adams Lake Indian Band

Band members were contacted and offered the opportunity for an informational

booth or presentation. No venue was suggested.

2.6.17. Ashcroft First Nations: July 7th

A PowerPoint presentation was given to approximately 20 band members at the

community hall. Following the 25 minute presentation, many members asked questions

and provided feedback.

2.6.18. Bonaparte Indian Band:

Band members were contacted and offered the opportunity for an informational

booth or presentation. No venue was suggested.

2.6.19. Coldwater Indian Band:

This band requested a number of brochures to be distributed to band members.

Also, a letter explaining our mosquito program and West Nile virus was provided for

inclusion in their newsletter.

2.6.20. Cook’s Ferry Indian Band: August 12th

The Cook’s Ferry Indian Band Annual General Meeting covered a wide range of

topics and had displays and presenters from within and around the community. Our staff

set up a booth for attendees to browse throughout the day and provided a 30 minute

PowerPoint presentation and question-and-answer period that followed.

2.6.21. High Bar First Nations

Repeated attempts were made to contact the High Bar First Nations. No contact

was made and therefore no public education occurred for this band.

2.6.22. Kamloops First Nation: August 5th

Our staff set up the booth at the KIB 2006 Pow-wow. This event is extremely

busy and many attendees stopped by to collect information and ask questions.

2.6.23. Kanaka Bar Indian Band: July 19th & Oct 24th

The First Nations Healing Gathering is an event with numerous participants from

all First Nations groups. This event took place a Pisalko Lake and was attended by a

number of bands from the Lytton area, including the Kanaka Bar Band. In addition to the



healing gathering, members of the Kanaka band have been invited to attend a

presentation scheduled for Oct 24th at the Siska Indian Band.

2.6.24. Lower Nicola Indian Band

Instead of having our staff attend an event at the Lower Nicola Indian Band, a

request was made for our staff to prepare an article for the band newsletter. A letter and

article was sent in early September.

2.6.25. Lytton First Nation: September 1st and July 19th



number of bands from the Lytton area, including the Lytton First Nation. In addition, a

booth was set up at the Lytton Farmer’s Market and band members were welcome to

attend this event as well.

2.6.26. Neskonlith Indian Band: July 27th

A half hour PowerPoint presentation was given to the chief and council of the

Neskonlith Indian Band on July 27th. This was a general meeting and many band

members were in attendance. The presentation outlined mosquito control , WNv and

mosquito surveillance. Many members asked questions following the presentation.

2.6.27. Nicomen Indian Band: July 19th and October 18th



number of bands from the Lytton area, including the Nicomen Indian Band. On October

18th a presentation was planned for the chief and council of the Nicomen band. However,

when our staff arrived at the reservation, a protest was in progress and the Administration

of the band had been shut down.

2.6.28. Nooaitch Indian Band, July 18th

On July 18th, approximately 12 people from the Nooaitch band gathered for an

informal presentation on the WNv. The presentation lasted about 1.5 hours and mosquito

biology, WNv, and mosquito control was covered. Attendees seemed quite interested

and a number of questions were asked during the presentation and afterwards.



2.6.29. Oregon Jack Creek Band

Repeated attempts were made to contact the Oregon Jack Creek Band. We were

unable to make contact with any band members.

2.6.30. Shackan Indian Band: October 6th

Instead of having our staff attend an event at the Shackan Indian Band, the

suggestion was made that we attend the Annual Tribal Council Meeting in Merritt, BC.

This meeting is attended by bands from throughout the Nicola Valley. This event took

place on October 6th and a staff member attended and set up a booth. This event was

extremely well attended.

2.6.31. Simpcw First Nations: August 15th

Staff attended a meeting at the Simpcw First Nation on August 15th. A short

PowerPoint presentation was given outlining the TNRD mosquito control program, West

Nile virus program and mosquito surveillance in the area.

2.6.32. Siska Indian Band: July 19th and October 24th



number of bands from the Lytton area, including the Siska Indian Band. Also, a

presentation is planned for October 24th at the Siska Indian Band.

2.6.33. Skeetchestn Indian Band: August 24th

Our staff attended a meeting on August 24th at the Skeetchestn Indian Band.

Approximately 50 band members were in attendance and many stopped by to ask

questions and chat with staff during a lunch following our presentation. We presented

information on WNv, mosquito trapping, and larval development sites.

2.6.34. Skuppah Indian Band: July 19th



number of bands from the Lytton area, including the Skuppah First Nation.

2.6.35. Upper Nicola Indian Band

Numerous attempts were made to arrange a time for us to attend a meeting at the

Upper Nicola Indian Band. As of October 10th this band has not selected a date or venue.



2.6.36. Whispering Pines/Clinton Indian Band

This band was contacted in early June and they asked that we not provide public

education this year.

3.0 MOSQUITO SURVEILLANCE

Adult and larval mosquito surveillance was used to determine species presence,

distribution, and abundance in numerous areas of the TNRD and its municipalities. The

results of this surveillance will help to give an indication of the level of risk for WNv in a

given area.

3.1. METHOD OF ADULT SURVEILLANCE

Adult mosquitoes were captured with the use of 41 CDC black-light mosquito

traps (Figure 2). In addition, as part of the annual TNRD Mosquito Control Program,

seven New Jersey traps were placed in areas that are near extensive mosquito habitats.

The Mosquito Nuisance Control Program traps are usually operated for 8 weeks, but the

trapping period was extended this summer at each of these sites, using a portion of the

WNv grant funding.

The CDC traps were originally designed to be powered by 6V batteries which will

operate the traps for 12-14 hours. In a number of trapping locations, power outlets were

unavailable so the traps were operated by a timer that activated the battery power only

during the night, thus attracting and trapping mosquitoes during dusk and dawn – when

mosquitoes are most active. In other locations, the traps were adapted to use 110V power

sources by wiring them to 6V adaptors; they were plugged in to the available power

source, and samples were collected once per week.

The CDC traps were equipped with photocells to detect dawn and dusk (when

mosquitoes are most active). At dusk, a fluorescent black-light and a small fan were

switched on. Mosquitoes are attracted to the light and, when they come near the fan, they

are “sucked” into a collecting jar. In addition to the light, a chemical attractant called

octenol was used; octenol was attached to the trap and its slow release formulation

allowed it to last for weeks. Finally, when it was available, we used dry ice in all of the

traps except those located in Area A, and in Blue River. Once a week, the dry ice was

placed in beverage coolers that were lined with reflective insulation. There was a tube



extending from the cooler to the area of the sucking fan; as the dry ice sublimated into

carbon dioxide (CO2), it traveled down the tubing. CO2 is a powerful mosquito attractant

because it mimics animal and bird breath.

Figure 2. CDC mosquito black-light trap with octenol and dry ice canister.

Sampling sites were selected based on recommendations from municipal and band

councils and on staff knowledge of the surveilled areas. There was at least one trapping

site within each municipality and First Nations reservation except Oregon Jack Creek



reservation (as we were unable to contact anyone on this reserve after numerous

attempts).

Each trap was operated for 10 to 14 weeks. There were problems with some of

the traps at various times during the summer, but defective (or stolen) traps were replaced

with substitutes (whenever possible) and the non-operating traps were taken to an

electronics dealer to be repaired. Each trap was visited once a week and the contents

were collected and returned to Kamloops for identification of the adult mosquitoes.

The 48 trapping location have been grouped based on their geographic position;

the data will be discussed based on these groupings. The groupings are: North Thompson

Valley, Kamloops Area, South Thompson Valley, Thompson River Valley, Fraser River

Valley, Cariboo Area, and Other.

3.2. RESULTS OF MOSQUITO SURVEILLANCE IN THE NORTH THOMPSON VALLEY

Ten mosquito traps were placed in the North Thompson Valley from Blue River

to Noble Creek (Table 1, Figure 3). Six of the trapping sites (Clearwater, Blackpool, East

Blackpool, Darfield, McLure, and Noble Creek) are ongoing trapping sites that are set

annually to assess the TNRD nuisance control program. The other four sites (Blue River,

Simpcw, Barriere, and Whispering Pines) were set with WNv grant funding.



Table 1. Location of mosquito trapping sites in the North Thompson River Valley, 2006.

Trap Location GPS Description

Trap First Set Landowner

Battery or 110V operation*

Address/ Comments

TNRD: Blue River N52° 06.843 W119° 18.193 25-Jun David Hanna 110V Behind Esso Station

TNRD: Clearwater** N51° 39.633 W120° 2.933 7-Jun Chris Fleury 110V Archibald Street

TNRD: Blackpool** N51° 29.433 W120° 10.830 7-Jun Rosy Mark 110V Near Roundtop

Wildlife Sanctuary

TNRD: East Blackpool** N51° 31.624 W120° 9.057 7-Jun Mike Grenier 110V Auldgirth Road

TNRD: Darfield** N51° 16.974 W120° 10.317 7-Jun Colin

Wetterstrom 110V 180 Mac Coll Rd.

Simpcw First Nation N51° 15.81 W120° 9.5 12-Jun Battery

TNRD: Barriere N51° 11.057 W120° 7.955 12-Jun DJ's

Campground Battery Near Barrier River

TNRD: McLure** N51° 1.097 W120° 13.793 7-Jun Robert Hearn 110V Glenacres Rd

Whispering Pines/Clinton Indian Band

N50° 59.24 W120° 14.375 7-Jun Band Office 110V

TNRD: Noble Creek** N50° 51.467 W120° 17.577 7-Jun Edward

Babcock 110V 6675 Westsyde Rd

*Battery operated traps ran overnight, one night per week. 110V traps were plugged in and ran every night, all week **Trapping site is used annually to assess TNRD Nuisance Control Program



Figure 3. Map of North Thompson Valley Mosquito Sampling Sites, 2006.



3.2.1. Blue River @ David Hannah’s Residence Behind the Blue River Esso

At the Blue River site, the trap ran for 12 weeks at the residence of David

Hannah, capturing a total of only 15 mosquitoes and five species (Table 2). Last year, a

trap just down the road at Mike Wiegeles Helicopter Ski Resort captured 231 mosquitoes,

comprised of 11 species. Dry ice was not used as an attractant at this sampling site.

Neither of the primary WNv vectors, Culex tarsalis nor Culex pipiens, were present in

any of the collections. The most abundant species this year were the floodwater

mosquitoes, Ochlerotatus sticticus and Aedes vexans which are probably coming from a

larval development site along the North Thompson River. Although these species can be

ferocious nuisance mosquitoes, they are rarely implicated in WNv transmission.

Table 2. Numbers of adult mosquitoes captured each week in a CDC black-light trap at the residence of Mr Hannah in Blue River, BC.

Date (2006)

Species Jul 04

Jul 11

Jul 18

Jul 25

Aug 01

Aug 08

Aug 15

Aug 22

Aug 29

Sep 5

Sep 12

Sep 16 Total

Aedes vexans 2 1 3 Aedes cinereus 1 1 Culiseta inornata 1 1 Ochlerotatus intrudens 1 1 Ochlerotatus sticticus 6 3 9

Total Number Captured 7 4 3 0 0 0 0 1 0 0 0 0 15 Total Males Captured 1 0 0 0 0 0 0 0 0 0 0 0 1



3.2.2. Clearwater @ the Residence of Chris Fleury on Archibald Street

In Clearwater, the trap was set up at the residence of Chris Fleury on Archibald

Street. Trapping sites in Clearwater are used annually to assess the TNRD nuisance

control program. This year, the trap was operated for twelve weeks (Table 3). Dry ice

was not used as an attractant at this sampling site. Over the collecting period, 106

specimens were captured, representing 14 mosquito species, which is twice as many

species as were captured in Clearwater last summer. The WNv vector Culex pipiens was

the most abundant species at this site comprising 28% of the total catch. The second

most abundant species was Culiseta incidens, comprising 26% of the total catch. These

urban mosquitoes are probably developing in containers and tires in landowners’ and

business owners’ yards in the immediate area. Culiseta inornata, a mosquito rated as a

moderate WNv vector, was the next most abundant species, making up approximately

14% of the total catch. A small number of Culex tarsalis were also captured at this site.

Table 3. Numbers of adult mosquitoes captured each week in a New Jersey black-light trap at the residence of Chris Fleury on Archibald Rd in Clearwater, B.C.

Date (2006)

Species Jun 14

Jun 21

Jun 28

Jul 05

Jul 12

Jul 19

Jul 26

Aug 02

Aug 09

Aug 16

Aug 23

Aug 30 Total

Aedes vexans 2 2 1 1 1 1 1 9 Aedes cinereus 1 1 Anopheles earlei 1 1 Anopheles freeborni 1 1 Coquillettidia perturbans 2 2 Culex pipiens 1 4 4 8 5 4 1 2 1 30 Culex tarsalis 2 2 2 6 Culiseta incidens 3 2 1 1 4 2 4 6 3 2 28 Culiseta impatiens 3 3 6 Culiseta inornata 1 1 5 2 2 1 2 1 15 Ochlerotatus canadensis 1 3 4 Ochlerotatus fitchii 1 1 Ochlerotatus intrudens 1 1 Ochlerotatus punctor 1 1




3.2.3. Blackpool next the Roundtop Road Wildlife Sanctuary

The Blackpool trapping site is another of the annual trapping sites used in the

assessment of the TNRD Nuisance Mosquito Control Program. This year, the New

Jersey trap was located at the residence of Rosy Mark on a property that is adjacent to the

Roundtop Wildlife Sanctuary. There tends to be high numbers of mosquitoes in this area

since treatment of the Sanctuary has not been permitted under the TNRD Nuisance

Control Program in the past. As of July 2005, permission was granted for treatment in

this Wildlife Sanctuary due to concerns associated with WNv. Dry ice was not used as an

attractant at this sampling site.

This trap captured 737 mosquitoes during twelve weeks of sampling, which is

almost 10 times as many as were captured last summer and is to be expected given the

greater amount of flooding seen this summer as compared to 2005. As expected, the

majority of the mosquitoes captured were the floodwater species Aedes vexans (90% of

the total catch) (Table 4). In terms of WNv vectors, no Culex pipiens and only six Culex

tarsalis were captured. This could be due to intensive larviciding in the immediate area

and the landowner’s diligence at reducing larval habitat around the property.

Table 4. Numbers of adult mosquitoes captured each week in a New Jersey black light trap near the Roundtop Road Wildlife Sanctuary in Blackpool, BC.

Date (2006)

Species Jun 15

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 24

Aug 31 Total

Aedes vexans 31 10 81 92 64 26 295 55 7 2 1 664 Aedes cinereus 3 2 5 1 11 Anopheles earlei 1 1 3 1 4 10 2 22 Anopheles freeborni 3 3 Anopheles punctipennis 3 3 Culex tarsalis 1 3 1 1 6 Culiseta inornata 2 2 1 1 3 9 Ochlerotatus fitchii 1 1 2 Ochlerotatus intrudens 1 1 Ochlerotatus sticticus 2 1 4 5 4 16




3.2.4. East Blackpool, Auldgirth Road

The New Jersey light trap was located on the property of Mr. Grenier in East

Blackpool, and it acts as another of our Nuisance Control Program traps. There is an

extensive larval development habitat near this trap during the spring freshet. Dry ice was

not used as an attractant at this sampling site.

This summer, the trap was operated for 12 weeks. During the trapping period,

1979 mosquitoes from 13 species were captured. This is 25% less mosquitoes than was

captured last year, and although the flooding was greater, the effort put forth to control

these mosquitoes was increased and appears to have made a difference. As expected,

most of the mosquitoes captured were of the nuisance species, Aedes vexans (76% of the

total catch) (Table 5). There were no specimens of Culex pipiens (as compared to 14

specimens last year) and six specimens of Culex tarsalis captured. These are low

numbers of these vector species considering the extensive larval development habitat in

the area.

Table 5. Numbers of adult mosquitoes captured each week in a New Jersey black-light trap set on Auldgirth Road in East Blackpool, BC.

Date (2006)

Species Jun 14

Jun 21

Jun 28

Jul 05

Jul 12

Jul 19

Jul 26

Aug 02

Aug 09

Aug 16

Aug 23

Aug 30 Total

Aedes vexans 224 136 190 244 314 92 190 94 7 4 1 1 1497 Aedes cinereus 26 50 31 26 3 2 5 143 Anopheles earlei 3 1 1 5 Anopheles freeborni 1 1 Coquillettidia perturbans 4 4 Culex tarsalis 3 2 1 6 Culiseta alaskaensis 2 2 Culiseta inornata 2 2 13 4 1 5 2 29 Ochlerotatus fitchii 6 6 Ochlerotatus intrudens 9 4 13 Ochlerotatus provocans 3 3 Ochlerotatus pullatus 3 3 Ochlerotatus sticticus 30 72 64 43 33 12 8 4 1 267




3.2.5. MacColl Road, Darfield, BC

A New Jersey mosquito light-trap is set annually in Darfield as part of the TNRD

Nuisance Control Program. This summer, the trap was operated for fourteen weeks on

MacColl road at the residence of Mr. Wetterstrom, and staff used dry ice at this site to

augment their captures. This year 285 specimens were identified in 13 samples, which

time 100 more specimens than were captured last summer (Table 6). There were 11

different mosquito species represented in the samples. The most significant species was

Aedes vexans (48% of the catch), followed by Culex tarsalis (18% of the catch), and

Culiseta inornata (6.7% of the catch). Culiseta inornata is considered to have a

moderately high potential for transmitting WNv and Culex tarsalis has proven to be the

primary vector in Western North America. Numbers Culex tarsalis could be considered

moderately high during the month of July, but dropped off in August as the larval

development site in the area dried up.

Table 6. Numbers of adult mosquitoes captured each week in a CDC black-light trap at MacColl Road in Darfield, BC.

Date (2006)

Species Jun 14

Jun 26

Jul 04

Jul 12

Jul 16

Jul 18

Jul 28

Aug 03

Aug 04

Aug 15

Aug 21

Aug 22

Sep 13 Total

Aedes vexans 12 12 23 1 31 53 2 2 136 Aedes cinereus 1 2 3 Anopheles earlei 2 3 1 6 Coquillettidia perturbans 6 6 Culex tarsalis 2 1 5 17 16 4 5 1 51 Culiseta alaskaensis 1 1 Culiseta incidens 1 1 1 3 Culiseta inornata 2 3 3 3 7 1 19 Ochlerotatus intrudens 17 1 18 Ochlerotatus mercurator 1 1 Ochlerotatus sticticus 4 5 5 26 40 Ochlerotatus Male* 1 1

Total Number Captured 20 39 39 1 85 0 79 2 10 0 0 8 2 285 Total Males Captured 8 3 5 0 9 0 15 0 2 0 0 1 1 44

*Male Ochlerotatus can be difficult to identify



3.2.6. Simpcw First Nation

A CDC light trap with dry ice was operated for 12 weeks (one night per week) on

the Simpcw First Nation reservation, north of Barriere. During this time, 919 specimens

were captured which is three times more than were captured at this site last summer. The

most abundant species was the flood-water, nuisance mosquito Ochlerotatus sticticus

(67% of the total catch) follow by Aedes vexans with 28% of the total catch (Table 7).

These two species share the same larval development habitats and were seen in increased

numbers this summer due to higher than normal flooding of the North Thompson River.

Neither of these species are of great concern in terms of WNv.

Last summer, moderately high numbers of the WNv vector species, Culex

tarsalis, appeared in the trap in mid-July. This did not happen this summer and only

eight specimens were captured all summer. Last summer it was theorized that the

increase in Culex tarsalis numbers was due to over-irrigation in a neighbouring field, it is

expected that the irrigation practices were improved this summer.

Table 7. Numbers of adult mosquitoes captured each week in a CDC black-light trap set once per week on the Simpcw First Nation reservation, BC.

Date (2006)

Species Jun 13

Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29 Total

Aedes vexans 79 2 150 2 12 5 9 259 Coquillettidia perturbans 2 6 8 16 Culex tarsalis 5 3 8 Ochlerotatus campestris 1 1 Ochlerotatus dorsalis 5 5 Ochlerotatus fitchii 5 5 Ochlerotatus increpitus 1 1 Ochlerotatus sticticus 122 98 373 17 7 1 618 Mosquito unidentifiable* 4 2 6

Total Number Captured 201 106 544 3 32 23 1 0 0 0 9 0 919 Total Males Captured 2 0 0 1 0 0 0 0 0 0 0 0 3 *Mosquito specimen was too damaged for a positive identification



3.2.7. Barriere @ DJ’s Campground

During a 12 week sampling period (one night per week), a CDC black-light trap

baited with dry ice was set at DJ’s Campground in Barriere. During this sampling period,

only 151 mosquitoes were captured, as compared to 483 in 2005. This year, thirteen

mosquito species were captured with the most abundant being the floodwater, nuisance

species, Aedes vexans (comprising 33% of the catch) followed by Culex tarsalis (18.5%

of the catch). Only a single Culex pipiens was captured in the Barriere trap this summer.

It is expected that well-timed helicopter applications of larvicide followed by weekly

monitoring and larval control helped to reduce the mosquito population in this area.

Table 8. Numbers of adult mosquitoes captured each week in a CDC black-light trap, at DJ’s Campground in Barriere, BC.

Date (2006)

Species Jun 13

Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29 Total

Aedes vexans 15 14 9 6 1 2 3 50 Anopheles earlei 1 1 Anopheles punctipennis 1 1 2 4 Coquillettidia perturbans 7 3 10 Culex pipiens 1 1 Culex tarsalis 5 1 1 2 5 2 8 1 3 28 Culiseta incidens 1 1 Culiseta inornata 1 1 Ochlerotatus canadensis 7 1 2 10 Ochlerotatus excrucians 15 4 19 Ochlerotatus fitchii 1 5 6 Ochlerotatus increpitus 6 2 2 1 11 Ochlerotatus sticticus 1 2 3 6 Mosquito unidentifiable* 1 1 1 3


*Mosquito specimen was too damaged for a positive identification



3.2.8. McLure @ Bob Hearn’s residence on Glenacres Road

The trapping site at Bob Hearn’s residence in McLure is another site utilized

annually by the TNRD Nuisance Mosquito Control Program. This year, the trap operated

for 14 weeks and captured 122 mosquito specimens representing 10 species (Table 9).

This summer, there were some problems with the light and timer at this location so no

samples were obtained in June and early-July when one would expect high numbers of

the floodwater species. When the trap was operating properly in late-July through

August, the most abundant species was Culex tarsalis (39% of the total catch), the

primary WNv vector in western North America.

Table 9. Numbers of adult mosquitoes captured each week in a New Jersey light trap at McLure, BC.

Date (2006)

Species Jul 16

Jul 28

Aug 03

Aug 15

Aug 21

Aug 22

Aug 30

Sep 13 Total

Aedes vexans 29 2 5 36 Aedes cinereus 1 1 Anopheles earlei 2 1 1 1 1 1 7 Anopheles freeborni 3 3 Culex pipiens 1 1 Culex tarsalis 15 2 4 7 5 14 1 48 Culiseta inornata 1 1 Ochlerotatus intrudens 12 12 Ochlerotatus pullatus 1 1 Ochlerotatus sticticus 12 12

Total Number Captured 70 5 5 10 6 23 1 2 122 Total Males Captured 0 3 3 7 4 13 0 1 31

3.2.9. Whispering Pines@ Indian Band Office

A trap was set at the Whispering Pines band office and operated throughout July

and August. During this time, not one mosquito specimens was captured at this site.

Last year, there were 215 mosquito specimens captured at this site, 80% of which were

Culex tarsalis. It is unknown as to why there were no mosquitoes captured at this site

this summer. It is recommended that a new sampling location be selected next summer.



3.2.10. Noble Creek @ Edward Babcock’s Residence

The Noble Creek sampling site is located on the property of Edward Babcock and

Linda Wrightson. It is another of the annual trapping locations for the TNRD Nuisance

Mosquito Control Program. A New Jersey light trap operated at this site for 14 weeks

captured 522 mosquitoes representing 14 species (Table 10). Last year only 136

mosquitoes were captured at this site. This summer the most abundant species was Culex

tarsalis comprising 38% of the total catch with 200 specimens. Just south of Mr

Babcock’s residence, a large field flooded and remained wet throughout most of the

summer. This field hosted multiple generations of Culex tarsalis larvae despite intense

efforts to maintain control of the larvae. In this past, this trap captured a higher

percentage of floodwater mosquitoes; however, intensive larviciding on this property has

resulted in significant decreases in nuisance species.

Table 10. Numbers of adult mosquitoes captured each week in a New Jersey light trap at the residence of Edward Babcock in Noble Creek, BC.

Date (2006)

Species Jun 13

Jun 26

Jul 05

Jul 10

Jul 18

Jul 25

Jul 27

Aug 04

Aug 08

Aug 21

Aug 29

Sep 12 Total

Aedes vexans 19 13 42 34 5 1 7 6 5 1 1 134 Anopheles earlei 2 5 1 1 9 Anopheles freeborni 1 1 2 4 4 14 27 53 Anopheles punctipennis 2 2 Culex pipiens 3 1 2 6 Culex tarsalis 2 4 18 86 52 11 4 9 4 1 9 200 Culiseta incidens 5 1 1 2 9 Culiseta impatiens 1 1 Culiseta inornata 2 6 11 23 20 9 2 13 4 3 2 95 Culiseta morsitans 1 1 Ochlerotatus canadensis 1 1 Ochlerotatus fitchii 1 1 Ochlerotatus increpitus 1 1 1 3 Ochlerotatus mercurator 1 1 Ochlerotatus Male* 2 3 1 6

Total Number Captured 31 28 74 145 80 1 30 17 36 14 23 43 522 Total Males Captured 9 11 45 34 9 0 5 6 11 6 7 25 168 *Male Ochlerotatus can be difficult to identify



3.3. SUMMARY OF WNV VECTORS IN THE NORTH THOMPSON VALLEY

Ten mosquito traps were placed in the North Thompson Valley from Blue River

to Noble Creek (Table 1, Figure 3). In the most of the northernmost locations, floodwater

species such as Aedes vexans and Ochlerotatus sticticus predominated in the mosquito

catches (Blue River, Blackpool, East Blackpool, Darfield, Simpcw, and Barriere). These

mosquitoes can be a significant nuisance, but are unlikely to be of concern in terms of

WNv transmission.

Culex tarsalis was present in all trapping location except Blue River and

Whispering Pine. In the two southernmost sites, McLure and Noble Creek, Culex tarsalis

was the most abundant species. This species is the most competent WNv vector species

in Western Canada. Culex pipiens was quite common in the Clearwater location, and was

present in low numbers in the Barriere, McLure and Noble Creek sites. Other mosquito

species that offer a moderate potential for transmitting WNv, such as Coquillettidia

perturbans and Culiseta inornata were found sporadically throughout the North

Thompson Valley in low to moderate numbers.



3.4. RESULTS OF MOSQUITO SURVEILLANCE IN THE CITY OF KAMLOOPS

Nine mosquito traps were placed in the City of Kamloops (Table 11, Figure 4)

One of the trapping sites (Mission Flats) is an ongoing trapping site that is set annually to

assess the TNRD nuisance control program. The other eight sites were set with WNv

grant funding to determine the mosquito species composition and distribution in various

areas of the City.

Table 11. Location of Trapping Sites within the City of Kamloops, 2006.




Address/ Comments

Kamloops: Rayleigh N50° 48.187 W120° 19.105 12-Jun George Boulter Battery 129 Beachview

Kamloops: Westsyde N50° 47.017 W120° 19.495 19-Jun Dunes Golf

Course Battery 652 Dunes Drive

Kamloops: Cinnamon Ridge N50° 42.597 W120° 28.225 12-Jun 3765 Tranquille

Road Battery Next to Tranquille Wildlife Sanctuary

Kamloops: Mission Flats** N50° 41.407 W120° 27.908 7-Jun 110V Waste Water

Treatment Plant

Kamloops: Brocklehurst N50° 41.76 W120° 22.817 19-Jun Battery McArthur Park Golf

Course

Kamloops First Nation N50° 40.734 W120° 18.245 20-Jun Silver Sage

Trailer Park 110V Near confluence of N & S Thompson

Kamloops: Valleyview N50° 40.675 W120° 14.59 20-Jun Battery End of Peter Rd @

Paddlewheeler dock

Kamloops: Barnhartvale N50° 39.004 W120° 10.418 21-May D & M Horvath

1399 Lamar Dr. Battery In a semi-rural area

Kamloops: Dufferin N50° 39.804 W120° 24.055 14-Jun C & B Phippen Battery #23-1940 Hillside Dr.

*Battery operated traps ran overnight, one night per week. 110V traps were plugged in and ran every night, all week **Trapping site is used annually to assess TNRD Nuisance Control Program



Figure 4. Locations of Mosquito Trapping Sites within the City of Kamloops, 2006.



3.4.1. Kamloops: 129 Beachview Drive, Rayleigh

A dry ice baited CDC light trap was operated once per week in Rayleigh on

Beachview Drive. This sampling site is within a few meters of the North Thompson

River in Rayleigh. There are substantial flood-water mosquito larval development sites

just upstream of Rayleigh on both the east and west sides of the river. This trapping site

has been utilized since 2004 under the WNv grant funding opportunities.

This year, during 12 weeks of sampling (one night per week), 91 mosquitoes

representing nine species were captured (Table 12). This trap count is three times less last

year’s count and is a reflection of a reduction in floodwater mosquitoes (Aedes vexans).

The most abundant species captured at this site this summer were Culex tarsalis and

Ochlerotatus increpitus which each made up 32% of the total catch. Culex tarsalis is the

primary vector of WNv in western North America and Ochlerotatus increpitus is a early-

season snowmelt species on little importance in terms of WNv.

Table 12. Numbers of adult mosquitoes captured each week in a CDC black-light trap at 129 Beachview Drive, Rayleigh in Kamloops, BC.

Date (2006)

Species Jun 13

Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29 Total

Aedes vexans 10 3 6 1 2 22 Culex tarsalis 3 1 1 6 14 1 3 29 Culiseta incidens 3 1 4 Culiseta inornata 1 1 2 Ochlerotatus communis 1 1 Ochlerotatus dorsalis 1 1 Ochlerotatus implicatus 1 1 Ochlerotatus increpitus 26 3 29 Ochlerotatus sticticus 1 1 Mosquito unidentifiable* 1 1





3.4.2. Kamloops: Dunes Golf Course, Westsyde

A dry ice baited light trap was located at the Dunes Golf Course in Westsyde for

12 weeks (one night per week). This trapping location was selected last summer after a

number of complaints were received in the area. The trap was hung in a tree near the 18th

green, next to a substantial larval development site beside the North Thompson River.

Last summer, this trap captured 1050 mosquitoes, primarily floodwater nuisance species.

This summer, special attention was paid to this area early in the season and trap counts

were reduced by almost 3.5 times to only 313 specimens.

This year, the species of primary concern was the WNv vector, Culex tarsalis. In

one sampling night in early August, 110 specimens of Culex tarsalis were collected. This

was immediately reported to our field staff that visited the area and found an area of

standing water with Culex tarsalis larvae present. Following an application of larvicide

in this area, the numbers of Culex tarsalis dropped rapidly (Table 13).

Table 13. Numbers of adult mosquitoes captured each week in a CDC black-light trap at the Dunes Golf Course, Kamloops, BC.

Date (2006)

Species Jun 20

Jun 22

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29

Sep 05 Total

Aedes vexans 5 2 3 2 1 2 2 2 19 Aedes cinereus 4 4 Anopheles earlei 1 1 Coquillettidia perturbans 1 2 3 2 8 Culex pipiens 3 7 1 1 12 Culex tarsalis 1 5 3 32 10 110 24 9 8 1 203 Culiseta inornata 4 12 19 35 Ochlerotatus campestris 3 1 4 Ochlerotatus dorsalis 1 1 2 Ochlerotatus melanimon 1 1 Ochlerotatus sticticus 8 4 2 1 5 20 Mosquito unidentifiable* 1 1 1 3 Ochlerotatus Male** 1 1


*Mosquito specimen was too damaged for a positive identification **Ochlerotatus males can be difficult to identify



3.4.3. Kamloops: Cinnamon Ridge near Tranquille Wildlife Sanctuary

This is the third year that a dry ice baited trap has been located in Cinnamon

Ridge area next to an extensive Wildlife Sanctuary that floods each year and is known to

be an important larval development site for both nuisance mosquitoes and WNv vector

species. In addition, there are hectares of hay fields that are consistently over-irrigated

with outflow water from the Kamloops Waste Water Treatment Plant which is situated

directly across the Thompson River from this site. In the past, this area has been one of

our greatest challenges and the mosquito population can reach incredible levels in this

area.

In the past, requests to enter the Wildlife Sanctuary for the purpose of mosquito

control have been denied. However, last summer, due to concerns regarding WNv,

permission was granted in early-June our staff to larvicide in the Wildlife Sanctuary.

This was quite late in the season, and therefore a great number of mosquitoes had already

emerged. This year, we were able to launch an excellent larviciding campaign in this

area, at the appropriate time. In addition, staff was able to attempt to control larval

development in the over-irrigated fields. It was felt that the long-acting product, Altosid

was the best choice for these fields that produce multiple larval generations throughout

the summer. WNv funding was used to purchase Altosid and apply it throughout all low-

lying areas in the fields.

The results were fantastic. This year was an exceptionally high water year, and

yet, mosquito trap numbers were the lowest they have been since trapping started (only

1960 adults were trapped in 12 weeks as compared to 5470 mosquitoes in 2005 and 2518

mosquitoes in 2004). The floodwater mosquitoes were most significantly reduced from

previous years; however the counts of Culex tarsalis and Culex pipiens were also

reduced. (Table 14).



Table 14. Numbers of adult mosquitoes captured each week in a CDC black-light trap at Cinnamon Ridge, Kamloops, BC.

Date (2006)

Species Jun 13

Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29 Total

Aedes vexans 261 231 60 23 52 76 5 261 108 56 85 1218 Aedes cinereus 7 2 9 Anopheles punctipennis 1 1 Culex pipiens 1 1 11 2 12 24 51 Culex tarsalis 28 25 3 1 13 7 2 77 27 32 4 219 Culiseta inornata 4 4 4 11 2 2 4 31 Ochlerotatus campestris 7 1 3 7 1 5 24 Ochlerotatus communis 4 4 Ochlerotatus dorsalis 7 1 7 6 9 4 34 Ochlerotatus increpitus 3 1 4 Ochlerotatus melanimon 1 1 2 Ochlerotatus sticticus 41 98 12 2 104 51 18 3 329 Mosquito unidentifiable* 5 6 7 1 10 5 34





3.4.4. Kamloops: Mission Flats, Waste Water Treatment Plant

The Kamloops Waste Water Treatment Plant is situated in Mission Flats near the

head of Kamloops Lake. There is a large area of flood-water habitat next to the plant and

much of the flood water remains trapped and stagnant throughout the summer. In

addition, there are many waste water settling ponds that have the potential to produce a

few mosquitoes, although historically we have not found larvae in these ponds. A New

Jersey light trap is set up at the Waste Water Treatment Plant every year as part of a

monitoring program for the TNRD Nuisance Mosquito Control Program. When

available, dry ice is used at this location to augment the light trap action.

During a 14 week sampling period, 382 mosquitoes from seven species were

captured (Table 15). This is twice as many as were captured at this site last year. Of

greatest concern is that the majority of the specimens captured were Culex pipiens (274

specimens). Last year, this site yielded only 17 specimens of Culex pipiens. In addition,

Culex tarsalis numbers were also increased this year from 67 specimens in 2005 to 88

specimens in 2006. Currently, it is unknown where the larval development site is located

that produced these high numbers of vector species, however special attention will be

paid in this area next summer to try and solve this problem.

Table 15. Numbers of adult mosquitoes captured each week in a New Jersey black-light trap at the Waste Water Treatment Plant in Kamloops, BC.

Date (2006)

Species Jun 12

Jun 19

Jun 26

Jul 05

Jul 10

Jul 18

Jul 27

Aug 08

Aug 14

Aug 21

Aug 29

Sep 12 Total

Anopheles freeborni 1 1 Culex pipiens 1 2 7 3 5 13 39 10 12 69 113 274 Culex tarsalis 3 5 11 13 10 28 5 1 1 11 88 Culiseta inornata 1 2 3 3 3 12 Ochlerotatus communis 2 2 Ochlerotatus dorsalis 1 1 Ochlerotatus implicatus 1 1 Ochlerotatus Male* 2 1 3

Total Number Captured 0 4 8 25 16 20 42 47 10 13 73 124 382 Total Males Captured 0 2 2 12 6 7 13 35 7 8 50 82 224 *Ochlerotatus males can be difficult to identify



3.4.5. Kamloops: Brocklehurst, McArthur Island Park

A CDC trap was set on McArthur Island at the McArthur Island Golf Course.

The trap was operated once per week for 12 weeks and captured 88 mosquitoes which is

twice as many as were captured at this location last summer (Table 16). Last summer the

majority of mosquitoes captured were floodwater species, however this year, the

predominant species were the WNv vectors Culex tarsalis (15% of the total catch) and

Culex pipiens (43% of the total catch). It is expected that the Culex pipiens larvae are

developing somewhere on the golf course, and an effort will be made next summer to

locate this habitat.

Table 16. Numbers of adult mosquitoes captured each week in a CDC black-light trap at the McArthur Park Golf Course in Kamloops, BC.

Date (2006)

Species Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29

Sep 05 Total

Aedes vexans 2 4 2 5 1 14 Anopheles earlei 1 1 Coquillettidia perturbans 1 1 Culex pipiens 3 15 1 17 2 38 Culex tarsalis 1 2 1 7 2 13 Culiseta inornata 2 1 3 Ochlerotatus campestris 1 1 Ochlerotatus fitchii 1 1 Ochlerotatus flavescens 1 1 Ochlerotatus increpitus 3 3 Ochlerotatus sticticus 4 3 1 8 Mosquito unidentifiable* 1 2 1 4





3.4.6. Kamloops: Kamloops First Nation Reservation

A dry ice baited, CDC black-light trap was set at a residence in the Silver Sage

trailer park on the Kamloops First Nation Reservation in Kamloops. This summer this

trap captured 75 mosquitoes representing seven species during a 10 week sampling

period (Table 17). This is three times less mosquitoes than were captured last summer.

The most abundant species was the potential WNv vector Culiseta inornata (37% of the

total catch) followed by the primary WNv vectors Culex tarsalis (33% of the total catch)

and Culex pipiens (21% of the total catch). Each of these species will breed easily in

urban habitats such as small containers, bird baths, plastic containers, ditches and rain

barrels.

Table 17. Numbers of adult mosquitoes captured each week in a CDC black-light trap at the Kamloops First Nation reservation in Kamloops, BC.

Date (2006)

Species Jul 05

Jul 10

Jul 18

Jul 27

Aug 08

Aug 14

Aug 21

Aug 29

Sep 06

Sep 12 Total

Aedes vexans 1 1 2 Culex pipiens 3 6 2 2 2 1 16 Culex tarsalis 1 6 12 2 1 1 1 1 25 Culiseta incidens 2 2 4 Culiseta inornata 5 14 9 28 Ochlerotatus sticticus 1 1

Total Number Captured 6 4 25 27 4 2 4 1 1 2 76 Total Males Captured 0 3 6 7 0 0 0 0 0 2 18



3.4.7. Kamloops: Peter Rd, Valleyview

A dry ice baited CDC black light trap was set next to the South Thompson River

at the end of Peter Road in Valleyview. The trap was operated one night per week for 12

weeks and 113 mosquitoes from six species were captured (Table 18). This is twice as

many mosquitoes as were captured in 2005. This year, the majority of the specimens

were the floodwater nuisance mosquitoes Aedes vexans and Ochlerotatus sticticus (75%

of the total catch). The WNv vectors Culex tarsalis and Culex pipiens were both trapped

in low numbers. The peak of the nuisance mosquito population appeared to occur in late

June and no nuisance mosquitoes were captured in July or August.

Table 18. Numbers of adult mosquitoes captured each week in a CDC black-light trap at Peter Road in Valleyview, Kamloops, BC.

Date (2006)

Species Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 21

Aug 31

Sep 07 Total

Aedes vexans 28 15 1 44 Culex pipiens 1 9 1 11 Culex tarsalis 1 1 1 2 2 7 Culiseta incidens 1 1 1 3 Ochlerotatus increpitus 1 2 2 5 Ochlerotatus sticticus 32 9 41 Mosquito unidentifiable* 1 1 2





3.4.8. Kamloops: Lamar Drive, Barnhartvale

Lamar Drive is located in Barnhartvale, a semi-rural area of Kamloops. A dry ice

baited CDC black-light trap was set up once per week for 12 weeks and it captured 53

mosquitoes from nine species (Table 19). This is half as many mosquitoes as were

captured at this location in 2005. The most abundant species was Culiseta incidens,

which is probably developing in the many water-holding containers scattered around the

property. Last summer there were 41 specimens of this species captured and in 2006 this

number dropped to 18. The second most common species was the WNv vector Culex

tarsalis, comprising 21% of the total catch. Culex pipiens was also present at this location

in low numbers. It is expected that the decrease in the numbers of mosquitoes trapped at

this location is related to the effort made by the landowners to reduce larval habitats on

their property.

Table 19. Numbers of adult mosquitoes captured each week in a CDC black-light trap at 1399 Lamar Drive, Kamloops, BC.

Date (2006)

Species Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 24

Aug 31

Sep 07 Total

Aedes vexans 2 1 1 1 5 Anopheles earlei 1 1 Culex pipiens 1 1 3 5 Culex tarsalis 1 1 2 3 4 11 Culiseta incidens 3 2 9 4 18 Culiseta inornata 1 1 3 5 Ochlerotatus campestris 2 2 Ochlerotatus dorsalis 2 2 Ochlerotatus excrucians 1 1 2 Mosquito unidentifiable* 1 1 2





3.4.9. Kamloops: Hillside Drive, Dufferin

A dry ice baited CDC trap was set in a new duplex complex at 1940 Hillside

Drive. The trap was set one night per week for 12 weeks and captured only 11

mosquitoes (Table 20). Last year, 227 mosquitoes were captured at this location, and

57% of them were Culex tarsalis. Given the presence of such high numbers of this

important WNv vector species, an effort was made to determine the larval development

site producing these mosquitoes. A ditch was found at the entrance to the complex and it

was found to contain stagnant standing water with upwards of 50 Culex tarsalis larvae

per 300ml dip. This year, the ditch was treated with a long-acting larvicide, Altosid,

early in the season and it appears that adult mosquito populations have been greatly

reduced as a result of this application.

Table 20. Numbers of adult mosquitoes captured each week in a CDC black-light trap set at #23-1940 Hillside Drive, Dufferin, Kamloops, BC.

Date (2006)

Species Jun 15

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 19

Aug 21

Aug 31 Total

Aedes vexans 3 3 Coquillettidia perturbans 1 1 Culex pipiens 1 1 Culex tarsalis 2 1 1 4 Culiseta inornata 1 1 Ochlerotatus campestris 1 1


3.5. SUMMARY OF WNV VECTORS IN THE CITY OF KAMLOOPS

Nine mosquito traps were placed in the City of Kamloops (Table 11, Figure 4).

The WNv vector species Culex tarsalis was present at all locations and Culex pipiens was

present at all locations except Rayleigh. Last summer, Culex tarsalis were found in

exceptionally high numbers (over 100 specimens) in four locations: Rayleigh, Cinnamon

Ridge, Westsyde, and Dufferin. They were found in moderately high numbers (between

50 and 100 specimens) at the Kamloops First Nations Reservation and Mission Flats.

Culex pipiens were prevalent (over 15 specimens) in Cinnamon Ridge, Mission Flats,

Westsyde, Kamloops First Nation reservation, Valleyview, and Barnhartvale. This

summer, numbers of these species appears to be decreased throughout the City. This



summer Culex tarsalis was found in high numbers (over 100 specimens) in only two

locations (Cinnamon Ridge and Westsyde) and in moderate numbers (between 50 and

100 specimens) in only one location (Mission Flats). Culex pipiens numbers also appear

to be reduced in most areas with only the Kamloops Indian Band, Cinnamon Ridge,

Mission Flat (274 specimens) and McArthur Island Park having more than 15 specimens.

This overall decrease in adults of these vector species is most likely due to intensive

larviciding in standing water and catch basins throughout the City.

Overall, based on the trapping carried out this summer Kamloops can be

considered at reasonably high risk for cases of WNv when the virus makes its way to this

portion of the province.

3.6. RESULTS OF MOSQUITO SURVEILLANCE IN THE SOUTH THOMPSON RIVER

VALLEY

Four mosquito trapping sites were selected along the South Thompson River

Valley between the Little Shuswap Lake and the City of Kamloops (Table 21, Figure 5).

Table 21. Locations of trapping sites along the South Thompson River Valley, 2006.




Address/ Comments

Adams Lake Indian Band N50° 49.737 W119° 42.021 21-Jun Battery Band Office

Village of Chase

N50° 48.307 W119° 42.666 12-June Peter Dunn Battery 5973 Veteran Road

Neskonlith Indian Band N50° 46.257 W119° 42.976 14-Jul Battery near Band Office

TNRD: Pritchard Community N50° 41.237 W119° 50.109 12-Jun 110V 1249 DeCamillis Rd

*Battery operated traps ran overnight, one night per week. 110V traps were plugged in and ran every night, all week



Figure 5. Locations of Mosquito Trapping Sites along the South Thompson River

Valley, 2006.



3.6.1. Adams Lake Indian Band

A dry ice baited CDC black-light mosquito trap was operated for 12 weeks at the

Adams Lake Indian Band office. During this sampling period, 102 mosquitoes were

captured, representing five mosquito species (Table 22). The flood-water mosquito,

Aedes vexans, and the cattail mosquito, Coquillettidia perturbans, made up the majority

of the catch. Aedes vexans can be a serious pest when found in high numbers, but is

unlikely to be implicated in WNv transmissions. Coquillettidia perturbans are rated as

having a moderate potential as WNv vectors. The two most serious WNv vector species

in the province, Culex tarsalis and Culex pipiens were both present in the catch, however

both were in extremely low numbers.

Table 22. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at the Adams Lake Indian Band office, near Chase, BC.

Date (2006)

Species Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 24

Sep 05 Total

Aedes vexans 6 12 2 1 21 Coquillettidia perturbans 15 17 3 25 15 75 Culex pipiens 1 1 Culex tarsalis 2 1 3 Ochlerotatus sticticus 1 1 Mosquito unidentifiable* 1 1





3.6.2. Veterans Road, Chase, BC

This is the third year that a dry ice baited CDC light trap has been used in Chase

under the WNv funding. The trapping site is at the residence of Peter Dunn on VLA Road

in Chase. During a 12 week sampling period, the Chase trap captured 222 specimens

from nine species (Table 23) which is similar to last year’s catch of 229 specimens and

12 species. In 2004, 2372 specimens and 17 species were captured at this location, but

the discovery and larval treatment of two new larval development sites on small islands

nearby in the South Thompson River seems to have made a significant impact on the

mosquito population in the area. This is likely due to the discovery and larval treatment

of two new larval development sites on small islands in the South Thompson River. The

majority of the specimens were Aedes vexans (64% of the total catch).

Both WNv vector species, Culex tarsalis and Culex pipiens, were present with 77

and 6 specimens respectively.

Table 23. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Veteran’s Road, in Chase, BC.

Date (2006)

Species Jun 13

Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29 Total

Aedes vexans 33 5 1 2 17 8 16 3 85 Anopheles punctipennis 1 1 2 Coquillettidia perturbans 6 3 9 Culex pipiens 1 1 4 6 Culex tarsalis 11 2 1 13 14 14 14 6 2 77 Culiseta inornata 5 1 2 1 2 11 Culiseta morsitans 1 1 Ochlerotatus dorsalis 1 1 Ochlerotatus sticticus 4 3 5 8 20 Mosquito unidentifiable* 1 1 6 8 Ochlerotatus Male** 1 1 2





3.6.3. Neskonlith Indian Band

A dry ice baited CDC black-light mosquito trap was operated at the power

building beside the Neskonlith Indian band office for eight weeks. On a number of

occasions, staff visited the trap and found it unplugged; however, they were unable to

gain access to the building to plug the trap back in. This year, only five specimens were

collected all summer as compared to 102 mosquitoes in 2005 (Table 24). Neither of the

primary WNv vectors, Culex tarsalis or Culex pipiens, were captured this year, although

a small number of Culex tarsalis were captured last summer at this site.

It is recommended that a new sampling location be selected next summer.

Table 24. Numbers of adult mosquitoes captured each week in a CDC black-light trap on the Neskonlith Indian Band reservation, BC.

Date (2006)

Species Jul 24

Aug 02

Aug 09

Aug 14

Aug 25

Aug 30

Sep 06

Sep 12 Total

Aedes vexans 1 1 Anopheles earlei 1 1 Coquillettidia perturbans 1 1 Ochlerotatus dorsalis 2 2

Total Number Captured 0 0 1 0 0 0 0 4 5 Total Males Captured 0 0 0 0 0 0 0 0 0



3.6.4. Community of Pritchard

A dry ice baited CDC black-light mosquito trap was operated for 12 weeks in the

Community of Pritchard. During the sampling period, 243 mosquitoes were captured,

representing 12 mosquito species (Table 25). This is similar to last year’s total catch of

273 adults. The flood-water mosquito, Aedes vexans made up 39% of the catch this

summer, while last summer it comprised 49% of the total catch. Aedes vexans can be a

serious pest when found in high numbers, but is unlikely to be implicated in WNv

transmissions. The two most serious WNv vector species in the province, Culex tarsalis

and Culex pipiens, were both present. Culex tarsalis was present in moderate numbers

and Culex pipiens was present in lower numbers.

In 2004, there was much concern about the mosquito population in this

community. Last year, a new larval development site was discovered and treated near

Hoffman’s Bluff; a flood-irrigated field next to the community was treated with a long-

acting larvicide; and the ditches running through the community were also treated with a

long-acting larvicide. These actions were repeated this summer and they appear to have

significantly decreased the mosquito populations in this area.

Table 25. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at 1249 DeCamillis Road, in Pritchard, BC.

Date (2006)

Species Jun 13

Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29 Total

Aedes vexans 2 10 10 4 2 10 18 2 18 12 3 4 95 Aedes cinereus 3 3 Anopheles earlei 1 1 Anopheles freeborni 1 1 Coquillettidia perturbans 1 1 Culex pipiens 2 2 Culex tarsalis 2 1 1 1 19 5 2 10 1 2 1 45 Culiseta inornata 2 2 3 2 9 Ochlerotatus dorsalis 2 1 9 2 1 64 Ochlerotatus increpitus 1 1 2 4 Ochlerotatus sticticus 6 2 8 Mosquito unidentifiable* 2 1 7 10





3.7. SUMMARY OF WNV VECTORS IN THE SOUTH THOMPSON RIVER VALLEY

Four mosquito traps were placed in the South Thompson River Valley (Table 21,

Figure 5). The WNv vector species Culex tarsalis and Culex pipiens were present in all

trapping locations except at the Neskonlith Indian Band reserve. Numbers of these

species varied according to location and proximity to larval development sites. Chase

and Pritchard had the highest numbers of vector species, as well as highest overall

numbers. The traps in both locations were positioned close to known larval development

sites along the South Thompson River. The Adams Lake Indian Band and Neskonlith

Indian Band traps had lower overall trap counts and were positioned further away from

the river, in drier locations.

3.8. RESULTS OF MOSQUITO SURVEILLANCE IN THE THOMPSON VALLEY

Seven mosquito trapping sites were selected along the Thompson River Valley

between the community of Savona and the Fraser River (Table 26, Figure 6).

Table 26. Locations of trapping sites along the Thompson River Valley, 2006.




Address/ Comments

Skeetchestn Indian Band N50° 47.808 W120° 55.725 22-Jun Joy Persson 110V #55-909 Deadman-

Vidette Rd

Bonaparte Indian Band N50° 50.275 W121° 22.555 22-Jun 110V At band office

Village of Cache Creek N50° 48.1 W121° 19.21 4-Jun Battery Sage and Sands

Trailer park

Village of Ashcroft N50° 43.859 W121° 16.438 4-Jun Battery

Old Cariboo Road (West side of the Thompson River)

Ashcroft First Nation N50° 43.167 W121° 19.283 22-Jun Christina

Wilson 110V 705 Dick Street

TNRD: Spences Bridge N50° 25.478 W121° 20.003 4-Jun Battery

At Acacia Grove Campground 3814 Riverview Ave

Cook’s Ferry Indian Band N50° 25.388 W121° 20.616 22-Jun 110V At Band Office

Nicomen Indian Band N50° 15.695 W121° 24.11 22-Jun Ray Drynock 110V 2946 Nicomen Place




Figure 6. Locations of Mosquito Trapping Sites along the Thompson River Valley,

2006.



3.8.1. Skeetchestn Indian Band

A dry ice baited CDC black-light mosquito trap was plugged at the residence of

Christina Wilson (#55-909 Deadman-Vidette Road). The trap was operated for 12 weeks

and captured 151 mosquitoes representing 15 species (Table 27).

The most abundant species captured at this location was Culiseta inornata which

comprised 50% of the total catch. Culiseta inornata has been predicted to have a

moderate potential for transmitting the virus. The next most abundant species was the

primary WNv vector, Culex tarsalis which comprised 12.6% of the total catch. There

was a single specimen of Culex pipiens captured at this location as well. The rest of the

catch was made up of a number of flood-water nuisance species that, although they can

be significant pests, are rarely implicated in WNv transmission.

Table 27. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at #55- 909 Deadman-Vidette Road on the Skeetchestn Indian Band Reserve, BC.

Date (2006)

Species Jul 04

Jul 11

Jul 19

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 23 Total

Aedes vexans 1 1 1 1 4 Aedes cinereus 1 1 Anopheles earlei 1 1 2 Culex pipiens 1 1 Culex tarsalis 1 2 2 1 1 2 2 1 2 5 19 Culiseta alaskaensis 1 1 2 Culiseta incidens 1 1 3 2 6 1 3 1 18 Culiseta inornata 17 20 7 10 8 1 3 2 3 4 75 Ochlerotatus canadensis 1 1 Ochlerotatus dorsalis 1 1 2 Ochlerotatus excrucians 1 1 Ochlerotatus fitchii 1 1 2 Ochlerotatus increpitus 6 7 2 1 16 Ochlerotatus mercurator 1 1 2 4 Ochlerotatus sticticus 2 2 Ochlerotatus Male* 1 1


*Ochlerotatus males can be difficult to identify



3.8.2. Bonaparte Indian Band

A dry ice baited CDC black-light mosquito trap was plugged in at the Bonaparte

Indian Band office north of Cache Creek along the Bonaparte River. The trap was

operated for 12 weeks and captured 54 specimens from nine species (Table 28). The

peak of the mosquito population occurred in July and the primary species captured at this

site were Culiseta inornata (41% of the total catch), Culex tarsalis (22% of the total

catch), and Ochlerotatus dorsalis (18.5% of the total catch).

Culex tarsalis is the most important WNv vector species in western Canada and

both Culiseta inornata and Ochlerotatus dorsalis have been predicted to have a moderate

potential for transmitting the virus. Larvae of these three species can often be found

together in the same larval development site.

Table 28. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Bonaparte Indian Band office, BC.

Date (2006)

Species Jul 04

Jul 11

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 23 Total

Aedes vexans 1 1 Anopheles earlei 1 1 Culex tarsalis 1 5 1 1 1 1 1 1 12 Culiseta alaskaensis 1 1 2 Culiseta incidens 1 1 2 Culiseta inornata 1 2 6 6 7 22 Ochlerotatus campestris 1 1 Ochlerotatus dorsalis 4 5 1 10 Ochlerotatus implicatus 1 1 Mosquito unidentifiable* 2 2





3.8.3. Village of Cache Creek

A dry ice baited CDC black-light mosquito trap was operated once a week at the

Sage and Sands Trailer Park in Cache Creek along the Bonaparte River. The trap was

operated for 12 weeks and captured 239 specimens which is 5.5 times fewer than the

2005 trap count of 1335 specimens (Table 29). The most prevalent species trapped at this

site were Ochlerotatus increpitus (52% of the total catch), and Aedes vexans (19% of the

total catch). Both of these are significant nuisance species associated with flood-water

and snowmelt pools, however each of them is considered to have low potential to

transmit WNv.

Both of the most important WNv vector species in western Canada were present

in moderate numbers. There were 23 specimens of Culex tarsalis and 11 specimens of

Culex pipiens captured.

Last July, a large mosquito development site was found after many of the larvae

had emerged. This year the site was visited at the appropriate time in late-May and the

site was treated with larvicide. This treatment appears to have made a significant impact

on the mosquito population and, provided that funding continues, we will continue to

monitor and larvicide in this important area.

Table 29. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Sage and Sands Trailer Park in the Village of Cache Creek, BC.

Date (2006)

Species Jun 05

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 21

Aug 31 Total

Aedes vexans 8 5 6 24 2 1 46Anopheles earlei 2 1 3Anopheles freeborni 1 1Coquillettidia perturbans 1 1Culex pipiens 3 4 1 1 2 11Culex tarsalis 2 3 2 3 5 1 6 1 23Culiseta alaskaensis 1 1Culiseta inornata 2 2 3 3 10Ochlerotatus campestris 2 2Ochlerotatus dorsalis 1 1Ochlerotatus increpitus 2 24 46 34 1 10 2 1 3 1 124Ochlerotatus provocans 1 1Ochlerotatus sticticus 1 1Mosquito unidentifiable* 3 3 1 1 4 12Ochlerotatus Male** 1 1 2

Total Number Captured 13 29 55 64 3 21 7 16 10 9 9 3 239Total Males Captured 0 0 1 0 0 0 3 0 0 1 0 0 5




3.8.4. Village of Ashcroft

A dry ice baited CDC black-light mosquito trap was operated once per week at a

residence on Old Cariboo Road in Ashcroft. This is the third year that trapping has taken

place at this location; however this year ownership of the property changed and the new

owners made some positive changes to reduce larval development habitat on their

property. The trap was operated one night per week for 12 weeks and captured only 21

mosquitoes (Table 32) compared to last summer’s catch of 154 specimens and a catch of

331 mosquitoes in 2004. Seven different species were captured at this site.

Last summer, the most prevalent species trapped at this site was the WNv vector

Culex tarsalis. This species made up 27% of the total trap count in 2005. This summer,

Culex tarsalis numbers dropped considerably and only two specimens were captured

during the summer. Similarly, in 2005, Culex pipiens, another important WNv vector,

was present in moderate numbers, making up 11% of the 2005 catch. This year only a

single specimen of Culex pipiens was captured. The final species of significance in 2005

was Ochlerotatus dorsalis, a species with a moderate potential as a WNv vector. This

summer there was only one specimen of Ochlerotatus dorsalis. Larvae of all three of

these species will readily develop in water that settles in irrigated pastures. Culex tarsalis

and Culex pipiens will also develop in water standing in ditches and pools around the

yard. This summer, two ponds were filled in on the property, and irrigation practices

were improved in the surrounding fields. These actions appear to have greatly reduced

the mosquito population in the area.

Table 30. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on Old Cariboo Road in the Village of Ashcroft, BC.

Date (2006)

Species Jun 05

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 21

Aug 31 Total

Aedes vexans 2 1 1 4 Culex pipiens 1 1 Culex tarsalis 1 1 2 Ochlerotatus campestris 1 2 2 5 Ochlerotatus dorsalis 1 1 Ochlerotatus increpitus 3 3 6 Ochlerotatus provocans 1 1 Mosquito unidentifiable* 1 1





3.8.5. Ashcroft First Nations

A dry ice baited CDC black-light mosquito trap was plugged in at the residence of

Christina Wilson (705 Dick Street) and operated for 12 weeks. Last year, the trap was

located at the Ashcroft First Nation race track and it was repeatedly unplugged and

therefore only a single mosquito was captured all summer. This summer, the trap was

relocated at a private residence and a band meeting was held to describe the purpose of

the trap. This year the trap was operated for 12 weeks, and 43 specimens representing

seven species were captured (Table 31).

The most common species captured at this location was Culiseta inornata which

made up 32% of the total catch. This species is described as having a moderate ability to

transmit WNv, especially to horses. Both of the primary WNv vectors in western

Canada, Culex tarsalis and Culex pipiens, were present with five and two specimens

respectively. Overall, the numbers of all species captured can be considered quite low

compared to other areas of the TNRD.

Table 31. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at 705 Dick Street on the Ashcroft First Nations Reservation, BC.

Date (2006)

Species Jul 04

Jul 11

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 23 Total

Culex pipiens 1 1 2 Culex tarsalis 1 2 1 1 5 Culiseta incidens 4 1 5 Culiseta impatiens 1 1 Culiseta inornata 1 2 1 2 1 1 2 2 2 14 Ochlerotatus campestris 2 2 Ochlerotatus increpitus 6 6 12 Ochlerotatus Male* 2 2





3.8.6. Spences Bridge

A dry ice baited CDC black-light mosquito trap was operated once per week at

the Acacia Grove RV Park in Spences Bridge, at the confluence of the Thompson and

Nicola Rivers. The trap was operated for 12 weeks and captured 88 specimens (Table

32) which is considerably less than last year’s catch of 276 specimens. This spring, the

area was investigated to try to determine where the larval development sites were in the

area. With the assistance of the Acacia Grove owner, two development sites were located

along the railway tracks and the Thompson River. These were treated with larvicide and

this appears to have made a difference to the adult mosquito population.

The most prevalent species trapped at this site was Aedes vexans, which made up

72% of the total catch. This is the most common nuisance species in the province and is

associated with floodwater from rivers and creeks. This mosquito is of low concern as a

WNv vector.

Ochlerotatus dorsalis and Ochlerotatus melanimon were two species that were

captured in low numbers in the Spences Bridge trap. These species will often share the

same habitat in standing water produced by over-irrigation of fields and ditches. Both

have a tolerance for somewhat saline water. Both of these species have been described as

having a moderate potential for transmitting WNv.

The most important WNv vectors in western Canada, Culex pipiens and Culex

tarsalis, were both present in the catch, but only a single specimen of each of these

species was captured this summer.



Table 32. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at Acacia Grove RV Park in Spences Bridge, BC.

Date (2006)

Species Jun 05

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 21

Aug 31 Total

Aedes vexans 9 2 12 3 21 15 1 63 Anopheles earlei 1 1 Culex pipiens 1 1 Culex tarsalis 1 1 Ochlerotatus dorsalis 1 1 1 3 Ochlerotatus fitchii 1 1 Ochlerotatus melanimon 2 2 4 1 9 Ochlerotatus sticticus 1 1 2 Mosquito unidentifiable* 1 4 5 Ochlerotatus Male** 1 1 2





3.8.7. Cook’s Ferry Indian Band

A dry ice baited CDC black-light mosquito trap was located at the Cook’s Ferry

Indian Band office. The trap was operated for 11 weeks and captured 85 specimens from

10 species (Table 33). The most prevalent species trapped at this site was Culiseta

inornata, which made up 36% of the total catch. This species is considered to have a

moderate ability to transmit WNv, especially to horses. The next most common species

was Aedes vexans which made up 26% of the total catch; however, although this species

is considered the worst pest species in BC, it is rarely implicated in WNv transmission.

There were only two specimens of Culex tarsalis, which is the most important WNv

vector species in western Canada, and only four Culex pipiens, the most important WNv

vector to bird populations.

Table 33. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at the Cook’s Ferry Indian Band office, BC.

Date (2006)

Species Jul 04

Jul 11

Jul 18

Jul 26

Aug 09

Aug 16

Aug 21

Aug 31

Aug 28

Sep 05

Sep 12

Sep 19 Total

Aedes vexans 6 14 2 22 Culex pipiens 1 1 1 1 4 Culex tarsalis 1 1 2 Culiseta incidens 1 1 Culiseta impatiens 1 1 Culiseta inornata 7 6 3 2 2 11 31 Ochlerotatus dorsalis 1 1 Ochlerotatus increpitus 1 1 Ochlerotatus melanimon 3 2 9 14 Mosquito unidentifiable* 3 2 2 1 8





3.8.8. Nicomen Indian Band

A dry ice baited CDC black-light mosquito trap was located on the Nicomen

Indian Band reservation at 2946 Nicomen Place at the residence of Ray Drynock. The

trap was operated for 12 weeks and captured 64 specimens, which is considerably less

than last year’s catch of 491 specimens (Table 34). The most prevalent species trapped at

this site was Culiseta inornata, which made up 53% of the total catch. This species is

considered to have a moderate ability to transmit WNv, especially to horses. Culex

tarsalis and Culex pipiens, the most important WNv vector species in western Canada,

were present, but both were in low numbers (eight and one specimens respectively.

Table 34. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at 2946 Nicomen Place on the Nicomen Indian Band reservation near Spence Bridge, BC.

Date (2006)

Species Jul 04

Jul 10

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Culex pipiens 1 1 Culex tarsalis 2 2 1 2 1 8 Culiseta alaskaensis 3 3 Culiseta incidens 9 1 2 3 1 16 Culiseta inornata 3 1 22 1 2 1 1 3 34 Ochlerotatus hexodontus 1 1 Ochlerotatus increpitus 1 1


3.9. SUMMARY OF WNV VECTORS IN THE THOMPSON RIVER VALLEY

Eight mosquito traps were placed in the Thompson River Valley between the

community of Savona and the Fraser River (Table 26, Figure 6). The important WNv

vector species, Culex tarsalis, was present in all trapping locations except at the Ashcroft

First Nations trapping locations. Culex pipiens was captured in all locations except at the

Bonaparte Indian Band office. Numbers of these species varied according to location and

proximity to larval development sites. Neither of these species was seen in high numbers

(i.e. over 25) at any of the trapping sites.

Three species of mosquito that are predicted to have a moderate ability to transmit

WNv were seen in various numbers throughout the Valley. Culiseta inornata was seen in

moderate numbers in the Nicomen, Cook’s Ferry, and Skeetchestn traps.



The Cache Creek site had the highest overall trap counts. The majority of

the mosquitoes collected at this site were, however, Ochlerotatus increpitus, which has

not been implicated in WNv transmission.

Overall, the occurrence of WNv vectors in the Thompson Valley this year

appeared to be sporadic, and vector species were rarely found in high numbers. Also,

trap counts in all locations were lower than last year (except at the Ashcroft Indian Band)

and this could be due to an increase in larviciding activities in all areas of the Thompson

Valley.

3.10. RESULTS OF MOSQUITO SURVEILLANCE IN THE NICOLA VALLEY

Five mosquito trapping sites were selected along the Nicola Valley between

Guichon Ranch (north of Nicola Lake) and Spences Bridge (Table 35, Figure 7).

Table 35. Locations of trapping sites along the Nicola Valley, 2006.




Address/ Comments

TNRD: Nicola Valley N50° 15.427 W120° 26.825 14-Jun Battery Guichon Ranch at N.

end of Nicola Lake

Upper Nicola Indian Band N50° 11.988 W120° 28.656 29-Jun Nicola Gas

Station 110V Hwy 5A

Lower Nicola Indian Band N50° 8.268 W120° 51.538 29-Jun Barry

Coodlican 110V 188 Eagle Road.

Nooaitch Indian Band N50° 9.22 W121° 2.187 22-Jun 110V Show home across

from Band Office

Shackan Indian Band N50° 17.59 W121° 10.39 22-Jun Jim Bergh 110V Near Lower Nicola

River *Battery operated traps ran overnight, one night per week. 110V traps were plugged in and ran every night, all week



Figure 7. Locations of Mosquito Trapping Sites along the Nicola Valley, 2006.

3.10.1. TNRD: Nicola Valley

A dry ice baited CDC black-light mosquito trap was set at the north end of Nicola

Lake near a Ducks Unlimited marshland on Guichon Ranch. The trap site was next to an

extensive larval development habitat that we are unable to larvicide as the landowner has

not given us permission. A dry ice baited CDC black-light trap was operated once per

week for 12 weeks, capturing 1026 specimens (Table 36) which is over twice as many as

last year’s catch of 437 specimens.

The primary species captured at this site were Ochlerotatus campestris (335

specimens), Ochlerotatus dorsalis (262 specimens). Ochlerotatus dorsalis is described

as having a moderate probability for transmitting WNv, while Ochlerotatus campestris is

not considered a concern in terms of WNv transmissions. Both of these species are



aggressive biters and both can tolerate reasonably saline conditions. They will breed

readily in ditches, marshes, and irrigated pastures.

Other species of interest captured at this site include Culex tarsalis and Culiseta

inornata. There were 224 specimens of Culex tarsalis captured. This species is the most

important WNv vector in western Canada. The trap captured 34 specimens of Culiseta

inornata, a species that is considered to have a moderate ability to transmit WNv,

especially to horses.

The other species captured at the site may be important from a nuisance

standpoint, but have a low likelihood of transmitting WNv.

Table 36. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on Guichon Ranch in the Nicola Valley, BC.

Date (2006)

Species Jun 15

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 22

Aug 03

Aug 10

Aug 17

Aug 21

Aug 31 Total

Aedes vexans 1 16 13 5 5 16 6 12 5 79 Aedes cinereus 1 1 2 Anopheles earlei 1 2 3 Anopheles freeborni 1 1 1 1 4 Coquillettidia perturbans 1 1 Culex pipiens 1 1 2 Culex tarsalis 3 45 2 13 50 5 31 9 61 5 224 Culiseta inornata 1 3 2 1 9 13 3 2 34 Ochlerotatus campestris 1 237 2 36 2 15 4 4 16 3 12 3 335 Ochlerotatus dorsalis 1 70 9 2 4 4 135 12 18 7 262 Ochlerotatus flavescens 2 2 Ochlerotatus increpitus 17 9 8 1 35 Ochlerotatus melanimon 1 1 1 3 6 Ochlerotatus provocans 2 2 Ochlerotatus sticticus 6 3 1 3 1 14 Mosquito unidentifiable* 7 3 4 3 4 21





3.10.2. Upper Nicola Indian Band

A dry ice baited CDC black-light mosquito trap was set at the service station

located on the Upper Nicola Indian reservation on Hwy 5A. The trap was operated for 12

weeks and 125 specimens were captured (Table 37). This is substantially less than last

summer’s collection of 1603 specimens from a trap located at Dean Tom’s residence.

The new location was selected as we were unable to contact Dean until late in August.

The primary species captured at this site was Culiseta inornata (36 specimens).

This species has a moderate likelihood of transmitting the virus, especially to horses. The

next most abundant species was Aedes vexans (29 specimens). This species is considered

to be the worst nuisance species in BC; however it is rarely implicated in West Nile virus

transmissions. The final species of interest was Culex tarsalis. This insect is considered

the most import WNv vector in western Canada. There were 21 specimens of this

mosquito captured, which is a relatively low level of incidence.

Most of the other species captured at the site may be important from a nuisance

standpoint, but have a low likelihood of transmitting WNv.

Table 37. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Upper Nicola Indian Band reservation, BC.

Date (2006)

Species Jul 07

Jul 12

Jul 19

Jul 27

Aug 01

Aug 08

Aug 17

Aug 01

Aug 30

Sep 06

Sep 13

Sep 18 Total

Aedes vexans 18 9 1 1 29 Aedes cinereus 2 2 Anopheles earlei 1 1 Anopheles freeborni 1 2 1 4 Culex tarsalis 5 8 5 2 1 21 Culiseta inornata 9 17 7 3 36 Ochlerotatus fitchii 1 1 2 Ochlerotatus increpitus 2 1 6 2 1 12 Ochlerotatus melanimon 2 4 1 1 8 Ochlerotatus Male* 7 2 1 10 Total Number Captured 47 39 25 10 1 1 1 0 1 0 0 0 125 Total Males Captured 19 11 4 1 0 0 0 0 0 0 0 0 35




3.10.3. Lower Nicola Indian Band

A dry ice baited CDC black-light mosquito trap was set at 188 Eagle Road on the

Lower Nicola Indian Band reservation, at the residence of Barry Coodlican. The trap was

operated for 12 weeks and 279 specimens were collected which is far fewer than last

year’s collection of 746 specimens. There were representatives from a staggering 14

mosquito species (Table 38). The primary species captured at this site were Culex

tarsalis (41% of the total catch), and Culiseta inornata (26% of the total catch). Culex

tarsalis is considered the most important WNv vector in Canada, and Culiseta inornata is

expected to be implicated in WNv transmissions to horses. The remaining species

occurred in low numbers and, although they may together produce quite a nuisance, none

of them are significant in regards to WNv transmission.

Table 38. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Lower Nicola Indian Band reservation, BC.

Date (2006)

Species Jul 05

Jul 13

Jul 20

Jul 27

Aug 01

Aug 10

Aug 16

Aug 22

Aug 30

Sep 06

Sep 13

Sep 18 Total

Aedes vexans 1 2 1 4 1 3 1 13 Anopheles earlei 1 1 Anopheles freeborni 1 3 1 3 8 Coquillettidia perturbans 3 1 1 5 Culex pipiens 1 1 Culex tarsalis 2 17 8 27 15 14 21 3 8 115 Culiseta inornata 4 5 7 7 3 22 10 4 8 2 72 Ochlerotatus communis 1 1 2 Ochlerotatus dorsalis 1 7 8 Ochlerotatus increpitus 1 2 6 1 10 Ochlerotatus intrudens 2 2 Ochlerotatus melanimon 1 2 3 Oc. spencerii var idahoensis 1 1 Ochlerotatus sticticus 2 2 Mosquito unidentifiable* 33 1 1 35 Ochlerotatus Male** 1 1





3.10.4. Nooaitch Indian Band

A dry ice baited CDC black-light trap was set up on the Nooaitch Indian Band

reservation at the Log Show Home across from the Nooaitch Indian Band office. The

trap was operated for 13 weeks and 278 specimens from 11 species were collected (Table

39). This is nearly twice as many as were captured on the Nooaitch reservation in 2005.

The primary species captured at this site was Culiseta inornata (71% of the total catch).

This species is rated as having a moderate competency for transmitting WNv, especially

to horses. The two most important WNv vectors in western Canada, Culex tarsalis and

Culex pipiens, were also present at this location with 48 and seven specimens

respectively.

Table 39. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Nooaitch Indian Band reservation, BC.

Date (2006)

Species Jun 29

Jul 05

Jul 13

Jul 20

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Aedes vexans 1 1 2 Culex pipiens 2 2 3 7 Culex tarsalis 5 7 3 3 17 9 4 48 Culiseta alaskaensis 1 1 Culiseta incidens 1 2 3 6 Culiseta impatiens 1 1 2 Culiseta inornata 2 13 14 1 11 7 43 15 60 9 22 197 Culiseta morsitans 1 1 Ochlerotatus communis 3 1 4 Ochlerotatus euedes 1 1 Ochlerotatus increpitus 1 2 1 1 5 Mosquito unidentifiable* 1 1 Ochlerotatus Male** 3 3





3.10.5. Shackan Indian Band

A dry ice baited CDC black-light trap was set up on the Shackan Indian Band

reservation at the residence of Jim Bergh. The trap was operated for 12 weeks and 49

specimens from seven species were collected (Table 40). This is close to last year’s total

trap count of 50 specimens. The primary species captured at this site was Culiseta

inornata (57% of the total catch). This species is rated as having a moderate competency

for transmitting WNv, especially to horses. One of the most important WNv vectors in

western Canada, Culex pipiens, was also present in this trap, however only two

specimens were captured all summer. All other species captured in this site occurred in

low numbers and are unlikely to be causing a nuisance nor will they be significant

vectors should WNv make its way to this area of the province.

Table 40. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Shackan Indian Band reservation, BC.

Date (2006)

Species Jun 29

Jul 5

Jul 13

Jul 20

Jul 26

Jul 31

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Aedes vexans 1 1 Anopheles earlei 1 1 2 Coquillettidia perturbans 1 1 Culex pipiens 2 2 Culiseta incidens 8 2 10 Culiseta inornata 2 24 2 28 Ochlerotatus increpitus 4 4 Mosquito unidentifiable* 1 1





3.11. SUMMARY OF WNV VECTORS IN THE NICOLA VALLEY

Five mosquito traps were placed in the Nicola Valley (Table 35, Figure 7). The

important WNv vector species, Culex tarsalis, was present in all trapping locations,

except at the Shackan location. There were high numbers of this species at the Guichon

Ranch location (224 specimens), and Lower Nicola Indian Band reservation (115

specimens) and moderate numbers at the Nooaitch reservation (48 specimens). Culex

pipiens were found in low numbers in all locations except the Upper Nicola Indian Band

location. Culiseta inornata was the most common mosquito species in the Upper Nicola,

Lower Nicola, Nooaitch and Shackan traps. This species is considered to have a

moderate ability to transmit WNv, especially to horses. The relatively high numbers of

Culiseta inornata and Culex tarsalis makes this valley a reasonably high risk for seeing

cases of WNv when the virus reaches this region of the province.

3.12. RESULTS OF MOSQUITO SURVEILLANCE IN THE FRASER RIVER VALLEY

Six mosquito trapping sites were selected along the Fraser River Valley between

the Big Bar Ferry and Kanaka Bar (Table 41, Figure 8).

Table 41. Locations of trapping sites along the Fraser River Valley, 2006.




Address/ Comments

High Bar First Nation N51° 11.023 W122° 7.917 07-Jul 110V Big Bar Ferry

Lytton First Nation Numerous sites-see discussion 28-Jun 110V Numerous sites-see

discussion

Village of Lytton N50° 13.88 W121° 34.876 28-Jun 110V At community aquatic

center

Skuppah Indian Band N50° 11.442 W121° 34.392 28-Jun Cassandra

McIntyre 110V 995 McIntyre Road

Siska Indian Band N50° 8.185 W121° 34.231 28-Jun 110V Community Hall

Kanaka Bar Indian Band N50° 6.238 W121° 33.429 28-Jun 110V Kanaka Bar Café




Figure 8. Map of mosquito trapping locations along the Fraser River Valley

(excluding High Bar to the north).



3.12.1. High Bar First Nation

After repeated attempts, we have been unable to contact anyone at the High Bar

First Nation for the last two years. A staff member traveled to the area of the reservation

and hired the Big Bar Ferry operators to maintain a CDC black-light trap for 12 weeks.

During the trapping period, 229 specimens from 11 species were collected (Table

42). The primary species captured at this site was Culiseta inornata (53% of the total

catch). This species is rated as having a moderate competency for transmitting WNv,

especially to horses. The two most important WNv vectors in western Canada, Culex

tarsalis and Culex pipiens, were also present in this trap; however both occurred in low

numbers (24 and one specimens, respectively). Another relatively common species at

this location was Ochlerotatus dorsalis which is a species that is rated as having a

moderate competency to vector WNv.

The overall number of mosquitoes trapped in this area was surprising given the

hot, dry characteristics of the area. The species composition suggests that there is

stagnant water nearby, most likely an irrigation ditch or standing water in an over-

irrigated pasture.

Table 42. Numbers of adult mosquitoes captured each week in a CDC black-light trap located at the Big Bar Ferry, just north of the High Bar First Nation.

Date (2006)

Species Jul 14

Jul 21

Jul 28

Aug 04

Aug 11

Aug 18

Aug 25

Sep 01

Sep 08

Sep 15

Sep 22

Sep 29 Total

Aedes vexans 1 1 1 3 Coquillettidia perturbans 1 1 Culex pipiens 1 1 Culex tarsalis 1 5 1 9 2 2 2 2 24 Culiseta alaskaensis 1 1 1 1 14 2 4 8 32 Culiseta incidens 2 5 1 5 1 14 Culiseta inornata 1 3 6 70 12 7 6 7 2 6 1 121 Ochlerotatus communis 2 1 3 Ochlerotatus dorsalis 2 1 15 4 5 27 Ochlerotatus fitchii 1 1 Ochlerotatus mercurator 1 1 2




3.12.2. Lytton First Nation

Multiply attempts were made to find a suitable location for a dry ice baited CDC

trap on the Lytton First Nation reservation. The trap was first set on June 28th at the

residence of Dennis Murphy on 3 Mile Road (N50°15’58.2” W121°35’46.5”). No

mosquitoes were captured at this location and on one occasion, the collecting cup had

been torn from the trap by the owner’s dog. The trap was moved on July 26th to the

residence of Gladis Grenier on Rex Road (N50°15’57.1” W121°35’46.8”). Again, no

mosquitoes were captured and then on Aug 21st the trap was found in pieces on the

ground and our staff was asked to remove the trap as the landowner felt that it was

attracting wasps. On Aug 21st the trap was again moved to the residence of Verna Isaac

at 1455 Old Wagon Road (N50°15’36.8” W121°35’31.9”).

At this final location, four good light trap samples were obtained and in those

samples two mosquito specimens were identified (Table 43). The first species captured

at this site was Culiseta inornata. This species is rated as having a moderate competency

for transmitting WNv, especially to horses. The other specimen was Culex tarsalis, which

is the most important WNv vector in Canada.

Table 43. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Lytton First Nation reservation, BC.

Date (2006)

Species Aug 28

Sep 05

Sep 12

Sep 19 Total

Culex tarsalis 1 1 Culiseta inornata 1 1 Total Number Captured 1 0 0 1 2 Total Males Captured 0 0 0 0 0



3.12.3. Village of Lytton

A dry ice baited CDC black-light trap was set up at the Aquatic Center in the

Village of Lytton. The trap was operated for 12 weeks and captured only 13 mosquitoes

from three species (Table 44). This is approximately half of last year’s catch of 28

specimens. The primary species captured at this site was Culex pipiens (54% of the total

catch). This species is considered to be an important “amplifying vector,” as it is often

responsible for passing the virus between birds and thereby increasing the virus presence

in an area. Culex tarsalis was also present in Lytton. This species is the most important

WNv vector in western Canada, and it is usually responsible for “bridging” the virus

from bird populations to mammal populations. The final species present was Culiseta

inornata, which is considered to have a moderate ability to transmit WNv, especially to

horses. Each of these important species was present in very low numbers when compared

to populations in other areas of the province.

Table 44. Numbers of adult mosquitoes captured each week in a CDC black-light trap located in the Village of Lytton, BC.

Date (2006)

Species Jul 04

Jul 10

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Culex pipiens 3 2 1 1 7 Culex tarsalis 1 1 Culiseta inornata 1 2 1 4 Mosquito unidentifiable* 1 1





3.12.4. Skuppah Indian Band

A dry ice baited CDC black-light trap was set up at on the Skuppah Indian

Reserve, at the residence of Doug and Cassandra McIntyre on 955 McIntyre Road. The

trap was operated for 12 weeks and captured only 6 mosquitoes (Table 45) which is

considerably fewer than last year’s count of 51 mosquitoes. The primary species

captured at this site was Culiseta inornata (five out of the six specimens). This species is

rated as having a moderate competency for transmitting WNv, especially to horses.

Table 45. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Skuppah Indian Reserve, BC.

Date (2006)

Species Jul 04

Jul 10

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Culiseta alaskaensis 1 1 Culiseta inornata 1 1 3 5


3.12.5. Siska Indian Band

A CDC black-light mosquito trap was set up at the Community Hall on the Siska

Indian Reserve. The trap was operated for 12 weeks and captured only 8 mosquitoes from

three species (Table 46). The primary species captured at this site was Culiseta inornata

(6 out of the 8 specimens). This species is rated as having a moderate competency for

transmitting WNv, especially to horses. There was a single specimens of Culex pipiens,

which is one of the most important WNv vectors in North America.

Table 46. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Siska Indian Band reservation, BC.

Date (2006)

Species Jul 04

Jul 10

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Culex pipiens 1 1 Culiseta incidens 1 1 Culiseta inornata 1 4 1 6




3.12.6. Kanaka Bar Indian Band

A CDC black-light mosquito trap was set up at the Kanaka Bar Café on the

Kanaka Bar Indian Reserve. The trap was operated for 12 weeks and captured only 24

mosquitoes from four species (Table 47). The primary species captured at this site was

Culiseta incidens (37.5% of the total catch), which is a common rain-barrel mosquito.

This species readily breeds in any water-holding container left with standing water. This

species is not implicated in WNv transmissions. Seven specimens of Culex pipiens and

three specimens of Culex tarsalis were also captured at this site. These mosquitoes can

share the same larval development habitat as Culiseta incidens, but unlike Culiseta

incidens, they are very important mosquitoes in terms of WNv transmissions in North

America. The final species present was Culiseta inornata, which is rated as having a

moderate ability to transmit WNv, especially to horses. Overall, the numbers captured at

this site are very low compared with other areas of the province.

Table 47. Numbers of adult mosquitoes captured each week in a CDC black-light trap located on the Kanaka Bar Indian Band reservation, BC.

Date (2006)

Species Jul 04

Jul 11

Jul 18

Jul 26

Jul 31

Aug 09

Aug 16

Aug 21

Aug 28

Sep 05

Sep 12

Sep 19 Total

Culex pipiens 1 3 2 1 7 Culex tarsalis 1 1 1 3 Culiseta incidens 2 1 1 1 2 2 9 Culiseta inornata 1 1 2 1 5




3.13. SUMMARY OF WNV VECTORS IN THE FRASER RIVER VALLEY

Six mosquito traps were placed in the Fraser River Valley (Table 41, Figure 8).

Except for the High Bar location, all of the traps captured low numbers of mosquitoes,

which was to be expected given the hot, dry, desert-like geography of the area. Culiseta

inornata was present at each of the trapping locations and was the prominent mosquito

species at three of the trapping locations (High Bar, Skuppah, and Siska reservations).

This species is expected to have a moderate likelihood to transmit WNv, especially to

horses. Culex tarsalis was present in all trapping locations except Skuppah and Siska, and

Culex pipiens was present in all locations except Skuppah and Lytton First Nation. These

are the most important WNv vector species in the province; however, their numbers were

low in all locations. The relatively low numbers of WNv vector species captured in the

dry Fraser Valley this summer makes this area relatively low risk for seeing cases of

WNv when the virus reaches this region of the province.

3.14. RESULTS OF MOSQUITO SURVEILLANCE IN THE SOUTHERN CARIBOO

Two mosquito trapping sites were selected in the South Cariboo Region of the

TNRD (Table 48).

Table 48. Locations of mosquito trapping sites in the South Cariboo Region.




Address/ Comments

Village of Clinton

N51° 5.548 W121° 34.282 4-Jun battery Waste Water

Treatment Plant

TNRD: 70 Mile House N51° 18.236 W121° 23.59 13-Jun Sally Watson 110V 2452 North

Bonaparte Road




3.14.1. Village of Clinton

A dry ice baited CDC black-light mosquito trap was located at the Clinton Waste

Water Treatment area. The trap captured 529 mosquitoes from 10 species over 12 weeks

of sampling (Table 49). This is less than half of last year’s total of 1346 mosquitoes, and

is probably due to mosquito larviciding activities in the Village this summer.

The most prevalent species was Ochlerotatus campestris (30% of the total catch),

followed by Ochlerotatus dorsalis (21.5% of the total catch). While Ochlerotatus

campestris is not rated as a concern for WNv, Ochlerotatus dorsalis is rated as having a

moderate ability to transmit WNv. Culiseta inornata and Culex tarsalis were both

present in moderate numbers (53 and 35 specimens respectively). Culiseta inornata is

rated as having a moderate likelihood of transmitting WNv, especially to horses and

Culex tarsalis is rated as the most important WNv vector in Canada.

Ochlerotatus dorsalis are known to breed in standing water along the Bonaparte

River, and it is likely that Culiseta inornata are sharing these same habitats. Culex

tarsalis are known to occupy water at the waste water treatment plant, and it is likely that

they are also developing in pools of standing water along the Bonaparte River.

Table 49. Numbers of adult mosquitoes captured each week in a CDC black-light trap at Waste Water Treatment area in Clinton, BC.

Date (2006)

Species Jun 05

Jun 22

Jun 29

Jul 06

Jul 13

Jul 20

Jul 27

Aug 03

Aug 10

Aug 17

Aug 21

Aug 31 Total

Aedes vexans 1 3 2 5 1 12 Culex tarsalis 1 1 1 6 20 5 1 35 Culiseta inornata 9 2 1 3 36 1 1 53 Ochlerotatus campestris 13 46 37 9 1 4 20 1 2 3 8 15 159 Ochlerotatus dorsalis 5 8 14 7 5 11 30 5 4 8 7 10 114 Ochlerotatus excrucians 1 1 2 Ochlerotatus fitchii 1 1 Ochlerotatus increpitus 1 20 8 7 1 12 5 1 55 Ochlerotatus provocans 10 59 6 1 1 2 79 Ochlerotatus sticticus 4 2 3 1 10 Mosquito unidentifiable* 3 1 3 1 1 9





3.14.2. TNRD: 70 Mile House

A dry ice baited CDC black-light mosquito trap was located at the residence of

Sally Watson at 2452 North Bonaparte Road in 70 Mile House. During a 14 week

sampling period, 514 specimens were captured from 13 species of mosquitoes (Table 50).

This is nearly one-third as many as were captured at this site last summer (1566

specimens in 2005), and is similar to the trap counts seen in 2004. Last year, there was

extensive larval development habitat due to a large snowmelt. It is expected that the

larval development sites were back to a normal size this summer.

As expected at this location, the dominant species was Ochlerotatus campestris

(79% of the total catch), which is a ferocious biter that breeds in semi-alkaline pools

throughout the Cariboo-Chilcotin, but is of little concern as a WNv vector. The primary

WNv vector in western Canada, Culex tarsalis, was the second most common species

captured at this location (30 specimens were captured). The final species of significance

was Culiseta inornata, making up 5% of the total catch. This species is expected to have

a moderate likelihood to transmit WNv, especially to horses. All other species were

present in low numbers, and although they may be of concern from a nuisance standpoint,

they are of little concern with regards to WNv.

Table 50. Numbers of adult mosquitoes captured each week in a CDC black-light trap at 70 Mile House, BC.

Date (2006)

Species Jun 20

Jun 27

Jul 05

Jul 14

Jul 19

Jul 25

Aug 01

Aug 06

Aug 16

Aug 23

Aug 31

Sep 08

Sep 21 Total

Aedes vexans 1 1 Culex tarsalis 1 5 13 4 1 5 1 30 Culiseta alaskaensis 1 1 Culiseta inornata 2 2 8 4 3 3 2 1 25 Ochlerotatus campestris 18 129 26 4 49 119 19 1 32 7 2 406 Ochlerotatus communis 1 1 Ochlerotatus euedes 2 2 Ochlerotatus excrucians 5 1 6 Ochlerotatus fitchii 1 1 1 8 11 Ochlerotatus flavescens 1 1 Ochlerotatus increpitus 1 10 1 1 1 14 Ochlerotatus mercurator 1 3 2 6 Ochlerotatus provocans 2 4 1 7 Mosquito unidentifiable* 2 1 3





3.15. SUMMARY OF WNV VECTORS IN THE SOUTHERN CARIBOO

Two mosquito traps were placed in the Southern Cariboo area of the TNRD in the

Village of Clinton and the community of 70 Mile House (Table 48). Both of these traps

captured high numbers of mosquitoes. The primary species of WNv concern in each of

the traps were Ochlerotatus dorsalis, Culiseta inornata, and Culex tarsalis. Both

locations trapped high numbers of nuisance mosquitoes.

Overall, at this time, both Clinton and 70 Mile House can be considered at

relatively low risk for WNv due to the relatively low numbers of primary vector species

coupled with distance from the US and Alberta borders and the direction of WNv

progression across North America.

3.16. RESULTS OF MOSQUITO SURVEILLANCE IN FOUR TRAPPING SITES

SITUATED OUTSIDE OF THE PRIMARY VALLEYS OF THE TNRD.

Four mosquito trapping sites were selected in areas that did not fall in one of the

main river valleys of the TNRD (Table 51).

Table 51. Locations of mosquito trapping sites Logan Lake, Brookmere, Coldwater Indian Band and Westwold.




Address/ Comments

District of Logan Lake N50° 29.446 W120° 49.736 22-Jun Highland

House B&B 110V Tunkwa Lake Rd

TNRD: Brookmere N49° 49.07 W120° 52.305 21-Jun Ken & Betty

Harris 110V 5105 L’il Caboose Road

Coldwater Indian Band N50° 2.167 W120° 51.597 30-Jun Merl Harry 110V #110-250th Street

TNRD: Monte Creek “Duck Meadow” a Duck’s Unlimited project

N50° 37.517 W119° 56.367 19-Jun Battery

Intersection of Hwy 97 and Barnhartvale Road




3.16.1. Logan Lake

In Logan Lake, there is extensive habitat along Guichon Creek and along

Meadow Creek Road. A dry ice baited CDC black-light trap was set at the Highland Bed

and Breakfast on Tunkwa Lake Road for 13 weeks and collected 322 mosquitoes

representing 16 species. This higher than last year’s count of 220 specimens and could

be due to increased floodwater along Guichon Creek.

Similar to last summer, the majority of the trap count was Culiseta inornata (77%

of the total catch) (Table 52). This species is characterized as having a moderate

potential to transmit WNv when the virus arrives in the province. Both of the primary

WNv vectors in western Canada, Culex tarsalis and Culex pipiens, were present, however

both were in very low numbers (two and one specimens, respectively). All other species

collected are of little significance in terms of WNv, although their combined numbers

may pose somewhat of a nuisance.

Overall, at this time, Logan Lake can be considered relatively low risk for WNv

due to the low numbers of primary WNv vector species present.

Table 52. Numbers of adult mosquitoes captured each week in a CDC black-light trap at the Highland Bed and Breakfast in Logan Lake, BC.

Date (2006)

Species Jul 01

Jul 06

Jul 11

Jul 19

Jul 27

Jul 31

Aug 09

Aug 16

Aug 22

Aug 31

Sep 08

Sep 15

Sep 23 Total

Aedes cinereus 1 1 Anopheles earlei 1 1 2 Culex pipiens 1 1 Culex tarsalis 1 1 2 Culiseta alaskaensis 2 1 3 Culiseta incidens 2 1 2 2 1 2 10 Culiseta inornata 3 42 44 22 66 50 8 4 1 7 247 Ochlerotatus communis 1 2 5 8 Ochlerotatus dorsalis 1 1 Ochlerotatus euedes 1 1 Ochlerotatus fitchii 1 1 2 Ochlerotatus implicatus 2 2 3 3 10 Ochlerotatus increpitus 5 11 16 Ochlerotatus mercurator 1 2 1 3 2 9 Ochlerotatus provocans 1 1 Ochlerotatus punctor 2 2 4 Mosquito unidentifiable* 1 1 Ochlerotatus Male** 1 2 3





3.16.2. TNRD: Brookmere

Brookmere is located near the southern border of the TNRD. A dry ice baited

CDC black-light trap was set up at 5105 L’il Caboose Road in Brookmere and was

operated for 13 weeks (Table 53). During this time, the trap captured 194 mosquitoes

from 12 species. The most abundant species in this trap was Culiseta impatiens followed

by Culiseta inornata. Both of these species are predicted to have a potential to transmit

WNv when the virus arrives in the province.

Both of the primary WNv vectors in western Canada, Culex tarsalis and Culex

pipiens, were present, however both were in very low numbers (two and three specimens,

respectively). All other species collected are of little significance in terms of WNv,

although their combined numbers may pose somewhat of a nuisance.

Overall, at this time, Brookmere can be considered of relatively low risk for WNv

due to the low numbers of primary WNv vector species present.

Table 53. Numbers of adult mosquitoes captured each week in a CDC black-light trap in the community of Brookmere, BC.

Date (2006)

Species Jun 30

Jul 07

Jul 13

Jul 20

Jul 27

Aug 01

Aug 10

Aug 17

Aug 23

Aug 30

Sep 06

Sep 13

Sep 18 Total

Anopheles earlei 1 1 2 4 Culex pipiens 1 1 1 3 Culex tarsalis 1 1 2 Culiseta alaskaensis 1 1 Culiseta incidens 1 1 4 4 7 4 3 1 1 26 Culiseta impatiens 2 3 5 10 10 14 9 1 54 Culiseta inornata 8 1 6 5 4 2 3 4 5 38 Culiseta morsitans 5 1 6 7 19 Ochlerotatus communis 17 3 15 2 1 38 Ochlerotatus fitchii 3 3 Ochlerotatus increpitus 1 1 Ochlerotatus mercurator 2 1 3 Ochlerotatus punctor 2 2




3.16.3. Coldwater Indian Band

A dry ice baited CDC black-light trap was set up at #110-250th Street, Coldwater

Indian Reserve, at the residence of Merl Harry The trap was operated for 12 weeks and

during this time it captured 61 mosquito specimens (Table 54). The most abundant

species in this trap was Culiseta inornata. This species is predicted to have a moderate

potential to transmit WNv when it arrives in the province.

The primary WNv vector in western Canada, Culex tarsalis, was present in low

numbers (2 specimens over the sampling period). All other species collected are of little

significance in terms of WNv.

Overall, at this time, the Coldwater Indian reservation can be considered at

relatively low risk for WNv due to the low numbers of primary vector species present.

Table 54. Numbers of adult mosquitoes captured each week in a CDC black-light trap at the Coldwater Indian Band reservation, BC.

Date (2006)

Species Jul 07

Jul 13

Jul 20

Jul 27

Aug 01

Aug 10

Aug 17

Aug 23

Aug 30

Sep 06

Sep 13

Sep 18 Total

Coquillettidia perturbans 1 1 Culex tarsalis 1 1 2 Culiseta inornata 9 4 5 4 2 2 1 1 1 1 1 31 Ochlerotatus dorsalis 1 1 Ochlerotatus increpitus 1 15 5 1 22 Oc. spencerii var idahoensis 1 1 Oc. spencerii var spencerii 2 2 Ochlerotatus Male* 1 1





3.16.4. TNRD: Monte Creek at Duck Meadow (Duck’s Unlimited Site)

Duck Meadow is a Duck’s Unlimited Marsh located at the intersection of Hwy 97

(Vernon Hwy) and Barnhartvale Road. This is the first year trapping has taken place in

this location, and it was selected since we do not currently control mosquitoes in the area

and we wanted to know if control was warranted, especially in the event of a WNv

outbreak. A dry ice baited CDC black-light trap was set up alongside Monte Creek. The

trap was set once per week for 12 weeks and during this time the trap captured 600

specimens from 15 species (Table 55).

The most abundant species captured in this trap was Culex tarsalis (314

specimens). This species is the most important WNv vector in Canada, and is of great

concern due to its high numbers.

At this time, it is not recommended that larviciding take place in this marsh since

it is located in a rural area with very few people. However, should WNv arrive in the

province and make its way to the interior, this area should become a high priority for

larviciding activities.

Table 55. Numbers of adult mosquitoes captured each week in a CDC black-light trap in Duck Meadow, Monte Creek, BC.

Date (2006)

Species Jun 20

Jun 27

Jul 04

Jul 11

Jul 18

Jul 25

Jul 31

Aug 08

Aug 15

Aug 19

Aug 29

Sep 05 Total

Aedes vexans 3 3 11 24 13 3 57 Anopheles earlei 1 1 1 2 1 1 7 Anopheles freeborni 1 2 1 1 5 Coquillettidia perturbans 5 8 13 Culex pipiens 1 1 Culex tarsalis 3 25 39 3 5 125 106 2 6 314 Culiseta incidens 1 1 Culiseta inornata 1 2 1 2 2 8 Ochlerotatus campestris 1 1 Ochlerotatus communis 1 1 Ochlerotatus dorsalis 1 1 Ochlerotatus excrucians 3 4 1 8 Ochlerotatus fitchii 5 5 Ochlerotatus increpitus 6 2 23 104 5 4 144 Ochlerotatus provocans 1 1 Mosquito unidentifiable* 4 25 4 33





3.17. SUMMARY OF RESULTS OF ALL ADULT SAMPLING

This summer 13,494 specimens of adult mosquitoes from 34 species were

captured in 48 mosquito traps this summer (Table 56, Table 57). This is approximately

half of last year’s catch of 22,605 mosquitoes. In many areas of the TNRD, there was

more floodwater and snowmelt than has been present for a number of years. It is

expected that a comprehensive larviciding program (introduced to many areas for the first

time) had a significant impact on adult mosquito numbers throughout the TNRD.

Aedes and Ochlerotatus species were the most common overall, comprising 65%

of the total of all trap counts. The second most common mosquito was Culex tarsalis

which made up 14.6% of the total of all trap counts, and was found in all but six trapping

locations (Blue River, Whispering Pines, Neskonlith, Shackan, Skuppah and Siska).

Culex tarsalis comprised a higher proportion of the total number of mosquitoes captured

than occurred last summer; however the actual number of Culex tarsalis was similar to

that of last summer (1971 specimens in 2006 and 2047 specimens in 2005). Also

common was the species Culiseta inornata, which comprised 10% of all mosquitoes

captured this summer and appeared at every trapping site except Simpcw, Whispering

Pines, Valleyview, Adams Lake Indian Band, Neskonlith, Ashcroft and Spences Bridge.

Culex pipiens were less common; however they were present at 33 of the trapping

sites, where a total of 509 specimens were captured. Culex pipiens are more common in

urban habitats and the majority of trapping sites were in rural settings.

In most instances, Culex pipiens and Culex tarsalis began to show up in

increasing numbers in late July and August. These mosquitoes have multiple generations

in a summer and, by August, the populations are generally at their peaks. The population

of floodwater mosquitoes (Aedes and Ochlerotatus) tended to peak in mid-June to mid-

July and their numbers decreased as the summer progressed, because their eggs are laid

in the soil and hatch when they become wet with the spring snow-melt and freshets.

Overall there was great variability in species composition and numbers across the

TNRD. Throughout this report, comments concerning likelihood of WNv occurrence are

offered. These comments are based solely on the data collected at these specific trapping

sites and therefore can only be used as a general guideline. Mosquito species and

numbers can fluctuate considerably year to year. Also, the placement of traps within an



area can greatly impact the trap numbers and may reflect either higher or lower numbers

than the actual average for a given community, municipality, or First Nation reservation.



Table 56. Distributions of mosquito species found in the TNRD in 2006.

TNR

D: B

lue

Riv

er

TNR

D: C

lear

wat

er*

TNR

D: B

lack

pool

*

TNR

D: E

. Bla

ckpo

ol*

TNR

D: D

arfie

ld*

Sim

pcw

FN

TNR

D: B

arrie

re

TNR

D: M

cLur

e*

Whi

sper

ing

Pine

s

TNR

D: N

oble

Ck

Kam

: Ray

leig

h

Kam

: Wes

tsyd

e

Kam

: Cin

nam

on R

g

Kam

: Mis

sion

Fla

ts*

Kam

: Bro

ckle

hurs

t

Kam

Firs

t Nat

ion

Kam

: Val

leyv

iew

Kam

Bar

nhar

tval

e

Kam

: Duf

ferin

Ada

ms

Lake

IB

Villa

ge o

f Cha

se

Nes

konl

ith IB

TNR

D: P

ritch

ard

Skee

tche

stn

I.B.

Bon

apar

te IB

Cac

he C

reek

Ash

crof

t

Ash

crof

t FN

TNR

D: S

penc

es B

g

Coo

k's

Ferr

y IB

Nic

omen

IB

TNR

D: N

icol

a Vy

Upp

er N

icol

a IB

Low

er N

icol

a IB

Noo

aitc

h IB

Shac

kan

IB

Hig

h B

ar F

N

Lytto

n FN

Lytto

n

Skup

pah

IB

Sisk

a IB

Kan

aka

Bar

IB

Clin

ton

TNR

D: 7

0 M

ile

Loga

n La

ke

TNR

D: B

rook

mer

e

Col

dwat

er IB

TNR

D: M

onte

Cre

ek

Ae vexans Ae cinereus An earlei An freeborni An punctipennis Coq perturbans Cx pipiens Cx tarsalis Cs alaskaensis Cs impatiens Cs incidens Cs inornata Cs morsitans Oc canadensis Oc campestris Oc communis Oc dorsalis Oc euedes Oc excrucians Oc fitchii Oc flavescens Oc hexodontus Oc implicatus Oc increpitus Oc intrudens Oc melanimon Oc mercurator Oc provocans Oc pullatus Oc punctor Oc sierrensis

Oc s. idahoensis

Oc s. spencerii Oc sticticus



Table 57. Summary of compositions of each of the mosquito light traps employed in the TNRD during the summer of 2006.

Description of Location No of

Samples Culex

tarsalis Culex

pipiens Culiseta inornata

Anopheles spp

Coquillettidia perturbans

Aedes/ Ochlerotatus Other* Total

TNRD: Blue River 12 1 14 1 16 TNRD: Clearwater 12 6 30 15 2 2 17 34 106 TNRD: Blackpool 12 6 9 28 694 737 TNRD: E. Blackpool 12 6 29 6 4 1932 2 1979 TNRD: Darfield 13 51 19 6 6 199 4 285 Simpcw FN 12 8 16 889 913 TNRD: Barriere 12 28 1 1 5 10 105 1 151 TNRD: McLure 8 48 1 1 10 62 122 Whispering Pines/Clinton IB 0 0 TNRD: Noble Creek 12 200 6 95 64 146 11 522 Kamloops: Rayleigh 12 29 2 56 4 91 Kamloops: Westsyde 12 203 12 35 1 8 51 3 313 Kamloops: Cinnamon Ridge 12 219 51 31 1 1624 34 1960 Kamloops: Mission Flats 12 88 274 12 1 7 382 Kamloops: Brocklehurst 12 13 38 3 1 1 28 4 88 Kamloops First Nation 10 25 16 28 3 4 76 Kamloops: Valleyview 12 7 11 90 5 113 Kamloops: Barnhartvale 12 11 5 5 1 11 20 53 Kamloops: Dufferin 12 4 1 1 1 4 11 Adams Lake IB 12 3 1 75 22 1 102 Village of Chase 12 77 6 11 2 9 108 9 222 Neskonlith IB 8 1 1 3 5 TNRD: Pritchard 12 45 2 9 2 1 174 10 243 Skeetchestn IB 12 19 1 75 2 34 20 151 Bonaparte IB 12 12 22 1 13 6 54 Cache Creek 12 23 11 10 4 1 177 13 239 Ashcroft 12 2 1 17 1 21 Ashcroft First Nation 12 5 2 14 16 6 43 TNRD: Spences Bridge 12 1 1 1 80 5 88



Description of Location No of

Samples Culex

tarsalis Culex

pipiens Culiseta inornata

Anopheles spp

Coquillettidia perturbans

Aedes/ Ochlerotatus Other* Total

Cook's Ferry IB 12 2 4 31 38 10 85 Nicomen IB 12 8 1 34 2 19 64 TNRD: Nicola Valley 12 224 2 34 7 1 737 21 1026 Upper Nicola IB 12 21 36 5 63 125 Lower Nicola IB 12 115 1 72 9 5 42 35 279 Nooaitch IB 13 48 7 197 10 15 1 278 Shackan IB 12 2 28 2 1 5 11 49 High Bar First Nation 12 24 1 121 1 36 46 229 Lytton First Nation 4 1 1 2 Village of Lytton 12 1 7 4 1 13 Skuppah IB 12 5 1 6 Siska IB 12 1 6 1 8 Kanaka Bar IB 12 3 7 5 9 24 Clinton 12 35 53 432 9 529 TNRD: 70 Mile House 13 30 25 455 4 514 Logan Lake 13 2 1 247 2 56 14 322 TNRD: Brookmere 13 2 3 38 4 47 100 194 Coldwater IB 12 2 31 1 27 61 TNRD: Monte Creek 12 314 1 8 12 13 218 34 600 Totals 551 1971 509 1404 190 157 8749 514 13494

*Other: Mosquitoes in the genus Culiseta, except Culiseta inornata.



4.0 SUMMARY OF WEST NILE VIRUS VECTOR COMPETENCY FOR BC MOSQUITO SPECIES

Although it is widely accepted that Culex pipiens and Culex tarsalis are the two

primary vectors of WNv in western Canada, Dr. Peter Belton (2004), a retired professor

from Simon Fraser University and an expert in the field of mosquito biology, has

assembled a list of potential WNv vectors that are present in British Columbia, and has

assigned them “vector competency” ratings.

It is important to understand the factors that must be met for a mosquito to be

considered a good WNv vector. First, the mosquito must be willing to bite birds. In a

natural setting, WNv can only be contracted from birds, as other hosts contain

insufficient amounts of the virus to be infectious. Next, the mosquito must have the

correct receptors in its gut to accept the virus and transfer it into the mosquito’s

circulatory system. Later, the mosquito must be able to transfer the virus from its

circulatory system into its salivary glands so it can inject the virus during its next blood

meal. This brings us to the next point: a mosquito must be willing to take more than one

blood meal in its life, and must be a long-lived species, since it can take up to two weeks

for the virus to be transported to a mosquito’s salivary glands and render that mosquito

infectious. Another factor is the temporal distribution of a species: WNv tends to be at

its worst in July and August, so the vector must be present in high numbers during this

time of the year. Finally, in order to be a human vector, the mosquito must not only be

willing to bite birds, but it must also be willing to bite humans.

With all of these factors considered, Culex tarsalis should be identified as the

most significant concern as a vector to humans in British Columbia and Culex pipiens as

the most significant vector within bird populations. However, Peter Belton has included

21 British Columbian species in his list, based on the United States Centre for Disease

Control rankings, tests of mosquito pools in Eastern Canada (virus was found present in

the mosquito, but the mosquito may not be able to transmit the virus), and a study at UC

Davis in California. He has assigned them a relative competency ranking of + to +++

(Table 58). Species not included in the studies mentioned above, but still given

consideration by Peter Belton based on their ability to transmit other viruses, are ranked

with a question mark.



Table 58. Mosquito species in British Columbia identified as potential human West Nile Virus Vectors (Belton, 2004).

Potential Vectors in BC Positive (P) Competence (+) Feeding preference, biology Culex tarsalis P +++ Birds, mammals3 Ochlerotatus togoi +++? Birds, mammals4 Culex pipiens P ++ Mostly birds3 Coquillettidia perturbans P ++ Birds, mammals2 Culiseta inornata P ++ Birds, mammals3 Culiseta morsitans P ++ Mostly birds5 Ochlerotatus dorsalis P ++ Mammals, occasionally birds1 Ochlerotatus melanimon P ++ Mammals, occasionally birds1 Ochlerotatus canadensis P + General feeder1 Ochlerotatus sierrensis + Mammals4 Ochlerotatus sticticus P + Mammals1 Aedes vexans P + Mostly mammals1 Aedes cinereus P + Birds? mammals1 Anopheles punctipennis P + Mammals, birds?3 Anopheles earlei P + Mammals, birds?3 Ochlerotatus hendersoni +? Birds? mammals1 Culiseta incidens +? Mostly mammals3 Ochlerotatus fitchii P Mostly mammals1 Ochlerotatus provocans P Mostly mammals?1 Culex territans P Mostly amphibia3 Culiseta impatiens P Mostly mammals5

1 Eggs overwinter, one or two generations/year 3 Females overwinter, several generations/year 5 Females overwinter, one generation/year 2 Larvae overwinter, one generation/year 4 Eggs and larvae overwinter, several generations/year

5.0 BIOLOGY OF MAJOR MOSQUITO SPECIES COLLECTED IN THE TNRD IN 2006 5.1. ANOPHELES SPECIES

Anopheles species of mosquitoes are quite different in appearance than other

mosquitoes, with narrow wings and long slender bodies. When standing, their hind legs

are well elevated from their bodies, distinguishing them from other mosquito species.

Because of these anatomical differences, they have been placed in their own subfamily.

Females overwinter as adults and hide in culverts, bridges, inside eaves, and in the roofs

of sheds (Belton, 1983). In urban areas, they hibernate in burrows, caves, hollow trees,

and other sheltered places (Belton, 1983). They prefer fresh, clean water, and they lay

eggs singly among vegetation at the edges of water bodies. Anopheles species have been

implicated in the transmission of malaria, and were no doubt involved in malarial



outbreaks in Canada in the 19th century. All three of BC’s Anopheles species were

captured in the TNRD.

5.1.1. Anopheles earlei

Female Anopheles earlei overwinter in buildings, caves, and mammal burrows, as

well as in hollow logs and in tree trunks (Wood et al. 1979). When they overwinter, they

are not blood-fed and have not laid eggs, but feed soon after leaving hibernation (Wood

et al. 1979). In the southern part of the province, they are capable of two generations per

year, weather permitting. The species is widely distributed throughout BC, and the

females are vicious biters, able to attack in weather so cold that other mosquitoes are not

capable of flying (Belton, 1983). Because of their ferocity, they can be localized pests

when present in significant numbers. Belton (2004) gives this species a vector

competency rating of ‘+’ (Table 58).

5.1.2. Anopheles freeborni

Anopheles freeborni females overwinter in various sites including talus slopes,

abandoned mines and buildings, and root cellars. They tend to breed in pools and

sloughs formed by creeks, large marshes, and irrigated pastures (Wood et al. 1979).

They are capable of rearing in slightly saline water (salinity as much as 5%). This

species has the potential to be an effective vector of malaria and has been found to be

naturally infected with Western Equine Encephalitis, but it is rarely found in high enough

concentrations to be important for disease transmission. Belton (2004) does not include

this species on his list of vector competency.

5.1.3. Anopheles punctipennis

Anopheles punctipennis is fairly widespread throughout the province. Larvae are

found in almost any kind of standing water (Belton, 1983), and there are generally two or

three generations annually (Wood et al. 1979). Females bite humans freely after dark and

are persistent in entering houses, but are not found in high enough concentrations to be a

concern as disease vectors (Belton, 1983). Belton (2004) does not include this species on

his list of vector competency.

5.2. AEDES AND OCHLEROTATUS SPECIES

Until recently, all of the “floodwater” species (i.e. laying their eggs on moist soil

rather than on the water’s surface) of mosquitoes in BC were classified as Aedes, but a



number of species have now been reclassified into the genus Ochlerotatus. However, the

life cycle and the physiology of Aedes and Ochlerotatus species are similar.

Aёdes is the Greek word for disagreeable (Belton, 1983), and is an accurate

reflection of these species in terms of both numbers and ferocity. Aedes and

Ochlerotatus species lay their eggs at the edges of water bodies and rely on warm

temperature and/or low oxygen levels in flood-water to induce their eggs to hatch. Most

of the floodwater species peak in late June (following snowmelt and then river flooding)

and die in late summer and the populations over-winter as eggs. Mosquitoes that are

viewed as nuisance species (i.e. present in high numbers and biting ferociously) are

generally from this group, as large areas of habitat often become active at once with

rising floodwaters and therefore huge batches of mosquitoes hatch at the same time. This

is due primarily to the fact that eggs laid by most species remain viable for a number of

years, and therefore egg concentrations in the soil can become very dense. Adults are

generally short-lived (two to six weeks), and generally seek shade during hot summer

days as they are prone to desiccation. Most species have only one generation each year,

although some species are capable of two or more generations when conditions are

suitable. Twenty-three species of Aedes and Ochlerotatus mosquitoes were trapped in

the TNRD. Some of the more significant species are discussed below.

5.2.1. Aedes cinereus

Aedes cinereus is present throughout British Columbia and is capable of

completing up to three generations per year (Belton, 1983; Wood et al., 1979). Larvae

have been found in rain pools, swamps, and flood water (Belton, 1983). This species is

not known to fly any great distance, and is generally considered a minor pest although

isolated populations may be aggressive and persistent biters, even during the heat of the

day (Belton, 1983). This species is given a vector competency rating of ‘+’: low in

Belton’s (2004) list of potential WNv vectors. This species was found in a few traps in

the TNRD, but never in high numbers.



5.2.2. Aedes vexans

This mosquito species is considered the worst mosquito pest in Canada (Wood et

al., 1979). Aedes vexans appear in extremely large numbers in almost any habitat where

there are permanent, semi-permanent, or transient pools that have been flooded from

snowmelt or rain. In the heat of summer, these mosquitoes can mature from the egg to

adult in as short as five days, existing as larvae for as little as three days (Wood et al.,

1979). Eggs of Aedes vexans can remain viable in the soil for many years, and because

not all individuals hatch when submerged, multiple cycles of flooding and drying are

needed for all eggs to hatch (Wood et al., 1979). Adult Aedes vexans are notorious fliers,

capable of flying as far as 20 to 50 km, or of riding low jet streams for hundreds of

kilometers (Belton, 1983).

Specimens of Aedes vexans have been found carrying the western equine

encephalitis (WEE) virus in Alberta, Saskatchewan, and the north western United States

(Belton, 1983). Belton (2004) has included Aedes vexans as a potential WNv vector with

a vector competency rating of ‘+,’ since individuals of this species have tested positive

for the virus in some areas of the United States (Table 58). However, even though some

specimens have tested positive, it is not clear if this species is actually capable of

transmitting WNv since it rarely takes a second blood meal.

Aedes vexans were numerous in each of our sites that are affected by floodwater

(Blackpool, East Blackpool, Darfield, Simpcw, Barriere, Noble Creek, Cinnamon Ridge,

Valleyview, Chase, Pritchard, and Spences Bridge).

5.2.3. Ochlerotatus campestris

Ochlerotatus campestris tend to breed in somewhat alkaline pools (as high as pH

8.4), temporary or semi-permanent snowmelt ponds, rain pools, roadside ditches, and

sub-arctic pools in birch and willow scrub at the tree line (Wood et al. 1979). They

prefer water rich in organic matter, and generally hatch as soon as the snow has melted

(Belton, 1983). In BC, they are predominantly found in the dry interior and throughout

the Chilcotin, where they are one of the dominant mosquito pests (Hearle, 1932, in

Belton, 1983). In northern areas there is only one generation per year, but there are

occasionally multiple generations in the south during warmer weather (Wood et al.

1979). It is a significant pest for humans and cattle, and the females bite when disturbed



at any time of the day (Belton, 1983). It has occasionally been found to be infected with

Western Equine Encephalitis, but likely plays only a minor role in disease transmission

(Belton, 1983). Belton (2004) does not include this species on his list of potential vectors

of WNv. This was the most significant species collected in the 70 Mile House trap.

5.2.4. Ochlerotatus communis

This species is one of the most abundant and widely distributed species, occurring

throughout the forested part of Canada as well as throughout the northern US and

northern Eurasia (Wood et al. 1979). Larvae generally rear in shaded pools (Belton,

1983), and can develop in large numbers in deciduous forest pools with a high tannic acid

content (Wood et al. 1979). Eggs generally hatch in early spring, and female adults bite

fiercely throughout the day. Although it is a fierce biter, it is not considered a major pest

in BC due to relatively low numbers (Belton, 1983), except in northern areas.

5.2.5. Ochlerotatus dorsalis

This species thrives on the interior plateau, developing in saline swamps and

pools, as well as in fresh water (especially irrigation seepages) (Belton, 1983). It is

capable of traveling many kilometers, and females of this species are vicious biters both

during the day and at night (Belton, 1983). When conditions are favourable,

Ochlerotatus dorsalis may have two or more summer generations, resulting in a very

large population (Wood et al. 1979). Belton (2004) gives Ochlerotatus dorsalis a vector

competency rating of ‘++,’ primarily because Western Equine Encephalitis and West

Nile Virus have occasionally been discovered in isolated numbers of adult females.

Ochlerotatus dorsalis were plentiful in the Pritchard, Clinton, and Guichon Ranch

(Nicola Valley) locations.

5.2.6. Ochlerotatus excrucians

Ochlerotatus excrucians can be found throughout Canada south of the arctic

tundra (Woods et al., 1979). Larvae of this species can be found in almost any ground

pool, but seem to prefer the edges of larger semi-permanent marshes. Adults are large in

size and will survive well into late summer. When present, females are fierce biters, but

rarely occur in large numbers in British Columbia (Belton, 1983). This species does not

appear on Peter Belton’s list of potential WNv vectors (Table 58).



5.2.7. Ochlerotatus fitchii

Ochlerotatus fitchii occur nearly everywhere in Canada south of the tree-line,

(Woods et al.,1979). Larvae of this species are often collected in the same locations as

the larvae of Ochlerotatus excrucians, or – early in the spring – in snowmelt pools with

Ochlerotatus increpitus (Belton, 1983; Woods et al., 1979). It is described as an

aggressive pest mosquito of the southern interior which can be a nuisance at elevations as

high as 1500m (Belton, 1983). Although individuals of this species have been found

infected with WNv, they are unlikely to transmit the illness.

5.2.8. Ochlerotatus implicatus

Ochlerotatus implicatus is one of the earliest species to emerge as adults,

developing in temporary snow or rain pools in woodland areas (Belton, 1983; Wood et al.

1979). It is one of the most widely distributed species in Canada south of the tree line,

but is seldom found in high enough concentrations to be considered a nuisance (Wood et

al. 1979). Adults tend to be short lived. This mosquito has been known to bite vigorously

in shaded conditions during the day, however its low numbers rarely make it a significant

pest (Belton, 1983). Belton (2004) does not include this species on his list of potential

WNV vectors.

5.2.9. Ochlerotatus increpitus

Ochlerotatus increpitus is fairly widespread and numerous throughout BC, with

larvae found in flood waters, irrigation seepage, ditches, and rain or snowmelt pools

(Belton, 1983; Wood et al. 1979). While female increpitus are an important pest in

Nevada and Utah, they are generally not common enough in Canada to be considered a

significant pest (Wood et al. 1979). However, in those localized areas of BC where large

numbers are found, the females are eager biters and can be a serious pest of cattle

(Belton, 1983). Belton (2004) does not include this species on his list of potential WNV

vectors. Ochlerotatus increpitus were plentiful in the Cache Creek and Duck Meadow

(Monte Creek) trapping locations.

5.2.10. Ochlerotatus melanimon

Ochlerotatus melanimon can be found in the same habitats as Ochlerotatus

dorsalis, although they are often found in less saline waters (Belton, 1983). This species

breeds in irrigated pastures, roadside ditches, and sloughs (Belton, 1980; Woods et al.,



1979). This species is a good vector of Western Equine Encephalitis in California

(Belton, 1983), and has been rated ‘++’ as a WNv vector by Peter Belton (Table 58).

Ochlerotatus melanimon were collected at Cinnamon Ridge and in many of the

Thompson and Nicola Valley traps.

5.2.11. Ochlerotatus spencerii (both variants)

Ochlerotatus spencerii larvae can be found very early in the spring, and then

throughout the summer. They can be found in snow and rain pools, irrigation seepage,

and floodwater sites (Belton, 1983). In the interior of BC, they have been found in the

same pools as Aedes vexans and Ochlerotatus dorsalis. When this mosquito is present in

high numbers, it can be an aggressive and persistent biter, even during the heat of the

day. There are two variants of this species in BC, idahoensis and spencerii. The

difference between these two variants lies in the markings present on their tergites.

5.2.12. Ochlerotatus sticticus

Ochlerotatus sticticus is primarily a floodwater mosquito and is therefore usually

associated with the floodplains of large rivers and where there is widespread excessive

precipitation (Wood et al., 1979). With each peak of a river, a fresh hatch of

Ochlerotatus sticticus can appear (Belton, 1983). This species is almost always

associated with Aedes vexans (Wood et al., 1979). Eggs of Ochlerotatus sticticus can

remain viable for about five years, so there may be years when this species may not

appear at all as it waits for a significant flood (Belton, 1983). Like Aedes vexans,

Ochlerotatus sticticus are ferocious biters and readily enter houses day and night (Belton,

1983). This species is not considered to be a strong WNv vector in British Columbia,

with a vector competency rating of ‘+’ (Table 58). Because of the extensive flooding

seen this summer, Ochlerotatus sticticus showed up in significant numbers in many of

our floodwater traps (East Blackpool, Darfield, Simpcw, Cinnamon Ridge, and

Valleyview).

5.3. COQUILLETTIDIA SPECIES

5.3.1. Coquillettidia perturbans

The genus Coquillettidia has replaced the genus Mansonia in most of the recent

literature, although Mansonia is still used by some authors. Only one species from this

genus, Coquillettidia perturbans, is found in Canada. They are often called ‘cattail



mosquitoes,’ as the siphon of the larvae and ‘trumpets’ of the pupae are modified to

attach themselves to the outside of a cattail and burrow through the side, leaving the body

of the larvae protruding (Belton, 1983). This exposure to the air inside the cattail fulfils

their oxygen requirements, enabling them to remain buried in the mud at the bottom of

the swamp (Wood et al. 1979). The marshes where they are found must remain

permanently wet, because although there is only one generation per year, larvae are

present year-round and are killed by drought, especially in the winter (Wood et al. 1979).

Females are strong fliers and feed on both birds and mammals, and will occasionally feed

more than once before laying eggs (Wood et al. 1979). For this reason, Belton (2004)

has given them a vector competency rating of ‘++’.

5.4. CULEX SPECIES

Culex is the Latin word for ‘mosquitoes’ and was used to describe all mosquito

species prior to 1818, at which time the genera Anopheles and Aedes were named

(Belton, 1983). There are only three species of Culex in BC (Culex tarsalis, Culex

pipiens, and Culex territans). Culex females lay their eggs in rafts on the surface of

almost any water, and all species found in BC overwinter as fertilized females. As well,

all Culex species in BC can produce several generations a year, providing that the

summer is warm enough. These mosquitoes are generally not considered a nuisance as

they are usually found in lower concentrations and are not particularly vicious biters

(they tend to prefer either birds or amphibians). Because they have multiple broods in

their lifetime, they have the potential to transmit viruses such as WNv and other

encephalitis such as Western Equine Encephalitis. This is because they must take a blood

meal before laying each batch of eggs, and after feeding on an infected host, the female

has the potential to transmit the virus to her next host. Two species of Culex were

identified in the TNRD this summer (Culex pipiens and Culex tarsalis), although the third

species , Culex territans has been captured in the past.

5.4.1. Culex pipiens

The common names for Culex pipiens are “rain-barrel mosquito” and “Northern

House Mosquito.” These mosquitoes are common in both urban and sub-urban settings,

and since they rarely fly more than 2-3 km from their larval development sites, when they

are found, it can be assumed that they developed in a local larval development site



(DeBess, 2003). These mosquitoes breed readily in highly organic water such as storm

water catch basins, sewage treatment plants, ditches, birdbaths, rain gutters, plant pot drip

trays, tires, and basically any water-holding containers that are commonly found in urban

areas (DeBess, 2003).

Females emerge in the spring in search of a blood meal; this species has a strong

preference for the blood of birds. The blood is used by the female to help develop her

eggs – she lays approximately 140-340 eggs on the surface of her chosen water habitat.

Larvae emerge from the eggs in 1-2 days, after which the development of the larvae into

adults is temperature–dependent, but usually takes approximately 8-12 days in the

summer (Savage & Miller, 1995). A single female may take multiple blood meals and

lay multiple batches of eggs in a summer.

This species has been known to transmit Western Equine Encephalitis and St.

Louis Encephalitis, and is listed as a potential human vector of WNv in British Columbia

with a competency rating of ‘++’ (Belton, 1983; 2004), although it is unlikely to actually

serve as a human vector because it rarely, if ever, bites humans. If WNv is found in

British Columbia, this species will likely be responsible for the “amplification” of the

virus in bird populations. Culex pipiens were found in high numbers in the Cinnamon

Ridge and Mission Flats trapping locations (51 and 274 specimens respectively).

5.4.2. Culex tarsalis

The common name for Culex tarsalis is the Western Encephalitis Mosquito, due

to its implication in the transmission of various encephalitis-causing viruses in western

North America. Culex tarsalis larvae can be found in permanent and semi-permanent

ponds, irrigation ditches, and sewage ponds (Belton, 1983). They can also be found in

small temporary pools and artificial containers as the populations increase through the

summer (Wood et al., 1979). In general, they prefer warm, stagnant water with high

concentrations of organic materials. Culex tarsalis females overwinter as adults, hiding

in caves, rock piles, and talus slopes. Adults feed primarily between sunset and sunrise,

with peak activity occurring within two hours after sunset (Wood et al., 1979).

This species will readily feed on both birds and mammals, which is why it is the

major vector of WNv to humans (Belton, 2002). WNv is primarily a disease of wild

birds, so when populations of both birds and Culex tarsalis are high, the risk of WNv



increases and is likely to start showing up in mammal populations, especially in

unvaccinated horses (Belton, 2002; Wood et al., 1979). This species is rated at ‘+++’ for

vector competency in British Columbia (Belton, 2002).

Culex tarsalis were present in exceptionally high numbers at a number of trapping

locations this summer: Noble Creek, Westsyde, Cinnamon Ridge, Mission Flats, Chase,

Pritchard, Nicola Valley, Lower Nicola Indian Band, Nooaitch and Duck Meadows

(Monte Creek).

5.5. CULISETA SPECIES

The life-history of Culiseta mosquitoes is similar to that of Culex, with females

laying their eggs directly on the surface of water (with the exception of Culiseta

morsitans, which lay their egg rafts on vegetation at the margin of their larval

development sites) (Belton, 1983). Females of most species lay multiple broods each

year, and most overwinter as fertilized females. Members of these genera tend to prefer

the cooler, temperate climates that are typical of Canada. Five species of Culiseta were

captured in the TNRD.

5.5.1. Culiseta alaskaensis

Culiseta alaskaensis is one of the largest mosquitoes in BC, with a wing length of

five to seven millimeters (Belton, 1983). It is widely distributed throughout the Province,

as well as throughout the boreal forests of northern Europe and Russia, but is generally

found in low numbers (Belton, 1983; Wood et al. 1979). Females overwinter in sheltered

locations, often under tree bark, and lay only one brood each year, even during warmer

conditions (Belton, 1983). They tend to utilize small, deep, semi-permanent ponds with

large amounts of emergent vegetation (Wood et al. 1979). While the females will bite

humans in the shade, they are seldom significant pests (Belton, 1983). Belton (2004)

does not include this species on his list of potential WNV vectors.

5.5.2. Culiseta incidens

Culiseta incidens is a common species, and in 1932 was considered the most

common and most widespread species in the province (Belton, 1983). This was due to

the fact that almost every rain barrel in the lower mainland was infested with larvae all

summer long, which reflects this mosquito’s propensity for laying eggs in artificial

containers and having multiple broods each year. They are also found in catch basins,



ditches, and permanent and semi-permanent pools, and are capable of tolerating polluted

waters (Wood et al. 1979). They overwinter in rock slides and talus slopes and emerge

early in the spring; their large size coupled with their early appearance often causes

strong reactions from people, even though they are not significant biters of humans.

Females generally take blood meals from large mammals, but Belton (1983) has noted

that they appear to feed more freely on humans during warm (> 20°C) evenings in the

lower mainland. Belton (2004) gives this species a vector competence rating of ‘+,’

primarily because of its widespread distribution, although it has not been found to be

infected with WNv and is quite unlikely to transmit the illness. This species was

common throughout the TNRD.

5.5.3. Culiseta inornata

Culiseta inornata is a widespread mosquito, but since it prefers large mammals to

man, it is seldom considered a pest. It breeds in deep woodland ponds, seepage ditches,

and polluted open water (Belton, 1983). This species overwinters as adults in mammal

burrows and crevices, and emerges very early in the spring when it is still too cold for

other species. These are the large mosquitoes often seen “hovering” close to people at

dusk during early spring. Larvae have been found in ice-covered ponds (Wood et al.,

1979). This widespread species is listed as a potential WNv vector with a competency

rating of ‘++’ (Belton, 2002) since it will feed on both birds and mammals and it has

multiple generations. This species is one of the commonest species in the TNRD. It was

trapped in 39 trapping locations and it was the dominant species in many trapping

locations.

5.5.4. Culiseta impatiens

Overwintering female Culiseta impatiens are probably the earliest species of

mosquito to emerge and bite in the spring, and have been sighted as early as March in

Alaska (Woods et al., 1979). Larvae are found in semi-permanent ponds and in dark,

shaded, permanent woodland pools (Woods et al., 1979). Members of this species have

been found in low numbers across the province. This species has a strong preference for

large mammals, although it will occasionally bite humans (Belton, 1983). Culiseta

impatiens is on Belton’s WNv vector list (Table 58), however it is not rated. It appears



on the list since it has tested positive for the virus, but it is unclear as to whether it is

capable of transmitting the virus.

5.5.5. Culiseta morsitans

In most of Canada, Culiseta morsitans overwinter as eggs, or possibly as larvae

deep in silt or peat at the bottom of deep ponds (Belton, 1983). It has a fairly northern

distribution, but has been found in a few widely scattered locations in BC (Belton, 1983).

It is usually found in shaded conditions, associated with springs, sphagnum bogs, and

cedar swamps. They are almost exclusively bird feeders (Belton, 1983; Wood et al.

1979), and females that have been captured in flight or reared from larvae will not take a

human blood meal (Belton, 1983). Because this species lays multiple batches of eggs

each year (Wood et al. 1979), and because it feeds on birds, Belton (2004) has given it a

vector competency rating of ‘++’.

6.0 PREVENTION OF WEST NILE VIRUS THROUGH MOSQUITO ABATEMENT In British Columbia, we have been able to watch WNv as it has spread across

North America and we have consequently learned and benefited from activities and

studies that have occurred in response to its spread. During the virus’s progression across

the continent, numerous studies have shown that cases of WNv infection can be reduced

with comprehensive mosquito abatement. In a recent study in Cook County Illinois, it

was shown that areas that employed mosquito control conducted with Integrated Pest

Management principles (primarily larviciding, with adulticiding conducted only when

necessary) yielded fewer cases of WNv than areas of the county where mosquito

abatement was not adequate (Ruiz et al, 2002). Next, a study by Haramis (2004)

suggested that areas with intensive larval control in catch basins resulted in fewer cases

of WNv than in areas where less intensive control or no control had taken place. In

Michigan, it was found that individuals living in areas with no abatement programs were

nearly eight times more likely to be infected with WNv compared to residents in areas

with comprehensive mosquito control programs (Walker, 2004). Finally, a study in Fort

Collins, Colorado suggested that adulticiding resulted in significantly lower numbers of

vector species and seemed to significantly reduce the number of cases of WNv infection

(Nasci, 2004).



WNv vector mosquito control is different from nuisance mosquito control in that

it targets specific species of mosquitoes. These targeted mosquitoes, namely Culex

tarsalis and Culex pipiens, are usually not considered a nuisance and so are rarely

targeted in nuisance control programs, thus deeming a need for a separate, focused

control program. They often live in different habitats than do nuisance mosquitoes, and

they tend to be more prevalent in July and August, when most nuisance species tend to

decrease in numbers.

7.0 HABITAT MAPPING AND EQUIPMENT PURCHASE During the last three years, with grant funding from the Ministry of Health

Services, habitat mapping was completed over much of the TNRD. Larval development

habitat in the North Thompson (from Vavenby to Kamloops), the South Thompson, the

Thompson, and the Nicola Valleys have been identified. In addition, all participating

municipalities and First Nations have been visited and larval development sites have been

identified. Last year, Morrow BioSciences Ltd was hired to assist BWP Consulting to

obtain GIS shape files for many larval development sites in the North Thompson, South

Thompson, Kamloops, Pinantan and Pritchard areas. This year, grant funding was used

to purchase a similar GPS and software as is used by Morrow BioSciences to allow BWP

Consulting crews to continue mapping polygons in the remainder of the TNRD including

all municipalities and First Nations. In addition, grant funding will be used to purchase

two Tablet PC’s to allow for data management and online database access in the field.



8.0 MONITORING AND LARVICIDING FOR WNV VECTORS This year, an extensive larviciding program was launched throughout the TNRD

to treat sites that harbored WNv vector mosquitoes. In the majority of larval

development sites, larvicides containing the active ingredient Bti (Aquabac and

Vectobac) were applied; however, methoprene (Altosid) was also used in a few

permanent larval development sites and catch basins. Last summer’s trial of the newly

registered product, VectoLex (Bacillus sphaericus), proved effective in the treatment of

catch basins in the City of Kamloops, and so was used in the program’s catch basins

treatments again this summer, a program that expanded to include catch basin testing and

treatments outside of Kamloops. This summer’s catch basin program included the

municipalities of Kamloops, Ashcroft , Cache Creek, Clinton, and Chase.

The TNRD applied to the Ministry of Health Services for permission to conduct

mosquito control under the Provincial Pesticide Use Permit (No. 776-001-2003/2006),

which was issued to the Ministry of Health in order to facilitate local governments’

permits for the purposes of WNv control. Larviciding aimed at the reduction of vector

mosquitoes took place from April through August and was performed by both hand and

helicopter.

9.0 LARVAL SURVEILLANCE AND TREATMENT Potential larval development sites were monitored on a regular basis with a

standard 300ml dipper. Any larvae captured were counted and identified in the field at

the genus level. When Culex or Culiseta larvae were present, the larval development site

was treated. This year, a portion of the WNv funding was utilized to purchase two

Murayama backpack granular spreaders. These machines allow crews to cover a greater

area quicker than with hand broadcasting, and they produce a more even spread of the

larvicide over the treatment area.

A total of 3363.67 kg of larvicide containing the active ingredient Bti (1913.12 kg

of Aquabac, and 1450.55 kg of Vectobac) was applied by hand, by blower, and by

helicopter to 334.987 ha of water within the TNRD this summer. (Staff applied 756.87

kg of that total by hand and by blower, covering 74.247 ha of mosquito larval

development sites. WNv helicopter campaigns accounted for 260.74 ha of treated

mosquito larval development habitats, using 2606.8 kg of the total Bti product applied



over the summer). In addition, 36.0 kg of methoprene (Altosid pellets) was applied to

standing water and 0.28 kg of methoprene was applied to catch basins. Finally, 2562

pouches of Bacillus sphaericus (VectoLex) were applied to catch basins.

9.1. OVERVIEW OF HELICOPTER APPLICATIONS

Helicopter larvicide application still remains our most effective method of

treatment, and we conducted a number of helicopter WNv larviciding campaigns this

summer.

Our first helicopter campaign occurred on April 26 in Area “A” and 14.0 kg of

Vectobac was applied to standing water in the Roundtop Road Wildlife Sanctuary. This

site was treated by helicopter a second time on May 30 with 36.2 kg of Vectobac. This

site was treated with West Nile virus funding as it contained a number of Culex and

Culiseta larvae in addition to large numbers of Ochlerotatus larvae.

In June, we completed four helicopter applications of larvicide on standing water

containing Culex larvae. On June 1st, we treated standing water on crown land and

private land near the Kamloops Waste Water Treatment Plant, Cinnamon Ridge and at

the Tranquille Wildlife Management Area. This application was used 1.9 hours of flight

time and 90.5 kg of Vectobac was applied.

On June 6, we completed a campaign in the Nicola Valley between Quilchena and

the City of Merritt. On this date, we used 3.9 hours of helicopter time and distributed

778.3 kg of larvicide (488.7 kg of Aquabac and 289.6 kg of Vectobac).

Next, on June 12th, we staged a campaign at the Kamloops airport (Cariboo-

Chilcotin Helicopters hangar) and we applied 906.8 kg of larvicide (327.6 kg Aquabac

and 579.2 kg Vectobac) to standing water near Cinnamon Ridge, Weyerhaeuser, the

Kamloops Waste Water Treatment Plant and the Tranquille Wildlife Management Area.

All of the larvicide was applied to Crown Land during this campaign. This application

cost us two hours of helicopter time.

Finally, on June 15th, five hours of helicopter time were used to treat active areas

in Barriere, McLure, Blackpines and Noble Creek. A total of 781 kg of larvicide was

applied on this date (636.2 kg of Aquabac and 144.8 kg of Vectobac).



9.2. OVERVIEW OF HAND APPLICATIONS

A total of 756.87 kg of larvicide containing the active ingredient Bti was applied

by hand throughout the TNRD (296.2 kg of Vectobac and 460.62 kg of Aquabac). More

specifically, 358.6 kg of this was applied in Area “A”, 136.0 kg was applied in Mosquito

Area North, 49.5 kg was applied in Mosquito Area South, 73 kg was applied to the

Nicola Valley between Quilchena and Merritt, 33 kg was applied to Cache Creek and

Clinton, and 106.77 kg was applied to participating First Nations.

A total of 36 kg of product containing the active ingredient methoprene (Altosid

pellets) was applied to 5.387 ha of mosquito larval development sites in two separate

areas that are consistently flooded by irrigation throughout the summer, and have thus

been consistently active with mosquito larvae. The first area – a large hayfield in

Pritchard – has been treated in the past using Altosid pellets, but the second area –

hayfields in the Cinnamon Ridge community – received Altosid treatments for the first

time this summer. Over the summer, continued testing of both the Pritchard and the

Cinnamon Ridge sites indicated that the Altosid treatments were effective.

This summer’s expanded catch basin program treated a total of 2602 catch basins

within the City of Kamloops, the Village of Ashcroft, the Village of Cache Creek, the

Village of Clinton, and the Village of Chase. In the City of Kamloops, catch basins on

the North and South Thompson flood plains were treated (Rayleigh, Westsyde,

Brocklehurst, North Shore, Downtown, Valleyview and Dallas), and catch basins in

higher elevation areas were not, as they did not become active with larvae. A total of

0.28 kg of Altosid pellets (containing the active ingredient, methoprene) were used to

treat 40 catch basins in the City of Kamloops and 2562 pouches of Vectolex (10 grams

each, containing the active ingredient Bacillus sphaericus) were used to treat the

remaining catch basins in the TNRD. The catch basins were monitored and treated in

two waves over the summer, one wave of treatment in July, and the other in August

(Table 59).



Table 59. Breakdown of Larvicide Applications for WNv Vector Control* within the TNRD in 2006.

Amount of Area Treated (ha) Treatments with Aquabac/Vectobac

Adams Lake Indian Band 22 2.2 Barriere 111.4 11.14 Birch Island 35 3.5 Blackpines 178.1 17.81 Blackpool 188.55 18.855 Cache Creek 10 1 Chase 27 2.7 Cherry Creek 4 0.4 Chinook Cove 26 2.6 Chu Chua (Simpcw) Indian Band 22.5 2.25 Chutter Ranch 318.7 31.87 Clearwater 119.5 11.95 Clinton 23 2.3 Darfield 27 2.7 East Blackpool 18.75 1.875 Heffley Creek 4 0.4 Kamloops Indian Band 2.25 0.225 Lower Nicola Indian Band 25 2.5 Lytton First Nation 6.52 0.652 McLure 316.3 31.63 Neskonlith Indian Band 16.5 1.65 Noble Creek 163.3 16.33 Nooaitch Indian Band 3.5 0.35 North Thompson 72.4 7.24 Pritchard 2.5 0.25 Quilchena to Merritt 532.6 51.82 Rayleigh 12 1.2 Shackan Indian Band 3 0.3 Skeetchestn Indian Band 1 0.1 Thompson 997.3 99.79 Upper Clearwater 46.5 4.65 Upper Nicola Indian Band 27 2.7 Vavenby 0.5 0.05

Total Bti applied 3363.67 334.987 Treatments with Altosid

Pritchard 20 3.1 Thompson 16 2.287 Catch Basins (Kamloops) 0.28 40 basins

Total Altosid applied 36.28 5.387 Treatments with VectoLex

City of Kamloops 24.58 2458 basins Village of Clinton 0.20 20 basins Village of Ashcroft 0.39 39 basins Village of Cache Creek 0.15 15 basins Village of Chase 0.30 30 basins *Many other larviciding activities occurred in 2006 and will be reported under the TNRD Nuisance Control Program



10.0 CONCLUSIONS A number of conclusions can be drawn from the results of the West Nile Virus

Risk Reduction Program this summer. First, it appears that the public education work

through presentations, booth appearances, one-to one contact and media advertising has

increased the public’s overall awareness of mosquitoes and mosquito control efforts in

the TNRD. It is not uncommon for our staff to visit landowners and find that they have

put forth a great effort to reduce habitat on their properties. In a few instances,

landowners at our trapping locations have worked hard to reduce larval development sites

and this has been reflected nicely in this year’s trap counts (Section 3.2.3, Section 3.4.8,

Section 3.8.4). An increased awareness has also been evidenced by the number of calls

that were received this summer from concerned individuals reporting potential larval

development sites in their areas.

Next, adult mosquito trapping has allowed us to pinpoint areas within the TNRD

that are producing large numbers of Culex mosquitoes and are therefore at increased risk

for WNv transmission when the virus arrives in the province. It appears that the highest

numbers of Culex mosquitoes are captured in the lower elevation valleys including the

Thompson, South Thompson, North Thompson (from Clearwater to Kamloops) and the

Nicola. Each of these valleys suffers extensive flooding each spring, followed by

intensely hot summers- a combination that is ideal for the production of Culex larvae.

Trap counts from these areas in 2004 and 2005 allowed us to pinpoint these areas as our

priority “high-risk” areas and larviciding efforts were concentrated in these areas this

summer.



11.0 RECOMMENDATIONS It is expected that WNv will eventually find its way to British Columbia, and

when it does, some predictions can be made concerning areas of the TNRD that are most

likely to see cases of the illness. When surveillance data is considered, along with

mapping and treatment data, it appears that the highest priority (in terms of vector

treatment) should be the North Thompson Valley (from Kamloops to Clearwater), the

South Thompson Valley, the Nicola Valley, and the municipalities of Kamloops, Cache

Creek, Chase, and Clinton.

1. It is recommended that the TNRD continue to search for and map vector

habitats. In the future, all areas of the TNRD should be photographed and mapped using

GIS technologies.

2. It is recommended that the TNRD adopt a vector mosquito larviciding program

if provincial funding continues in the coming years. This program should include vector

control in standing water, marshes, and catch basins.

3. It is recommended that public education continue. We are now starting to meet

and speak with people who have seen us at previous events and who have made changes

on their properties to reduce larval development habitats. This is a positive indication

that our messages are reaching the public. Each year, the opportunity to meet landowners

at public education events leads us to find significant sites from which we were denied

access, or sites that were previously unmapped, and thus untreated. These opportunities

also indicate the value in public education.

4. It is recommended that an adult mosquito surveillance program continue.

Predictions have been made, based on the adult surveillance program (trap counts and

vector presence), that allow the program to determine intensity of focus on any given

region or site. These numbers can change from year to year, and sometimes even with a

change in trap location of just a few hundred meters. Also, it is important to continue

surveillance as a means of assessing the effectiveness of a larviciding program. Trap

count numbers will reflect the number of mosquitoes hatching in an area, and thus

identify both successful areas and problem areas (most likely because of an undiscovered

larval development site).

5. It is recommended that funding be provided in expectation of the constant flow



of new technology that improves the methods and rates of application of larvicide. In

only two years, the granular blowers have altered the operation of the entire program,

allowing quicker, easier, and more efficient treatment of larval development sites.



REFERENCES BCCDC (2006). On-line. West Nile Virus Information Page. http://www.bccdc.org Belton, P. (1983). The Mosquitoes of British Columbia. British Columbia Provincial

Museum Publication: Handbook No. 41. Belton, P. Personal communications and presentation at the West Nile Virus Planning

Meeting November 28th, 2002 at the British Columbia Center for Disease Control in Vancouver, B.C.

Belton, P. (2004) British Columbia Mosquitoes as Vectors of West Nile Virus. SFU

Website: www.sfu.ca/~belton CDC (2004). On-line. West Nile Virus Maps and Stats. http://www.cdc.gov/

DeBess, E. (2003). Mosquito control chemical guide: 2003 West Nile Virus response plan. Oregon Department of Human Services.

Haramis, L. (2004). Factors impacting effectiveness of mosquito abatement operations, 2002 and 2003. Presentation at the National Planning Meeting for Surveillance, Prevention and Control of WNV in the US. Denver, CO, Feb 3-5, 2004.

Health Canada (2003). On-line. West Nile Virus Monitor. http://www.hc-sc.gc.ca/pphb-dgspsp/wnv-vwn/mon_e.html

Nasci, R. (2004). Adulticiding in Fort Collins Colorado, 2003. Presentation at the Provincial West Nile Virus Planning Meeting, 2004.

Ruiz, M.O., Tedesco, C., McTighe, T.J., Austin, C. & Kitron, U. (20024). Environmental and social determinants of human risk during a West Nile virus outbreak in the greater Chicago area, 2002. Int. J. of Health Geographics 3:8.

Savage, H., & Miller, B. (1995). House Mosquitoes of the U.S.A: Culex pipiens complex. Wing Beats, Vol. 6(2):8-9.

Walker, N. (2004). Mosquito management programs and West Nile Virus in Michigan, 2002. Presentation at the National Planning Meeting for Surveillance, Prevention and Control of WNV in the US. Denver, CO, Feb 3-5, 2004.

Wood, D.M., Dang, P.T., & Ellis, R.A. (1979). The Insects and Arachnids of Canada, Part 6: The Mosquitoes of Canada, Diptera: Culicidae. Ottawa, ON: Biosystematics Research Institute.

Documents

TNRD WNv Final Report 2006 - CivicWeb