WHY DO MOSQUITO SURVEILLANCE?

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Rosmarie KellyPublic Health EntomologistGDPH

Nuisance mosquito control programs (MOSQUITO CONTROL)

Vector mosquito control programs (PUBLIC HEALTH)

Used to control various species of mosquitoes which cause distress to humans and animals due to biting.

Used to control one or more species of mosquitoeswhich transmit diseases to humans or animals.

Both programs can co-exist and be mutually beneficial.Both programs can co-exist and be mutually beneficial.

Large numbers of mosquitoes can have serious economic implications.

Types of Control Programs

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In the absence of diseases, mosquitoes can become so abundant that they cause disruptions in community services and cause severe stress in the affected local human, pet and livestock populations.

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Without surveillance, mosquito control becomes a matter of luck.

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With surveillance, mosquito control becomes more targeted, more effective, and more economical.

Integrated Pest Management (IPM)Integrated Pest Management (IPM)

IPM IPM reducesreduces dependence on pesticides by integrating non-chemical dependence on pesticides by integrating non-chemical methods to help control or prevent pest populations.methods to help control or prevent pest populations.

IPM Practices

•Identify the pest

•Use surveillance of some type to evaluate pest level

•Target control - don’t make applications based on a calendar

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Integrated Mosquito Management

Source ReductionLarval Surveillance - Larval Control Adult Surveillance - Adult Control Community Education / CommunicationMapping / Record Keeping

Arboviral Surveillance (where appropriate)

Best Management PracticesBest Management Practices

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S.P.L.A.T.S.P.L.A.T.

SSurveillance

PPublic Awareness

LLarviciding

AAdulticiding

TTiming

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Some CommonMosquito Species

Larval Habitat

Biting Time

Flight Range

Aedes albopictus

artificial containers & tree holes

Day100 - 300 yards

Culex quinquefasciatus

ground pools, catch basins, artificial containers

Crepuscular, Night

1/4 - 1/2 mile

Aedes vexansFlooded grassy and wooded areas

Day,Crepuscular, Night

5 - 8 miles

Coquillettidia perturbans

Cattail marshes

Crepuscular, Night 1 - 5 miles

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Mosquito Surveillance

Mosquito surveillance is the cornerstone of mosquito control.

No mosquito control program can operate effectively without a surveillance program.

Mosquito surveillance can reveal:

•The species of mosquitoes that are active in a community

•The presence of human-biting mosquitoes

•The presence of disease vector species

•The presence of mosquitoes infected with arboviral diseases

•The breeding habitats of the local species

•The size of the local mosquito population

•When to apply pesticides to control the mosquito population.9

ALL MOSQUITO SURVEILLANCE SHOULD HAVE A PURPOSE:

•MOSQUITO CONTROL – LARVAL OR ADULT•ARBOVIRAL SURVEILLANCE•PUBLIC EDUCATION

MOSQUITO SURVEILLANCE SHOULD NEVER BE DONE WITHOUT A SPECIFIC GOAL IN MIND.

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Basic Cornerstone of Surveillance

COMPLAINTSCOMPLAINTS

Complaints should ALWAYS be followed up by a site visit.

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HANDLING COMPLIANTSHANDLING COMPLIANTS

• Be fairBe fair• Be consistentBe consistent• Be courteousBe courteous• Don’t make Don’t make

promises that promises that you cannot keepyou cannot keep

• Follow upFollow up

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Dealing with complaints

In urban and suburban area in Georgia, at least 90% of mosquito calls will involve Aedes albopictus, the Asian tiger mosquito.  Things to ask the caller:

a. Is the mosquito biting during the day? Asian tigers are daytime biters.

b. Where is the mosquito landing to bite?  Asian tigers are primarily leg biters.

c. Is the mosquito small and black and white? 

If yes, truck spraying may not help.

If yes, truck spraying may not help.

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gravid trap light trap

larval dipping

landing counts

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LANDING COUNTS

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"Landing Rate" - the number of mosquitoes that land on

the observer over a designated period of time.

It is suggested that they be taken over either a 1 or 5 min

period. If the landing rates exceed 50 in 30 sec, the interval

can be shortened to protect observers that are expected to

conduct numerous counts.

Landing rates may involve identification, but they are

normally employed in areas where a single, known

species is the sole cause of annoyance.

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•Wait a period of time before starting to collect.

•Disturb the vegetation before starting.

•Wear light solid-colored clothes.

•Wear no repellents.

•Wear no perfumes or aftershave.

•Stand up and stand still while taking count.

•Remember, mosquitoes react differently to each individual

Guidelines

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Information to Collect:

Collector's NameCountySite DateTimeLocation on Body

For counts of less than one minute, multiply to get landings per minute.

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Thresholds for Landing Counts Vary

Excessive Landing Rate Counts:

•In populated areas >25 mosquitoes/minute•In relatively unpopulated areas >50 mosquitoes/ minute

THIS WILL VARY ACCORDING TO LOCATION, MOSQUITO SPECIES, AND HUMAN POPULATION

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Landing counts are useful for determining if adult mosquito control is needed.

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When to do landing counts?

•Mosquito control is complaint driven

•Aedes albopictus is a problem in the area

•Emergency mosquito control is needed due to flooding

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For Aedes albopictus, remind the caller to dump out or throw out containers that can hold water (this will also help with Culex quinquefasciatus, our WNV vector). 

Containers need to be dumped at least once a week.  Larvicides can be applied to water that can not be dumped out or eliminated.  Both mosquito dunks (Bti) and mosquito torpedoes (methoprene) can be bought at stores like Home Depot, Lowes, and some of the big chain pet stores in the ornamental pool area. 

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Always remind people to wear mosquito repellent when outside. 

Recommended repellents are those that contain DEET, picaridin, IR3535, or PMD (oil of lemon eucalyptus). 

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If the mosquitoes are biting after dark, or during the day in shady areas, they can be any of a number of species. 

Floodwater species may be abundant after heavy rains.

Face biters tend to be any number of Psorophora spp, although other mosquitoes will bite above the waistline. 

Landing counts done after dark will help determine if the mosquitoes constitute a serious problem needed adulticiding.

THIS WILL NOT TELL YOU WHERE TO APPLY LARVICIDES.THIS WILL NOT TELL YOU WHERE TO APPLY LARVICIDES.25

Remember, landing counts will give you info on whether human biting mosquitoes are present.

Landing counts, along with field ID of Aedes albopictus, will let you know if adulticiding is needed.

Landing counts will NOT give you info about where to larvicide unless you are also ID’ing the mosquitoes.

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ADULT MOSQUITO SURVEILLANCEADULT MOSQUITO SURVEILLANCE

CDC light trapCDC light trap

gravid trapgravid trap

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What Kind of Trap Should You Use?

depends on your need and your budget

Mosquito Gravid Trap Operation

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Another Type of Gravid Trap

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Gravid Traps

• USE – primarily for monitoring container breeding mosquitoes

• Used in the WNV surveillance program

• NOT USEFUL for monitoring most nuisance species

• NOT USEFUL for monitoring EEE

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Preparation of Hay Infusion for Gravid Traps

• Equipment Requirements– Sturdy water tight 35 gallon container– Hay– 16 ounces of Brewer’s yeast– Paddle for stirring– Jugs or containers for transport to field

sites

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Preparation of Hay Infusion for Gravid Traps

• Cover container for 7 to 10 days

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Preparation of Hay Infusion for Gravid Traps

• Infusion can be used for several days in the individual gravid traps if Culex egg rafts are removed.

• You can also add Altosid to the infusion

• Recharge gravid trap as needed; especially after heavy rains.

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Mosquito Gravid Trap OperationSetting the Trap

Helpful Hints• Label the tub in

BIG letters to avoid “losing” your trap

• Put holes in the side of the tub to regulate the level of gravid infusion

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Mosquito Gravid Trap Operation

• Place the set up trap in a shaded area preferably where there is lots of undergrowth.

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Mosquito Light Trap OperationMosquito Light Trap Operation

Mosquito CDC Trap Overview

The CDC traps are portable, battery-operated traps that are useful for investigating newly identified mosquito problem areas, and regular trapping sites.

CDC traps are ideal for collecting mosquitoes for species identification.

CDC type traps attract mosquitoes with a small light and are generally baited with carbon dioxide (dry ice).

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It is recommended to place the trap in an wooded area where mosquitoes usually rest. Hang the trap so the bottom of the net is about one foot above the ground

Mosquito CDC Trap Operation

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Traps are usually collected

the next morning.

Mosquitoes are taken back to the lab and identified to species

Mosquito CDC Trap Operation

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Larval Surveillance – “get them before they get you” 42

Anopheline Larvae

Surface

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Culicine Larvae

Breathing tube

Hang from surface at an angle

Head

Surface

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FACTS ABOUT MOSQUITO LARVAE

• All larvae are found in water• What types of water?

– ALL TYPES! Each species has its own water requirements

• How much water is required? – FROM A JAR LID TO HUGE RESERVOIRS TO PITCHER

PLANTS!• How long from egg to adult?

– IT DEPENDS ON THE SPECIES, BUT MOST TAKE 7-10 DAYS!

• Where should I look for larvae? – ANYWHERE YOU FIND WATER, REGARDLESS OF

SIZE!• What is the best stage of the mosquito to control?

– THE LARVAL STAGE! 45

WHY YOU NEED TO KNOW ABOUT MOSQUITO LARVAL HABITATS?

• The best method to control mosquitoes is by targeting the larval stage. IF NO ADULTS EMERGE, YOU WIN THE GAME!

• If you wait until the adults emerge, they fly in all directions, are not concentrated like larvae, and are harder to control.

Targeting mosquito larvae for control is very “PROACTIVE”.

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Equipment

http://www.rci.rutgers.edu/~insects/dipping.htm 47

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The SIMPLE SCOOP is the "dipping to get water" method that is the least effective method used.

It consists of simply scooping a dipperful of water. This is probably the most commonly used method, particularly by new inspectors, and it is often the method referred to in much of the literature as "the standard dipping procedure." While it can be successfully used to collect Culex larvae, it is still not the method of choice.

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WHAT NOT TO DOWHAT NOT TO DO

The first and usually the best method to start with is the SHALLOW SKIM.

The shallow skim consists of submerging the leading edge of the dipper, tipped about 45 degrees, about an inch below the surface of the water and quickly, but gently, moving the dipper along a straight line in open water or in water with small floating debris. End the stroke just before the dipper is filled to prevent overflowing. The shallow skim is particularly effective for Anopheles larvae that tend to remain at the surface longer than Aedes and Culex. Anopheles are usually associated with floating vegetation and debris.

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Slide the dipper

The second method to try in open water, with or without floating objects, is the COMPLETE SUBMERSION.

Many mosquito larvae, particularly those of the genera Aedes and Psorophora, are very active and usually dive below the surface quickly if disturbed. In this case, a quick plunge of the dipper below the surface of the water is required, bringing the dipper back up through the diving larvae. Bring the dipper up carefully to avoid losing the larvae in the overflow current.

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When you need to sample at the edges of emergent vegetation, try the PARTIAL SUBMERSION technique.

To do this, push the dipper, tilted at about 45 degrees, straight down adjacent to the vegetation. This causes the water around the vegetation to flow into the dipper, carrying the larvae with the flow. There is no need to move the dipper horizontally. Pull the dipper up before it is full.

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In very shallow water, try the FLOW-IN method.

Larvae can be collected by pushing the dipper into the substrate of the pool and letting the shallow surface water, debris and larvae flow into the dipper. Do not move the dipper horizontally.

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Dip shallows next to Pools

To sample for larvae that may be under floating or emergent vegetation, use the SCRAPING technique.

This method is used in habitats that contain clumps of vegetation such as tussocks of sedges, floating mats of cattails or water lettuce or other plants that are too large to get in the dipper, or clumps of submerged vegetation such as hydrilla or bladderwort. Dip from the water in towards the vegetation and end by using the dipper to scrape up against the base or underside of the vegetation to dislodge larvae. This method is usually more effective if the bottom of the dipper is screened and it is often used to sample for Coquillettidia and Mansonia mosquitoes.

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Dip through the plant material

The dipper can also be used as BACKGROUND.

This is especially useful in woodland pools and other shallow water or when larvae are disturbed and dive to the bottom. Submerge the dipper completely to the bottom litter and slowly move it around. The darker mosquito larvae and pupae will stand out against the background of a white or aluminum dipper. Once larvae appear in the dipper, just lift it upward.

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One or more of these methods, properly used, can determine the mosquito species composition of most aquatic habitats, excluding those whose openings are smaller than the dipper, such as tires, rock pools, treeholes and tree root systems like those found in cedar and red maple swamps.

In those cases, a smaller container, such as a vial, measuring spoon or tea strainer can be used in the same seven ways as the dipper described above.

Then there is the tubular dipper, the chef's poultry baster, for those really hard to get to places like plant axils, treeholes and tree root holes.

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ID OF LARVAE IS IMPORTANT

NOT ALL LARVAE NEED TO BE CONTROLLED

The larvae of this mosquito are found in permanent vegetated waters. The adults are not known to bite humans.

An action point is a trigger for initiating a control measure. It is a point at which pest populations or environmental conditions indicate that pest control action must be taken

USING THE DATA – when should control occur

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Here, an action point would occur whenever mosquito populations rose above the baseline. This is useful when controlling vector species where you have well-defined risk and population data.

Mosquito surveillance

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27 28 29 30 31 32 33 34 35 36 37

week

# m

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Average #Mosquitoes

current data

take action

Human cases

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For nuisance species, a threshold can be set based on numbers of complaints and/or mosquito population size.

EIL – economic injury level; angry population

ET – economic threshold; acceptable level of complaints

num

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MAPPING

A picture is worth a thousand words.

1. map complaints2. map service calls3. map breeding sites

65USEFUL TIP – Google Maps

Knowing which species are present can help determine:

•disease risk•control needs

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Disease Mapping

information about mosquito species at complaint sites could help determine disease risk in areas surrounding WNV human cases

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69CSO

Combined Sewer OverflowsEffluent Exit

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Combined Sewer OverflowsTanyard Creek at Ardmore Park

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Combined Sewer OverflowsTanyard Creek at Tanyard Park

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MODEL PROGRAMMODEL PROGRAM

1. Data are collected at sentinel sites

2. Mosquitoes are identified and graphs are used to monitor changes in mosquito populations

3. When predetermined action thresholds are exceeded, an action (press release, education, monitoring, larviciding, adulticiding, etc) occurs

4. Arboviral “testing” sites are established throughout the area

5. The public, the community, and the municipalities are encouraged to take active roles in decreasing mosquito populations through community cleanup, personal protection measures, and mosquito control - the role of the health department is supportive 73REQUIRES SUSTAINABLE FUNDINGREQUIRES SUSTAINABLE FUNDING

http://health.state.ga.us/epi/vbd/mosquito.asp

http://www.GAmosquito.org

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Any Questions?75