2008-2009 Jacumba 2008-2009 Jacumba Eye Gnat Research ProjectEye Gnat Research Project

University of California Cooperative ExtensionUniversity of California Cooperative ExtensionSan Diego CountySan Diego County

Bryan Vander Mey, Staff Research AssociateBryan Vander Mey, Staff Research AssociateJames Bethke, Floriculture & Nursery Farm AdvisorJames Bethke, Floriculture & Nursery Farm Advisor

AcknowledgementsAcknowledgements

• Community of Jacumba – patients, friendliness, hospitality, trial cooperation

• John Prock and Josh Waddell, Bornt Farms• Tom L. – provided chain to pull me out • Julie C. & Beverly - emergence trap participants• David W. – various experiments• Sonia (Jacumba Spa) – emergence trap and

spray trial• Bill Pape – gnat influxes and community info• Paula W. – helpful and happy

Eye Gnat QuizEye Gnat Quiz

1) Eye Gnats are a native species to California?

True False

1) Eye Gnats are a native species to California?

True False

2) There are eye gnats in other parts of the United States?

True False

2) There are eye gnats in other parts of the United States?

True False

3) Eye Gnats hover in large numbers by non-animal objects (trees, telephone

poles, etc.)?

True False

3) Eye Gnats hover in large numbers by non-animal objects (trees, telephone

poles, etc.)?

True False

4) Eye Gnats will lay their eggs in manure?

True False

4) Eye Gnats will lay their eggs in manure?

True False

5) Removing water for 3-4 weeks will kill eye gnat eggs?

True False

5) Removing water for 3-4 weeks will kill eye gnat eggs?

True False

Who are these guys?Who are these guys?

• Liohippelates Collusor

Eye Gnat FactsEye Gnat Facts

• Life cycle varies greatly- 3 weeks to 6 months (up to 2 months for adults)

• Prefer light sandy soil with rich organic matter and moist conditions (not swamp)

• Attracted to people/animals, putrefied eggs, fish meal, freshly tilled land

• Not attracted to UV light, conventional fly traps, garbage, dung

• Use lawns/foliage as shelter. Walking around stirs them up. Attracted to movement

• Require protein for egg production• Not strong fliers - low flying & seek shelter

when windy– Have been documented up to 4 miles from

origin

• Eggs/larvae overwinter in soil.

• Have not responded well to pesticide applications – Entrust (Spinosad) has little effect on adult eye gnats

“lower than 20% mortality at the highest dosage of 0.08 mg A.I. cm2”- Susceptibility of the adult eye gnat L. Collusor to neonicotinoids and spinosad insecticides, Y. Jiang, M. Mulla. 2005

• No single natural predator; cumulative predators have light to moderate impact.

2008 Jacumba Summer Trials 2008 Jacumba Summer Trials

• Goals – To find out where they are coming from and where they are concentrated

• 1st & 2nd emergence test – Where the gnats are breeding (Do plant stages effect where gnats lay eggs?)

• 3rd emergence test – What cultural practices reduce the number of emergence

• Bait trap trial - Where are the highest populations

Emergence Trial – How it worksEmergence Trial – How it works

• Cages consist of PCV covered with a white mesh (2’W X 2’L X 1’H)

• Prevents gnats from entering and escaping• Set cages on the ground for 3-4 weeks• Jars with holes are attached to the inside of the

cages and filled with egg bait• Emerging adults drown in egg bait• Egg bait filtered and eye gnats counted

Emergence TrapsEmergence Traps

Emergence Trial #1 DataEmergence Trial #1 DataTrap # Trap Location Ave. Mean Gnats/Acre

1 Lawn 2.583 4,447

22 Days after plantingRed Leaf Lettuce

5 8,609

38 Days after planting Spinach

13.583 23,388

415 Days after plantingRed Leaf Lettuce

10.1 17,219

Emergence Trial #2Emergence Trial #2

• Located at Jacumba Spa and Resort

• Treated lawn with Tempo Ultra WSP

• Put trap in treated and non-treated areas

• Measured number of gnats for two weeks

• Expect gnats emerging from non-treated area

• No gnats were caught in either the treated or untreated

What did we learn?What did we learn?

• Eye gnats are not primarily breeding in grass or lawns

• Most of the gnats are emerging from the soil at the farm

• 8 day spinach almost always had the highest number of emerging gnats – Soil preference? Higher OM? Why?

Emergence Trial #3Emergence Trial #3

• Old way (pre 2007 – disc in crop residue)

• New way (2008) – blade crop on surface and let the organic matter dry up in the sun, reducing organic matter incorporated into soil

• Expectations- New way should reduce the number of gnats emerging

Emergence Trial #3 DataEmergence Trial #3 Data

Trap # Trap Location2-OctAve.

6-Oct Ave.

9-Oct Ave.

13-OctAve.

16-Oct Ave.

20-OctAve.

Ave. Mean

1North Hwy 80 (burned) 7.8 2.6 0.75 2.4 0.25 5.5 3.216

2South Hwy 80 (disc) 1 0.6 0.33 1.4 0.75 0.6 0.78

What did we learn?What did we learn?

• Soil preference more important than previously thought? South field heavier soil than north side– Should have done soil sample to measure OM

during test

• Believe this practice was the main reason for the lower gnat populations this year

Collar Bait TrapCollar Bait Trap

• Traps put every 1000 ft. around town and at the farm

• Traps consist of two canning jars attached by a 3-inch ABS coupler. Funnel inside upper jar to prevent gnats from escaping.

• Left 24 - 48 hours and collected

• Gnats counted in each trap to get a “snapshot” of population distribution

Collar TrapCollar Trap

Collar Trap Trail #3 (October 28-30, 2008)Collar Trap Trail #3 (October 28-30, 2008)No. of gnats/48 hours

Green = 0-180

Yellow = 181-360

Orange = 361-540

Red = 540-720

What did we learn?What did we learn?

• Higher population in town than at the farm.

Summer ConclusionsSummer Conclusions

• Eye gnats are emerging primarily at the farm

• After hatching, they head to town for : Food? Shelter? What & Why?

• Return to farm to lay eggs

Needed ResearchNeeded Research

• Mycotrol O / Botanigard ES– Fungus (Beauveria bassianna) that attacks insects

and larvae

• Gnatrol– Bt (bacteria) that may have effect on larvae

• Neemix 4.5– Insect Growth Regulator– Kills larval stages of insects; interferes with the

insects ability to molt– Any activity with eye gnats?

Needed ResearchNeeded Research

• Predatory Nematodes– Small worms that attack larvae in the soil– Test untreated/treated emergence traps

• Flight Characteristics– Set traps at different heights to see how high

the gnats are traveling – How do they migrate? When?

Potential SolutionsPotential Solutions

• Construct a tree or solid fence barrier with bottle traps along east side of town. – Creates place of shelter– Creates food source/trap– Creates wind/dust barrier between farm and

town– Long term/Low maintenance

Potential SolutionsPotential Solutions

• Hire a commercial applicator to spray community vegetation

Potential SolutionsPotential Solutions

• Continued work at the farm involving new cultural practices– Reducing organic matter production– Irrigation timings– Weed control– Pesticide applications if proved effective in the

lab– Spray oil (applications on crop residue)

Trap DesignTrap Design

• 2 liter or water bottle traps– 2 to 3 holes on upper portion and filled with

egg bait

• Collar Traps

Angled Entrance DesignAngled Entrance Design

The “Gnatinator”The “Gnatinator”

Eye Gnat AvoidanceEye Gnat Avoidance

• Products containing DEET

• Avon’s Skin-So-Soft

• Absorbine Jr.

• Dryer sheets (attached to hats, around sunglasses, etc.)

• Mosquito head net

• Screened canopies / enclosures

• Community involvement with trapping

THANK YOU!THANK YOU!

University of California Cooperative Extension, County of San Diego

Jim Bethke, Floriculture & Nursery Farm Advisorjabethke@ucdavis.edu

Bryan Vander Mey, Staff Research Associate, Eye Gnat Projectbvandermey@ucdavis.edu

Farm & Home Advisors Office334 Via Vera Cruz, Suite 152

San Marcos, CA 92078(760)752-4724