1. Pesticide Resistance: Can It Happen in Turf?
Eileen A. Buss
Associate Professor & Extension Specialist
Entomology & Nematology Dept.

2. Resistance in Ornamental, Vegetable and Fruit Pests
Aphids
Beetles
Caterpillars
Leafminers
Planthoppers
Scales
Spider mites
Stink bugs
Thrips
Whiteflies
Resistance has been documented against every group of insecticides, and in more than 500 insect and mite species:
56% are crop pests
39% are medical/veterinary pests
5% are beneficial species
to every group of insecticides
in > 500 insect and mite species
56 % are crop pests
39 % are med/vet pests
5 % are beneficial species

3. Brief History…
Cases of resistance to several key pests developed within 2-20 years after the introduction of the cyclodienes, organophosphates, carbamates, pyrethroids, Bacillus thuringiensis, spinosyns, and neonicotinoids.

4. Resistance Mechanisms
Metabolic resistance
Target site insensitivity
Reduced penetration
Behavioral resistance

5. Resistance Mechanisms
Metabolic resistance
Resistant insects break down the toxin faster than susceptible insects can.

6. Resistance Mechanisms
2. Target site insensitivity
The site where the toxin binds in the insect has changed.

7. Resistance Mechanisms
3. Reduced penetration
Resistant insects may absorb the toxin slower through the cuticle than susceptible insects can.

8. Resistance Mechanisms
4. Behavioral resistance
Resistant insects may detect and behaviorally avoid the toxin.

9. Resistance in Turf Pests
Annual bluegrass weevil Southern chinch bug
Lyle Buss, UF/IFAS

10. Is pesticide resistance more likely to develop in home lawns or golf courses?

11. Is pesticide resistance more likely to develop in home lawns or golf courses?
It depends more on the pest’s biology and the intensity of management against it.

13. Other turf pests that have potential to become resistant… (but nothing is documented yet!)

14. Fall armyworm egg mass on tree leaf. FAW egg mass on post.
J. Castner, UF
FAW adult male.
FAW larva showing white Y-mark on head.

15. Hunting Billbug Life Cycle15

16. What About Mole Crickets?

17. Speed of Resistance Development
Depends on:
how fast the insects reproduce
migration and host range of the pest
availability of nearby susceptible populations
persistence and specificity of the pesticide
rate, timing and number of applications made

18. The “Pesticide Treadmill”
After repeated applications, pests evolve resistance to the insecticide and the resistant strain becomes harder to manage at the labeled rate and frequency.
Thus, the insecticide is applied more frequently.
Resistance intensity and the frequency of insecticide-resistant individuals in the population both increase and control failures continue as yet more product is applied.
Users switch to another pesticide.

19. History of Insecticide Resistance in the Southern Chinch Bug
1953: Chlordane
1957: DDT
1960: Parathion
1976: Chlorpyrifos, Diazinon, Trichlorfon
2005: Bifenthrin

20. Why Control Failures Occur
Application errors
Misidentification of pest or damage
Improper control timing
Use of wrong rate or formulation
Inadequate spray volume/irrigation
Improper spray solution pH
Photodegradation
Volatilization
Microbial degradation
Insect resistance

21. Goal: Reduce the selection pressure on the pest.

22. How to Develop a Resistance Management Plan
1. Learn about IPM strategies and create a season-long plan to minimize pesticide applications.
D. Potter, UKY

23. Best Management Practices

24. A Successful IPM Program Depends on:
Knowledge of pest biology
Monitoring and estimating pest density
Knowledge of economic/aesthetic injury levels (i.e., action thresholds)
Everyone needs to tolerate some insects or their damage (threshold should not = 1 bug)
Change from routine or “preventive” applications to as-needed

25. How to Develop a Resistance Management Plan
2. When designing, installing, or renovating, select plant species or cultivars that are resistant to insect attack.

26. Host Plant Resistance
Cultivars of different turfgrass species have been screened for resistance to:
Fall armyworm
Japanese beetle
Mole crickets
Chinch bugs
Bermudagrass mites
Billbugs

27. How to Develop a Resistance Management Plan
3. Use as many different control methods as possible.
Use a variety of synthetic and biorational insecticides
Conserve or release beneficial insects
Adjust cultural practices
Use chemical attractants / deterrents

28. Natural Enemies Parasitic wasps, flies Big-eyed bugs
Minute pirate bugs
Damsel bugs
Earwigs
Ground beetles
Rove beetles
Several ant species
Spiders

29. Possible Cultural Controls
Alter amount / frequency of irrigation
Reduce thatch thickness
Adjust amount/frequency of fertilization

30. Irrigation / Moisture Management
Insect eggs and immatures need water / humidity to survive
Reduce watering to desiccate the pests
Increase watering to drown them out

31. Drought Stress / Irrigation
Chemical Application / Formulation?
What formulation will work best in this situation?
Granular / Fertilizer carrier
Sprayable
Flexibility?
Does the spray technician have flexibility to choose between formulations, depending on an individual situation?

32. Heavy Fertilization… Attracts female moths that are ready to lay eggs
Increases thatch
Improves habitat for thatch-dwelling pests
Makes turf more succulent
Insects could pierce the plants more easily

33. Importance of Nitrogen (N)
Nitrogen content in host plants influences insect survival, development time, body size, and reproduction (Mattson 1980, McNeill & Southwood 1978)
Increasing N fertilization reduces plant resistance to some insect species (esp. beetles and moths) (Barbour et al. 1991)
Southern chinch bug damage seems related to increased ammonium nitrate use (Horn and Pritchett 1962, Busey and Snyder 1993)

34. How to Develop a Resistance Management Plan
4. Carefully select insecticides
Consider more than cost & effectiveness
Beneficial insects
Product class
Rates and treatment intervals
Product application methods
Tank mixes
Timing of applications

35. Which Products to Use: Practical Considerations
Choice is limited by:
Crop / use site
Number of applications / amount of product allowed for use
Sensitivity of the plant species

36. Vary the Mode of Action (MoA)
Insecticides act on different physiological and biochemical target sites in insects to kill them
Nervous system (e.g., neurotransmitters, receptor sites)
Growth and development (e.g., hormones)
Energy production (e.g., prevent feeding)

37. Possible Rotation Products
Pyrethroids (Group 3)
Bifenthrin (Talstar/Onyx), Beta-cyfluthrin (Tempo), Deltamethrin (DeltaGard), lambda-cyhalothrin (Scimitar)…
Carbamates and Organophosphates (Groups 1 A and B)
Carbaryl (Sevin) and trichlorfon (Dylox)
Neonicotinoids (Group 4A)
Clothianidin (Arena), imidacloprid (Merit)

38. Reduced-Risk (Biorational) Insecticides
Molt-accelerating compounds and other IGR’s
Mach2
Dimilin 2L
Confirm
Microbial insecticides
Bt, Conserve, insect-parasitic nematodes

39. Entomopathogenic Nematodes
Several species (Steinernema spp., Heterorhabditis spp.) occur naturally in the soil, but some can be purchased
Some insecticides, like imidacloprid (Merit), may slow grub behavior down and make them more susceptible to nematode infection

40. Getting the Best Chemical Control
Properly calibrate and maintain equipment
Rotate insecticides with different modes of action
Use enough volume to penetrate thatch
Add an adjuvant to improve coverage, if needed
Don’t spray if rain could wash product off

41. Application Issues…
Photos by R. Clemenzi,
Bayer Environmental Science

42. Application Issues Granular / Formulated products Spreader placement
Tire on sidewalk vs. Tire on grass edge
Photo by R. Clemenzi,
Bayer Environmental Science

43. Application Issues
Photo by R. Clemenzi,
Bayer Environmental Science

44. Online Resource
Insecticide Resistance Action Committee (IRAC) website:

45. Eileen Buss