Pesticide Resistance In Natural Enemies

whitefly from Cloyd research

Pesticide resistance is always a concern because once an arthropod (insect or mite) pest population can no longer be adequately suppressed with existing pesticides, then management options become limited.

Resistance is the genetic ability of some individuals in an arthropod pest population to survive an application or multiple applications of a pesticide. In other words, the pesticide no longer effectively kills a sufficient number of individuals in the arthropod pest population.

Resistance develops at the population level and is an inherited trait. As such, surviving arthropod pests can pass traits genetically onto their offspring or next generation, enriching the gene pool with resistant genes (alleles). The amount of “selection pressure,” or the frequency of applying pesticides, is the main factor that influences the ability of an arthropod pest population to develop resistance to pesticides. This then increases the proportion or frequency of resistant individuals.

However, there are sometimes inquires or issues regarding why pesticide resistance is rare or occurs less often in natural enemies (e.g., parasitoids and predators) in comparison to arthropod pests. There are two hypotheses that may possibly explain this phenomenon: 1) the food limitation and 2) pre-adaptation hypotheses.

Food Limitation Hypothesis

The food limitation hypothesis proposes that natural enemies tend to not readily develop or evolve resistance because pesticide applications, depending on frequency, reduce their food supply by killing susceptible prey. After applying pesticides, natural enemy populations tend to rebound at a slower rate in response to the lack of food, whereas insect and mite pests recover quickly in the absence of natural enemies. This is associated with a low density of prey, which results in natural enemies being negatively impacted in terms of consumption rates, fecundity and survival.

Pre-Adaptation Hypothesis

The pre-adaptation hypothesis advances the notion that herbivores or plant-feeding insects and mites are already pre-adapted to detoxify pesticides because they have evolved the ability to detoxify plant defensive compounds (e.g., secondary plant metabolites) such as plant alkaloids. Because plant-feeding insects and mites are typically exposed to a broad diversity of plants and thus plant allelochemicals (non-nutritional chemicals synthesized by an organism that affect growth, survival and behavior of certain member species), they are able to metabolize a broad range of chemical defenses by producing inducible enzymes in response to particular enzymes associated with specific compounds.

How Pests Overcome Defenses

The mechanisms, by which insect and mite pests can overcome these plant defenses, include detoxification of chemicals, altering target site or sites, reduced penetration and behavioral avoidance. As such, insect and mite pests are more likely to be pre-adapted to detoxify pesticides than natural enemies.

For example, the western flower thrips (Frankliniella occidentalis) has various metabolic detoxification enzyme systems designed to overcome secondary plant defenses, including esterases, cytochrome P-450 mono-oxygenases and glutathione S-transferases. These same enzyme systems can be used to detoxify insecticides, which may explain why western flower thrips has developed resistance to numerous insecticides with different modes of action.

The Effect On Natural Enemies

Well, how may this influence natural enemy populations? Any remaining resistant arthropod pests that survive, following exposure of a spray application, may have an abundant food supply (e.g. plants). However, those natural enemies that survive an application of an insecticide may find their food supply of prey substantially reduced. Therefore, resistance evolves more slowly in natural enemy populations than arthropod pest populations because natural enemies either starve or emigrate to a new location after spray applications have substantially reduced or eliminated their food source.

Excessive pesticide use may initially result in the suppression of arthropod pest populations. However, natural enemies such as parasitoids and predators may starve or emigrate in response to the low prey densities present, resulting in local extinction of natural enemies under intensive pesticide use.

As a consequence of natural enemy extinction, frequent applications of pesticides will be required, which may promote rapid resistance development in the prey population due to selection pressure. This results in an increase in the proportion or frequency of resistant individuals in the population.

Less pesticide use may still reduce natural enemy numbers. However, prey populations are likely to remain at sufficient levels to sustain natural enemy populations. Furthermore, reducing pesticide use may decrease resistance developing in prey populations. Applying pesticides at high rates may effectively suppress prey populations such that a natural enemy’s food supply is substantially reduced.

Additionally, in the absence of immigration, natural enemy populations tend to decline due to the frequency of applying pesticides. As such, natural enemies will starve. This can be avoided by allowing more susceptible individuals to survive, which may be fed upon by natural enemies. This also may slow the evolution of resistance by reducing selection pressure or the number of pesticide applications required; and thus, resistance developing in arthropod pest populations. Moreover, an increase in the survival of prey results in an abundant food supply for natural enemies, decreasing starvation and emigration. Finally, reduced pesticide use allows natural enemies to maintain or regulate arthropod pest populations over an extended time period.

Leave a Reply

One comment on “Pesticide Resistance In Natural Enemies

More From Insect Control...

March 20, 2017

Neonic Insect Control Alternative Offers Favorable Profile for Honeybees and Bumblebees

Altus, a butenolide class insecticide with the active ingredient flupyradifurone, will be available beginning May 1, and is labeled for greenhouse and nursery use on ornamental plants, vegetable transplants, and indoor vegetable production.

Read More

February 28, 2017

OHP Launches New Ovicide/Miticide, Announces Partnership With Vestaron

Applause is a new miticide that targets eggs and immature stages of several mite species. Through the Vestaron partnership, OHP will market Spear-O, a toxin-derived bioinsecticide.

Read More
Remote Sensing Feature

February 12, 2017

Using Remote Sensing to Optimize IPM in Greenhouses

Researchers at the University of California Davis are developing advanced remote sensing technologies to automate detection of insect pest infestations in greenhouses, which could revolutionize integrated pest management practices.

Read More
Latest Stories

March 20, 2017

Neonic Insect Control Alternative Offers Favorable Prof…

Altus, a butenolide class insecticide with the active ingredient flupyradifurone, will be available beginning May 1, and is labeled for greenhouse and nursery use on ornamental plants, vegetable transplants, and indoor vegetable production.

Read More

February 28, 2017

OHP Launches New Ovicide/Miticide, Announces Partnershi…

Applause is a new miticide that targets eggs and immature stages of several mite species. Through the Vestaron partnership, OHP will market Spear-O, a toxin-derived bioinsecticide.

Read More
Remote Sensing Feature

February 12, 2017

Using Remote Sensing to Optimize IPM in Greenhouses

Researchers at the University of California Davis are developing advanced remote sensing technologies to automate detection of insect pest infestations in greenhouses, which could revolutionize integrated pest management practices.

Read More
Adult Thrips feature

January 25, 2017

Tips to Stay Ahead of Aphids, Mites, and Thrips

Control these persistent pests with innovative chemistries that will expand your rotation options with new modes of action.

Read More
Effective pest control

January 12, 2017

Prevention and Early Intervention: The Keys to Biocont…

Advance preparation and starting out right helps you implement an effective biocontrol program that reduces pest pressure.

Read More
Two-spotted spider mites, adults and eggs

January 10, 2017

Pest Management Workshop to Take Place in Virginia on J…

Battlefield Farms will host the workshop, which is being coordinated by Virginia Cooperative Extension and will focus on new techniques in disease and insect control.

Read More
foxglove-aphid

November 29, 2016

How Greenhouse Growers Can Manage The Foxglove Aphid

Recent research is shedding new light on the foxglove aphid. Understanding host plants, identification, and biology will help growers deal with this pest.

Read More

October 25, 2016

Why Logic May Be The Best Defense Against Q-Biotype Whi…

Greenhouse Grower Editor Laura Drotleff says while you may feel you're in a lose-lose situation with pest control, there are some solutions that can help.

Read More
Downy mildew lesions on light coleus cultivars feature

October 4, 2016

Crop Protection Manufacturers Detail 2017 Early Order D…

Greenhouse Grower asked crop protection product manufacturers to send us the details for their 2017 Early Order Discount Programs and ongoing rebate programs, to provide you with a compiled knowledge resource of all discount offers at a time when you're making decisions for 2017.

Read More

September 28, 2016

Floriculture Industry Working To Solve The Whitefly Pro…

This summer, the floriculture industry has been faced with a dangerous new development — the detection of the Q-Biotype whitefly (Bemisia tabaci) in outdoor landscapes. It’s the first time that the Q-Biotype has been found in the U.S., outside of a greenhouse or wholesale nursery, since the pest was first detected on an ornamental plant in an Arizona greenhouse in December 2004. This year in Florida, there have been 47 detections of the Q since April, in retail nurseries and residential landscapes in 10 counties in Florida, from Miami-Dade to Duval County, primarily on hibiscus. Other hosts involved are crossandra, eggplant transplants, lantana, ficus, and porter weed. The detections have been in 17 retail nurseries, eight wholesale nurseries, 10 residential landscapes, and two agricultural fields. Other states have reported Q-Biotype detections this year, as well. The discovery of Q-Biotype whitefly in the landscape is troubling for the entire ornamentals industry, […]

Read More
Chrysanthemum Aphid

August 22, 2016

How To ID And Manage Black Aphids In Chrysanthemums

Growers in Michigan have recently been reporting a higher presence of this pest. Here are some tips on how to control it.

Read More
Greenhouse Whitefly

August 18, 2016

Vestaron Planning For More Research And Development Of …

On the heels of launching Spear-T, its first bioinsecticide, Vestaron has received additional financing that will be used to develop new products with new modes of action.

Read More
BioWorks Mycotrol

August 17, 2016

New Organic Mycoinsecticide From BioWorks Now Registere…

BioWorks’ Mycotrol can be used to manage whitefly, thrips, aphids, and other insects in greenhouses and nurseries.

Read More
Poinsettia, Heavy Whitefly Infestation -Lower Leaves, Insect - Feature

August 3, 2016

Tips For Successful Late-Season Whitefly Control

Managing late-season whiteflies successfully on poinsettia requires preventative measures put in to action early in the production cycle.

Read More
Aphids On Older Leaves

July 25, 2016

How You Can Stop Aphids By Understanding Their Interact…

Knowing which aphids target which crops and how aphids colonize and move on plants goes a long way toward setting up an effective management plan.

Read More
Eretmocerus eremicus adult, Parasitic Wasp

July 2, 2016

Beneficial Predators Can Help Control Whiteflies On Poi…

Whitefly infestations are a recurring problem that often plagues poinsettia growers. Successfully keep them in check by letting beneficial predators take the work out of pest control.

Read More
Greenhouse Whitefly

June 26, 2016

Michigan State University Offers Tips On Whitefly Manag…

Whiteflies are making headlines in Florida, but they are found across the U.S. Michigan State experts say it’s important to know how to manage each type of whitefly.

Read More
Whitefly

June 2, 2016

Breaking News: Florida Growers Reporting Major Whitefly…

Reports have come from the Florida Keys to Palm Beach County that whitefly populations in landscapes are reaching unprecedented levels and are not responding to pesticide applications. Biotype-Q has been found in four different communities. University of Florida/Institute of Food and Agricultural Science researchers are working with USDA-APHIS, USDA-ARS, the Florida Department of Agriculture, and growers and landscape professionals to manage the developing problem.

Read More