University of FloridaSolutions for Your Life

Download PDF
Publication #ENY-841

Causes and Management of Insect and Mite Resistance in Strawberry Production1

James F. Price and Curtis Nagle2

Resistance of arthropods to crop management chemicals has been problematic since the early era of synthetic organic pesticides. During the late 1990s, the twospotted spider mite (Tetranychus urticae Koch) became resistant to abamectin, the miticide used in strawberry culture. Since then, several new miticides, including acequinocyl, bifenazate, etoxazole, fenpyroximate, hexythiazox, and spiromesifen, have been integrated into strawberry production; overuse of abamectin has ceased; and abamectin once again is effective in rotation with the new materials. This latter development could prove temporary, especially if growers again use abamectin regularly.

Poor performance of pesticides does not always indicate pest resistance. Such factors as pesticide degradation in storage, hydrolysis in acid or alkaline preparations, applications to an incorrect life stage of the pest, or other inadequate application procedures may contribute to poor control.

A Definition of Resistance

Pest populations can be susceptible or resistant to a pesticide. Resistance occurs when a formerly susceptible pest population becomes significantly less susceptible to a properly applied pesticide. Pesticide resistance is a population-based phenomenon in which the group genetic composition shifts and individuals with genes that confer resistance to a pesticide begin to dominate the population, reducing the pesticide’s effectiveness .

Establishment of Resistance

Resistant populations are protected from formerly effective pesticides through one or more means. For example, resistant pests may: (1) deactivate (break down) the toxin; (2) sequester the toxin (safely store it within their bodies); (3) avoid the toxin; (4) excrete the toxin from their bodies more effectively; (5) have an altered target site that will not accumulate the toxin; or (6) reduce the permeability by the toxin through their exoskeletons (“shells”).

Individuals within a susceptible pest population often vary in their level of susceptibility; however, the non-susceptible type occurs only very rarely. When a pesticide is applied repeatedly, the susceptible pests die and the resistant ones survive, mate with other survivors and reproduce. Some of their offspring inherit the parents' characteristic for survival. Upon additional applications, the susceptible offspring within the remaining population die and the resistant ones survive, mate with other survivors and produce more offspring. Further applications additionally select for the resistant individuals until that form (genotype) is common. The population then is regarded as resistant and the effectiveness of the pesticide is lost.

Resistance Management

Resistance can develop rapidly with pests that have many generations per year, when multiple generations are exposed to a pesticide, and when new individuals do not move into a treated area to dilute the frequency of the resistant genes. Some of these factors occurred on strawberry farms in the 1990s, contributing to development of abamectin resistance in spider mites.

The main objectives of on-farm resistance management programs should be to minimize the number of exposures of pests to pesticides with a similar mode of action and to use non-chemical approaches to arthropod management. (Mode of action is the specific activity of the toxin that results in the death of the pest. For instance, one mode of action is to inhibit mitochondrial complex I electron transport. This kills pests by preventing them from producing energy in affected cells, essentially “starving” them.)

Repeated exposures to a pesticide are the primary drivers of resistance, but much can be done to manage pests by means other than chemicals. Care can be taken to rotate strawberries with other crops, use pest-resistant varieties, plant pest-free transplants, conserve and release natural enemies, etc. Pest-specific tactics are available for particular situations; for instance, removal of all ripe strawberries from a field will eliminate reproductive sites for sap beetles.

Strawberry fields should be scouted weekly and pesticide applications made only when pest densities approach economic injury levels. When pesticide use is required, products should be rotated among the different modes of action indicated on many modern product labels. A list of modes of action can be found by selecting “MoA Classification Scheme” at the Insecticide Resistance Action Committee Website: http://www.irac-online.org [version 7.2 April, 2012].

Tables 1through 3 present insecticide and miticide modes of action summaries for Florida strawberry production. Sound rotation plans often recommend pesticides of one mode of action for one pest generation and a pesticide of a different mode of action for another generation. If multiple pesticide applications are required, rotations should continue through all practical modes of action before returning to a previously used one. The use of certain unique products with known general modes of action (such as soaps and oils) is unlikely to result in pest resistance, and no codes are assigned these products. These products can be used without regard to a rotation plan for resistance management.

When pesticides are used, it is important to assure that fresh, fully potent pesticides are prepared and applied in accordance with label directions. Aqueous pesticidal preparations should be adjusted to near neutral pH (pH 7.0) or as specified by the label. Sprayer calibration, nozzle condition and pressure, and spray placement must be correct. Applications also should be timed and directed to contact the most susceptible life stage of the pest.

Conclusion

Episodes of pest resistance to popular pesticides can cause yield losses, reduction of fruit quality, added control costs, environmental degradation, and emotional stress among farmers. These consequences can be alleviated if resistance management is practiced throughout the strawberry industry. If they minimize pesticide application by depending more on biological and cultural pest control measures, and take care not to expose pest populations to pesticides with identical modes of action, growers can avoid causing pesticide resistance.

Tables

Table 1. 

Mode of action of insecticides and miticides registered for use in Florida's strawberry crops (presented by active ingredient). (Insecticide Resistance Action Committee (IRAC) mode of action classification codes version 7.2).

Active Ingredient (common name)

Trade Name Examples

Mode of Action Code

1,3-dichloropropene

Inline

no codea

Telone

abamectin

Abacus

6

Agri-Mek

acequinocyl

Kanemite

20B

acetamiprid

Assail

4A

avermectin & bifenthrin

Athena

6 & 3A

azadirachtin

Aza-Direct

un

Azatrol

Bacillus thuringiensis aizawai

Agree

11A

Xentari

Bacillus thuringiensis kurstaki

Dipel

11A

Javelin

Beauveria bassiana

Botanigard

no codeb

 

Mycotrol

 
 

Naturalis

 

bifenazate

Acramite

un

bifenthrin

Brigade

3A

bifenthrin & avermectin

Athena

3A & 6

bifenthrin & imidacloprid

Brigadier

3A & 4A

buprofezin

Courier

16

carbaryl

Sevin

1A

chlorantraniliprole

Coragen

28

chlorantraniliprole & thiamethoxam

Voliam Flexi

28 & 4A

chlorpyrifos

Govern

1B

Lorsban

Chromobacterium subtsugae

MBI-203

no code

clarified hydrophobic extract of neem oil

Trilogy

no code

diazinon

Diazinon

1B

etoxazole

Zeal

10B

fenbutatin oxide

Vendex

12B

fenpropathrin

Danitol

3A

fenpyroximate

Portal

21A

flubendamide

Synapse

28

hexythiazox

Savey

10A

imidacloprid

Admire

4A

Provado

imidacloprid & bifenthrin

Brigadier

4A & 3A

iron phosphate

Sluggo

no code

Isaria fumosorosea

PFR-97

no code

Preferal

malathion

Malathion

1B

metaldehyde

Deadline

no code

Slug-Fest

metam sodium

Vapam

no code

methoxyfenozide

Intrepid

18

naled

Dibrom

1B

novaluron

Rimon

15

potassium salts of fatty acids

AllPro Insecticidal Soap

no code

M-Pede

pyrethrins

Diatect

3A

 

PyGanic

 
 

Pyrenone

 
 

Pyreth-It

 

pyrethrins & rotenone

Pyrellin

3A & 21B

pyriproxyfen

Esteem

7C

refined petroleum distillate

Ultra-Fine Oil

no code

rotenone & pyrethrins

Pyrellin

21B & 3A

s-methoprene

Extinguish

7A

sorbitol octanoate

SorbiShield

no code

spinetoram

Radiant

5

spinosad

Entrust

5

Spintor

spiromesifen

Oberon

23

sucrose octanoate

SucraShield

no code

thiamethoxam

Actara

4A

Platinum

thiamethoxam & chlorantraniliprole

Voliam Flexi

4A & 28

aWhen no mode of action code is present, there is no code established and the product can be used without regard to mode of action.

b”un” means this compound has an unknown or uncertain mode of action.

Table 2. 

Mode of action of insecticides and miticides registered for use in Florida's strawberry crops (presented by mode of action code). (Insecticide Resistance Action Committee mode of action classification code version 7.2).

Mode of Action Code

Active Ingredient (common name)

Trade Name Examples

no codea

1,3-dichloropropene

Inline

 

Telone

 

Beauveria bassiana

Botanigard

 

Mycotrol

 

Naturalis

 

Chromobacterium subtsugae

MBI-203

 

clarified hydrophobic extract of neem oil

Trilogy

 

iron phosphate

Sluggo

 

Isaria fumosorosea

PFR-97

 

Preferal

 

metaldehyde

Deadline

 

Slug-Fest

 

metam sodium

Vapam

 

potassium salts of fatty acids

AllPro Insecticidal Soap

 

M-Pede

 

refined petroleum distillate

Ultra-fine Oil

 

sorbitol octanoate

SorbiShield

 

sucrose octanoate

SucraShield

1A

carbaryl

Sevin

1B

chlorpyrifos

Govern

 

Lorsban

 

diazinon

Diazinon

 

malathion

Malathion

 

naled

Dibrom

3A

bifenthrin

Brigade

 

fenpropathrin

Danitol

 

pyrethrins

Diatect

   

PyGanic

   

Pyrenone

   

Pyreth-It

3A & 21B

pyrethrins & rotenone

Pyrellin

3A & 4A

bifenthrin & imidacloprid

Brigadier

3A & 6

bifenthrin & avermectin

Athena

4A

acetamiprid

Assail

 

imidacloprid

Admire

 

Provado

 

thiamethoxam

Actara

 

Platinum

4A & 28

thiamethoxam & chlorantraniliprole

Voliam Flexi

4A & 3A

imidacloprid & bifenthrin

Brigadier

5

spinetoram

Radiant

 

spinosad

Entrust

 

Spintor

6

abamectin

Abacus

Agri-Mek

6 & 3A

avermectin & bifenthrin

Athena

7A

s-methoprene

Extinguish

7C

pyriproxyfen

Esteem

10A

hexythiazox

Savey

10B

etoxazole

Zeal

11A

Bacillus thuringiensis aizawai

Agree

 

Xentari

 

Bacillus thuringiensis kurstaki

Dipel

 

Javelin

12B

fenbutatin oxide

Vendex

15

novaluron

Rimon

16

buprofezin

Courier

18

methoxyfenozide

Intrepid

20B

acequinocyl

Kanemite

21A

fenpyroximate

Portal

21B & 3A

rotenone & pyrethrins

Pyrellin

23

spiromesifen

Oberon

28

chlorantraniliprole

Coragen

flubendamide

Synapse

28 & 4A

chlorantraniliprole & thiamethoxam

Voliam Flexi

unb

azadirachtin

Aza-Direct

 

Azatrol

 

bifenazate

Acramite

aWhen no mode of action code is present, there is no code established and the product can be used without regard to mode of action.

b”un” means this compound has an unknown or uncertain mode of action.

Table 3. 

Mode of action of insecticides and miticides registered for use in Florida's strawberry crops (presented by trade name). (Insecticide Resistance Action Committee mode of action classification codes version 7.2).

Trade Name Examples

Active Ingredient (common name)

Mode of Action Code

Abacus

abamectin

6

Acramite

bifenazate

una

Actara

acetamiprid

4A

Admire

imidacloprid

4A

Agree

Bacillus thuringiensis aizawai

11A

Agri-Mek

abamectin

6

AllPro Insecticidal Soap

potassium salts of fatty acids

no codeb

Assail

acetamiprid

4A

Athena

avermectin & bifenthrin

6 & 3A

Aza-Direct

azadirachtin

un

Azatrol

azadirachtin

un

Botanigard

Beauveria bassiana

no code

Brigade

bifenthrin

3A

Brigadier

bifenthrin & imidacloprid

3A & 4A

Coragen

chlorantraniliprole

28

Courier

buprofezin

16

Danitol

fenpropathrin

3A

Deadline

metaldehyde

no code

Diatect

pyrethrins

3A

Dipel

Bacillus thuringiensis kurstaki

11A

Diazinon

diazinon

1B

Dibrom

naled

1B

Entrust

spinosad

5

Esteem

pyriproxyfen

7C

Extinguish

s-methoprene

7A

Govern

chlorpyrifos

1B

Intrepid

methoxyfenozide

18

InLine

1,3-dichloropropene

no code

Javelin

Bacillus thuringiensis kurstaki

11A

Kanemite

acequinocyl

20B

Lorsban

chlorpyrifos

1B

M-Pede

potassium salts of fatty acids

no code

Malathion

malathion

1B

MBI-203

Chromobacterium subtsugae

no code

Mycotrol

Beauveria bassiana

no code

Naturalis

Beauveria bassiana

no code

Oberon

spiromesifen

23

PFR-97

Isaria fumosorosea

no code

Platinum

acetamiprid

4A

Portal

fenpyroximate

21A

Preferal

Isaria fumosorosea

no code

Provado

imidacloprid

4A

PyGanic

pyrethrins

3A

Pyrellin

pyrethrins & rotenone

3A & 21B

Pyrenone

pyrethrins

3A

Pyreth-It

pyrethrins

3A

Radiant

spinetoram

5

Rimon

novaluron

15

Savey

hexythiazox

10A

Sevin

carbaryl

1A

Slug-Fest

metaldehyde

no code

Sluggo

iron phosphate

no code

SorbiShield

sorbitol octanoate

no code

Spintor

spinosad

5

SucraShield

sucrose octanoate

no code

Synapse

flubendamide

28

Telone

1,3-dichloropropene

no code

Trilogy

clarified hydrophobic extract of neem oil

no code

Ultra-Fine Oil

refined petroleum distillate

no code

Vapam

metam sodium

no code

Vendex

fenbutatin oxide

12B

Voliam Flexi

thiamethoxam & chlorantraniliprole

4A & 28

Xentari

Bacillus thuringiensis aizawai

11A

Zeal

etoxazole

10B

a”un” means this compound has an unknown or uncertain mode of action.

bWhen no mode of action code is present, there is no code established and the product can be used without regard to mode of action.

Footnotes

1.

This document is ENY-841 (IN713), a publication of the Department of Entomology and Nematology, Florida Cooperative Extension Service, IFAS, University of Florida. Publication date November 2007. Revised November 2012. Please visit the EDIS website at http://edis.ifas.ufl.edu.

2.

James F. Price, associate professor, Gulf Coast Research and Education Center; and Curtis Nagle, biological scientist, Gulf Coast Research and Education Center. Cooperative Extension Service, IFAS, University of Florida, Gainesville, FL 32611.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.