Regulatory Directive: Voluntary Pesticide Resistance-Management Labelling Based on Target Site/Mode of Action

October 6, 1999
ISBN: N/A
Cat. No.: N/A
(DIR99-06)

The Pest Management Regulatory Agency (PMRA) has introduced a voluntary pesticide resistance-management labelling initiative based on target site/mode of action for agricultural uses of herbicides, fungicides/bactericides and insecticides/acaricides. This document provides schemes of classification of pesticides according to their sites/modes of action (Appendices I-III), a standard format for showing group identification symbols on the end-use product labels, and guidelines for labelling resistance-management strategies in the use directions. It covers both new products governed by the registration process and old (existing) products governed by the re-evaluation process.

This document replaces Regulatory Proposal Pro96-03, Pesticide Resistance Management Labelling, published for public comments in December 1996. Comments received were taken into consideration in the final version of the guidelines.

Canada, the United States (U.S.) and Mexico, working cooperatively under the auspices of the North American Free Trade Agreement (NAFTA), are developing and publishing these guidelines for voluntary pesticide resistance-management labelling to a uniform standard for implementation in North America. This activity forms part of the work done by the Risk Reduction Subcommittee of the NAFTA Technical Working Group (TWG) on Pesticides. A uniform approach across North America will help reduce the development of pesticide resistance and support joint registration decisions by providing consistency in the resistance-management labelling being considered for approval in any or all of the NAFTA countries.

Table of Contents

1.0 Scope

This Directive applies to resistance-management labelling for herbicide, fungicide/ bactericide and insecticide/acaricide products that are intended for general agricultural use. This document covers both new products governed by the registration process and old (existing) products governed by the re-evaluation process.

2.0 Implementation

The implementation of this program is to be on a voluntary basis by the pesticide industry. Close cooperation of all registrants is required to achieve this important task. Registrants are encouraged to add the resistance-management grouping symbols and statements to both new and existing product labels. Revisions to labels for existing products can be made at the next printing of the labels. All new and existing products are encouraged to have the resistancemanagement grouping symbols and statements on the label by January 1, 2004. Information on amending labels can be obtained from the PMRA Information Service at 1-800-267-6315 (toll-free within Canada) or (613) 736-3799. In view of the importance of resistance management to a sustainable pest-management system, the PMRA will closely monitor the progress of the industry's implementation of resistance-management labelling.

3.0 Introduction

The PMRA, the U.S. Environmental Protection Agency (EPA) and the Cicoplafest of Mexico are committed to encouraging the development of sustainable pest-management systems. Under the auspices of NAFTA, Canada, the U.S. and Mexico have joined together to develop and publish guidelines for voluntary pesticide resistance-management labelling for implementation in North America. The development of these guidelines is part of the activities of the Risk Reduction Subcommittee of the NAFTA TWG on Pesticides. A uniform approach across North America will help reduce the development of pesticide resistance and support joint registration decisions by providing consistency in resistance-management labelling being considered for approval in any or all of the NAFTA countries.

Pesticide resistance, defined for the purpose of this document as a heritable and significant decrease in the sensitivity of a pest population to a pesticide, reduces the field performance of pesticides. Pests include insects, mites, weeds, fungi and bacteria. The management of pesticide resistance development is an important part of sustainable pest-management and this, in conjunction with alternative pest-management strategies and integrated pest-management (IPM) programs, can make significant contributions to reducing risks to humans and the environment. In support of this goal, the purpose of this document is to provide guidance on resistance-management labelling to registrants.

Pesticides are important pest-management tools. Many pesticides have gradually lost their effectiveness due to the development of resistance by pests. An important proactive pesticide resistance-management strategy is to avoid the repeated use of a particular pesticide, or pesticides, that have a similar site of action, in the same field, by rotating pesticides with different sites of action. This approach will slow the development of one important type of resistance, target-site resistance, without resorting to increased rates and frequency of application and will prolong the useful life of pesticides.

A resistance-management strategy should also consider more detailed information regarding cross-resistance between pesticides with different modes of action resulting from the development of other types of resistance (e.g., enhanced metabolism, reduced penetration, or behavior changes). All members of a class may not be cross-resistant based merely on mode of action. However, this labelling initiative will provide pesticide users with easy access to important information regarding target-site resistance, the cornerstone of most resistancemanagement programs.

To ensure consistency in pesticide grouping and labelling, and to contribute to the management of the pesticide-resistance problem, the following guidelines have been developed for agricultural uses of herbicides, fungicides/bactericides and insecticides/acaricides. The following classification schemes are based on target site of action.

4.0 Site of Action Grouping and Identification Symbol

Herbicides, fungicides/bactericides and insecticides/acaricides are separately grouped according to their primary sites of action (or target site modes of action) by various technical/research committees consisting of representatives of the pesticide industry, researchers, extension specialists and regulatory officials. The industry committees providing guidance on the pesticide groupings were the Herbicide Resistance Action Committee (HRAC), the Fungicide Resistance Action Committee (FRAC) and the Insecticide Resistance Action Committee (IRAC). Primary guidance for herbicides was provided by the Weed Science Society of America (WSSA). The site of action groups plus the identifier numbers for herbicides, fungicides/bactericides and insecticides/acaricides are located in Appendix I, II and III, respectively.

The site of action identification symbol should be shown on all end-use product labels (except products for homeowner/residential uses) in a standard format as outlined below, and should:

  • be located on the front panel (preferably at the upper right corner), surrounded by a black rectangle;
  • be in black on a white background except the site of action number(s), which is to be white on a black background with a clear white gap between the site of action number(s); and
  • include the words "Group" and "Herbicide" or "Fungicide" or "Insecticide" in capital letters, and between these words the number(s) representing the site of action group(s) of each active ingredient(s). Where a product has two or more active ingredients, and these are represented by two or more sites of action, then two or more appropriate site of action identifier numbers should be used. For products containing an active ingredient that has multiple sites of action, the letter "M" should be used to represent the site of action group. Alternatively, if sites of action are known, specify each site of action by the appropriate number.

Example 1: Product containing one or more active ingredients of the same site of action.

Group-1-Herbicide

Example 2: Product containing two or more active ingredients represented by two or more sites of action.

Group-1-2-3-Herbicides

Example 3: Outside label for prepackaged products where each component is in a different container.

Group-1-Herbicide and Group-2-Herbicide

Example 4: Premixture of a fungicide and an insecticide.

Gropup-1-Fungicide and Group-2-Insecticide

5.0 Resistance-Management Statements

Resistance-management statements are recommended to be included in the use directions for all end-use products for the control of weeds, plant pathogens (diseases), insects and arthropods (except products for homeowner/residential uses) under the heading "Resistance-Management Recommendations". The section "Resistance-Management Recommendations" should be segregated under the "General" portion of "Use Directions" in the U.S., and under "Use Directions" in Canada. Product-specific labelling is recommended. The recommended standard resistance-management labelling statements listed below focus on the prevention and mitigation of pest resistance and should be used where applicable. Efforts should be made to include all appropriate active ingredients and products. These recommendations should also be included in any product-specific literature.

5.1 Herbicides

For resistance management, (name of product) is a Group (site of action group number) herbicide. Any weed population may contain or develop plants naturally resistant to (name of product) and other Group (site of action group number) herbicides. The resistant biotypes may dominate the weed population if these herbicides are used repeatedly in the same field. Other resistance mechanisms that are not linked to site of action, but specific for individual chemicals, such as enhanced metabolism, may also exist. Appropriate resistance-management strategies should be followed.

To delay herbicide resistance:

  • Where possible, rotate the use of (name of product) or other Group (site of action group number) herbicides with different herbicide groups that control the same weeds in a field.
  • Use tank mixtures with herbicides from a different group when such use is permitted.
  • Herbicide use should be based on an IPM program that includes scouting, historical information related to herbicide use and crop rotation, and considers tillage (or other mechanical), cultural, biological and other chemical control practices.
  • Monitor treated weed populations for resistance development.
  • Prevent movement of resistant weed seeds to other fields by cleaning harvesting and tillage equipment and planting clean seed.
  • Contact your local extension specialist or certified crop advisors for any additional pesticide resistance-management and/or integrated weed-management recommendations for specific crops and weed biotypes.
  • For further information or to report suspected resistance, contact (company representatives) at (toll free number) or at (Internet site).

Note The above is a standard statement for products containing one or more active ingredients from the same group. For products containing two or more active ingredients from different groups, the statement should be modified to reflect the situation.

For example:

For resistance management, please note that (name of product) is both a Group (site of action group number) and a Group (site of action group number) herbicide. Any weed population may contain plants naturally resistant to Group (site of action group number) and/or Group (site of action group number) herbicides. The resistant biotypes may dominate the weed population if these herbicides are used repeatedly in the same fields.

5.2 Fungicides and Bactericides

For resistance management, please note that (name of product) contains a Group (group number) (fungicide/bactericide). Any (fungal/bacterial) population may contain individuals naturally resistant to (name of product) and other Group (group number) (fungicides/bactericides). A gradual or total loss of pest control may occur over time if these (fungicides/bactericides) are used repeatedly in the same fields. Other resistance mechanisms that are not linked to site of action but specific for individual chemicals, such as enhanced metabolism, may also exist. Appropriate resistance-management strategies should be followed.

To delay fungicide/bactericide resistance:

  • Where possible, rotate the use of (name of product) or other Group (site of action group number) fungicides/bactericides with different groups that control the same pathogens.

Note This statement may be modified if repeated application is necessary, e.g., Avoid application of more than (maximum number) and consecutive sprays of (name of product) or other (fungicides/bactericides) in the same group in a season.

  • Use tank mixtures with fungicide/bactericides from a different group when such use is permitted.
  • Fungicide/bactericide use should be based on an IPM program that includes scouting, historical information related to pesticide use and crop rotation and considers cultural, biological and other chemical control practices.
  • Monitor treated fungal/bacterial populations for resistance development.
  • If disease continues to progress after treatment with this product, do not increase the use rate. Discontinue use of this product, and switch to another (fungicide/bactericide) with a different target site of action, if available.
  • Contact your local extension specialist or certified crop advisors for any additional pesticide resistance-management and/or IPM recommendations for specific crops and pathogens.
  • For further information and to report suspected resistance, contact (company representatives) at (toll free number) or at (Internet site).

Note The above is a standard statement for products containing one or more active ingredients from the same group. For products containing two or more active ingredients from different groups, the statement should be modified to reflect the situation.

For example:

For resistance management, please note that (name of product) contains both a Group (group number) and Group (group number) fungicide/bactericide. Any fungal/bacterial population may contain individuals naturally resistant to (name of product) and other Group (group number) or Group (group number) fungicides/bactericides. A gradual or total loss of pest control may occur over time if these (fungicides/bactericides) are used repeatedly in the same fields.

5.3 Insecticides and Acaricides

For resistance management, please note that (name of product) contains a Group (group number) insecticide (or acaricide). Any (insect/mite) population may contain individuals naturally resistant to (name of product) and other Group (group number) (insecticides/acaricides). The resistant individuals may dominate the insect/mite population if this group of insecticides/acaricides are used repeatedly in the same fields. Other resistance mechanisms that are not linked to site of action but are specific for individual chemicals, such as enhanced metabolism, may also exist. Appropriate resistance-management strategies should be followed.

To delay insecticide resistance:

  • Where possible, rotate the use of (name of product) or other Group (site of action group number) insecticides/acaricides with different groups that control the same pests in a field.

Note The above statement may be modified on a pest by pest basis if a number of applications each year are necessary, e.g., Avoid application of more than (maximum number) and consecutive sprays of (name of product) or other insecticides in the same group in a season.

  • Use tank mixtures with insecticides/acaricides from a different group when such use is permitted.
  • Insecticide/acaricide use should be based on an IPM program that includes scouting, record keeping, and considers cultural, biological and other chemical control practices.
  • Monitor treated pest populations for resistance development.
  • Contact your local extension specialist or certified crop advisors for any additional pesticide resistance-management and/or IPM recommendations for the specific site and pest problems in your area.
  • For further information or to report suspected resistance contact (company representatives) at (toll free number) or at (Internet site).

Note The above is a standard statement for products containing one or more active ingredients from the same group. For products containing two or more active ingredients from different groups, the statement should be modified to reflect the situation.

For example:

For resistance management, please note that (name of product) contains both a Group (group number) and Group (group number) insecticides/acaricides. Any insect/mite population may contain individuals naturally resistant to (name of product) and other Group (group number) or Group (group number) insecticides/ acaricides. The resistant individuals may dominate the insect/mite population if these insecticides/acaricides are used repeatedly in the same fields.

6.0 Pesticides of Unspecified Groups

Some herbicides, fungicides, bactericides, insecticides and acaricides have not been assigned to any particular target site/mode of action group or have not been shown on the lists in this document because of the lack of clear understanding of their target site/mode of action or the absence of a history of resistance development for the product. The registrants should establish the appropriate group identifications for their products in consultation with representatives of the pesticide industry, researchers, extension specialists and regulatory officials. The use directions should include the appropriate resistance-management statements for this product, i.e., herbicides, fungicides/ bactericides and insecticides/acaricides.

The above procedure also applies to new pesticides when they are registered for use. The pesticide lists (Appendices I-III) will be updated from time to time (approximately annually) to include product names and/or new/revised site/mode of action classification. The revised appendicies will be posted on the Agency's web site under the title of this Regulatory Directive. Hard copies will be made available from the Agency upon request.

Appendix I Herbicide Groups Based on Sites of Action

This list is based on the Herbicide Classification of the Weed Science Society of America (Weed Technology, 1997, 11:384-393). Microbial herbicides are not included.

Group 1

Site of Action: Inhibitors of acetyl CoA carboxylase ACCase

Chemical Family: Aryloxyphenoxy propionates

Active Ingredient:

  • clodinafop-propargyl
  • diclofop-methyl
  • fenoxaprop-ethyl
  • fenoxaprop-p-ethyl
  • fluazifop-p-butyl
  • fluazifop-butyl
  • quizalofop-ethyl
  • quizalofop-p-ethyl

Chemical Family: Cyclohexanediones

Active Ingredient:

  • clethodim
  • sethoxydim
  • tralkoxydim

Group 2

Site of Action: Inhibition of acetolactate synthase (ALS) and also called aceto-hydroxyacid synthase (AHAS)

Chemical Family: Sulfonylureas

Active Ingredient:

  • chlorimuron
  • chlorsulfuron
  • ethametsulfuron-methyl
  • metsulfuron-methyl
  • nicosulfuron
  • prosulfuron
  • rimsulfuron
  • sulfosulfuron
  • thifensulfuron-methyl
  • triasulfuron
  • tribenuron-methyl
  • triflusulfuron-methyl

Chemical Family: Imidazolinones

Active Ingredient:

  • imazamethabenz
  • imazamox
  • imazapyr
  • imazethapyr

Chemical Family: Pyrimidinylthio-benzoateFootnote 4

Chemical Family: Triazolopyrimidime

Active Ingredient:

  • flumetsulam

Group 3

Site of Action: Microtubule assembly inhibitors

Chemical Family: Dinitroanilines

Active Ingredient:

  • ethalfluralin
  • pendimethalin
  • trifluralin

Chemical Family: Pyridazine

Active Ingredient:

  • dithiopyr

Site of Action: Unknown

Chemical Family: None

Active Ingredient:

  • chlorthal-dimethyl (DCPA)

Group 4

Site of Action: Synthetic auxins (action like indoleacetic acid)

Chemical Family: Phenoxys

Active Ingredient:

  • 2,4-D
  • 2,4-DB
  • dichlorprop (2,4-DP)
  • MCPA
  • MCPB
  • mecoprop (MCPP)

Chemical Family: Benzoic acids

Active Ingredient:

  • dicamba

Chemical Family: Carboxylic acids

Active Ingredient:

  • clopyralid
  • fluroxypyr
  • picloram
  • triclopyr

Chemical Family: Quinoline carboxylic acid

Active Ingredient:

  • quinclorac

Chemical Family: Semicarbazone

Active Ingredient:

  • diflufenzopyr

Group 5

Site of Action: Inhibitors of photosynthesis at photosystem II Site A

Chemical Family: Triazines

Active Ingredient:

  • atrazine
  • cyanazine
  • prometon
  • prometryn
  • simazine

Chemical Family: Triazinones

Active Ingredient:

  • hexazinone
  • metribuzin

Chemical Family: Uracils

Active Ingredient:

  • bromacil
  • terbacil

Chemical Family: Pyridazinone

Active Ingredient:

  • pyrazon

Chemical Family: Phenyl-carbamates

Active Ingredient:

  • desmedipham
  • phenmedipham

Group 6

Site of Action: Similar to group 5, but different binding behavior

Chemical Family: Nitriles

Active Ingredient:

  • bromoxynil

Chemical Family: Benzothiadiazoles

Active Ingredient:

  • bentazon

Chemical Family: Phenyl-pyridazine

Active Ingredient:

  • pyridate

Group 7

Site of Action: Inhibitors of photosynthesis at photosystem II Site B

Chemical Family: Ureas

Active Ingredient:

  • diuron
  • linuron
  • metobromuron
  • monolinuron
  • siduron
  • tebuthiuron

Chemical Family: Amide

Active Ingredient:

  • propanil

Group 8

Site of Action: Inhibition of lipid synthesis, not ACCase inhibition

Chemical Family: Thiocarbamates

Active Ingredient:

  • butylate
  • cycloate
  • EPTC
  • pebulate
  • triallate
  • vernolate

Chemical Family: None

Active Ingredient:

  • bensulide

Site of Action: Unknown

Chemical Family: None

Active Ingredient:

  • difenzoquat

Group 9

Site of Action: Inhibitors of 5- enolpyruvylshikimate-3- phosphate (EPSP) synthase

Chemical Family: None

Active Ingredient:

  • glyphosate

Group 10

Site of Action: Inhibitors of glutamine synthetase

Chemical Family: None

Active Ingredient:

  • glufosinate-ammonium

Group 11

Site of Action: Bleaching: Inhibitors of carotenoid biosynthesis (unknown target)

Chemical Family: Triazole

Active Ingredient:

  • amitrole

Group 12

Site of Action: Bleaching: Inhibitors of carotenoid biosynthesis at the phytoene desaturase step (PDS)

Chemical Family: PyridazinoneFootnote 4

Chemical Family: NicotinanilideFootnote 4

Chemical Family: Others

Active Ingredient:

Group 13

Site of Action: Bleaching: Inhibition of all diterpenes

Chemical Family: Isoxazolidinone

Active Ingredient:

  • clomazone

Group 14

Site of Action: Inhibitors of protoporphyrinogen oxidase (PPO)

Chemical Family: Diphenylethers

Active Ingredient:

  • acifluorfen
  • fomesafen
  • oxyfluorfen

Chemical Family: N-phenylphthalimidesFootnote 4

Chemical Family: Oxadiazole

Active Ingredient:

  • oxadiazon

Chemical Family: TriazolinoneFootnote 4

Group 15

Site of Action: Unknown

Chemical Family: Chloroacetamides

Active Ingredient:

  • metolachlor
  • s-metolachlor
  • propyzamide
  • dimethenamid

Chemical Family: Acetamides

Active Ingredient:

  • napropamide

Chemical Family: OxyacetamidesFootnote 4

Group 16

Site of Action: Unknown

Chemical Family: Benzofuran

Active Ingredient:

  • ethofumesate

Group 17

Site of Action: Unknown

Chemical Family: Organoarsenicals

Active Ingredient:

  • Arsenic, present as monosodium salt of methylarsonic acid (MSMA)

Group 18

Site of Action: Inhibits dihydropteroate (DHP) synthase step

Chemical Family: Carbamate

Active Ingredient:

  • asulam

Group 19

Site of Action: Inhibits indoleacetic acid action

Chemical Family: Phthalamate

Active Ingredient:

  • naptalam

Group 20

Site of Action: Inhibits cell wall synthesis Site A

Chemical Family: Nitrile

Active Ingredient:

  • dichlobenil

Group 21

Site of Action: Inhibits cell wall synthesis Site B

Chemical Family: Benzamide

Active Ingredient:

  • isoxaben

Group 22

Site of Action: Photo system I-electron diverters

Chemical Family: Bipyridyliums

Active Ingredient:

  • diquat
  • paraquat

Group 23

Site of Action: Inhibitors of mitosis

Chemical Family: Carbamates

Active Ingredient:

  • chlorpropham

Group 24

Site of Action: Uncoupling membrane disruptors

Chemical Family: Dinitrophenol

Active Ingredient:

  • dinoseb

Group 25

Site of Action: Unknown

Chemical Family: Arylaminopropionic acid

Active Ingredient:

  • flamprop-methyl

Group 26

Site of Action: Unknown

Chemical Family: None

Active Ingredient:

  • trichloroacetic acid (TCA)

Group 27

Site of Action: Unknown

Chemical Family: Various

Active Ingredient:

Group 28

Site of Action: Inhibition of 4-hydroxyphenyl- pyruvatedioxygenase (4-HPPD)

Chemical Family: benzoylisoxazoleFootnote 4

Chemical Family: IsoxazoleFootnote 4

Chemical Family: PyrazoleFootnote 4

Chemical Family: TriketoneFootnote 4

Appendix II Fungicide/Bactericide Groups Based on Activity Group/Sites of Action

This list is based on the fungicide listing compiled by the Fungicide Resistance Action Committee (FRAC). FRAC is a Specialist Technical Group of the Global Crop Protection Federation (GCPF). Microbial fungicides are not included.

Group 1

Activity Group/ Site of Action: Inhibition of tubulin formation

Chemical Group: Benzimidazole

Active Ingredient:

  • benomyl
  • carbendazim
  • thiabendazole
  • thiophanate-methyl

Group 2

Activity Group/ Site of Action: Affect cell division, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis, and metabolism

Chemical Group: Dicarboximide

Active Ingredient:

  • iprodione
  • vinclozolin

Group 3

Activity Group/ Site of Action: Demethylation Inhibitor (DMI): Inhibition of demethylation in sterol biosynthesis

Chemical Group: ImidazolesFootnote 4

Chemical Group: Piperazine

Active Ingredient:

  • triforine

Chemical Group: PyridineFootnote 4

Chemical Group: PyrimidinesFootnote 4

Chemical Group: Triazoles (includes conazoles)

Active Ingredient:

  • myclobutanil
  • difenoconazole
  • propiconazole
  • triadimenol

Group 4

Activity Group/ Site of Action: Phenylamides Affect RNA synthesis

Chemical Group: Acylamines

Active Ingredient:

  • metalaxyl
  • metalaxyl M

Chemical Group: OxazolidinonesFootnote 4

Chemical Group: ButyrolactonesFootnote 4

Group 5

Activity Group/ Site of Action: Morpholines Inhibition of an isomerase in sterol biosynthesis

Chemical Group: Morpholines

Active Ingredient:

  • dimethomorph
  • dodemorph

Chemical Group: PiperidineFootnote 4

Chemical Group: SpiroketalamineFootnote 4

Group 6

Activity Group/ Site of Action: Phosphorothiolate Inhibition of chitin and phospholipid synthesis

Chemical Group: OrganophosphorousFootnote 4

Group 7

Activity Group/ Site of Action: Oxathiin Affect mitochondrial transport chain

Chemical Group: Anilide (Oxathiin)

Active Ingredient:

  • carbathiin (carboxin)
  • oxycarboxin

Group 8

Activity Group/ Site of Action: Hydroxyprimidine

Chemical Group: PyrimidinolFootnote 4

Group 9

Activity Group/ Site of Action: Anilinopyrimidine Inhibition of amino acid synthesis

Chemical Group: Anilinopyrimidine

Active Ingredient:

  • cyprodinil

Group 10

Activity Group/ Site of Action: N-Phenyl carbamates Interfere with cell division

Chemical Group: DiethofencarbFootnote 4

Group 11

Activity Group/ Site of Action: Strobilurin Type Action and Resistance (STAR) Inhibit mitochondrial respiration

Chemical Group: StrobilurinFootnote 4

Chemical Group: OxazolidinedioneFootnote 4

Group 12

Activity Group/ Site of Action: Phenylpyrroles

Chemical Group: Phenylpyrroles

Active Ingredient:

  • fludioxonil

Group 13

Activity Group/ Site of Action: Quinolines

Chemical Group: Quinoline

Active Ingredient:

  • quinoxyfen

Group 14

Activity Group/ Site of Action: Aromatic hydrocarbons

Chemical Group: Chlorophenyl

Active Ingredient:

  • dicloran quintozene (PCNB)

Chemical Family: Thiadiazole

Active Ingredient:

  • etridiazole

Group 15

Activity Group/ Site of Action: Cinnamic acids

Chemical Group: Cinnamic acidFootnote 4

Group 16

Activity Group/ Site of Action: Melanin Biosynthesis Inhibitors (MBI)

Chemical Group: Reductase inhibitorsFootnote 4

Chemical Group: Dehydratase inhibitorsFootnote 4

Group 17

Activity Group/ Site of Action: Hydroxyanilide

Chemical Group: HydroxyanilideFootnote 4

Group 18

Activity Group/ Site of Action: Antibiotics

Chemical Group: Antibiotics

Active Ingredient:

  • streptomycin

Group 19

Activity Group/ Site of Action: Polyoxins

Chemical Group: PolyoxinFootnote 4

Group 20

Activity Group/ Site of Action: Phenylurea

Chemical Group: PhenylureaFootnote 4

Group 21

Activity Group/ Site of Action: Plant host defence inducers

Chemical Group: Benzothiadiazole (BTH)Footnote 4

Group U

Activity Group/ Site of Action: Unknown Miscellaneous

Chemical Group: Amino acid amideFootnote 4

Chemical Group: Carbamate

Active Ingredient:

  • propamocarb

Chemical Group: Cyano-acetamide oximeFootnote 4

Chemical Group: Organo-tins

Active Ingredient:

  • tri-phenyl tins
  • dinocap
  • fenfuram
  • fosetyl-aluminum

Group M

Activity Group/ Site of Action: Multi-site activity

Chemical Group: Inorganics

Active Ingredient:

  • copper (hydroxide)
  • copper (oxychloride)
  • copper (sulphate)
  • sullphur (wettable)

Chemical Group: Dithiocarbamates and relatives

Active Ingredient:

  • ferbam
  • mancozeb
  • maneb
  • metiram
  • thiram
  • zineb
  • ziram

Chemical Group: Phthalimide

Active Ingredient:

  • captan
  • folpet

Chemical Group: Chloronitrile

Active Ingredient:

  • chlorothalonil

Chemical Group: SulphamideFootnote 4

Chemical Group: Guanidine

Active Ingredient:

  • dodine

Chemical Group: Anilazine

Active Ingredient:

  • anilazine

Chemical Group: Phenyl-pyridinamineFootnote 4

Chemical Group: Quinoxaline

Active Ingredient:

  • chinomethionat (oxythiquinox)

Appendix III Insecticide and Acaricide Groups Based on Sites of Action

The classification scheme was developed in consultation with the Insecticide Resistance Action Committee (IRAC). IRAC is a Specialist Technical Group of the Global Crop Protection Federation (GCPF). It is recognized that resistance of insects and mites to insecticides and acaricides can also result from enhanced metabolism, reduced penetration or behavioral changes that are not linked to any site of action classification, but are specific for individual chemicals or chemical groups. All members of a class may not be cross-resistant based merely on site of action. Most biological insecticides are not included in this Appendix because they are thought not to pose a great concern for resistance development. Microbial products involving Bacillus sp. are included as well as products derived from the Neem tree such as azadirachtin.

Group 1A

Site of Action: Acetylcholinesterase inhibitors
Inhibition of the enzyme acetylcholinesterase, interrupting the transmission of nerve impulses

Chemical Group: Carbamates

Active Ingredient:

  • aldicarb
  • aminocarb
  • bendiocarb
  • carbaryl
  • carbofuran
  • formetanate hydrochloride
  • methiocarb
  • methomyl
  • oxamyl
  • pirimicarb
  • propoxur

Group 1B

Site of Action: Acetylcholinesterase inhibitors
Inhibition of the enzyme acetylcholinesterase, interrupting the transmission of nerve impulses

Chemical Group: Organophosphates

Active Ingredient:

  • acephate
  • azamethiphos
  • azinphos-methyl
  • chlorfenvinphos
  • chlorpyrifos
  • coumaphos
  • diazinon
  • dichlorvos (DDVP)
  • dimethoate
  • disulfoton
  • ethion
  • fenitrothion
  • fensulfothion
  • fenthion
  • fonofos
  • malathion
  • methamidophos
  • methidathion
  • naled
  • oxydemeton-methyl
  • parathion
  • phorate
  • phosalone
  • phosmet
  • sulfotep
  • temephos
  • terbufos
  • tetrachlorvinphos
  • trichlorfon

Group 2A

Site of Action: Gamma-aminobutyric acid (GABA)-gated chloride channel antagonists
Interferes with GABA receptors of insect neurons, leading to repetitive nervous discharges

Chemical Group: Chlorinated cyclodienes

Active Ingredient:

  • endosulfan
  • dienochlor

Chemical Group: Polychlorocycloalkanes

Active Ingredient:

  • lindane

Group 2B

Site of Action: GABA-gated chloride channel antagonists
Interferes with GABA receptors of insect neurons, leading to repetitive nervous discharges - fiprole site

Chemical Group: PhenylpyrazolesFootnote 4

Group 3

Site of Action: Sodium channel modulators
Acts as an axonic poison by interfering with the sodium channels of both the peripheral and central nervous system stimulating repetitive nervous discharges, leading to paralysis

Chemical Group: diphenylethanes

Active Ingredient:

  • dicofol
  • methoxychlor

Chemical Group: Synethetic pyrethroids

Active Ingredient:

  • d-allethrin
  • d-trans allethrin
  • cyfluthrin
  • cypermethrin
  • deltamethrin
  • fenpropathrin
  • fenvalerate
  • flucythrinate
  • tau-fluvalinate
  • permethrin
  • resmethrin
  • tefluthrin
  • tetramethrin

Chemical Group: Pyrethrins

Active Ingredient:

  • pyrethrins

Group 4

Site of Action: Acetylcholine receptor agonists/antagonists
Binds to nicotinic acetylcholine receptor, disrupting nerve transmission

Chemical Group: Chloronicotines (nitroguanidines)

Active Ingredient:

  • imidacloprid

Chemical Group: Nicotine CartapFootnote 4 BensultapFootnote 4

Active Ingredient:

  • nicotine

Group 5

Site of Action: Acetylcholine receptor modulators
Alters acetylcholine receptor site and disrupts binding

Chemical Group: SpinosynsFootnote 4

Group 6

Site of Action: Chloride channel activators
Interferes with the GABA nerve receptor of insects.

Chemical Group: Avermectin

Active Ingredient:

  • abamectin

Chemical Group: MilbemycinFootnote 4

Group 7

Site of Action: Juvenile hormone mimics (insect growth regulator)
Mimic juvenile hormones, which prevent moulting from the larval to the adult stage

Chemical Group: Juvenile hormone analogues

Active Ingredient:

  • methoprene

Group 8A

Site of Action: Unknown or non-specific site of action (fumigants)

Chemical Group: Fumigant

Active Ingredient:

  • methyl bromide

Group 8B

Site of Action: Unknown or non-specific site of action (fumigants)

Chemical Group: Fumigant

Active Ingredient:

  • aluminum phosphide

Group 9A and 9B

Site of Action: Compounds of unknown or non-specific site of action (feeding disruptors)

Chemical Group: Feeding disruptorsFootnote 4 (pymetrozine, cryolite)

Group 10

Site of Action: Compounds of unknown or non-specific site of action (mite growth inhibitors)

Chemical Group: Mite growth inhibitors (ovicide)

Active Ingredient:

  • clofentezine

Group 11

Site of Action: Microbial disruptors of insect mid-gut membranes (includes Cry proteins expressed in transgenic plants)
Organism has protein inclusions that are released in the gut of the target pest resulting in gut paralysis and a cessation of feeding

Chemical Group: Bt Microbials (biological insecticide/larvicide)

Active Ingredient:

  • Bacillus thuringiensis var. Aizawai, encapsulated delta endotoxin
  • Bacillus thuringiensis var. Tenebrionis
  • Bacillus thuringiensis var. Israelensis
  • Bacillus thuringiensis var. Kurstaki

Group 12

Site of Action: Inhibition of oxidative phosphorylation at the site of dinitrophenol uncoupling [disrupt adenosine triphosphate (ATP) formation]

Chemical Group: Organotin matricides

Active Ingredient:

  • fenbutatin oxide

Group 13

Site of Action: Uncoupler of oxidative phosphorylation (disrupt H proton gradient formation)

Chemical Group: Pyrrole compoundFootnote 4 (broad spectrum contact and stomach poison)

Group 14

Site of Action: Inhibit magnesium - stimulated ATPase

Chemical Group: Sulfite ester matricides

Active Ingredient:

  • propargite

Group 15

Site of Action: Inhibit chitin biosynthesis

Chemical Group: Substituted benzoylurea

Active Ingredient:

  • diflubenzuron

Group 16

Site of Action: Inhibit chitin biosynthesis type 1 - Homopteran

Chemical Group: ThiadiazineFootnote 4

Group 17

Site of Action: Inhibit chitin biosynthesis type 2- Dipteran

Chemical Group: Triazine

Active Ingredient:

  • cyromazine

Group 18

Site of Action: Ecdysone agonist/disruptor
Disrupts insect molting by antagonizing the insect hormone ecdysone

Chemical Group: Benzoic acid hydrazide

Active Ingredient:

  • tebufenozide

Chemical Group: BotanicalFootnote 4 (Neem oil or azadirachtin)

Group 19

Site of Action: Octopaminergic agonist

Chemical Group: Triazapentadiene

Active Ingredient:

  • amitraz

Group 20

Site of Action: Site II electron transport inhibitors

Chemical Group: None

Active Ingredient:

  • hydramethylnon

Group 21

Site of Action: Site I electron transport inhibitors

Chemical Group: Botanical

Active Ingredient:

  • rotenone

Chemical Group: Pyridazinone

Active Ingredient:

  • pyridaben
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