The CropLife Australia Insecticide Resistance Management Review Group (IRMRG) has drafted insect resistance management strategies in conjunction with growers, researchers and agronomists to minimise the development of insect resistance to insecticides. These strategies provide growers with guidelines for insecticide use (and other methods) for sustainable insect control.
PRINCIPLES OF RESISTANCE MANAGEMENT
Insecticide or acaricide resistance management strategies seek to minimise the selection for resistance to any one type of insecticide or acaricide. This requires an understanding of insecticides as they are grouped according to similarity of Mode of Action (MoA) in controlling insects and mites.
In practice, sequences or rotations of compounds from different MoA groups providean effective approach to resistance management. In practice, sequences or rotations of compounds from different MoA groups provide an effective approach to resistance management. These MoA groups are shown in the Mode of Action Classification for Insecticides Table.
EFFECTIVE RESISTANCE MANAGEMENT STRATEGIES USE ALTERNATIONS OR SEQUENCES OF DIFFERENT MODES OF ACTION
The objective of Insecticide Resistance Management is to prevent or delay resistance developing to insecticides, or to help regain susceptibility in insect pest populations in which resistance has already arisen. IRM is important in maintaining the efficacy of valuable insecticides. It is usually easier to prevent resistance occurring than it is to reactively regain susceptibility.
Insecticide applications are often arranged into MoA spray windows or blocks that are defined by the stage of crop development and the biology of the pest(s) of concern. Local expert advice should always be followed with regard to spray windows and timings. Several sprays of a compound may be possible within each spray window but it is generally essential to ensure that successive generations of the pest are not treated with compounds from the same MoA group.
WHAT IS RESISTANCE?
Resistance to insecticides and acaricides may be defined as ‘a heritable change in the sensitivity of a pest population that is reflected in the repeated failure of a product to achieve the expected level of control when used according to the label recommendation for that pest species’.
Resistance arises through the over use or misuse of an insecticide or acaricide against a pest species and results in the selection of resistant forms of the pest and the consequent evolution of populations that are resistant to that insecticide or acaricide.
There are a number of ways insects can become resistant to insecticidal crop protection products.
Resistant insects may detoxify or destroy the toxin faster than susceptible insects, or quickly rid their bodies of the toxic molecules. Metabolic resistance is the most common mechanism and often presents the greatest challenge. Insects use their internal enzyme systems to break down insecticides. Resistant strains may possess higher levels or more efficient forms of these enzymes. In addition to being more efficient, these enzyme systems also may have a broad spectrum of activity (i.e., they can degrade many different insecticides).
The target site where the insecticide acts in the insect may be genetically modified to prevent the insecticide binding or interacting at its site of action thereby reducing or eliminating the pesticidal effect of the insecticide.
Resistant insects may absorb the toxin more slowly than susceptible insects. Penetration resistance occurs when the insect’s outer cuticle develops barriers which can slow absorption of the chemicals into their bodies. This can protect insects from a wide range of insecticides. Penetration resistance is frequently present along with other forms of resistance, and reduced penetration intensifies the effects of those other mechanisms.
Resistant insects may detect or recognize a danger and avoid the toxin. This mechanism of resistance has been reported for several classes of insecticides, including organochlorines, organophosphates, carbamates and pyrethroids. Insects may simply stop feeding if they come across certain insecticides, or leave the area where spraying occurred (for instance, they may move to the underside of a sprayed leaf, move deeper in the crop canopy or fly away from the target area).
MODE OF ACTION, TARGET-SITE RESISTANCE AND CROSS-RESISTANCE
In the majority of cases, not only does resistance render the selecting insecticide ineffective but it often confers cross-resistance to other chemically related compounds. Compounds within a specific chemical group usually share a common target site within the pest, and thus share a common Mode of Action (MoA). It is common for resistance to develop that is based on a genetic modification of this target site. When this happens the compound loses its pesticidal efficacy. Because all compounds within the chemical sub-group share a common MoA, there is a high risk that the resistance will automatically confer cross-resistance to all the compounds in the same sub-group. It is this concept of cross-resistance within chemically related insecticides or acaricides that is the basis of the Mode of Action classification.
ALTERNATION OF CHEMISTRY
Constant use of insecticides from one chemical grouping (MoA) will increase the risk of rapid build-up of resistance to that chemical group. Alternate use of chemical groups with different MoAs will slow down the process of selection for resistance.
USE OF CULTURAL PRACTICES
Incorporation of cultural techniques for controlling an insect pest will reduce selection pressure from the insecticides. Any resistance management strategies should incorporate all available methods of control for the insect pest concerned.
UNDERSTANDING OF THE INSECT/MITE LIFE CYCLE
A good understanding of the life cycle of the pest is essential so that control methods can be effectively targeted. An insecticide or acaricide should always be targeted at the pest growth stage that is most susceptible for that insecticide or acaricide.
Insecticide labels have been carefully developed to ensure the most effective control of the pest. The label should at all times be carefully read and adhered to.
Full recommended rates of registered insecticides should always be used to ensure the most effective control of the pest.
The majority of insecticides require good coverage of the target area to ensure the best possible chance of contact and subsequent control of the pest.
RESISTANCE MANAGEMENT STRATEGY DESIGN
Crop/Pest or Regional Strategies
The strategies below are provided on a CROP by PEST basis (eg. Tomato – Heliothis). However, in horticultural and agricultural areas often a range of crops are grown that are attacked by a range of pests.
In many cases, a specific MoA insecticide can be used across this range of crops to control multiple pests that have the ability to move from crop to crop. There is interaction between intensive horticulture and broadacre farming, as with Diamondback Moth (DBM) in Brassica vegetables and resistance strategies that could be compromised by widespread use of insecticides for DBM control in canola.
Also, the pest complex for a specific crop will vary within production regions, especially between Northern and Southern Australia.
For this reason, CROP by PEST strategies can be flawed and further Insecticide Resistance Management (IRM) advice for specific pests should always be sought on a local basis.
An alternative to the CROP by PEST strategy is that of “Regional strategies” such as those for Cotton, Brassicas and the Southern NSW and Northern Victorian IRM strategy for grain and annual horticultural crops”.
These regional or specific crop strategies are located on the CropLife Australia website.
The overall Resistance Management Strategy of avoiding overuse of individual Modes of Action insecticides should be followed, not just on a specific crop and pest but on a broad perspective of crops and pest complex.
Further information on Insecticide Resistance, Management Strategies and Insecticide Mode of Action can be found on the International IRAC (Insecticide Resistance Action Committee) website www.irac-online.org.
Insect(s): Banana weevil borer (Cosmopolites sordidus) and Rust Thrips (Chaetanaphothrips signipennis)
Components of the Strategy:
The following two diagrams are alternative Resistance Management Strategies depending on which product(s) are chosen for banana weevil borer and rust thrips control.
Where products other than controlled release formulations of imidacloprid are being used to control insects in bananas.
Where products including controlled release formulations of imidacloprid are being used to control insects in bananas.
Crop(s): Sorghum, Maize, Summer and Winter Grain Legumes
Insect(s): Heliothis/Cotton bollworm/Native budworm (Helicoverpa spp.)
Mode of Action Group as specified on product label Active ingredient Number applications permitted per crop per season from product label Labelled crops
1A methomyl, thiodicarb not specified All cereal grains, oilseed, pulses
3A synthetic pyrethroids (various) not specified All cereal grains, oilseed, pulses
5 spinetoram TBC All pulses
6 emamectin benzoate 2 All pulses
11A Bacillus thuringiensis not specified All cereal grains, oilseed, pulses
22A indoxacarb 1 chickpea, faba bean, mung bean, soybean, azuki bean
28 chlorantraniliprole Refer to label All pulses
Not Categorised Nucleopolyhedrovirus (NPV) no limit but avoid season long use of low rates All cereal grains, oilseed, pulses
For more information refer to the IPM Guidelines H. armigera RMS for Australian grains: https://ipmguidelinesforgrains.com.au/ipm-information/resistance-management-strategies/
Insect(s): Diamondback Moth
|Mode of Action Group as specified on the product labeled on product label||Active ingredient||Number applications permitted per crop per season from product label|
|1A||methomyl, thiodicarb||Not specified|
|2B||fipronil||4 per year within 8 week period|
|3A||synthetic pyrethroids (various)||Not specified|
|6||emamectin benzoate||4 per any one crop|
|11A||Bacillus thuringiensis||not specified|
|13||chlorfenapyr||2 but 4 in brussel sprouts|
|23||spirotetramat||2 but 3 in brassica leafy vegetables|
|28||chlorantraniliprole, flubendiamide||3 but 1 for mixtures of chlorantraniliprole and thiamethoxam|
Insect(s): Cotton/Melon Aphid and Green Peach Aphid
|Group*|| Chemical sub-group < strong >||Example Chemical|
|23||Tetronic and Tetramic acid derivatives||spirotetramat|
1. There is known cross-resistance between Groups 1A and 1B. Rotate between Group 1 and Group 4, 9B, 9D, 12A, 23, 28 and 29.
2. Consecutive applications of a Group 4A and Group 4C product may be made only if no other effective option is available – either because
a) no other group is registered in the crop or
b) the target pest is resistant to the other Groups.
3. Seek advice from the manufacturers and/or government advisory services to determine local resistance levels for particular mode of action Groups
4. Do not exceed the maximum number of applications permitted on the insecticide label.
5. When using insecticides/miticides to control other pests, consider the chemical group in relation to contributing to resistance development of Cotton/Melon Aphid and Green Peach Aphid.
6. When using insecticides/aphicides to control other pests consider the effect on beneficial insects and the potential to flare aphid populations.
7. For more detail on resistance management of aphids in cotton refer to the current Cotton Pest Management Guide or for more detail on resistance management for Green Peach Aphid in grain refer to https://ipmguidelinesforgrains.com.au/ipm-information/resistance-management-strategies/ or https://grdc.com.au/resources-and-publications/all-publications/factsheets/2015/07/grdc-fs-greenpeachaphid.
Crop(s): Sweet Corn
Insect (s): Corn earworm (Helicoverpa armigera) aka Heliothis
|Mode of Action Group as specified on product label||Active ingredient|
|3A||Synthetic pyrethroids (several)|
Insect(s): Heliothis/Tomato Budworm (Helicoverpa spp.)
Insect(s): Potato Moth (Leafminer)
|Group*||Chemical sub-group||Example chemical|
|1B||Organophosphates||acephate, azinphos-methyl, methamidophos, diazinon, dichlorvos|
Crop(s): Pasture/Winter Crops
Mite: Redlegged Earth Mite (RLEM) Halotydeus destructor
|Crop Stage ||Group*||Chemical Sub-group||Example chemical|
|Seed Treatment (or in-furrow)||4A|
|Neonicotinoids or organophosphates or phenylpyrazoles||Imidacloprid dimethoate fipronil|
|Bare Earth (Preemergent)||1B|
|organophosphates or synthetic pyrethroids||omethoate bifenthrin|
|Early Season (Autumn when limited green growth)||3A|
|synthetic pyrethroids or organophosphates||alpha-cypermethrin chlorpyrifos|
|organophosphates or synthetic pyrethroids||Omethoate gamma-cyhalothrin|
*Groups are the International Resistance Action Committee Insecticide Groups based on mode of action of the insecticides – refer MoA tables.
If both autumn and spring applications are needed, alternate between synthetic pyrethroids and organophosphates.
Timing of Sprays
Placement of Sprays
Insect(s): Silverleaf Whitefly
|Group*||Chemical sub-group||Example chemicals|
|4A||Neonicotinoid||acetamiprid, dinotefuran, imidacloprid, thiamethoxam|
|--||Petroleum oil||petroleum oil|
8. Seek advice from the manufacturers and/or government advisory services to determine local resistance levels for particular Mode of Action Groups.
9. DO NOT exceed the maximum number of applications permitted on the insecticide label.
10. When using insecticides to control other pests, consider the chemical group in relation to contributing to resistance development of Silverleaf Whitefly.
11. When using insecticides to control other pests consider the effect on beneficial insects and the potential to flare Silverleaf Whitefly populations.
Not all chemical groups listed have registered products available in all crops affected by Silverleaf Whitefly. Only use products registered for use in crop to be treated.
(a) Plough in crops within 2-3 days of application to kill all remaining nymphs on crop foliage to reduce pest migration into new plantings.
(b) Where moderate population levels remain after harvest, apply a registered insecticide or oil treatment effective against adults.
Crop(s): Pome Fruit
Mite : Two Spotted Mite, European Red Mite
|Group*||Chemical sub-group||Example chemical|
|6||Avermectins, milbemycins||abamectin, milbemectin|
|10A||Clofentezine, hexythiazox||clofentezine, hexythiazox|
|12B||Organotin miticides||fenbutatin oxide|
|21A||METI acaricides||fenpyroximate, tebufenpyrad|
Mite : Two Spotted Mite
Insect : Western Flower Thrips
For information refer to the NSW Department of Primary Industries website – Thrips in horticultural crops
For information refer to the Cotton Pest Management Guide 2018-19: https://www.cottoninfo.com.au/publications/cotton-pest-management-guide
For information refer to the IPM Guidelines: https://ipmguidelinesforgrains.com.au/ipm-information/resistance-management-strategies/
Content last updated: July 1, 2019