In this section:
Insecticide Resistance Management
The challenge of diamondback moth (DBM) insecticide resistance
DBM was the first crop pest in the world to develop resistance to Dichloro-Diphenyl-Trichloroethane (DDT). Today, it has evolved resistance to all modern groups of insecticides that were in use before the mid 1990s, including some toxins of the bacterium Bacillus thuringiensis (Bt).
Resistance arises as a result of the natural existence of resistant individuals (initially at very low levels in the pest population) and the selective killing of susceptible individuals each time an insecticide application is made. If there is no immigration from outside, the whole population will eventually become resistant if the same insecticide is used for a sufficient period of time.
This increase in resistance is illustrated in the Insecticide Resistance Management presentation.
Insecticide Resistance Management (IRM) for DBM in Australian Brassica vegetables
The Insecticide Resistence Management & Review Group (IRMRG) "Two-Window" IRM Strategy
In an effort to slow down the development of resistance to newly available insecticides, Australian DBM researchers, in conjunction with the chemical industry (IRMRG, the Insecticide Resistance Management and Review Group of CropLife Australia) and grower representatives, have devised a "two-window" insecticide resistance management (IRM) strategy. Under this strategy, the calendar year is split into two periods (or windows) and the use of each DBM insecticide that has become available since 1998 is restricted to either one of the two periods.
Because of regional differences in the seasonality of pest abundance, the calendar timing of these windows differs among the States.
Strategies below are current for 2009 use.
- 'Two-Window' IRM Strategy for New South Wales, Victoria, South Australia, Tasmania and Stanthorpe district QLD (.PDF)
- 'Two-Window' IRM Strategy for Lockyer Valley, Queensland (.PDF)
- 'Two-window' IRM Strategy for Western Australia - chart (.PDF) Updated Sept 2009
- 'Two-window' IRM Strategy for Western Australia - explanatory notes (.PDF) Updated Sept 2009
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Why haven't the older insecticides been included in the AIRAC 'Two-Window' IRM Strategy? One of the key requirements for a window IRM strategy to be effective is that the insecticides that are included do not share the potential for cross-resistance, i.e. each insecticide class must have a unique mode of action and metabolism. The five new insecticides met this requirement. However, overseas research had shown evidence of cross-resistance between certain synthetic pyrethroid, organophosphate and carbamate insecticides, and hence these older chemistries were not included. |
Other Measures to Combat DBM Insecticide Resistance
The following guidelines and measures are recommended:
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Labels of the new products place a limit on the number of applications to be used. If further control is required on one planting, different groups from within the same window should be rotated.
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Monitor your crops at least weekly and spray only when the DBM level is above your action threshold. Use the Monitoring Guide to construct a sampling plan.
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Whenever possible use insecticides that are soft on beneficials - refer to the Impact of Insecticides on Natural Enemies Found in Brassicas (.PDF) - English version or Impact of Insecticides on Natural Enemies Found in Brassicas (.DOC) Chinese version.
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Do not tank mix insecticides for the same target insect. If you are treating for DBM and you are using a Bt, don't mix it with something else because that will just exacerbate the problem of resistance developing to all the products at once, and is not cost-effective.
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Only use the recommended rate. Not less or more.
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Time product application for the most susceptible stage of the target pest.
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Use of Bacillus Thuringiensis (Bt) in the early stages of crop development is encouraged, but avoid continuous use of Bt products. More information can be found below in the IPM National Newsletter.
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Good crop hygiene, such as clean seedlings, will reduce your DBM problems.
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Plan with your neighbours (within several kilometres) to have a total brassica crop break of about 3 weeks in early to mid summer to starve out DBM.
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Ensure that your spray rig is achieving Good Spray Coverage.
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Apply the insecticide only to the areas of the crop that need it.
The following articles are of particular interest:
Resistance To Bt (Bacillus thuringiensis) products in Australian DBM
Newsletter 3 article: Resistance to Bt (Bacillus thuringiensis) Products in Australian DBM (.PDF)
Newsletter 10 article: Bt Resistance Management (.PDF)
National Insecticide Resistance Management Survey Results
Newsletter 10 article: February 2007 National Insecticide Resistance Management Survey Results (.PDF)
The Effect of Neighbours' Spray Actions
Newsletter 4 article: Property-to-Property Movement of Moths and Beneficial Insects (.PDF)
Insecticide Resistant DBM in Canola: Are They A Threat To Vegetables Crops?
Newsletter 2 article: Do DBM Come From Canola and What Is Their Resistance to Chemicals? (.PDF)
More Diamondback Moth Information
Description and enemies
Crop monitoring
Integrated pest management
Impact of insecticides chart
Diamondback Moth Newsletters
Publications
Useful websites
Contacts
