3rd April 2010
Through evolution plants and animals have developed defensive mechanisms, including chemical repellents and toxins, against attacking organisms. In turn the attacking organisms have developed mechanisms that enable them to detoxify or otherwise resist the defensive chemicals of their hosts. Thus, it appears that most pest species already contain genes that enable them to degrade enzymatically or otherwise circumvent the toxic effects of many types of chemicals that have been developed as modern pesticides1. Pesticide resistance, therefore, is a genetically based phenomenon and occurs when a pesticide is used on a population containing some individuals genetically predisposed to be resistant to that pesticide. Repeated applications and higher treatment rates will kill increasing numbers of the pest but resistant survivors will pass the resistance genes to the next generation. Unless a different treatment regime is used the population will contain increasing numbers of resistant pests and where reproductive rates are high, e.g. in insects, the entire population will quickly become resistant2.
Once a pest has developed resistance to a particular pesticide it is necessary to have other means of controlling it. One method is to use a different pesticide, especially one in a different chemical class that has a different mode of action against the pest2. Care must be taken, however, that multiple resistance, i.e. resistance to several classes of pesticides, is not introduced into the population. The best strategy is to avoid building up a resistant population and various procedures have been developed for this. Various management strategies have been recommended to avoid the build up of resistant populations due to the use of pesticides. The US EPA and the Canadian PMRA have drawn up a voluntary labelling scheme, together with recommendations for avoiding resistance, giving mode of action and target site information to users3.
Various “Action Committees” have been set up by industry and, with the input of academic and government scientists, have proposed management strategies to avoid the build up of resistance to pesticides.
Insecticides – A summary of the recommendations made by The Insecticide Resistance Action Committee (IRAC) is given below. Full details can be found on the IRAC website4.
Fungicides – A summary of recommendations made by the Fungicide Resistance Action Committee (FRAC) is given below. Full details can be found on the FRAC website5.
Herbicides - A summary of recommendations made by the Herbicide Resistance Action Committee (HRAC) is given below. Full details can be found on the HRAC website6.
Rodenticides – The Rodenticide Resistance Action Committee (RRAC) have issued a monograph on the strategy for anticoagulant resistance management, the recommendations of which are summarised below. Full details can be found on the RRAC website7.
1. The Magnitude of the Resistance Problem, G.P. Georghiou, Pesticide Resistance: Strategies and Tactics for Management,
2. Pest Resistance to Pesticides, R.G. Bellinger, Dept. of Entymology,
4. General Principles of Insecticide Resistance from IRAC
5. Fungicide Resistance in Crop Pathogens : How Can it be Managed ? K.J. Brent, FRAC Monograph No.1 (April 1995)
6. Guideline to the Management of Herbicide Resistance, HRAC
7. Anticoagulant Resistance Management for
Last modified 3rd April 2010
Date added: 2010-05-08 00:39:56
Last Updated 2010-05-10 03:08:56
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