Pesticide Resistance Strategies and Tactics for Management (1986) / Chapter Skim
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5 Tactics for Prevention and Management
5 Tactics for Prevention and Management
Pages 313-326
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From page 313... ...
Judicious use of pesticides reduces the selection pressure on pest populations for developing resistance. Use of pesticides only as needed not only avoids or delays resistance but tends to protect nontarget beneficial species.
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From page 314... ...
. The residual nature or persistence of pesticides varies greatly, which will affect the success of various tactics to manage resistance.
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From page 315... ...
Although resistance poses a most serious threat to a pesticide's economic life and has resulted in total loss of previously valuable chemicals from some major pest-control programs, no pesticide has been lost from the marketplace solely because of resistance. Resistance is not absolute throughout a pest's range, and susceptible populations of some pests continue to exist.
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From page 316... ...
+ + (T) Variation in dose or rate Frequency of applications Local rather than areawide applications Treatments only to economic threshold Less persistent pesticides Life stages of pest Pesticide mixtures Alternations, rotations, or sequences of pesticide applications Pesticide formulation technology Synergists Exploiting unstable resistance Pesticide selectivity New toxophores with alternate sites of action Protection and use of natural enemies with pesticide tolerance Reintroduction of susceptible pests Code for Suitability Ratings: +++ + +++ + + + + + (T)
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From page 317... ...
A specific herbicide is most commonly used only once per crop season. Postemergent herbicides or those having brief soil activity could be applied several times, especially in perennial crops, but this would tend to increase selection pressure for resistance.
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From page 318... ...
This is a means of reducing the selection pressure for resistance. The success of this tactic in managing insecticide resistance varies with the insect pest and conditions.
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From page 319... ...
In theory, the rate of developing resistance would be lessened by targeting insecticides against the adults or early instars, thereby reducing the selection pressure on later instars that have a higher resistance risk due to their greater enzymatic activity for pesticide metabolism. Applying a fungicide during the sexual stage theoretically should increase the chance of selecting for a higher level of resistance in the fungus.
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From page 320... ...
Limited laboratory data show that mixed populations of resistant and susceptible Phytophthora infestans shifted to the resistant populations more slowly when mixtures were used. On the other hand, some reports indicated that resistance to a specific site-inhibitor fungicide can continue to increase when one is used in combination with a multisite fungicide, due in part to the pathogen population's not being controlled by the multisite inhibitor (e.g., lack of translocation)
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From page 321... ...
Controlled release or longer residual type formulations might enhance the rate of resistance development due to longer selection pressure, but this has not been sufficiently tested and would depend on other factors, such as the life span of the target pest species and the effect of low levels of the insecticide on insect reproduction. No data are available, but the same factors would likely apply to fungicides and herbicides, except for bait attractants.
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From page 322... ...
These characteristics often make the resistant biotype of the target pest more susceptible to other control measures. Unstable resistance can be exploited by using other insecticides or control programs to control resistant insects preferentially or selectively until resistance diminishes.
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From page 323... ...
A selective pesticide is often a specific single-target-site chemical with a higher resistance risk, but this danger might be alleviated somewhat by using less specific pesticides applied more selectively, for example in baits, as systemic insecticides in furrow, or as seed treatments. This approach is the most useful in management of resistance in insects and mites.
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From page 324... ...
The reintroduced susceptibles must be numerous enough to swamp the endemic, resistant population, thereby reducing the likelihood of mating between resistant individuals (Suckling, 1984~. This tactic is often most applicable where pest control is not intensive.
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From page 325... ...
h. Investigate pest migration and the factors that influence it to determine the potential for assessing the spread of resistant forms to new areas and the reinvasion of resistant populations by susceptible pests from refuges.
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From page 326... ...
Davis, Auburn University JOHAN DEKKER, Agricultural University, Wageningen, The Netherlands TIMOTHY J DENNEHY, Cornell University VOLKER DITTRICH, Ciba-Geigy, Ltd., Switzerland GEORGE P
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