Management of Dicofol Resistance in California Cotton: An Applied Study

T.J. Dennehy, J. Granett and T.F. Leigh


 
ABSTRACT

For anyone who has dealt with cotton insect pests it is obvious that resistance to insecticides has been and probably will continue to be, one of the industry's major pest management dilemmas. The dilemma comes about because insecticides are seen as flexible, simple, cost-effective management tools over the short term. When we increase our time horizon to several years, however, insecticide use becomes a self-annihilating option due to resistance. The current challenge to entomologists is to ameliorate this problem. To meet this challenge we must devise integrated pest management models which are as cost- effective as the old pesticide paradigm, yet reduce the resistance problems inherent to heavy insecticide use.

We became interested in resistance management in 1981. The system which was suggested to us entailed reported problems of cotton growers in controlling spider mites An the San Joaquin Valley. Grower observations of dicofol (Kelthane®) field efficacy varied from poor to excellent. We approached this problem as a model for studying and implementing resistance management in an agricultural system. We set up the project as a 3-4 year research program as follows:

1). The first step in 1981 was to determine whether resistance was indeed a problem with dicofol or not. Dicofol has been used for many years in cotton and resistance had not been documented in this crop before. Methods were developed for isolating populations of mites in the laboratory. Laboratory bioassays were done on samples collected from several areas to assess variability in dicofol susceptibility.

2). The second step, our 1982 work, was to determine the relevance of our laboratory work to field mite control. We desired to determine if our laboratory bioassays of susceptibility accurately reflected field-mite susceptibility. We also surveyed the San Joaquin Valley to determine the extent of what we are now calling resistance.

3). The third step, our planned work for 1983, is to establish a straight forward, and simple field assay tool for mite resistance detection. Such a tool is central to resistance management-resistance can not be managed unless field personnel can determine the susceptibility of mites at any location at any time when a miticide might be used. In addition, in 1983, we plan to formulate management procedures for field use.

4). The last step, our projected work for 1984, is to test the resistance management program in the field, assay its feasibility, and determine its effectiveness.



Reprinted from Proceedings of the 1983 Beltwide Cotton Production Research Conference pp. 181 - 182
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998