Cyclodienes resistance, development

Table IV. Cyclodiene-Resistance developed in Soil Insects, 1955-65...

In one example (Lawrence and Casida 1984, Abalis et al. 1985) rat brain microsacs were used to test the action of cyclodiene insecticides such as dieldrin and endrin on the GABA receptors contained therein. The influx of radiolabeled CL into the microsacs via the pore channel of the receptor was inhibited by these chemicals. A similar assay was developed using microsacs from cockroach nerve. Assays with this preparation showed again the inhibitory effect of a cyclodiene (this time heptachlor epoxide) on CL influx. Also, that microsacs from cyclodiene resistant cockroaches were insensitive to the inhibitory effect of picrotoxinin, which binds to the same site on the GABA receptor (Kadous et al. 1983). 

Some held stndies have produced evidence snggesting that resistance is developed by wild vertebrates that have been regularly exposed to cyclodienes. Examples... 

The formation of polar metabolites from nonpolar materials may actually facilitate monitoring programs—in many cases the polar chemicals are highly concentrated in certain body fluids such as bile and urine. On the other hand, materials such as certain cyclodienes and polychlorinated biphenyls, which are very lipid soluble and resistant to metabolism, may accumulate and these chemicals may persist in the environment and may be transferred via the food chain to man. There is also interest in these biotransformation processes in lower organisms since the simplicity of these systems may lead to a better understanding of the phylogenetic development of xenobiotic metabolism. 

In fact, only two new classes of insecticides have been developed for commercial use in the last 30 years. Both the synthetic pyrethroids and the avermectins have excellent mammalian saftety. However, both are encumbered by previously evolved target site resistance, selected by over-use of DDT and cyclodiene insecticides, respectively. Thus, the remaining importance of the OPs and the carbamates is obvious. 

Synthetic organic insecticides made their debut in cotton protection shortly after World War II with the introduction of chlorinated hydrocarbons such as DDT, benzene hexachloride, toxaphene, and the cyclodienes. These chemicals were so highly effective and economical to use that they had a spectacular impact on the cotton production industry (4). Insect damage was kept under control at low cost, and yields increased dramatically. Unfortunately, this euphoric era of cotton pest management did not last long because of the development of resistance among certain major cotton pests,... 

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