A Comparison of Predator Populations in Cotton Under Different Control Programs in Mississippi1

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Abstract
Studies were conducted during 1964 and 1965 in the Delta area of Mississippi to determine effects of various insecticides on predator populations subjected to 2 pest-control programs: a season-long complete chemical control program with insecticide applications on an automatic 7-day schedule and a program with early- and late-season applications applied as needed to control cotton pests. Predators that occurred in greatest abundance were recorded. Lady beetles, Nabis and Geocoris species were the dominant predators in early season and spiders, 90% of which were the striped lynx, Oxyopes salticua Hentz, became dominant in mid- and late-season. Predators could tolerate low-dosage early-season applications in the complete chemical control program, but populations were decidely reduced after 2 insecticide applications to control plant bugs. Toxaphene was more toxic to Nabis species and spiders than the other materials used. All predators were much more affected by the mixture of toxaphene and DDT than by toxaphene alone. Spiders were able to withstand phosphate and carbamate materials much better than chlorinated hydrocarbons, with the exception of azinphosmethyl, which appeared to affect them more than endrin. Nabis species were affected less by azinphosmethyl than by the other materials used. Azodrin® (3-hydroxy-N-methyl-cis-crotonamide dimethyl phosphate) and Bidrin® (3-hydroxy-N,N-dimethyl-ciscroton amide dimethyl phosphate) were more toxic to predaceous species than trichlorfon and phosphamidon in the program with applications applied as needed. Applications of all insecticides at the mid- and late-season rates almost completely eliminated the predators. Cotton-pest species were adequately controlled with both programs and predaceous insects were conserved by applying insecticides only as needed to control pest species.

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