Efficiency of certain insecticides, insect growth inhibitors and their combinations against the cotton leafworm larvae in cotton plantations in Egypt

Abstract

Seven pesticides and their binary mixtures were applied to cotton in the field in Egypt and their initial and residual efficacy was studied in larvae of the noctuid Spodoptera littoralis on treated leaves transferred to the laboratory. Insect growth regulators potentiated knockdown of triazophos against 2nd-instar larvae, but did not potentiate the knockdown effects of cyfluthrin or thiodicarb. Methoprene had low initial effects and was apparently rapidly degraded in the field. The half-lives of diflubenzuron, triflumuron and chlorfluazuron were 2.7, 4.6 and 6.5 days, resp., against 2nd-instar, and 1.6, 3.0 and 4.6 days against 4th-instar larvae. Mixtures of insecticides and insect growth regulators gave different results for residual performance according to the mixture, the larval instar, and the time elapsed since application. This paper was presented at the International Symposium on Crop Protection in May 1990 in Ghent, Belgium.