Residual Activity of Permethrin, Chlordimeform and Permethrin + Chlordimeform Against Susceptible and Resistant Budworm

Abstract

Cotton was sprayed with permethrin, chiordimeform and the permethrin-chlordimeform combination to determine residual efficacy against resistant (R) and susceptible (S) populations of tobacco budworm (TBW) and reciprocal crosses of the two populations. Permethrin alone gave excellent results against susceptible tobacco budworm for the entire 7-day test period. However, against the resistant strain the highest level of mortality achieved was 40% on the 1-day post -treatment residue; results with the S:R and R: S (♂:♀) crosses were generally intermediate. Chlordimeform gave poor and erratic kill unrelated to the residue period regardless of the strain of TBW. The combination resulted in mortality similar to that of permethrin alone with the susceptible strain hut generally greater than that with permethrin alone against the resistant strain. The combination resulted in high mortality in the crosses, particularly the R. S (♂:♀) cross.