MONITORING FOR RESISTANCE TO ORGANOPHOSPHORUS, CARBAMATE, AND CYCLODIENE INSECTICIDES IN TOBACCO BUDWORM ADULTS (LEPIDOPTERA, NOCTUIDAE)

A glass vial bioassay procedure was used to monitor insecticide resistance to organophosphorus, carbarnate, and cyclodiene insecticides in field populations of adult male tobacco budworm, Heliothis virescens (F.). These tests indicated that resistance was present in field populations in Texas, Arkansas, and Mississippi in 1992 and 1993. Diagnostic concentrations needed to distinguish susceptible tobacco budworms from those that were heterozygous and homozygous for resistance were as follows: profenofos (10 mu g per vial), methomyl (1 mu g per vial), and endosulfan (1 mu g per vial). The seasonal pattern of resistance was similar for all insecticides in that relative proportions of resistant genotypes peaked in midseason and declined late in the season. The occurrence of resistance was higher in 1999 than in 1993. The data presented suggest that resistance management is possible with these insecticides just as it is with pyrethroids and strategies to manage resistance should involve conservative use of all classes of insecticides for tobacco budworm control.