Cotton is a vital cash crop because it is a key raw material for the textile industry, but its yield can be drastically reduced by insect pests. As of 2015, the pink bollworm (PBW), Pectinophora gossypiella, has emerged as a major insect pest on transgenic cotton in Pakistan. Bt. transgenic cotton lines expressing Cry1Ac toxin are widely used against Helicoverpa armigera and some Heliothis spp. but have reduced efficacy against the PBW. The use of chemical controls such as insecticide sprays is still an integral part of PBW management, but their potential negative effects on natural enemies that help keep bollworm populations in check must be evaluated. During the 2017-18 and 2018-19 growing seasons, field experiments were conducted to compare the effectiveness of various insecticides on Bt. and non-Bt. cotton against PBW. When tested against PBW, triazophos was found to be the most toxic insecticide, followed by the synthetic pyrethroids bifenthrin and deltamethrin, and chlorpyrifos from the organophosphate group. Plastic cups surface treated PBW moth bioassays with the same insecticides showed that Triazophos was the most toxic insecticide to the moths of pink bollworm with less LC50 values, i.e., 27.98 mg/L followed by deltamethrin (43.30 mg/L), bifenthrin (62 mg/L), and chlorpyriphos (255 mg/L). It could be concluded that insecticides, which are responsible for larval and moth mortality, gave better control because of the concealed behavior of larvae after hatching from the eggs. It is recommended to use these insecticides in rotation with each other for optimal PBW control. Significantly larger populations of spiders, green lacewings, and Geocoris species were recorded after treatment with triazophos compared to other insecticides. However, integrated approaches could be the best strategy for PBW management, like Bt cotton, the male disrupting technique employing pheromones (PB-ropes) at the flowering stage and one or two applications of insecticides. Insecticide applications at the end of the season would protect the crop next year from overwintering larvae which are the main source of infestation in the subcontinent and Indo-Pakistan region.
