Seasonal variation in resistance of diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) to selected insecticides

AbstractIn the present study, seasonal variation in resistance to five synthetic insecticides viz., profenophos 50% EC, methomyl 40% SP, cypermethrin 5% EC, fipronil 5% SC and Bt product (Dipel 8% L) representing different chemical groups was investigated over a period of twelve months by conducting laboratory ‘leaf dip’ bioassays at regular intervals. In general, the pest exhibited higher level of resistance to insecticides during summer months of April and June, and low resistance during the winter months of November and December.