Suscetibilidade de populações da traça-das-crucíferas, Plutella xylostella (L.,1758) (Lepidoptera : Plutellidae) a inseticidas

Abstract

The Plutella xylostella is a recurring pest on cruciferous crops around the world. The susceptibility of diamondback moth populations to the insecticides abamectin, deltamethrin, and spinosad, from three Brazilian regions was compared through collard leaf dipping bioassays in laboratory for the different treatments. Mortality data were assessed 48 hours after exposition to every insecticide and submitted to Probit analysis. All the populations showed significant resistance to at least one of the insecticides. The Bonito-PE population showed the highest resistance ratio (20.2 times) to abamectin when compared with the susceptible population and to other insecticides. The deltamethrin LC50s were very high for all the populations tested, ranging from 85.2 to 360.1 mg/L. All the populations from Pernambuco State were considered resistant to deltamethrin, with resistance ratios varying from 2.2 to 4.2 times. Five populations showed significant resistance to spinosad with ratios varying from 2.3 to 5.1. These results are discussed based on the spectrum of insecticides used in the regions. In conclusion, the need of resistance toinsecticides management programs for P. xylostella in conjunction with an integrated pest management is urgent in these regions.