Comparativo de parâmetros biológicos e da evolução da resistência de Plutella xylostella (Lepidoptera: Plutellidae) do Brasil e das Ilhas Fiji

Abstract

Plutella xylostella (L.) (Lepidoptera: Plutellidae) is an important pest of brassicas in Brazil and in several countries. Its control has basically been carried out with the use of insecticides, which can select resistant populations. The objective was to compare some biological parameters of populations of P. xylostella resistant to deltamethrin, the evolution of resistance and life table data of these populations under different selection pressure. Data were obtained by Barbosa (2019) studying populations collected in the Northeast region of Brazil and populations coming from Sigatoka Lower Valley in Viti Levu in Ilhas Fiji. Four generations were evaluated, as follows: successive application of deltamethrin (D-DeltaBR and D-DeltaIF); successive application of Bt (D-BtBR and D-BtIF); alternation of insecticides [(D-RotaçãoBR) - G2= exposure to chlorantraniliprole, G3= exposure to Bt, G4= exposure to metaflumizone and G5= exposure to chlorantraniliprole]; alternation of insecticides [(D-RotationIF) - G2=exposure to abamectin, G3=exposure to Bt, G4=exposure to indoxacarb and G5=exposure to abamectin] and maintained in the absence of insecticides (D-ControleBR and D-ControleIF). The egg-pupa cycle, pupae weight and adult longevity were the parameters evaluated. Resistance frequency was estimated based on the percentage of caterpillar survival in each generation. It was found that successive exposures to deltamethrin and B. thurigiensis subsp. kurstaki in populations from Brazil and Ilhas Fiji tend to select and increase the frequency of resistance. The application of deltamethrin high dosage in the D-DeltaIF population may have influenced the evolution of resistance in this population. Alternate applications reduced the frequency of resistance across generations for populations from Brazil and Ilhas Fiji. Populations from the Ilhas Fiji, under insecticide rotation, were more likely to reestablish susceptibility than those from Brazil. There were changes in pupae weight and adult longevity, suggesting the existence of adaptive costs associated with P. xylostella resistance to deltamethrin in populations from Brazil and Ilhas Fiji.