Biological response of Anticarsia gemmatalis (Lepidoptera: Noctuidae) to Bacillus thuringiensis berliner var. kurstaki at sublethal concentrations

The soybean caterpillar, Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae), damages this plant. This pest is controlled, mainly, with chemical products which makes it necessary to to develop management strategies for its management in the soybean crop. Feeding and development of A. gemmatalis larvae fed on soybean leaves treated with Bacillus thuringiensis Berliner var. kurstaki at different concentrations (0,5, 1, 2, 4, 6, 8 μg.mL-1 ) for 24 h were studied in the laboratory. The LC50 and LC90 after 24 h from hatching and at the last instar, development period, adult emergence, weight gain by larva, pupa weight, and dry food weight ingested besides of A. gemmatalis were evaluated. The LC90 value decrease with the development of this insect. Mortality in the third instar of this pest was proportional to the B. thuringiensis concentrations. Emergence of A. gemmatalis adults was higher with 0,5 μg.mL-1 concentration of this bacterium and in the control.