Efficacy of new formulations of Bacillus thuringiensis var. kurstaki (HD-1) against Helicoverpa armigera (Hubner)

摘要

Bioassays were conducted under laboratory conditions at Division of Entomology, Indian Agricultural Research Institute, New Delhi during 2008, to assess the efficacy of new wettable powder (WP) formulations of Bacillus thuringiensis var. kurstaki (HD-1) against IIF'* instar larvae of Helicoverpa armigera (Hubner). Sixteen new WP formulations of B. thuringiensis var. kurstaki (HD-1) were developed and relative efficacy was calculated on the basis of values. The results revealed that LC_50, values of recipe-2 (0.032%), recipe-7 (0.018%), recipe-9 (0.030) and recipe-15 (0.015%) were highly effective against IIP'' instar larvae of H. armigera in comparison to Dipel? 8L (0.037%) and Biolep~R (0.046%), a commercial formulation of B. thuringiensis var. kurstaki. On the basis of laboratory performance, recipe-7 and recipe-15 were selected for field efficacy against H. armigera in pigeonpea crop. Recipe-15 was found significantly more effective than the Dipel~R 8L under field conditions.