Novel formulations of Bacillus thuringiensis var . kurstaki: an eco-friendly approach for management of lepidopteran pests

AbstractBacillus thuringiensis (Bt) and entomopathogenic fungi (EPF) are in use for management of insect pests. Continuous use of Bt can lead to problem of resistance development in insect pests. Hence use of combination formulations (CF) of microbials with diverse modes of action has been attempted to slow down the process of resistance development. Suspension concentrate (SC) formulations of a local strain of Bt var.kurstaki DOR Bt-127 were developed singly and in combination with conidia of the EPFNomuraea rileyi (Nr) andBeauveria bassiana (Bb). Electron microscopy of Bt  + Bb CF treated larvae ofHelicoverpa armigera revealed simultaneous infection by both microbials indicating their compatibility. Endotoxin contents in Bt-SC, Bt  + Bb and Bt + Nr CFs were 5.0, 4.7 and 4.7%, respectively. These formulations were effective against larvae ofSpodoptera litura,H. armigera andAchaea janata coupled with a lowering of the effective requirement of Bt and EPF. In multi-location field trials, Bt-SC and Bt  + Nr CF were highly effective againstS. litura andA. janata on castor as well asH. armigera andThysanoplusia orichalcea on sunflower. However, Bt  + Bb CF was highly effective only on sunflower againstH. armigera andT. orichalcea. All formulations had 24  months shelf-life at room temperature. DOR Bt-127 based SC formulations developed singly and in combination with Nr and Bb were effective against major lepidopteran pests of castor and sunflower and did not l...
Source: World Journal of Microbiology and Biotechnology - Category: Microbiology Source Type: research