Evaluation of toxicity and cotoxicity of biopesticides against diamondback moth, Plutella xylostella (L.)

In India, the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous vegetables and causes severe economic losses. This pest has ability to evolve resistance in laboratory and field to almost all groups of synthetic insecticides. Despite of these, management with synthetic insecticides has been considered to be the easy and favorable option by farmers in India which indeed increase the cost of cultivation and obviously reduction in the actual net profit. The use of microbial and botanicals pesticides are also available in the market and they are relatively cheap. These pesticides are eco-friendly and the residual toxicity is extremely low. In this study, we have evaluated the in vitro toxicity and co-toxicity of different groups of microbial and botanicals pesticides on the field derived population of P. xylostella using leaf dip bioassay. Among microbial pesticides Lipel® (Bacillus thuringiensis subsp. kurstaki)) was found to be very effective than MVP II (Cry1Ac) and XenTari® (Bacillus thuringiensis subsp. aizawai). Anosom® (1% EC) was found to be most effective against P. xylostella among botanicals as evidenced from lowest LC50 value of only 0.1ppm. Being a botanical pesticide, Anosom® (1% EC) could be used as a substitute to synthetic insecticides in integrated management of P. xylostella. Co-toxicity of pesticides against second instars larvae of P. xylostella was assessed using binary mixture of two botanical pesticides at three different combinations (1:1, 1:2 and 2:1 ratio) and found that all the combinations show synergistic effect against diamondback moth. Objective of present research is to investigate toxicity and co-toxicity of botanical and microbial pesticides against diamondback moth so that it could be used as substitute to chemical pesticide for integrated management of diamondback moth. MS History: 4.2.2014 (Received)-23.4.2014 (Revised)-15.6.2014 (Accepted)