Biotoxicity assay of Bacillus thuringiensis combined with sodium citrate, Bifenthrin+Cypermethrin and Saraca indica on Tribolium castaneum

Microbial control of insect pest of crops using entomopathogens is pest management strategy. Bacillus thuringiensis has a great potential for this purpose. The focus of the present study was to determine the individual and combined effect of different insecticides such as Saraca indica as a botanical insecticide, B. thuringiensis and chemical insecticides against larvae and adults of T. castaneum. Results were analyzed by SPSS probit analysis, LC50 was noted for all these insecticides and results were compared with each other. According to the results from the individual insecticide B. thuringiensis show high mortality with harmless effect to environment. Synergistic effect with high mortality rate was observed at 24 to 48 h, for both larvae and adults of T. castaneum. From the study it was observed that mortality rate increases as the concentrations increases, and larvae show higher mortality because they were more susceptible to these insecticides as compared to adults. Percentage mortality of T. castaneum in combined bioassay sodium citrate, S. indica, B. thuringiensis and Bifenthrin+cypermethrin was compared with the mortality of individual insecticides. 61% larvae and 55% adult died in combine bioassay at high concentration.     Key words: Bacillus thuringiensis, Saraca indica, Tribolium castaneum, Bifenthrin, Cypermethrin, biotoxicity assay.