Evaluation of the residual activity of newly developed aqueous formulation of novel biopesticide Bacillus cereus VCRC-641 through simulated field trial

In the study a new aqueous formulation with the new mosquitocidal isolate of Bacillus cereus VCRC 641 was developed, and the residual activity was assessed from simulated field trials conducted in the natural environment. From laboratory bioassays, it was observed that the efficacy of aqueous formulation of Bacillus cereus was on par with lyophilized cell mass, as such. The LC50 values of formulated  B. cereus against Culex quinquefasciatus, Anopheles stephensi and Aedes aegypti were 0.002, 0.009 and 0.008 mg L-1 respectively. Correspondingly, the LC50 values of lyophilized cell mass of B. cereus against these three mosquito species were 0.0019, 0.005 and 0.004 mg L-1 respectively. Finally, simulated field trial was carried out using formulated B. cereus and the residual efficacy against all three mosquito larval species revealed 100 per cent larval mortality up to seven days and 69 to 78 per cent mortality were up to 15 days. Thereafter, the mortality was declining gradually up to 21 days. It is concluded that the formulation of B. cereus may be used for mosquito control program.