Effect of Pesticides on the Growth of Bacillus Thuringiensis Var. Israelensis and Bacillus Sphaericus 2362 Strain

Abstract

In this study, twenty-three different commercial pesticides including nine insecticides, six herbicides, four fungicides, three plant growth regulators and one acaricide were investigated for their effects spore viability and larvicidal activity of mosquito pathogenic Bacillus thuringiensis var. israeletisis and Bacillus sphaericus 2362 strain. Minimal inhibitor concentration (MIC) for each pesticide was determined for test bacteria grown into nutrient yeast salt (NYSM) broth. All pesticides except four had an adverse impact on bacterial growth, according to the MIC values. The most inhibitory insecticide, herbicide, fungicide and plant growth regulator were endosulfan 62.5 μL mL-1, diclofop-methyl 28 EC 62.5 μ mL-1, copper sulphate 12.5 μg mL-1 and gibberellic acid 0.25 mL mL-1, respectively. Neoron 500 EC, an acaricide, 31.2 μ mL-1 was the most inhibiting of all pesticides. In general, there was no significant difference between the susceptibility of Bacillus thutbigiensis var. israelensis and Bacillus sphaericus 2362 strain for pesticides examined in this study. High concentrations of all pesticides reduced heat-tolerant spore samples by suppressed spore germination. No larvacidal activity was observed at the MIC values or higher. These results should be considered for assessing the MIC value of these pesticides when both microbial pest agents used in field application. © International Scientific Publications, New Delhi.