ISOLATION OF Bacillus thuringiensis AND ITS EFFECT AGAINST Galleria mellonella

Abstract

The greater wax moth (GWM) galleria mellonella is a ubiquitous pest of the honey bee. The damage caused by G. mellonella is severe in tropical and sub tropical regions, and is believed to be one of the contributing factors to the decline in both feral and wild honey bee population. An integrated pest management (IPM) is required to control the GWM, within which biological controls play a key role. Bacillus thuringiensis is a gram positive rod shaped bacterium which has an insecticidal property. Hence, the main objective of this study was to isolate Bacillus thuringiensis and its effect against Galleria mellonella under laboratory conditions. 100 soil samples were collected from different areas of Itahari, Tarhara, Dharan and Vedetar. Out of 100 soil samples, 30 Bt isolates were obtained which were tested against GWM larvae. Three different concentration of crystal/spore mixture (1mg/ml, 500μg/ml, and 250μg/ml) was maintained. Mortality was observed after the four days of inoculation. Among 30 isolates, only four isolates showed an insecticidal activity. B. thuringiensis isolated from Tarhara showed the 57.78% efficacy which was much more than other isolates. The relation between treatment and control was statistically significant (p<0.05). The mean difference was significant at 0.05 levels on both bacterial death and survival. The result concluded that, there BT could be safe microbial agent in managing GWM.