EFFICACY OF BIOPESTICIDES AGAINST THE GRUB OF EPILACHNA BEETLE, Epilachna dodecastigma Wied. AT LABORATORY CONDITION

Abstract

The experiment was carried out in the laboratory of the Department of Entomology, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during July to October, 2019 to find out the effectiveness of some botanical oils and organic insecticides for their toxicity and repellency effects against the third instar larva of epilachna beetle, Epilachna dodecastigma. Four botanical oils like black cumin, sesame, castor and neem at four (10.0, 7.50, 5.00 and 2.5 %) concentrations and two organic insecticides like Ecomec 1.8 EC and Bioneem plus 1.0 EC at four (1.5, 1.0, 0.5 and 0.25ml/L) concentrations were used in this study. Average mortality percentage of the larva of Epilachna dodecastigma at 24, 48 and 72 HAT indicated that castor oil possessed the highest mortality (36.67 %) and sesame oil showed the lowest mortality (13.33 %) among the four botanical oils. On the basis of insect mortalty and LD50values the order of the toxicity of the four botanical oils were castor>neem>black cumin>sesame. On the other hand, Ecomec 1.8 EC showed the mortality (90.00 %) which was higher than Bioneem plus 1.0 EC (71.39 %). The order of toxicity of two organic insecticides on the basis of mortality and LD50 values were Ecomec 1.8 EC>Bioneem plus 1.0 EC. The lowest LD50 values indicated the highest effectivess against the third instar larva of Epilachna dodecastigma. The repellent effect of black cumin, sesame, castor and neem oils showed that the four botanical oils had moderate repellent action on the insect. Among the four botanical oils, castor oil also showed highest repellency (72.08 %) while sesame oil provided the lowest repellency (55.97 %). On the contrary, Ecomec 1.8 EC showed more repellency (88.19 %) effect than Bioneem plus 1.0 EC (72.64 %) between the organic insecticides. Mortality percentage was also found directly proportional to the hour after treatment in both the botanical oils and organic insecticides at different levels of concentration