EFFICACY OF SOME WEED EXTRACTS AGAINST RICE WEEVIL, SITOPHILUS ORYZAE L. (COLEOPTERA: CURCULIONIDAE)

Abstract

The experiment was carried out in the laboratory of the Department of Entomology, Hajee Mohammad Danesh Science and Technology University (HSTU), Dinajpur during June to October 2017 to find out the toxicity, repellency and residual effects of bishkatali, mutha and bothua weed extracts against rice weevil, Sitophilus oryzae. The doses were 1.7680, 1.4144, 1.0608 mg/cm2 for their toxicity effect and 30, 40, 50 mg/ml for repellency and residual effects against rice weevil. The result revealed that all the weed extracts had direct toxic, repellent and residual effect on rice weevil in storage. Average mortality percentage of rice weevil at 24, 48 and 72 hours after treatments indicated that bishkatali weed extract possessed the highest mortality (45.00 %) and bothua weed extract showed the lowest mortality (30.28 %). Mortality percentage was also found directly proportional to the level of concentrations of weed extracts and to the exposure period. Considering all the concentration and efficacy, the order of toxicity level of weed extracts were found as bishkatali >mutha >bothua. The bishkatali, mutha and bothua weed extracts had moderate repellent action on rice weevil. Bishkatali weed extract showed the highest repellency (44.44 %) while bothua extract provided the lowest repellency (35.56 %). Among the tested weed extracts, Bishkatali extract showed the lowest number (17.16%) of F1 progeny production and lowest (2.667%) weight loss whereas the highest number (44.00 %) of F1 progeny production and highest weight loss (54.82%) were found in control