EFFECT OF SOME INDIGENOUS PLANT EXTRACTS AGAINST LESSER GRAIN BORER, RHYZOPERTHA DOMINICA (COLEOPTERA : BOSTRICHIDAE)

Abstract

The study was carried out in the laboratory of the Department of Entomology, Hajee Mohammad Danesh Science and Technology University, Dinajpur during the period from April to December 2012 to evaluate the efficacy of different plant extract viz. Ata (Annona reticulata), Karabi (Nerium oleander), Neem (Azadirachta indica), Biskatali (Polygonum hydropiper) and Akanda (Calotropis gigantea) in petroleum ether for the toxicity, residual and repellent effects against lesser grain borer, Rhyzopertha dominica. The leaf extracts of above mentioned plants were applied at three doses viz. 4.0, 6.0 and 8.0% concentration. The result showed that extracts of five tested plants had toxic and repellent effects on lesser grain borer. Neem leaf extract showed the highest toxicity and repellent efficacy on lesser grain borer. Even though all the doses had toxicity, residual and repellency effects but the highest efficacy showed at 8% concentration ( 8% dose showed the highest response). On the basis of the LD50 values, it was observed that the neem extract showed the highest performance. Considering all the concentrations, the order of toxicity levels of five plant extracts on lesser grain borer was found as neem> biskatali> karabi> akanda > ata. Mortality percentages were directly proportional to the time after treatment. In case of repellency, it was found that all the tested extracts were in the same repellency class i.e. class II. As the progress of time mortality percentage increased (with the progress of time) meanwhile the repellency effect decreased.