EVALUATION OF Pongamia pinnata SEED EXTRACTS AS AN INSECTICIDE AGAINST AMERICAN BOLLWORM Helicoverpa armigera (HUBNER)

Abstract

Background - Karanj has been reported to possess insecticidal properties; however most of the work done so far is restricted to its oil. Karanj seeds (both mature as well as immature) methanolic extracts (2.5, 5.0, 7.5 and 10.0%) were assessed for their insecticidal activities against Helicoverpa armigera (Hubner). Results - The mature seed extract 5.0% exhibited more than 50% first instar larval mortality and more than 65% third instar larval feeding deterrence. Besides, a pronounced decrease in food consumption and utilization indices was noticed when fourth instar larvae were fed on extract treated chickpea pods. Adults when fed on the extract treated sucrose diet (0.5, 1.0, 1.5 and 2.0%) exhibited a marked reduction in oviposition and egg hatching. Extracts also deterred the adult females from egg laying when applied on to the oviposition substrate (nochoice, choice and without actual contact condition) at concentrations as low as 2.5%. Hatching inhibition of one-day old eggs on application of extracts was recorded. Mature seed extracts gave better results than the immature one, though both were effective. Conclusion - Repeated application of mature karanj seed methanolic extract 2.5% may be incorporated in integrated pest management programmes to take care of H. armigera menace on crop plants.