Laboratory Studies on Several Plant Materials as Insect Repellants for Protection of Cereal Grains1

Abstract

Three plant materials that are common in Pakistan, rhizomes of Curcuma longa (L.) (turmeric), leaves of Azadirachta indica A. Juss. (neem), and leaves of Trigonella foenum-graecum L. (fenugreek), were evaluated for their repellency against the adults of the three species of stored-product insects, Tribolium castaneum (Herbst), Sitophilus granarius (L.), and Rhyzopertha dominica(F.). Turmeric powder was the most effective of the three against S. granarius and R. dominica. and also the most effective of the solvent extracts against T. castaneum. For each plant material, the petroleum ether extracts were more effective than the acetone and ethanol extracts. The petroleum ether extract of fenugreek deteriorated much faster than the similar extracts of turmeric and neem. The petroleum ether extract of neem was the most effective of the three plant materials against penetration by R. dominica.