Effectiveness of some plant extracts as surface protectants of cowpea seeds against the pulse beetle,Callosobruchus chinensis

Abstract

A bioassay procedure for detecting and evaluating pest control agents in plant extracts was developed using the pulse beetle,Callosobruchus chinensis L. Four plant species common in Egypt,Clerodendrum inerme, Nerium oleander, Ipomoea palmata andAtriplex lentiformis, were extracted with petroleum ether. The crude extracts were evaluated as surface protectants for cowpea(Vigna sinensis) seeds againstC. chinensis infestation. All extracts showed some degree of oviposition deterrent effect at one or more of the concentrations applied. The extracts also had conspicuous activity against the eggs ofC. chinensis deposited on treated seeds, leading to a pronounced reduction in F1 progeny. At 0.5%, theI. palmata extract provided 97% seed protection against insect infestation, followed byN. oleander (94%),C. inerme (93%) andA. lentiformis (89%). Moreover, theI. palmata extract showed good insecticidal activity as a result of contact toxicity. TheC. inerme extract was the least toxic material to the insects.