Effect of volatiles and crude extracts of different plant materials on egg viability ofmaruca vitrata andclavigralla tomentosicollis

Abstract

The effect of volatiles and aqueous extracts of black pepper,Piper guineense; neem seed,Azadirachta indica; garlic bulb,Allium sativum; and onion bulb,Allium cepa on egg viability ofMaruca vitrata Fab. (Lepidoptera: Pyralidae) andClavigralla tomentosicollis Stal (Heteroptera: Coreidae) was evaluated in laboratory experiments. Compared with the other treatments, volatiles of black pepper and garlic bulb were superior in reducing hatch of freshly laid (12-h-old) eggs of both species of insects. Volatiles of onion bulb and neem seed had no effect on egg hatch. When aqueous extracts of the various plant materials were tested at 5%, 10% and 15%, extracts of black pepper, neem seed and garlic bulb caused a severe reduction in egg hatch, with black pepper and garlic bulb providing the highest reduction at all concentrations tested in both insects. When black pepper and garlic bulb were compared at 5% for their activity in relation to egg age, the effect of black pepper decreased with increasing egg age but the performance of garlic was consistent across the various age groups tested in both insects. This result is indicative of the potential of using these plant materials and especially garlic for the management ofM. vitrata andC. tomentosicollis.