Effects of Cold- and Hot-Pressed Neem Oil on Eggs of the Pod-Sucking Bug Clavigralla tomentosicollis Stål (Hemiptera: Coreidae) and Its Parasitoid Gryon fulviventre Crawford (Hymenoptera: Scelionidae) under Laboratory Conditions

Abstract

The control of major insect crop pests of cowpea in Africa often involves synthetic pesticides to protect these crucial agricultural products. However, consequent harms to the environment, humans, animals and beneficial insects by these synthetic pesticides have driven a search for more sustainable integrated insect pest management (IPM) approaches, including the use of biological controls and neem (Azadirachta indica A. Juss) oil as alternatives to synthetic pesticides for the control of the pod-sucking bug Clavigralla tomentosicollis Stal on African cowpea crops. To date, however, no study to the authors' knowledge has investigated the compatibility and effectiveness of biological controls and neem approaches used together. In this study, we assessed the effects of two available preparations of neem oil (cold-pressed and hot-pressed) on the eggs of C. tomentosicollis and its parasitoid Gryon fulviventre Crawford. The main results of the study support the hypothesis that both cold-pressed and hot-pressed neem oil sprays are compatible with biological/IPM control efforts using G. fulviventre. While hot-pressed neem showed stronger effects on levels of egg hatchability and mortality for C. tomentosicollis compared to cold-pressed neem, no differences in outcomes across tested neem concentrations were observed. Future research, including field trials, will have the potential to elucidate any underlying mechanisms of these results and/or to more exactly identify appropriate concentrations needed to successfully integrate biological and non-synthetic controls for major cowpea pests in Africa.