A Review of Insecticidal Plant Extractsand Compoundsfor Stored Maize Protection

Abstract

Insect pests cause significant losses to maize grains both in the fieldsand in storage. Maize weevil (Sitophilus zeamais) and larger grain borer (Prostephanus truncatus) are among the most destructive pests of maize in Africa. Currently, researchers have focused on identification of insecticidal plant extracts and compound through in-vivo and in-vitro experiments, as an alternative to synthetic chemicals which have been reported to have adverse effect on the environment.The aim of this study was to collate and review the fragmented information on plants extracts and compounds with insecticital activity against S. zeamais and P. truncatus and present recommendations for future research. Peer-reviewed articles were retrieved from Scopus, Science Direct, SciFinder and Google Scholar. This study led to identification of 123 plant species which have been examined for insecticidal activity focusing more on S. zeamais rather than P. truncatus.It is also evident that most studies end with the crude plant extracts. Effort towards identification of insecticidal principles from the plants is negligible despite the fact that insecticidal compounds from nature are preferred because they are environmentally safe. Future studies aimed in isolating and characterizing the active compounds from the plants is necessary. It is also necessary to develop plant based formulations to be used as altenatives in controlling the crop storage pests