Melia azedarach Extracts: A Potential Tool for Insect Pest Management

Plant derivatives possessing insect repellent and antifeedant properties could offer an alternative approach for managing crop pests and dealing with insect-transmitted diseases. This chapter summarizes results from studies on insecticidal effects of Melia azedarach extracts from Central Argentina. Extracts from different plant structures (green/ripe fruits, green/senescent leaves) and a variety of insect feeding strategies have been considered. Antifeedant effects were tested on more than 23 species in laboratory choice tests. Further effects on insect feeding and survival were studied in no-choice tests on 12 species. In the choice tests, M. azedarach extracts strongly deterred feeding in most of the species, with those in Coleoptera being particularly sensitive. Increased mortality rates, reduced food consumption, lower body weight and delayed development were recorded in no-choice tests. Increases in mortality might be related to the strong antifeedant activity of the extracts. Results from other authors are also reviewed, in order to provide an updated assessment of M. azedarach extract activity.