Effects of Melia azedarach L. extract on the teak defoliator Hyblaea puera Cramer (Lepidoptera: Hyblaeidae)

Methanolic extracts from leaves and seeds of chinaberry tree, Melia azedarach L. (Meliaceae) were tested against the larvae of Hyblaea puera (H. puera) Cramer (Lepidoptera: Hyblaeidae) under laboratory conditions. This insect defoliates teak, and is considered as a major pest that strongly influences the development of the teak tree. Chinaberry extracts were found to affect the growth, feeding and oviposition of H. puera. In general, the seed extracts showed high bioactivity at all doses, while the leaf extract, proved to be active, only at the higher doses. Our laboratory experiment showed that the seed extract suppressed the larval activity of H. puera even at low doses. Gross dietary utilization (efficiency of conversion of ingested and digested food) of H. puera decreased after treatment in the diet. The growth of surviving larvae decreased, and no late fourth and early fifth instars completed development on higher dose treatment of both leafs and seed extracts. Food consumption, digestion, relative consumption rate (RCR), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), and relative growth rate (RGR) values declined significantly, but concurrently a significant increase in approximate digestibility (AD) was observed. Clear dose-response relationships were established, with the highest dose of 4% seed extract evoking 94% feeding deterrence. Larvae that were chronically exposed M. azedarach extract showed a reduction in weight (65-84%). The less expensive and naturally occurring biopesticide may be an alternative for synthetic pesticides in order to protect forest trees. (c) 2005 Elsevier Ltd. All rights reserved.