( ~ Pergamon Biochemical Systematicsand Ecology, Vol. 22, No. 2, pp. 121-127, 1994 Copyright© 1994Elsevier ScienceLtd Printed in GreatBritain.All rights reserved 0305-1978/94 $6.00+0.00 Insecticidal Bioactivity of Crude Extracts of Aglaia Species (Meliaceae) C. SATASOOK,*t M. B. ISMAN,*$ F. ISHIBASHI,*§ S. MEDBURY,IIP. WlRIYACHITRA¶ and G. H. N. TOWERS* *Departments of Plant Science and Botany, University of British Columbia, Vancouver, B.C., Canada, V6T 1Z4; IIHonolulu Botanical Gardens, 50 North Vineyard Boulevard, Honolulu, HI 96817, U.S.A.; ¶Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50002, Thailand Key Word Index--Aglaia; Peridroma saucia; screening; natural insecticides. Abstract--Crude foliar extracts of 19 species of Aglaia (Meliaceae), mostly of Indo-Malaysian origin, were screened for larval growth inhibiting and insecticidal effects on the polyphagous lepidopteran Peridroma saucia (Noctuidae). Extracts of at least seven of these species significantly reduce larval growth of P. saucia. Aglaia odorata yielded the most inhibitory extracts, but there is significant (35-fold) geographical variation in the bioactivity of extracts within this widespread species. In addition, extracts of bark are significantly more active than foliar extracts. Foliar extracts significantly deter neonate larvae, but nutritional analyses of fourth instar larvae fed artificial diets laced with A. odorata extracts indicate that both diet consumption and dietary utilization are impaired. These results are similar to that obtained with pure (-)-rocaglamide, an insecticidal principle isolated from A. odorata. This species should provide a useful starting point for the development of a botanical insecticide. Introduction In the last two decades considerable effort has been devoted to the discovery of new sources of botanical insecticide and antifeedants. Among plant families studied, the Meliaceae and Rutaceae are perhaps the most promising (Schoonhoven, 1982), at least partly owing to the presence of limonoids, triterpenes characteristic of the order Rutales. The biological activity of limonoids from the Rutales has recently been reviewed (Champagne et al., 1992). Azadirachtin, a limonoid from the neem tree (Azadirachta indica) is well known for its antifeeding and growth disruption activities against various insect pests (Champagne et al., 1992). Some neem-based botanical insecticides have already been developed and marketed (Schmutterer, 1990). Screening for feeding deterrency and growth inhibitory effects of extracts from other members of the Meliaceae against a number of insect pests revealed that extracts from some species of Aglaia possessed promising bioactivity (Chiu, 1985; Mikolajczak and Reed, 1987; Champagne et aL, 1989). These reports suggest the potential of Aglaia as a source for natural pesticides and provided the impetus for a systematic investigation of the genus for bioactive taxa. About 130 species of Aglaia are found in Indo-Malaysia, South China and the Pacific Islands. They exist as dioecious trees, bushes or shrubs with minute or small fragrant flowers (Ridley, 1922; Li, 1977). Aglaia odorata is the type species and probably a native of Southeast Asia (Backer and van den Brink, 1965; Pennington and Styles, 1975). The present paper reports studies on screening the bioactivities of crude extracts from 19 Aglaia species against a polyphagous lepidopteran, the variegated cutworm, Peridroma saucia (HL~bner). tPresent address: Faculty of Science, Prince of Songkla University, Hat Yai 90112, Thailand. $Author to whom reprint requests and correspondence should be addressed. §Present address: Faculty of Fisheries, Nagasaki University, Nagasaki 852, Japan. (Received 23 June 1993) 121