Comparative bioactivity of selected extracts from Meliaceae and some commercial botanical insecticides against two noctuid caterpillars, Trichoplusia ni and Pseudaletia unipuncta Y. Akhtar Æ Y. -R. Yeoung Æ M. B. Isman Received: 6 July 2006 / Accepted: 2 November 2006 / Published online: 13 March 2007 Ó Springer Science+Business Media B.V. 2007 Abstract Plant-derived extracts and phytochem- icals have long been a subject of research in an effort to develop alternatives to conventional insecticides but with reduced health and environ- mental impacts. In this review we compare the bioactivities of some plant extracts with those of commercially available botanical insecticides against two important agricultural pests, the cab- bage looper, Trichoplusia ni and the armyworm, Pseudaletia unipuncta. Test materials included extracts of Azadirachta indica (neem), A. excelsa (sentang), Melia volkensii, M. azedarach (China- berry) and Trichilia americana, (all belonging to the family Meliaceae) along with commercial botanical insecticides ryania, pyrethrum, rotenone and essential oils of rosemary and clove leaf. Most of the extracts and botanicals tested proved to be strong growth inhibitors, contact toxins and signif- icant feeding deterrents to both lepidopteran species. However, there were interspecific differ- ences with T. ni generally more susceptible to the botanicals than the armyworm, P. unipuncta. All botanicals were more inhibitory to growth and toxic (through feeding) to T. ni than to P. unipuncta, except for M. azedarach which was more toxic to P. unipuncta than to T. ni. Athough, pyrethrum was the most toxic botanical to both noctuids, A. indica, A. excelsa, and M. volkensii were more toxic than ryania, rotenone, clove oil and rosemary oil for T. ni. As feeding deterrents, pyrethrum was the most potent against T. ni, whereas A. indica was the most potent against the armyworm. Based upon growth inhibition, chronic toxicity, and antifeedant activity, some of these plant extracts have levels of activity that compare favorably to botanical products currently in com- mercial use and have potential for development as commercial insecticides. Keywords Azadirachta indica Á A. excelsa Á Melia volkensii Á M. azedarach Á Trichilia americana Á Rotenone Á Rosemary oil Á Clove oil Á Ryania Á Feeding deterrence Introduction Biopesticides are an important group of naturally occurring, often slow-acting crop protectants that are usually safer to humans and the environment than conventional pesticides, and with minimal residual effects. Biopesticides can be biochemical or microbial. Biochemical pesticides may include Y. Akhtar Á M. B. Isman (&) Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, CanadaV6T 1Z4 e-mail: murray.isman@ubc.ca Y.-R.Yeoung Department of Applied Plant Science, Kangnung National University, Gangneung, Kangwon-Do 201-702, Korea 123 Phytochem Rev (2008) 7:77–88 DOI 10.1007/s11101-006-9048-7