The effects of aqueous extracts of different plant species on the development of Plutella xylostella (L.) were studied. Leaf discs of kale cultivar Portuguesa, Brassica oleracea var. acephala, were dipped in each plant extract per 30 seconds. Twelve neonate P. xylostela larvae (<12h) were fed on treated leaf discs and kept in petri dishes. The leaf discs were replaced at two-day intervals by fresh leaf discs treated with the plant extracts. Larvae of P. xylostella which fed on leaf discs treated with Melia. azedarach L. and Cissampelos aff. glaberrima St. Hil. delayed their development by 3.5 and 1.7 days, respectively. However, the other plant extracts studied did not affect larva development. Extracts of Aspidosperma pyrifolium Mart., Azadirachta indica A. Juss., and A. indica oil formulation caused 100% mortality of P. xylostella larvae, while, the extracts of M. azedarach, C. aff.glaberrima, Laurus nobillis L., Prosopis juliflora DC, Croton sp. and Eugenia uniflora L. caused larval mortality of 96.7, 93.3, 83.3, 66.7, 63.3 and 60%, respectively. The other studied extracts did not cause significant larval mortality. Duration of pupae stage was not affected by the studied plant extracts, however, the extracts of M. azedarach, L. nobillis, C. aff. Glaberrima and Croton sp. caused 100, 90, 66.7 and 65% of pupae mortality, respectively.
Insecta; diamondback moth; plant insecticide; cabbage pest
