Abstract

Novel strategies for Plutella xylostella management in cabbage need to be evaluated in order to increase its control and reduce adverse impacts on the environment. Thus, we evaluated the combined effects of the cabbage cultivars Ruby Ball, Matsukase Sakata, and Sessenta Dias, the aqueous extracts of Azadirachta indica, Aspidosperma pyrifolium, and Melia azedarach, and the parasitoid Oomyzus sokolowskii on P. xylostella control and selectivity to the parasitoid. This study attempted to give insights to further elaborate an IPM strategy for cabbage crop. The first assay recorded P. xylostella mortality, and the second assay recorded the number of parasitoids emerged from P. xylostella pupa and O. sokolowskii immature development in two successive generations. Cultivar Ruby Ball treated with A. pyrifolium extract increased P. xylostella mortality over 85%. Parasitism by O. sokolowskii combined with A. pyrifolium or A. indica extracts provided up to 95% mortality, regardless of the cabbage cultivar. Cultivar Matsukase Sakata treated with M. azedarach or A. indica extracts affected adversely O. sokolowskii development. The number of parasitoids emerged from P. xylostella pupa was increased from the first to the second generation on the resistant cvs. Ruby Ball and Matsukase Sakata. Further experiments are encouraged to confirm in greenhouse and field the high mortality rates of P. xylostella and selectivity to O. sokolowskii, in order to elaborate an efficient IPM program for cabbage against the diamondback moth.

Key words: Brassica oleraceae var. capitata, diamondback moth, host plant resistance, integrated pest management, Oomyzus sokolowskii, plant extracts.