EFFICACITÉ DU BAUME DE CAJOU ET DES HUILES VÉGÉTALES POUR LA LUTTE CONTRE LES POPULATIONS DE Plutella xylostella L. 1758 (LEPIDOPTERA: PLUTELLIDAE)

Abstract

Cabbage, Brassica oleracea L. (Capparales: Brassicaceae), is one of the crops most attacked by a complex of pests, including Plutella xylostella L. (Lepidoptera: Plutellidea). The objective of this study was to assess the effectiveness of vegetable oils and cashews for the control of P. xylostella in cabbage production. A study was carried out in the laboratory of the International Institute of Tropical Agriculture (IITA) in Benin Treatments included oils from three plants, namely Tephrosia purpurea, Ricinus communis, Thevetia neriifolia and cashew, versus a synthetic insecticide (Lambda cyhalothrin) and a botanical pesticide (Topbio). Two experiments were set for this study. In the first experiment, the products were tested on the L3 stage of P. xylostella, with the doses of 100, 75, 50, 25 and 10%; while in the second, the same products were tested on the L2 stage of the same insect with the doses of 50, 25, 10, 5, 3, 2 and 1%. All these were compared with the reference control Lambda cyhalothrin at the doses of 10, 5, 3, 2, 1 and 0.5%. The variables measured were the mortality rate, pupae formation and the emergence of adults of P. xylostella. The LD 50s were determined using the Cox regression method. The results showed that for all the botanical pesticides used, whatever the larval stage of P. xylostella was, the effect dose-response was significant, but less effective compared to the reference control Lambda cyhalothrin. Cashew and the three vegetable oils can effectively serve as alternatives to synthetic pesticides (Lambda cyhalothrin) against Plutella xylostella in cabbage production.