Abstract
Coelaenomenodera lameensis is the major pest of oil palm. The fight against this pest is achieved by using several methods including the injection of systemic insecticide in the trunk of the palm. The tests were conducted at the agro-industrial units of Toumanguié, located 90 km from Abidjan. Azadirachtin A was used in systemic treatment at four concentrations: 0.1, 0.2, 0.4 and 0.6 g/ml. Chiffon sleeves were placed on the palms to assess the effect of products on C. lameensis. Systemic injections were made during the dry and rainy seasons. The efficacy of azadirachtin was assessed by reference to thiamethoxam, an insecticide used in the fight against this pest. The effective minimal concentration was 0.4 g/ml of azadirachtin. This concentration generated the cumulated mortality rates of 38.92% in dry season and 19.28% in rainy season on the adults after 28 days of treatment. The percentages of efficiency achieved in the dry season on the larvae 7 days after treatment were 74.75% (stage 1), 57.23% (stage 2), 7.14% (stage 3) and 5.31 % (stage 4). In rainy season, the efficacy of azadirachtin on larvae was less than 29%. Azadirachtin can be used in dry season, at the beginning of the infestation period, to fight against C. lameensis.