| Abstract: | Defoliating caterpillars from the family Noctuidae are the most destructive insect pests on spearmint crop in Morocco. To control these pests, the growers apply several applications of non‐selective insecticides that are sometimes not registered for this use. This study investigates the efficacy of a set of selective chemical insecticides and other insecticides registered for organic farming against the defoliating caterpillars for better protection and in order to limit pesticide residues. Two insecticides authorized in organic farming and four other chemical insecticides were tested against the defoliating caterpillars under field conditions, following the randomized complete block experimental design with three replications. The comparative study of the efficacy of the different insecticides tested showed an average caterpillar reduction of 89.4, 82.5 and 68.1% with a defoliation reduction of 57.1, 53.8 and 43.9% for two of the tested synthetic insecticides, chlorantraniliprole (15cc/hl), emamectin benzoate (250g/ha) and for one of the tested bio‐insecticides, spinosad (30cc/hl) respectively. An increase of the total fresh mint weight compared to the non‐treated control was recorded for these three insecticides with 50.9%, 48.4%, and 40.5% for emamectin benzoate, chlorantraniliprole, and spinosad respectively. Insecticides containing chlorantraniliprole, emamectin benzoate, or spinosad active substances could be used as alternatives to other synthetic broad‐spectrum insecticides commonly used on spearmint in Morocco. |
