Mortality Of Adult Weevils Research Articles

Control of rice weevils, Sitophilus oryzae (L.) in stored maize with vegetable oils

Oils of coconut, groundnut and the African palm admixed with maize grains at dosage rates of 5 and 10 ml kg −1 killed 67–100% Sitophilus oryzae (L.) within 24 h. At 1 ml oil kg −1 mortality of adult weevils reached 100% in 7 days. The oils significantly reduced egg laying development of offspring by weevils in contact with oil-treated maize. Grain damage and loss in weight of infestedmaize were much lower in oil treatments than in the control. A positive correlation ( r = 0.94) was observed between emergence of weevil offspring and damage to maize grains and also between weight loss in grains ( r = 0.995) and the number of exit holes caused by emergence of weevil offspring. Vegetable oils did not affect water absorption by submerged maize seeds intended to be processed into porridge, nor was viability reduced. Reduction of grain damage and weight loss in oil-treated maize seeds was greatest when coconut and groundnut oils were used. All oils prevented weevil infestation for > 90 days.