Effects of Balanite (Balanites aegyptiaca) and Neem (Azadirachta indica) Oils against the Tropical Warehouse Moth (Ephestia cautella) in Stored Maize

Abstract

Ephestia cautella (Walker) is an important storage pest of maize. The control of this insect relies heavily on the use of synthetic insecticides. This leads to environmental hazards, toxicity to non-target organisms and development of resistant strains of insect pests. Therefore, in this study laboratory bioassays were conducted by treating 100 g of maize grains with different concentrations of neem and desert date oils (10, 15, 20 and 25 ml/l) and Dichlorvos (DDVP) (10 ml/l) as standard reference product. Data were collected on contact toxicity by grain treatment, effects on progeny production, grain damage, weight loss, germination and palatability test. The persistence of the oils and DDVP were also tested. Each treatment was replicated three times in a completely randomized design (CRD). The data obtained were analyzed using ANOVA. The results indicated that Dichlorvos, neem and desert date oils significantly (P<0.05) caused mortality of adults and reduced progenies emergence. There was no emergence on grains treated with the oils at 30 ml/l and some of the adults emerged were deformed and hence can affect their survival and reproductive ability. Consequently, the oils also significantly (P<0.05) reduced the grain damage and weight loss. The oils remained effective for 9 weeks with percent mean damage of 8.67% and 5.13 % on grains treated with neem and desert date oils, respectively, at 20 ml/l as against the control with 68.10 % damage. The oils were also found to have no effects on seed germination with 90 to 93.33 % and 86.67 to 91.67 % percent germination were recorded on neem and desert date treated grains, respectively. Palatability of the treated grains was not affected by the oils after three (3) months storage. It was therefore shown that The effectiveness of neem oil is nothing new or that to be proven neem and desert date oils significantly (P<0.05) reduced infestation of maize grains and provided good protection to maize grains and could therefore be considered as a substitute for DDVP and other synthetic insecticides.