Evaluation of the repellent effect of leaf and fresh kernel extracts of neem (Azadirachta indica A. Juss., 1830) on the sweet potato weevil (Cylas puncticollis Boheman, 1833) under laboratory conditions in Burkina Faso

The sweet potato, Lpomoea batatas (L) Lam. is a major subsistance crop in Africa. It plays a major role in the diets of many urban and rural house holds, and is a source of income for farmers. Its production is limited by several constraints, including the weevil Cylas puncticollis (Coleoptera:Apionidae). Weevil repellency tests were carried out in the laboratory using aqueous extracts of neem leaves and fresh neem kernels. The experimental design was a Fisher block with four treatments (different extract concentrations and distilled water) and five replicates. The test consisted in accessing the percentage of weevils present in the treated area. Each concentration was applied to one half of Whatman blotting paper placed in a 9-cm diameter Petri dish, on which 10 adult weevils were placed. The results showed that the aqueous extracts of neem leaves and fresh neem kernels caused 100% repulsion of the weevils after 1 hour's exposure, compared with the distilled water control. The tests revealed that aqueous neem leaf extracts had a higher repellent potential than almonds after 30 min of weevil exposure. Neem leaf extracts could be a more environmentally-friendly method of controlling this insect pest, both for human and animal health.