Evaluation of the Effect of Aqueous Extracts of Fresh Neem (Azadirachta indica A. Juss., 1830) Leaves and Kernels on the Mortality of the Sweet Potato Weevil (Cylas puncticollis Boheman, 1833) under Laboratory Conditions in Burkina Faso

Abstract

Aims: Evaluate the effect of neem extracts (kernels and fresh leaves) on the mortality of the sweet potato weevil Cylas puncticollis in the laboratory. Place and Duration of Study: The study took place in Bobo-Dioulasso, western Burkina Faso. It lasted for 6 months.  Methodology: The experimental design was a completely randomized Fisher block in 5 treatments with 5 replicates. The collected fresh neem leaves and kernels were weighed and crushed to which 2.5 l of distilled water was added to each. After 12 hours, the mixture was filtered. Four concentrations were prepared from this filtrate: 10; 20; 30 and 40 cl/l and a control (distilled water). The various tests were carried out with Whatman paper cut into two equal parts then placed at the bottom of a Petri dish and spaced one centimeter apart. One ml of each dose of the solutions prepared was spread evenly on one of the two parts of the paper called the treated area while the other part received nothing called the untreated area. A batch of 10 adult weevils was placed in the center of the paper treated with neem extract. Results: The results showed that after 1 hour's exposure to neem leaf extracts, a high mortality of 45% was recorded, whereas with neem kernels extracts, 30% mortality was observed after 30 minutes' exposure, then 32.5% after 1 hour. Conclusion: Neem leaves and kernels extracts can be used to control the potato weevil, Cylas puncticollis. This is an environmentally-friendly control method that could be used as an alternative to chemicals.