EFFECTS OF NEEM (Azadirachta indica) LEAF EXTRACT ON THE INSECT PESTS OF SWEET POTATOE (Ipomoea batatas) IN KANO STATE, NIGERIA

Abstract

Insect pests, such as the Sweet Potato Weevil (Cylas spp.) and various defoliators, pose a major constraint to sweet potato (Ipomoea batatas (L.) Lam.) production in Nigeria, with losses often exceeding 40%. This study investigated the efficacy of Neem Leaf Extract (NLE) as an organic biopesticide in managing insect pests of the Danchina sweet potato variety in Kano State during the 2024 rainy season. The field experiment utilized a Randomized Complete Block Design (RCBD) comparing three NLE concentrations (33.3%, 25%, and 20% weight-to-volume ratio), a Cypermethrin check, and an untreated control. NLE was prepared by soaking fresh leaves for 72 hours and was applied four times, starting at 6 Weeks After Planting (WAP) at two-week intervals. Data  analysis using ANOVA showed significant reductions in the total insect pest population across all NLE treatments compared to the untreated control (F-value < 0.05). The 33.3% NLE achieved the most sustained insect control among the botanical treatments, closely approaching the suppression level of the chemical check. Phytochemical analysis confirmed the presence of alkaloids, flavonoids, and phenols. Physical  analysis revealed a non-linear viscosity relationship, with the 25% NLE extract exhibiting the highest viscosity (930 cP}). This formulation's superior physical property is hypothesized to enhance adherence, contributing to its strong performance, which was often statistically comparable to the 33.3% concentration. Antimicrobial tests further confirmed the extract's dual role, exhibiting dose-dependent inhibitory activity against key bacterial (S. aureus, E. coli) and fungal (C. albicans) pathogens. In conclusion, NLE, particularly at the 33.3% concentration, is a highly effective, multifunctional, and eco-friendly alternative for sweet potato pest anagement. It is strongly recommended for integration into Integrated Pest Management (IPM) programs for smallholder farmers. However, acknowledging the single-season constraint, further trials across multiple agro-ecological zones are recommended to generalize its optimal use.