Professional Evaluation of Neem-Based Biopesticides for Management of Sooty Mould and Associated Insect Vectors in Mango Orchards in Enugu State

Sooty mould diseases of mango (Mangifera indica) in Enugu State are closely associated with populations of scale insects and mealybugs that excrete the honeydew substrate supporting fungal growth. Neem-based biopesticides offer an environmentally acceptable alternative to synthetic insecticides for managing the insect vectors responsible for sooty mould development. This professional study evaluated the efficacy of three commercial neem-based biopesticide formulations, applied at recommended and double-recommended rates, for controlling mealybug and scale insect populations and their subsequent effect on sooty mould incidence in mango orchards. Field trials were conducted in six orchards across three local government areas in Enugu State during the 2023 dry season. Insect population counts, honeydew deposition rates, sooty mould incidence, and fruit marketability scores were measured monthly over six months. Neem-based treatments reduced mealybug populations by an average of 64 percent after three applications and sooty mould incidence by 49 percent at double-recommended rates. Commercial efficacy was significantly lower at standard label rates under conditions of heavy pre-existing infestation, suggesting the need for revised application protocols under high-pressure conditions. All neem formulations were associated with lower natural enemy mortality compared to the synthetic insecticide reference treatment, supporting their use as selective vector management tools. The study recommends neem formulations as a component of an integrated vector management programme tailored to mango orchards in South East Nigeria. Keywords: mango, sooty mould, neem biopesticide, mealybug, Enugu State.