Population Dynamics of the Cowpea Weevil (Callosobruchus maculatus) in Stored Cowpea Grain in Zamfara State, North West Nigeria

The cowpea weevil, Callosobruchus maculatus, is the single most destructive storage pest of cowpea in sub-Saharan Africa, capable of completely destroying stored grain within a few months under ambient tropical conditions. In Zamfara State, cowpea storage by smallholders typically relies on traditional containers without pest control treatments. This study investigates the population dynamics of C. maculatus in cowpea stored under farmer-managed conditions in Zamfara State over a six-month post-harvest period. Grain samples will be collected from 50 storage units monthly and examined for adult weevil counts, damaged grain percentage, and weight loss. Temperature and moisture measurements will be taken inside each storage container at every sampling visit. Population growth parameters including intrinsic rate of increase will be estimated. The effectiveness of three low-cost management options (solar disinfection, hermetic storage bags, and ash treatment) will be compared against untreated controls in a randomized field trial at five farms. The study aims to provide evidence for scaling up low-cost pest management solutions appropriate for Zamfara State. Findings will be disseminated through the Zamfara State Agricultural Development Project extension network. Keywords: cowpea weevil, Callosobruchus maculatus, grain storage, population dynamics, Zamfara State