Characterization of Bruchid Resistance in Cowpea Accessions from North East Nigeria and Identification of Biochemical Resistance Mechanisms

Bruchid beetles, principally Callosobruchus maculatus, are the most destructive storage insects of cowpea, causing complete grain loss if unmanaged. Breeding for host plant resistance is the most sustainable control strategy, and identifying resistant accessions from local germplasm collections is a priority for Nigerian breeding programs. This study characterizes resistance levels in 40 cowpea accessions collected from farmers across Adamawa, Gombe, and Taraba states against C. maculatus and investigates biochemical mechanisms underlying resistance. Resistance screening will follow the no-choice oviposition and development assay protocol, measuring adult emergence, development period, and seed damage indices under controlled conditions. Selected resistant accessions will be analyzed for trypsin inhibitor activity, tannin content, lectin concentration, and seed coat hardness as candidate resistance biochemicals. Correlation and stepwise regression analyses will identify which biochemical traits best explain variation in resistance. The study addresses the need to catalog North East Nigerian cowpea germplasm for resistance traits, providing raw material for the International Institute of Tropical Agriculture cowpea improvement program and Gombe State seed production systems. Keywords: cowpea bruchid, Callosobruchus maculatus, host plant resistance, biochemical mechanisms, North East Nigeria