Transgenic Cowpea Expressing Synthetic BtCry1Ab Provides Enhanced Resistance to Maruca vitrata and Supports Sustainable Pod Borer Management

Cowpea, a vital legume crop, suffers substantial yield losses due to insect pests, particularly the legume pod borer ( Maruca vitrata ). The narrow genetic base of cowpea and the absence of effective host resistance against M. vitrata have limited the success of conventional breeding-based pest management. Given the increasing incidence of insecticide resistance and environmental concerns associated with chemical control, there is an urgent need for host plant-based solutions that fit within integrated pest management (IPM) frameworks. To address this challenge, we engineered transgenic cowpea plants expressing a synthetic cry1Ab gene under the control of the CaMV35S promoter. High expression of Cry1Ab was detected in leaves and pods, the primary feeding sites of key lepidopteran pests. Bioassays with M. vitrata and Helicoverpa armigera larvae demonstrated strong resistance in the transgenic lines, evidenced by reduced pod damage, suppressed larval feeding, and high insect mortality compared to non-transgenic controls. These results confirm the effective expression and bioactivity of Cry1Ab in planta, highlighting its potential as a reliable pest control trait under pest pressure. Importantly, the transgenic plants showed no detectable metabolic changes by NMR profiling and displayed normal growth and development without yield penalties. These findings underline the role of Bt-cowpea as a sustainable, environmentally compatible, and economically viable approach to reducing pest burden and pesticide dependence in legume production systems. Overall, the synthetic cry1Ab-expressing cowpea lines represent a promising next-generation tool for durable and broad-spectrum protection against major lepidopteran pests, contributing to the long-term goals of sustainable pest management and agricultural resilience.