Host plant resistance to insect pests of cowpea (Vigna unguiculata L. Walp.): achievements and future prospects

Cowpea (Vigna unguiculata L. Walp.) is an important cash, food and nutritional security grain legume crop in the semi-arid regions of sub-Saharan Africa. However, its productivity is hampered by several biotic stress factors including numerous insect pests that infest and damage the crop at all its development stages in the field as well as during storage. Host plant resistance is an environmental-friendly, cost-effective and sustainable pest management option for minimizing the pests' incidence and severity. This review article aims at describing the major insect pests in cowpea and highlight key past and recent research findings in cowpea resistance to insect pests. It also provides in-depth knowledge in the host-plant resistance mechanisms in cowpea i.e. biophysical, biochemical and physiological factors that regulate the defense systems in the plant. Furthermore, the paper discusses the need for advanced investigation on the genetic basis of the plant defense systems and its application to the crop breeding program for developing new improved materials. The review would support the cowpea breeding program with the overall expectations of developing insect-resistant lines, reducing the input costs of insecticides while also enhancing cowpea productivity in sub-Saharan Africa.