Screen house studies on the incidence and yield losses in three cowpea (Vigna unguiculata) varieties, TV × 3236, Ife Brown and Ife Bimpe due to the leaf beetle Ootheca mutabilis Sahl were carried out. Artificial infestation was done at two growth stages of cowpea: the 5-leaf stage (2 weeks after emergence) and 4 weeks after emergence. Variety TV×3236 was found to be the least susceptible, while var. Ife Bimpe was the most susceptible to leaf beetle damage. Young plants were more susceptible than older ones.
Flowering was delayed in plants infested with beetles and the extent of defoliation had a pronounced effect on the yield of cowpea.
The percentage grain yield loss ranged from 19.48% to 59.77% depending on level of beetle infestation, variety and age of the plant at infestation.
