Effect of the Infection of Callosobruchus maculatus (Fab.) on the Weight Loss of Stored Cowpea (Vigna unguiculata (L.) Walp)

Market survey and laboratory experiments were conducted to obtain more reliable estimates of cowpea weight loss caused by individual Callosobruchus maculatus. In both the market survey and laboratory experiments, a highly significant inverse linear relationship existed between C. maculatus feeding/emergence holes and cowpea weight loss (P 0.001, linear correlation coefficients (r) = -0.322,-0.959, and –0.921, for the market survey, laboratory experiments 1 and 2, respectively). Cowpea weight losses were 0.026g, 0.015g, and 0.016g per individual C. maculatus in the market survey, laboratory experiments 1 and 2, respectively while the highest number of C. maculatus feeding/emergence holes was 188, 1669, and 2028 per 200 cowpea seeds for the market survey, laboratory experiments 1 and 2, respectively. This is an important component in the establishment of an Economic Injury Level (EIL) for C. maculatus on V. unguiculata.