Studies on pest infestation of commercial samples of cowpeas and maize Marketed in Owerri, Imo State, Nigeria

Abstract

Samples of different varieties of brown beans, Vigna unguiculata and white maize, Zea mays randomly purchased from two open markets in Owerri, Imo State were studied for pest infestation. The grains were examined with x2 magnification hand lens for the eggs, larvae and adults of the pests. Callosobruchus maculates (Olivier) and Sitophilus zeamais (Motsch) were identified as insect pests infesting beans and maize respectively. On the overall, 43.3% of 7565 cowpea and 30.8% of 4640 of maize grains respectively were infested. Eggs, larvae, pupae and adults of the insect pests were recovered from both the beans and maize samples. In beans, eggs of C. maculates were found only on the pericarp while the larvae, pupae and adults were recovered from both the pericarp and from within the endosperm of the seeds. In the maize, the eggs, larvae and pupae of S. zeamais were located in the endosperm only, while the adults were found in both the endosperm and the outer surfaces of the grains. Weight loss as an index of degree of damage to the samples ranged from 23.3% to 35.7% in beans and 19.3% to 55.7% in maize. Weight loss in both the infested beans and maize increased with increase in the number of emergence holes. Public health implications of the insect infestation of the stored products such as reduction in nutritive value and accumulation of undesirable residues were discussed. Improved storage and pest control techniques are recommended.

Keywords: pest, infestation, cowpea, maize, Nigeria

International Journal of Natural and Applied Sciences Vol. 1(1) 2005: 5-9