Host-plant resistance: A viable non - chemical and environmentally friendly strategy of controlling stored products pests-a review

Harvested grains suffer enormous damage from insect pests during storage. Their protection in storage has been the subject of many studies including the search for resistant varieties. Screening of many seed varieties had led to the successful isolation of strains that are resistant to insect pests in some African countries. Amongst grain legumes, three out of the 12,000 cowpea (Vigna unguiculata (L.) Walp.) varieties screened were found to be effectively resistant to two cowpea bruchids (Callosobruchus maculatus F.) and C. subinnotatus (Pic.). Out of 31 Bambara groundnut (Vigna subterranea Thou.) varieties screened, 6 were found to be resistant to these bruchids. Similarly, four varieties of groundnut (Arachis hypogea L.) were found to be resistant to both Indian meal moth (Plodia interpunctella Hubner) and rust red flour beetle (Tribolium castaneum Herbest). Among the cereal grains, 175 maize (Zea mays L.) varieties were investigated and 28 found resistant against both the larger grain borer (Prostephanus truncatus Horn.) and the maize weevil (Sitophilus zeamais Motschulsky). These studies revealed that host-plant resistance is a very good method of combating pest depredation in storage. It is perhaps the easiest, most economical and effective means of controlling insect pests on stored grains as there is no special technology which has to be adopted by farmers. The expenses to the farmer are limited because he only has to buy the seeds and no environmental hazards are involved. Furthermore the method is quite compatible with other methods of control.