Survey of Insect Pest Diversity on Stored Beans in Markets of Adamawa State

Insect pest infestation is the primary cause of stored bean quality deterioration in Nigerian markets, and documenting the pest diversity and infestation levels on beans sold in Adamawa State markets provides a basis for improved storage management recommendations along the value chain. This study surveyed the species diversity and infestation intensity of storage insect pests on cowpea and black-eyed beans sold in markets in Yola North, Hong, and Numan LGAs of Adamawa State, North East Nigeria. Bean samples of 500 g each were collected from 60 market traders (20 per LGA) and transported to the Adamawa State University laboratory for pest extraction, identification, and counting. Moisture content and percentage damaged grain were also determined. Results identified seven storage pest species, with Callosobruchus maculatus (bean weevil) the most prevalent (found in 88.3 percent of samples), followed by Tribolium castaneum (flour beetle, 63.3 percent) and Actellic dust residues indicating prior chemical treatment in 41.7 percent. Mean infestation density was 18.4 insects per 500 g sample. Percentage damaged grain averaged 23.7 percent and was highest in open sack storage samples. Moisture content above 14 percent was associated with significantly higher infestation (p < 0.05). Most traders (71.7 percent) used no storage protection method. The study recommends hermetic storage technology demonstrations, Actellic dust application training, and bean market sanitation improvement as priority interventions in Adamawa State bean markets. Keywords: storage pests, beans, Callosobruchus maculatus, market survey, Adamawa State