Concept:Callosobruchus maculatus is a storage pest that mainly attacks legume seeds.Explanation:This beetle commonly infests cowpea seeds during storage.The female lays eggs on the seed coat, and the larvae bore into the seeds to feed.The feeding damage reduces seed quality and germination.Sorghum, rice, and maize are not its preferred hosts.Hence, it is a well-known pest of cowpea.Answer:D. Cowpea