Effects of short-term feeding by adults of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) on shelled maize

Abstract Laboratory tests were performed to determine the damage caused by adults of Prostephanus truncatus (Horn) feeding on shelled maize. Adults when fed at densities of 25, 50, or 100 on 200 maize kernels for 10–40 days did not preferentially feed on the endosperm or the germ and damaged both. Fifty or 100 adults of P. truncatus feeding on 100 g of maize for 10–40 days caused substantial damage resulting in decreased weight and kernel germination. Kernel damage, grain weight loss, and germination after 40 days of adult feeding was about 5–8, 6–8, and 68–72%, respectively. Adult survival during the 40-day period decreased linearly with time at the rate of 1.5 and 1.3% of adults/day at adult densities of 50 and 100, respectively. Fifty adults of P. truncatus when fed on 100 g of maize for 20 days at 75% r.h. caused significantly greater kernel damage and grain weight loss at 30°C than at 25 or 35°C. However, adult survival at the three temperatures was similar. Though P. truncatus develops less effectively on shelled maize than maize on the cob, our results suggest that a short period of adult feeding could result in substantial grain damage.