Rice Weevil Damage to Stored Corn1

Abstract

One of the most destructive insect pests of stored corn in North Carolina is the rice weevil, Sitophilus oryza (L.). No accurate figures on the amount of damage caused by this pest under North Carolina conditions have been available. This study attempts to determine not only the weight losses occasioned by the weevil but also the loss in nutritive value that results from weevil attack. Weevil damage and weight loss were determined in single kernels of corn as well as in lots of 20 and 250 grams stored at 60°, 70°, and 80° F. Nutritive losses were determined in 20- and 250-gram lots of corn by chemical analysis and by feeding tests on mice. The total loss in weight of corn was directly proportional to the number of weevils in the corn. The greatest loss occurred at 80° F. in each of the storage tests. In the single-kernel test, weevils were responsible for loss in weight of 74.7%; in the 20- gram test they caused a loss of 12.9%, and in the 250-gram test 25.9%. The protein content of the corn increased with a corresponding increase in weevil infestation. Mice ate less and showed the least gain in weight on meal prepared from heavily infested corn.