Factors Influencing Stored-oat Insect Populations in South Dakota

Abstract

Factors related to insect population fluctuations in stored oats were identified in a 2-year study. Oryzaephilus surinamensis (L.), Cryptolestes spp., and Tribolium castaneum (Herbst) were the predominant pests of stored oats and their population levels remained constant from 8 to 11% moisture. At moisture levels >11%, average insect density increased with increased moisture. High densities of O. surinamensis were found at moisture levels 13%. Average insect density levels peaked in November 1982 and again in September 1983. The incidence of live insects peaked at 74% in October 1982, while in September 1983 population levels peaked at 84%. The type of bin construction showed significant differences in insect density levels. Oats stored in flat storage and oats in large steel bins had significantly higher average insect density levels than oats stored in wooden bins. As bin size increased, the average insect density also increased. False or steel floors were found to have higher average insect density levels. Bins cleaned with a vacuum cleaner before filling had significantly lower average insect density levels than those cleaned with a scoop shovel or broom.