Cultivars of wheat, Triticum aestivum L., were assessed to determine their respective level of resistance to lesser grain borers, Rhyzopertha dominica (F.), in postharvest storage. Cultivars were representative of hard red winter, soft red winter, white spring, and durum wheat classes currently grown in the United States. Samples of each cultivar were maintained at 30.0°C and 70% RH and infested with 2- to 3-wk-old adult beetles for 1 wk. Adult progeny were counted at the end of one life cycle. Two temperatures, 27.0 and 34.0°C, were studied to examine the role of temperature (calculated in degree-days) in development. This experiment was conducted three times under similar conditions. Cultivars harboring a large quantity of progeny were considered more susceptible than those cultivars in which fewer progeny completed their life cycle. Each cultivar was analyzed for single kernel properties such as hardness, protein, and diameter. Wheat cultivar had a significant influence on quantity of progeny in all experiments. There were no significant effects on survivorship of progeny as a result of temperature when calculated in degree-days. Cultivars with smaller kernels were more susceptible to development of larger generation sizes in experiment 1 but not in the other two experiments. A kernel size experiment using large and small kernels from the same cultivar suggested that larger quantities of progeny are produced on small kernels compared with large kernels. Individual beetle weights were not influenced by temperature or cultivar. These results imply that stored grain managers should be aware of potential differences in susceptibility, attributable to wheat cultivar, to lesser grain borer infestations.
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