Development and progeny production of lesser grain borer, Rhyzopertha dominica (Fabricius) on hulled, dehulled Kernza® and wheat

Kernza^® (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey, KernzaTM), is a low-input perennial cool-season intermediate wheatgrass, grown as a dual-purpose crop for high-quality grazing in the winter and for nutritious whole grain in the summer. No data are available on Kernza^® grain susceptibility to stored-product insects. Susceptibility of hulled Kernza^®, dehulled Kernza^® and hard red winter wheat to infestation by the lesser grain borer, Rhyzopertha dominica (Fabricius) (Coleoptera; Bostrichidae), was evaluated in the laboratory. Twenty-five mixed sex adults were exposed to 50 g replicates of each of the grain types at 28 °C and 65% relative humidity. Adult mortality along with moisture content was assessed at 7, 14, 21, 28, 35, 42, and 56 d in independent samples. Adult progeny production and weight loss assessment was done only in 35, 42, and 56 d samples. Low survivorship of R. dominica was observed on hulled Kernza^®. Progeny production and grain damage at 35 to 56 d varied with grain type, but was generally lowest on hulled Kernza^®. Results suggested that hulled Kernza^® appears to be an unsuitable commodity for R. dominica to complete their development as compared to dehulled Kernza^® and hard red winter wheat.