Efficacy of grain protectants on hulled and dehulled Kernza® against two stored-product insect species

The efficacy of commercial formulations of grain protectants, deltamethrin and deltamethrin plus methoprene on hulled and dehulled Kernza® against two stored product insect species — the rice weevil, Sitophilus oryzae (L.) and the lesser grain borer, Rhyzopertha dominica (F.), were evaluated in the laboratory. No grain protectants are currently registered for use on this perennial grass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey), marketed under trade name Kernza®. Phosphine is the only fumigant approved for treating perennial grasses. The concentrations of the protectants used were 0.5 and 1 ppm for deltamethrin and 0.5 ppm deltamethrin plus 1.25 ppm methoprene as a combination product. Mortality was assessed after 7, 14 and 21 days of the application of protectants and insect introduction. Mortality of the insects was expressed as percentage of the total insects exposed. In separate replicates, grain was infested and observed at 42 d for progeny production and weight loss. After determination of progeny production, the grains were passed through Boerner® divider to get a representative sample of 6 g for wheat and 1.5 g for hulled and dehulled Kernza®. The number of damaged kernels was assessed and expressed as a percentage. The performance of grain protectants in hulled and dehulled Kernza® was compared with hard red winter wheat. The goal is to identify suitable grain protectants for use to protect Kernza® grains in storage from insect infestation.