Odor Preference, Feeding, Survival, and Reproductive Fitness of the Invasive Larger Grain Borer Prostephanus Truncatus on Acorns of Three Native North America Oak Species.

The larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), is a major invasive pest of stored grains with the potential to expand its range across North America. While primarily associated with stored grains, this species could exploit non-grain hosts that facilitate survival and dispersal across broader geographic ranges. Previous research has shown that acorns can be a suitable food for a related stored product bostrichid. Here, we assessed the odor preference of P. truncatus for acorns from black oak (Quercus velutina), red oak (Quercus rubra), and bur oak (Quercus macrocarpa) compared to maize and wheat, and analyzed their volatile organic compound (VOC) profiles. Further, we measured P. truncatus feeding and reproduction on these acorns. Results demonstrated that P. truncatus responded to volatiles of each acorn species but responded most positively to bur oak acorns. Interestingly, bur oak acorns were also more attractive than maize, its main host grain. VOC profiles showed that 3-hepten-2-one and 2-(5-methyl-furan-2-yl)-propionaldehyde were detected only in bur oak acorns, which may contribute to odor preference. Prostephanus truncatus also preferred to feed on bur oak acorns over other oak species. Among the oak species tested, F₁ progeny were detected only in bur oak acorns. These results suggest that P. truncatus exhibits host-use flexibility that enables it to utilize acorns in the absence of grains, highlighting the potential risk of landscape-level invasion by this pest in North America.