The Biology and Ecology of Bostrichid Beetles in Endangered Savanna Ecosystems of the Midwestern United States

Reed 330

Horned Powder-Post Beetles (Coleoptera: Bostrichidae) are a geographically widespread, though little studied, family of wood-boring beetles. Two species of Bostrichidae, Amphicerus bicaudatus and Scobicia bidentata, have been shown to be more abundant in black oak savanna ecosystems than in woodlands. These beetles may play an important and unique role in black oak savannas in the Midwestern United States. Amphicerus bicaudatus is a known minor pest of grape and apple in the Eastern United States that overwinters in the adult phase and becomes active in late spring, but most of its life history and ecology is unknown. Scobicia bidentata is known to emerge in early June, but otherwise nothing is known of its life history or its role in the black oak savanna ecosystem. Across two years, we used a variety of techniques, including trapping, dissections, and free-choice assays, to learn more about the phenology, reproduction, and feeding of these two little-known species in the context of a black oak savanna. No correlation was found between phenology and a degree-days development model. Nor did there appear to be any connection to maximum temperature. A. bicaudatus female size was correlated with number of eggs, suggesting a connection between larval food source and fecundity. In addition, A. bicaudatus was found to have a significant preference for black oak over several other native woody plants in the black oak savanna. This leads us to believe that there may be a connection between black oak and fitness in A. bicaudatus.