Phenology and host choice among common yet little understood wood borers (Coleoptera: Bostrichidae) in a Midwestern savanna

Horned powder-post beetles (Coleoptera: Bostrichidae) are a geographically widespread family of wood-boring beetles. While members of this family represent important grain pests, are often intercepted in ports, and may play an important role in ecosystem processes, little work has investigated bostrichid life history in their native ranges. This gap limits our ability to assess ecosystem services and invasiveness. Three native species, Amphicerus bicaudatus (Say), Scobicia bidentata (Horn), and Xylobiops basilaris (Say), are commonly found in savannas in Northern Illinois. Although little is currently known about the life history of S. bidentata, A. bicaudatus and X. basilaris can be minor pests of fruits and wood products. Over two years, we used field and laboratory methods to investigate characteristics of phenology, reproduction, and host use. We found that all three species are attracted to ethanol (stressed plants) in the spring but not in the fall, despite known adult activity. Initial catch of A. bicaudatus likely corresponds to an increase in early spring temperature over 18°C. S. bidentata and X. basilaris catch occurs in late spring and is not dependent on temperature thresholds, but probably occurs after additional development. Of the 7 common woody plants found in the savanna, female A. bicaudatus demonstrated a significant preference for black oak (Quercus velutina) twigs in choice assays and S. bidentata showed similar preferences. This study is the first to report factors influencing emergence and host choice in native Midwestern Bostrichidae, information that may increase understanding of the life history of this little-studied group.