Behavioral Responses of Hunting Billbug (Coleoptera: Curculionidae) Towards Odors from Different Turfgrass Species and Adult Conspecifics

Abstract

A series of bioassays involving a four-choice olfactometer were conducted to assess the behavioral responsiveness of adult hunting billbugs (Sphenophorus venatus vestitus Chittenden) towards odors emanating from samples of three different turfgrasses: Tall fescue (Festuca arundinacea Schreb. (Poales: Poaceae)), Kentucky bluegrass (Poa pratensis L. (Poales: Poaceae)), and zoysiagrass (Zoysia japonica Steud. (Poales: Poaceae)). When exposed to the three turf species simultaneously, the majority of billbugs preferred the zoysiagrass treatment over the tall fescue and Kentucky bluegrass treatments. When billbugs of both sexes were added to the three turf treatments, their presence with the turf did not enhance the released billbugs preference towards any of the treatments. Without the presence of turf, the released female billbugs were strongly attracted towards the male-only billbug treatment; however, a similar phenomenon was not observed for males. When a single turf type and/or mixed-sex adult billbugs were presented, treatments that contained the turf, especially zoysiagrass and tall fescue, strongly attracted the released billbugs compared with treatments that contained billbugs only. In the final bioassay experiment when billbugs were exposed to treatments of zoysiagrass and zoysiagrass + billbugs (with either sex), the released billbugs showed a significant preference towards the zoysiagrass + male billbugs treatment. Collectively, this series of experiments demonstrated the hunting billbugs preference to all three turf species tested, and their attraction to male conspecifics. This overall study was the first to investigate some basic aspects of the chemical ecology of the hunting billbug; specifically, the role turfgrass and adult billbug volatiles might have in billbug orientation and host selection.