CHEMICAL ECOLOGY Behavioral and Electrophysiological Responses of Listronotus maculicollis (Coleoptera: Curculionidae) to Volatiles From Intact and Mechanically Damaged Annual Bluegrass

Listronotus maculicollis Kirby is a highly destructive pest of low mown, cool-season turfgrasses in the northeastern United States and Canada. Behavioral and electrophysiological assays were conducted to identify compounds thatmaybeuseful in developingnovelmonitoring techniques. In Y-tube assays, males and females responded differently to volatiles from intact and clipped annual bluegrass (Poa annua L.). Females were signiÞcantly attracted to intact P. annua but repelled from clippings; males did not respond signiÞcantly to either treatment. Electroantennogram (EAG) recordings from both sexes showed a signiÞcant response to volatiles from both treatments. Gas chromatography mass spectrometry (GC-MS) identiÞed 12 volatile compounds from P. annua of which ninewere common to both intact plants and clippings.On average, seven-fold higher quantities of volatiles were collected from clippings than from intact plants (24.3 versus 3.4 ng/g of tissue/h). Eight compounds were released in signiÞcantly greater quantities from clippings of which 50% were the n-C6 compounds hexanal, (E)-2-hexenal, and (Z)-3-hexenyl acetate, commonly referred to as “green leaf volatiles” (GLVs). Only octanal was emitted in greater amounts from intact plants than clippings. These nine compounds were tested individually against male and female antennae. Both sexes displayed greatest sensitivity to nonanal, octanal, and (E)-2-hexenal, but a signiÞcant doseÐ response relationship was observed with all compounds tested. These studies indicate that both sexes respond physiologically and that L. maculicollis females exhibit behavioral responses to host-plant volatiles. Future studies will need to assess the effects of individual compounds and component mixtures on L. maculicollis behavior in the Þeld.