Host tree-related differences in foragaing and electroantennogram activity for the plum curculio, Conotrachelus nenuphar (Herbst.) (Coleoptera: Curculionidae)

Authors: Leskey, Tracy; Hancock, Torri; Wright, Starker

Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2010
Publication Date: 6/1/2010
Citation: Leskey, T.C., Hancock, T., Wright, S.E. 2010. Host tree-related differences in foragaing and electroantennogram activity for the plum curculio, Conotrachelus nenuphar (Herbst.) (Coleoptera: Curculionidae). The Canadian Entomologist. 142:284-293.

Interpretive Summary: The plum curculio is a serious and destructive pest of stone and pome fruit in eastern North America. In order to identify and develop effective attractants for this insect, we conducted studies aimed at measuring foraging activity in the field and electroantennogram (EAG) activity in the laboratory associated with four known host fruit trees of the plum curculio. They included the Japanese plum cultivar ‘Formosa’, a highly preferred host; the European plum cultivar ‘Stanley’, another preferred host; the apple cultivar ‘Empire,’ an economically important host; and the peach cultivar ‘Loring,’ another economically important host. We wanted to determine if hosts which are attractive to foraging plum curculio under field conditions also elicit positive EAG signals using odor extracts made from host tree volatile collections. This information will allow us to target which hosts will most likely yield a strongly attractive and competitive odor lure. Our laboratory and field results indicate that ‘Formosa’ plum odors were much more attractive to plum curculio compared with other hosts. Our next logical step will be to identify the particular compounds comprising ‘Formosa’ plum odor, and determine relative ratios of each of these compounds to allow us to produce a competitive olfactory attractant from this highly preferred host for use in attract-and-kill systems.

Technical Abstract: The plum curculio, Conotrachelus nenuphar (Herbst) is a serious pest of stone and pome fruit in eastern North America. We conducted studies aimed at measuring foraging activity in the field and electroantennogram (EAG) activity in the laboratory associated with four hosts, the Japanese plum cultivar ‘Formosa’, the European plum cultivar ‘Stanley’, the apple cultivar ‘Empire,’ and the peach cultivar ‘Loring’ to confirm that hosts which are attractive to foraging plum curculio under field conditions also elicit positive EAG responses. Foraging activity based on number of adults captured was significantly greater for ‘Formosa’ plum compared with any other host and corresponding headspace extracts also produced strong EAG responses throughout the active season. ‘Stanley’ plum and ‘Loring’ peach, the other stone fruit hosts included in this study, elicited strong EAG responses throughout the season, though foraging activity was not as high. Foraging activity was significantly lower for ‘Empire’ apple throughout the season compared with ‘Formosa’ plum and EAG responses were much lower compared with stone fruit hosts. Our results indicate that volatiles from ‘Formosa’ plum likely contain unique compounds or are comprised of ratios of stimulating compounds that make it much more attractive to plum curculio in the field. Our next logical step will be to conduct GC-EAD studies with each of these hosts to identify the particular stimulating compounds, and determine relative ratios of each of these stimulating compounds to allow us to produce a competitive olfactory attractant from a highly preferred host.