Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2009
Publication Date: 6/1/2009
Citation: Leskey, T.C., Wright, S.E., Anger, W., Chouinard, G., Cormier, D., Pichette, A., Zhang, A. 2009. An Electroantennogram Technique for the Plum Curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae). Environmental Entomology. 38(3):870-878. Interpretive Summary: The plum curculio is a serious pest of pome and stone fruit throughout eastern North America. However, development of monitoring and management tools to detect plum curculio entry into commercial orchards has not proven successful because of the lack of effective semiochemical baits or attractants. In order to aid in identification of strong and competitive attractants, we developed an electroantennogram system for the plum curculio. This system measures the strength of electrophysiological responses of adults to particular odor stimuli. Odor-laden air is passed over the antenna of the insect. Glass electrodes filled with KCl saturated AgCl solution pierce the antenna and the ventral surface of the head and are used to detect the electrophysiological signals based on receptors located on the antennae being stimulated by targeted odor sources. Initial evaluations revealed that we could detect signals when antennal receptors were stimulated by exposure to the odor of host fruit trees including 'Stanley' plum and 'Empire' apple and to grandisoic acid, the male-produced pheromone. This system will enhance our ability to identify potentially attractive compounds for use in monitoring and management programs for plum curculio in commercial fruit orchards.
Technical Abstract: Reliable electroantennogram (EAG) responses were obtained from the plum curculio, Conotrachelus nenuphar (Herbst), by using a whole-body mount with glass electrodes filled with KCl saturated AgCl solution that penetrated the antennal club (recording electrode) and the membrane attached to the cervical sclerite between the thorax and the head (indifferent electrode). Known attractive odor sources including extracts of headspace collections of 'Stanley' plum and 'Empire' apple tissues and a synthetic source of racemic grandisoic acid were used to verify the sensitivity of technique. The amplitude of responses was significantly greater for females than males among all candidate stimuli evaluated. The recorded amplitudes for all odor stimuli evaluated were significantly greater than the dichloromethane solvent control. The development of this EAG technique will facilitate use of a coupled gas chromatographic-electroantennographic detection (GC-EAD) system to aid in detection of potential novel, biologically and behaviorally active volatile sources that can be subsequently evaluated in behavioral trials, and ultimately lead to more powerful attractants for use in monitoring and management programs for plum curculios in commercial fruit orchards.