Electroantennogram technique for Conotrachelus nenuphar (Coleoptera: Curculionidae)

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 the 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 methylene chloride solvent control. The development of this EAG technique will facilitate use of a coupled gas chromatographic-electroantennographic detection system to aid in detection of 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.