Host-tree-related differences in trap captures and electroantennogram activity of Conotrachelus nenuphar (Coleoptera: Curculionidae)

Abstract

The plum curculio, Conotrachelus nenuphar (Herbst), is a serious pest of stone and pome fruits (Rosaceae) in eastern North America. We recorded captures of adult plum curculios in the field and measured electroantennogram (EAG) activity in the laboratory associated with cultivars of four hosts, 'Formosa' Japanese plum (Prunus salicina Lindl.), 'Stanley' European plum (P. domestica L.), 'Empire' apple (Malus domestica Borkh.), and 'Loring' peach (P. persica (L.) Batsch) (Rosaceae) to determine whether hosts that may be attractive to the plum curculio under field conditions also elicit positive EAG responses. Trap captures of adults on 'Formosa' plum were significantly greater than on 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 the study, elicited strong EAG responses throughout the season, although trap captures associated with these hosts were generally not as high as for 'Formosa' plum. Throughout the season, trap captures of adults were significantly lower for 'Empire' apple than for 'Formosa' plum, and EAG responses were much lower than for all stone-fruit hosts. Our results indicate that volatiles from 'Formosa' plum likely contain uniquecompounds or are comprised of ratios of stimulating compounds that make it much more attractive to plum curculio in the field.

Evaluating Electrophysiological and Behavioral Responses to Volatiles for Improvement of Odor-Baited Trap Tree Management ofConotrachelus nenuphar(Coleoptera: Curculionidae)

“…Each of the synthetic volatiles was evaluated at Þve concentrations: 10.0, 1.0, 0.1, 0.01, and 0.001 mg/ml, diluted in DCM. The ÔStanleyÕ plum standard, found to be highly stimulating in previous studies, was produced according to the protocol described in Leskey et al (2010). Brießy, a large polyethylene bag (48.26 by 58.42 cm, Reynolds Oven Bags, Richmond, VA) was used as a source containment device; bags were placed over four selected ÔStanleyÕ plum branches of equal volume (i.e., similar size, architecture, and abundance of plant tissue).…”

Establishing abiotic and biotic factors necessary for reliable male pheromone production and attraction to pheromones by female plum curculiosConotrachelus nenuphar(Coleoptera: Curculionidae)

“…Trials with multivoltine curculios were taken from a laboratory population established at the Appalachian Fruit Research Station (Kearneysville, West Virginia, United States of America) in 2001 and augmented annually with wild individuals, as per Leskey et al (2010). Adults were reared in the laboratory at 25 ± 2°C, 14:10 hour light:dark photoperiod on a diet of green thinning apples and water based on the methods of Amis and Snow (1985).…”

“…Multivoltine PCs used in EAG trials were treated as described above (bioassays) (Leskey et al 2010). Test subjects were fed, sexually mature females aged 14-21 days, since sexually mature females are considered to be the most damaging portion of the population and give statistically higher EAG responses compared to males (Leskey et al 2009(Leskey et al , 2010. There were four replicates per female, with seven females in the high dose modality, and six females for the low dose modality and also for the trials comparing GA.…”

“…Odour sources. Odour sources included the synthetic volatile trans-2-hexenal (T2H) and volatiles collected from "Stanley" plum (at 21 mm fruit) found previously to be highly stimulating (Leskey et al 2009(Leskey et al , 2010, both of which were used as standards. The "Stanley" plum standard was produced according to the methods described in Leskey et al (2010).…”

Separation of different pollen types by chemotactile sensing in Bombus terrestris.

“…Positive EAG signals have been reported many times in olfactory EAGs (Contreras et al, 1989;Haddad et al, 2010;Leskey et al, 2010;Light et al, 1988;Ramachandran et al, 1990;Schneider, 1957) and were hypothesized to be evoked by repellent compounds (Contreras et al, 1989). However, Leskey et al (2010) reported that the odor of preferred fruits evoked a positive signal in plum curculios (Conotrachelus nenuphar, Coleoptera), and Knaden et al (2012) postulated for Drosophila melanogaster that no reliable information about attractiveness or repellence was encoded in the neural signal before it reached the output neurons of the antennal lobe. We also found no preferences for either apple or almond pollen in a feeding experiment with B. terrestris (Ruedenauer et al, 2016).…”