Use of forested field edges by Rhagoletis mendax (Diptera: tephritidae) part III

Authors: DRUMMOND, FRANCIS - University Of Maine; COLLINS, JUDITY - University Of Maine Cooperative Extension; RODRIGUEZ-SAONA, CESAR - Rutgers University; Zhang, Aijun

Submitted to: Agricultural and Forest Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2020
Publication Date: 10/27/2020
Citation: Drummond, F.A., Collins, J.A., Rodriguez-Saona, C., Zhang, A. 2020. Use of forested field edges by Rhagoletis mendax (Diptera: tephritidae) part III. Agricultural and Forest Entomology. https://doi.org/10.1111/afe.12421.
DOI: https://doi.org/10.1111/afe.12421

Interpretive Summary: The blueberry maggot fly is a native North American oligophagous insect pest of native wild plants and crops. Adults usually have to migrate to fruit-bearing fields and it appears that forest edges play a significant role in the colonization of wild blueberry fields. In this study, we demonstrated that trees in the forest edge are selected by blueberry maggot and represent a consistent aspect of their dispersal dynamics to new oviposition sites. We also found that female antennae consistently responded to five volatile compounds extracted from red oak, which is non-host plant in the edges of blueberry fields. These newly discovered non-host volatiles could be added into the existing blueberry maggot trapping system to help growers/farmers to increase the trap efficiency, improving predictions of damage due to blueberry maggot relative abundance based upon trap captures.

Technical Abstract: The blueberry maggot fly, Rhagoletis mendax Curran, was found associated with forest trees surrounding wild blueberry fields. Flies were captured up to 6 m high (limited by our trap height) in trees and may occur at greater heights. Fly abundance in trees adjacent to fruit-bearing fields initially increased and then decreased as flies entered fields. There was no difference in fly abundance in trees adjacent to pruned fields compared to fruit-bearing fields and there was no difference between deciduous and coniferous trees. Fly abundance relative to tree species varied by year but overall, capture rates were highest in red oak, red maple, and white birch. Releases of marked flies from tree canopies showed that tree height had no effect on the distance into the field flies dispersed and flies were caught up to 30 m into the field. In the laboratory, flies preferred leaves and leaf extracts of red oak compared to other species of leaves including blueberry. Electroantennographs demonstrated that female antennae consistently responded to a series of compounds extracted from red oak leaves. Mass spectra and GC retention times of the five antennally-active compounds closely matched those of trans-ß-ocimene (1), linalool (2), 4,8-dimethyl-1,3,7-nonatriene (3), indole (4), and trans nerolidol (5). The electrophysiological activities of these five compounds were confirmed by strong antennal responses elicited by female R. mendax to a synthetic blend. We speculate that flies recruit to trees prior to movement into wild blueberry fields primarily for food as supported by their positive activity response to leaf extracts.