Plants, microorganisms and odorants involved in insect host plant location: who’s making the message?

Authors: WOLFIN, MICHAEL - Cornell University; VOLO, SARA - Hobart College; CHILSON, RONALD - Cornell University; LIU, YUXI - Hobart College; Cha, Dong; COX, KERIC - Cornell University; LOEB, GREGORY - Cornell University; LINN, CHARLES - Cornell University

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2018
Publication Date: 4/19/2019
Citation: Wolfin, M.S., Volo, S.L., Chilson, R.R., Liu, Y., Cha, D.H., Cox, K.D., Loeb, G.M., Linn, C.E. 2019. Plants, microorganisms and odorants involved in insect host plant location: who’s making the message? Entomologia Experimentalis et Applicata. 167(4):313-322. https://doi.org/10.1111/eea.12778.
DOI: https://doi.org/10.1111/eea.12778

Interpretive Summary: Insect pests use odors to locate their host plant and there are many host-plant based attractants available that are useful in integrated pest management. However, recent studies suggest that microbes living on plant surface may be actually responsible for the host plant odor. Researchers at the USDA-ARS laboratory in Hilo, HI and Cornell University in Geneva, NY tested this idea by evaluating attractiveness and volatile profiles of sanitized attractive host tissue (i.e. grape shoot) for the grape berry moth (GBM), a native specialist moth pest of juice and wine grapes in the northeastern US. Sanitized and unsanitized grape shoots were equally attractive to female GBM in flight tunnel bioassays and emitted the same profile of volatile compounds, suggesting that the previously identified grape shoot based chemical lure that has been developed to monitor female moth activity has a plant origin rather than a microbial origin.

Technical Abstract: The grape berry moth (GBM), Paralobesia viteana, is a specialist pest insect of cultivated grape, Vitis spp., in the eastern United States. An active blend of volatile compounds has been isolated from plant material that attracts female GBM in the flight tunnel and field. However, the origin of the volatile cue is potentially complicated by the presence of microbial organisms (bacteria and fungi) living on the surface of the plant. Microbial volatile organic compounds can affect insect behavior, and therefore must be considered to fully understand the olfactory mediated behaviors. We report here the chemical and behavioral analysis of the volatile profiles produced in both the sanitized and control shoot treatments. The sanitization treatment removed 96.4% of the surface microorganisms for the duration of the behavioral assays and volatile collections. Overall, the surface microorganisms did not significantly contribute to the volatile profile of the grape shoots, as all of the peaks in the volatile profile of sanitized shoots were found in the profile of control shoots. In the flight tunnel, female GBM displayed the same level of upwind oriented flight to sanitized shoots (flew upwind 57.4%, landed 30.9%) as they did to control shoots (flew upwind= 57.8%; landed 31.0%), suggesting minimal role of surface microorganisms in the production of previously identified blend of behaviorally active volatiles for GBM.