Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 17, 2011
Publication Date: February 1, 2011
Citation: Cha, D., Linn, C., Teal, P.E., Zhang, A., Roelofs, W., Loeb, G. 2011. Eaves-dropping on plant volatiles by a specialist moth: significance of ratio and concentration. PLoS One. 6(2):e17033.
Interpretive Summary: Grape berry moth (GBM) is a major pest of grapes in vineyard in eastern United States and can cause more than 90% berries to be damaged. In a previous study, we identified and synthesized the key volatiles from grape shoots used by female GBM to locate suitable host plants. In this study, we investigate the role of ratio and concentration using a synthetic blend essential for host location by the GBM in the laboratory assays. We found that GBM had the potential to determine host plant conditions by detecting the changes in chemical signal emissions and could generally avoid an unfavorable host. This information will help scientists and growers to understand the mechanism of direct and indirect plant defenses against pest insect; and, therefore, to develop more effective GBM management strategies based on green chemicals.
Volatile signals mediate many multitrophic interactions, some due to coevolution and others due to eavesdropping, but the role of specific concentrations and ratios has been controversial and difficult to test due to methodological limitations. We investigated the role of ratio and concentration using a previously identified seven-component blend essential for host location by the specialist grape berry moth (GBM). In flight-tunnel assays, doubling the amount of six compounds singly or mimicking the ratio changes caused by Japanese beetle foliar feeding significantly reduced GBM female upwind flight. The reduction was similar at high and low doses. Although our results indicate the importance of ratios of some compounds in providing specificity, GBM was also able to accommodate significant variation in the ratio of some compounds as well as the concentration of the overall mixture. Such plasticity may be critical for phytophagous insects to successfully eavesdrop on variable host plant volatile signals.