The goal of this project is to identify grapevine volatile cues used by female grape berry moth, the key insect pest of grapes in the eastern United States, to locate host grapevines and use this knowledge to develop a lure and new trapping system to help grape growers monitor grape berry moth phenology and better time management decisions. We have developed a six-component synthetic lure, based on host volatiles produced by grape foliage, that is as attractive as live grape shoots in laboratory behavioral assays. Under field conditions a trap baited with this six-component lure captured more female grape berry moth than control traps, although the total number of captures was relatively low. We are working to improve the efficiency of the lure and trap to make it more practical for use in commercial vineyards.

Pheromone traps are widely used for many agricultural pests to provide critical information on phenology for timing management decisions. Traps for Lepidopteran pests generally only monitor male activity, which presents problems when there is lack of correspondence between male captures and the timing of female activities, such as host location and oviposition. This is the situation for numerous economically important moth species, including grape berry moth (GBM). Grape berry moth is a serious pest of grapes grown east of the Rocky Mountains, displaying two-four distinct generations per season. However, results from pheromone traps often do not clearly indicate peaks in female oviposition activity, especially in later generations. Therefore, we reasoned that a lure that attracts females into traps would provide a more reliable signal of female egg-laying activity than a sex pheromone-based trap for this species. Initial behavioral trials indicated that female GBM use grape volatiles to locate mating and/or ovipostion sites. Our overall goal, therefore, was to identify and synthesize the attractive constituents of the grape volatile blend and develop a trap to assess female GBM populations and improve management practices.

To achieve our overall goal we pursued six objectives: 1) develop a bioassay system to measure GBM behavior, 2) determine the most antennally-active compounds present in grapevine volatiles, 3) determine the most behaviorally active compounds, 4) devise a trap design that efficiently captures female GBM, 5) test synthetic lure and trapping system under field conditions, 6) evaluate correspondence between trap captures of female GBM with patterns of egg-laying in the field. We have made substantial progress on objectives 1-5. We have identified a blend of six synthetic volatile compounds that are as attractive to female GBM as live grape tissue in laboratory tests. We evaluated the capture efficiency of four trap designs using the laboratory bioassay system, finding a plastic sheet trap covered in a sticky substance to work the best. We placed plastic sheet traps, baited with either the six-component lure or solvent control, in a commercial vineyard. Over four weeks we captured significantly more female GBM on traps with synthetic lure compared to traps baited with hexane only, although the number captured was low. Reasons for the low trap efficiency in the field are being investigated. Our current effort is geared toward improving efficiency of traps and assessing correspondence of female captures with pattern of egg laying in the field.

Research on host orientation of grape berry moth should lead to the development of a lure that can be used to monitor phenology of female berry moth leading to improved methods for assessing timing of management decisions for grape growers in the eastern United States. In addition, the finding that GBM seems to be using common plant volatiles indicates that ratios of compounds may be critical in allowing host specialists like GBM to find their host plants within the complex volatile landscape.

pest management