Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 8, 2011
Publication Date: August 1, 2011
Citation: Bergh, J.C., Zhang, A., Meyer, J.R., Kim, D. 2011. Response of grape root borer (lepidoptera: sesiidae) neonates to root extracts from vitaceae species and rootstocks. Environmental Entomology. 40:880-888.
Interpretive Summary: The grape root borer (GRB) is a native pest of grape in commercial vineyards in portions of the eastern USA. It has been particularly troublesome in the mid-Atlantic and southeastern states and is posing a significant, ongoing risk to the expanding eastern wine grape industry. The larval GRB feeds in the interior of grape roots, which can impair vine vigor and productivity and lead to plant death. In the laboratory bioassay, we found that GRB larvae responded most strongly to ethanol extracts of some commercially important rootstock, suggesting the presence of behaviorally-active, polar compounds associated with roots. This discovery will help us to continue the isolation and identification of the active compounds. Results of the experiments reported here not only provide numerous clues for researchers and growers to understand the plant-insect interactions between GRB larvae and grape plants, but also will enhance the opportunity toward further efforts to develop GRB management strategy based on the behaviorally active compounds instead of synthetic pesticides used today.
Observations at regular intervals of the location of newly hatched grape root borer larvae moving freely within Petri dish bioassays were used to measure and compare their response to filter paper discs treated with ethanol- and hexane-based extracts of roots from known and potential Vitaceae hosts and a non-host. Larvae responded most strongly to ethanol extracts, suggesting the presence of behaviorally-active, polar compounds associated with roots. In no-choice bioassays comparing extract- versus solvent-treated discs, larvae responded positively to ethanol extracts from all Vitis species and rootstocks and Virginia creeper, but not to apple. Choice bioassays using the commercially important 3309 rootstock as the standard revealed examples of equal, significantly weaker and significantly stronger responses to 3309 in pair-wise comparisons with extracts from other root sources. Extracts of the 420 A and V. riparia ‘Gloire’ rootstocks appeared to possess qualities that elicited a consistently greater response than to 3309 extract in choice bioassays. The active compounds were eluted in ethanol during a 30-min extraction; larvae responded equally to 30- and 60-min 3309 root extracts in choice bioassays. Larvae responded equally to extracts of 3309 roots from three spatially separate vineyards in northern Virginia. These results are discussed in relation to the subterranean, plant-insect interactions of grape root borer neonates with the numerous native and non-native Vitis species that may serve as hosts in the eastern United States.