Submitted to: Environmental Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/13/2013
Publication Date: 12/15/2013
Citation: Rijal, J., Zhang, A., Bergh, C. 2013. Behavioral response of grape root borer (Lepidopetera: Sesiidae) neonates to grape root volatiles. Environmental Entomology. 42(6):1338-1347. Interpretive Summary: Grape root borer (GRB) is an important pest of grape vines in the eastern United States. Larvae feed on vine roots and impair vine vigor and productivity resulting in extensive damage. In severe cases, it can lead to vine death. Using a newly developed bioassay method, the GRB larval behavioral response to volatile chemicals from host and non-host roots was evaluated. Significantly more GRB larvae were recovered from sites containing grape root volatile chemicals than from those containing only soil or apple volatiles. This research result will not only facilitate our efforts to isolate and identify the behaviorally active compounds from host roots, but also help scientists and growers to understand the plant-insect interactions between this pest and its wild and cultivated hosts. This will provide important information that will be used by researchers and growers to guide GRB sustainable management based on behaviorally active compounds, and thus reduce usage of synthetic pesticides.
Technical Abstract: Grape root borer, Vitacea polistiformis (Harris) (Lepidoptera: Sesiidae), is an oligophagous and potentially destructive pest of grape in commercial vineyards throughout much of the eastern United States. Larvae feed on vine roots, although little is known about their belowground interactions with host plants. The behavioral response of groups of grape root borer neonates to stimuli from host and non-host roots was evaluated in single and paired stimuli bioassays in which stimuli were presented in opposing wells attached to the bottom of Petri dish arenas. Stimulus sources included root pieces and root headspace volatiles from 3309 and 420-A grape rootstocks (host) and apple (non-host) and ethanol based extracts of 3309 and 420-A roots. In single stimulus assays, significantly more larvae were recovered from wells containing grape roots, apple roots, grape extracts, and grape root volatiles than from control wells, however, there was not a significant response to apple root volatiles. In paired stimuli assays, significantly more larvae were recovered from wells containing grape than apple roots. There was no difference in larval distribution between wells when 420-A and 3309 roots were presented simultaneously, although a significantly greater response to 3309 than 420-A root extract was recorded. When soil was added to the assays, significantly more larvae were recovered from wells containing grape roots than from those containing only soil, but this response was not detected in assays using buried apple roots. These results are discussed in relation to the plant-insect interactions between grape root borer larvae and their Vitaceae hosts.