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Ecological Impact of an Invasive Yellowjacket on Native Prey and CompetitorsEPA Grant Number: F6F21317
Title: Ecological Impact of an Invasive Yellowjacket on Native Prey and Competitors
Investigators: Wilson, Erin E.
Institution: University of California - San Diego
EPA Project Officer: Jones, Brandon
Project Period: September 1, 2006 through September 1, 2009
Project Amount: $104,978
RFA: STAR Graduate Fellowships (2006) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Academic Fellowships , Fellowship - Terrestrial Systems Ecology
The introduction of non-native organisms is a leading cause of species imperilment. Detailed studies of damaging invasive species contribute importantly to the development of effective strategies for conserving biodiversity. Among the many problematic invasive social insects, the western yellowjacket (Vespula pensylvanica) represents an emerging and harmful introduction. Because Hawaii lacks any native eusocial insects, the invasion of V. pensylvanica poses a potentially devastating threat to the native and largely endemic biota of this region. Using a combination of classic ecological approaches and modern molecular methods, I will quantify the effect of this invasive yellowjacket on native prey and competitor taxa.
Research will be conducted in Hawaii Volcanoes and Haleakala National Parks, which support large and growing populations of V. pensylvanica as well as diverse assemblages of endemic arthropods. Vespula nests will be experimentally removed to characterize and to quantify the impact of this wasp on native prey and competitor species. This manipulative approach complements ongoing control efforts in both national parks. Populations of potential prey (Lepidoptera and Araneae) will be sampled before and after yellowjacket nest removal to assess the predatory pressure exerted by V. pensylvanica on endemic taxa. In addition, I will collect prey samples from wasp foragers returning to the nest and identify these prey items by sequencing 16s rDNA. To characterize the competitive effect of V. pensylvanica, I will place trap nests for endemic solitary wasps where yellowjacket nests are present and where yellowjacket nests have been removed and analyze these trap nests for changes in diet, distribution and abundance of solitary wasp species after the removal of V. pensylvanica nests.
My research aims to quantify the impact of V. pensylvanica and to assess the recovery of native prey and competitors upon removal of the yellowjacket colonies. Differences in prey distribution between control and removal sites will serve as a quantitative measure of the effect of V. pensylvanica as a predator on native species. Preliminary data show that Lepidoptera populations increase following yellowjacket nest removal. Secondly, the molecular identification of masticated prey will provide definitive evidence as to which taxa are falling prey to V. pensylvanica. I expect that the most common prey items will exhibit substantial changes in abundance when wasp nests are removed. As endemic arthropods lack evolutionary experience with eusocial insects, we may see a preference for endemic species over introduced species. In the competition experiments, I expect increases in the local abundance of solitary wasps when V. pensylvanica nests are removed. Some common wasp species may alter their diet in response to competition from yellowjackets. These results will inform management strategies that seek to minimize the impact of V. pensylvanica on native prey and competitors.