Student-Faculty Collaborative Research Grant Report

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Tillberg, Chadwick V.
student-faculty collaborative research; Biology; Entomology; Plant Sciences; Population Biology
report description
Endangered species, like all organisms, exist in a complex web of interactions with their prey, predators, parasites, and mutualists. Management strategies to facilitate recovery of an endangered species by manipulating one portion of this web might inadvertently alter other parts of the network with consequences that are difficult to predict. We investigated how change in plant community composition and vegetative structure brought about by annual grass-specific herbicide application affects terrestrial arthropod communities, with special emphasis on the potential mutualists and predators of the endangered Fender’s blue butterfly, Plebejus icarioides fender (Family: Lycaenidae). Larvae of this species form facultative protective mutualisms with ants, and they may be preyed upon by numerous invertebrate predators. We used pitfall trapping to compare terrestrial invertebrate community structure between control and herbicide-treated plots through time. Our results for year one of a planned five-year study suggest that total ant abundance was lower in herbicide-treated plots. Assessment of other trophic levels is ongoing. The extent to which major changes in plant community composition affect the rest of the invertebrate community may have relevance for management decisions if the focus of the conservation effort has strong ecological interactions with greatly affected non-target species.