Effects of Garlic Mustard Invasion on Arthropod Diets as Revealed through Stable-Isotope Analyses

Alliaria petiolata (Garlic Mustard) is an invasive plant species which displaces native communities by lowering levels of mycorrhizal fungi essential to native plant nutrient acquisition. Consequently, the diets of arthropods using these native plants as a primary food source may be altered. To assess the magnitude of this disruption, stable-isotope analyses of carbon, nitrogen, oxygen, and hydrogen were used to trophically differentiate the diets of arthropods in Garlic Mustard-invaded areas. In invaded areas, arthropods were depleted in delta C-13 and enriched in delta N-15 relative to arthropods in uninvaded areas, suggesting a change in trophic position among generalist predators. Slight trophic repositioning was observed in all 4 isotopes, indicating interactions of 3 primary predators throughout the study area. Most observable shifts are likely due to predators either altering prey source or traveling further to acquire nutrients.