Plant-insect interactions are ecologically important relationships that are greatly affected by climate change. Previous research concerning an aphid species (Aphis asclepiadis) and its host plant (Ligusticum porteri) has shown that aphid abundances correlate significantly with snowmelt date in the subalpine zone of the Rocky Mountains. The mechanisms underlying this phenomenon have not been previously identified. Our construction of a structural equational model identified soil moisture and plant phenology as two major pathways by which snowmelt indirectly affects aphids. By comparing aphid and host plant populations at different elevations and experimentally manipulating soil moisture we observed significant responses in aphid abundance, ant abundance, aphid predators, and some measures plant quality. While bottom-up processes may be playing a role in determining aphid abundances, top-down pressures appear to have much more control over this aphid dominated ecosystem. iii ACKNOWLEDGEMENTS I would like to acknowledge all the help, direction, and mentorship Dr. Emily Mooney provided me in the completion of this study. I would also like to thank Dr. Shane Heschel and Dr. Jeremy Bono for their guidance and participation in my graduate committee. A special thanks to Dr. Janel Owens and Phuong Nguyen for their work on honeydew analysis and Benjamin Davidson and Samantha Trail for their assistance in the field. This research was supported by a grant from the National Science Foundation Division of Environmental Biology (award # 1655914), a graduate fellowship from the Rocky Mountain Biological Laboratory, and support from the Biology Department at the University of Colorado at Colorado Springs. iv
Knowledge graph centered on Snowmelt affects aphid (<i>Aphis asclepladis</i>) with 65 nodes and 75 connections. Top connected: Effects of climate change on phenology, frost dama, Subalpine meadow flowering phenology responses to , Ligusticum porteri, Effects of experimental warming on plant reproduct, phenological mismatch.
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