Effects of Genetic and Environmental Variation in Solidago Altissima on Associated Arthropod Communities

A common garden approach was used to assess the potential for genetic and environmental variation in a Solidago altissima population to structure an associated insect community and influence the colonization of a dominant herbivore species. Distinct S. altissima genotypes from four elevations (260 m, 585 m, 885 m, 1126 m) were planted in a common garden at the ASU Gilley Research Station. The insect community was quantified and leaves were collected to assess foliar metrics important to insects (e.g., Carbon:Nitrogen). Both host-plant genotype and environment affected insect community structure. Genotype, but not environment, affected colonization of a specialist aphid. Environmental variation affected insect community abundance, where plants from 885 m supported the highest number of insects. Plants from 885 m also had the highest nutritional quality and water content, providing a potential mechanism for observed insect community abundance patterns. These results suggest that small-scale genetic variation is more influential to specialist insect population dynamics, and large-scale environmental variation is more important to structuring the rest of the insect community.