Meeting Abstract
Insects serve as hosts to diverse microbial endosymbionts. Recent studies suggest that microbial endosymbionts may affect performance characters that reflect the ability of insects to respond to environmental stress. Insects living in montane habitats face many environmental stressors, including temperature, precipitation, and low oxygen. We examined the problem of how microbial endosymbionts affect performance in Sierra Nevada (California) populations of the leaf beetle Chrysomela aeneicollis, in which prior studies show evidence of local adaptation to temperature. Metagenomics analysis using Metaphlan2 of populations from three drainages distributed along a latitudinal thermal gradient revealed that 90% of sequences were similar to known species of Wolbachia. Analysis of 90 beetles collected in the central drainage, Bishop Creek, revealed that all were infected by two species of Wolbachia: one belonging to the WolA lineage, the other WolB. We used quant-PCR to assess the relationship between abundance of each Wolbachia strain in adult beetles exposed to either sub-lethal cold or control conditions in the laboratory; cold treatment corresponded to conditions beetles experience in nature. Running speed after stress exposure was significantly slower after exposure to cold for all beetles. We are currently studying the relationship between different concentrations of Wolbachia A and B strains in these experimental beetles, and how this affects running speed after cold exposure. Our findings will reveal whether this endosymbiont alters physiological responses to thermal stress in a native insect that has been documented to be under temperature selection.
