Abstract

not-yet-known not-yet-known not-yet-known unknown Animals that acquire beneficial microbial symbionts from their environment run the risk of acquiring a sub-optimal partner, or no partner at all. The leaffooted bug Leptoglossus zonatus (Coreidae) acquires its Caballeronia (Burkholderiaceae) bacterial symbiont from the environment, presumably from local soil. Despite large contributions to the bug’s fitness, young nymphs must re-acquire the symbiont every generation. To understand how the environmental reservoir of symbiont lineages shapes the insect’s biology, we examined the role of space and time in the distribution of Burkholderia sensu lato (including Caballeronia) strains in the bug and the soil. We compared samples within trees, within plots, within cities and among different cities in the Southwest USA. We also sampled Caballeronia in L. zonatus within a pomegranate orchard over two years. We found high Caballeronia diversity both in soils (29 lineages) and in bugs (26 lineages). Caballeronia lineages were spatially structured among soils and bugs, with fewer shared as distance between samples increased. Where a bug develops, therefore, influences the symbiont strain it acquires, consistent with a process of passive spatial turnover. Also, while some Caballeronia subclade frequencies in bugs approximated frequencies in soils, the coreoid subclade of Caballeronia appeared to be enriched in bugs. Turnover of strains between timepoints remained relatively constant, suggesting that the community composition of hosted Caballeronia is not undergoing directional change over time. Ultimately, understanding how symbiont strains of varying local benefit are distributed in space and time will help us predict how geography and seasonality are related to host fitness in environmentally acquired symbioses.