Arctic Insects Show a Highly Dynamic Microbiome Shaped by Abiotic and Biotic Variables.

Arctic regions are inhabited by terrestrial ectotherms that have adapted to an extreme environment where food resources are limited. The host associated microbiome may partly explain their ability to live under these conditions, but very little is known about the microbiome of Arctic ectotherms. We investigate how the bacterial community of the Greenlandic seed bug (Nysius groenlandicus) and damsel bug (Nabis flavomarginatus) is affected by different abiotic and biotic factors (time, acclimation temperature, humidity, and diet) under both field and laboratory conditions. We found large differences in the bacterial composition and diversity between the two species including species-specific presence of potentially symbiotic bacteria. The bacterial community of both species changed across the season, which may be explained by the changing climatic conditions, such as temperature and humidity. This was further supported by results from the laboratory experiments. We also found that diet changed the bacterial composition in both species and that bacteria could be transferred from prey to predator. Together, these results show that the bacterial community of some Arctic insects are highly dynamic and modulated by different abiotic and biotic factors, suggesting that the microbiome plays an important role for these organisms to persist in an extreme and resource-limited Arctic environment.