The Microbiome of an Invasive Antarctic insect, Eretmoptera Murphyi (Diptera: Chironomidae), and its Potential Role in Nutrient Cycling.

Eretmoptera murphyi Schaeffer 1914 is a flightless chironomid midge endemic to South Georgia in the sub-Antarctic. In the 1960s it was accidentally introduced to Signy Island (in the more extreme maritime Antarctic), where it is now considered an invasive species. Detritivorous E. murphyi larvae can increase soil nitrogen levels by up to five times compared with similar uncolonized substrates, although the mechanisms involved remain unknown. This study conducted the first larval microbiome characterisation of E. murphyi, with the aim of identifying groups of microorganisms that may contribute to the elevated nutrient availability associated with this species. We also compare the E. murphyi microbiome with information available for other Antarctic invertebrates. Dominant archaea and bacteria included Crenarchaeota, Actinobacteriota, Chloroflexi, Proteobacteria and Planctomycetota, many of which have known roles in nutrient cycling. The microbiome of E. murphyi appears more diverse than that of other Antarctic invertebrates studied to date and includes phyla (Chloroflexi and Mycococcota) not previously reported from Signy Island soils or other Antarctic terrestrial invertebrate species. Further research is needed to establish which of these taxa represent true endosymbionts and to confirm their functional roles. The impact of non-native species microbiomes on nutrient cycling has important implications for polar terrestrial ecosystems, as significant changes in nutrient availability could impact native microarthropod and plant communities, as well as open new pathways for future non-native species establishment.