Cold and lonely: low-abundance microbiota and no core microbiome across a broad geographic sampling of a mosquito species in Greenland

Microbial symbionts play a crucial role in the biology of their insect hosts. In recent years, the mosquito microbiome has emerged as a promising tool for controlling mosquito populations and altering their capacity to transmit diseases. However, while mosquitoes are widespread, most microbiome research focuses on a few model species, leaving many others understudied. In this study, we investigated how temporal and spatial variations influence the microbial abundance and diversity associated with Ochlerotatus mosquitoes in Greenland. We did this by conducting high-throughput sequencing of insect and bacterial marker gene amplicons and quantifying bacterial abundance across a large collection of mosquitoes sampled systematically from four regions of Greenland between 2009 and 2023.

Analysis of COI data identified two species within our collection: the widely distributed O. nigripes and the less common O. impiger . Quantitative 16S rRNA amplicon sequencing revealed a highly variable number of bacterial rRNA gene copies per mosquito, with overall microbiota abundance typically lower (Avg = ∼1.2×10 ⁵ , Mdn = 1.04×10 ⁴ ) than that estimated for both lab-reared Aedes aegypti and wild Culex pipiens from Poland. Despite identifying diverse bacterial taxa, including Pseudomonas, Wolbachia , and Bartonella , we observed significant microbiome variability between individual mosquitoes. Notably, there were no consistent patterns of microbiota distribution across sexes, geographic locations, or sampling years. These findings suggest that Ochlerotatus mosquitoes from the surveyed populations in Greenland may not rely on abundant or specialized microbiota for their reproduction or nutrition, indicating a flexible or minimal relationship with their associated bacterial communities.