Lack of abundant core virome inCulexmosquitoes from a temperate climate region despite a mosquito species-specific virome

Abstract

In arthropod-associated microbial communities, insect-specific viruses (ISVs) are prevalent yet understudied due to limited infectivity outside their natural hosts. However, ISVs might play a crucial role in regulating mosquito populations and influencing arthropod-borne virus transmission. Some studies have indicated a core virome in mosquitoes consisting of mostly ISVs. Employing single mosquito metagenomics, we comprehensively profiled the virome of native and invasive mosquito species in Belgium. This approach allowed for accurate host species determination, prevalence assessment of viruses andWolbachia, and the identification of novel viruses. Contrary to expectations, no abundant core virome was observed inCulexmosquitoes from Belgium. In that regard, we caution against rigidly defining mosquito core viromes and encourage nuanced interpretations of other studies. Nonetheless, our study identified 45 viruses of which 28 were novel, enriching our understanding of the mosquito virome and ISVs. We showed that the mosquito virome in this study is species-specific and less dependent on the location where mosquitoes from the same species reside. In addition, becauseWolbachiahas previously been observed to influence arbovirus transmission, we report the prevalence ofWolbachiain Belgian mosquitoes and the detection of severalWolbachiamobile genetic elements. The observed prevalence ranged from 83% to 92% in members from theCulex pipienscomplex.ImportanceCulex pipiensmosquitoes are important vectors for arboviruses like West Nile virus and Usutu virus.Culex pipiensvirome studies, and virome studies on mosquitoes from theCulexgenus in general, are underrepresented in publications about the mosquito virome. To mitigate this, we sequenced the virome of 190 individualCulexand eight individualAedes japonicusmosquitoes. We report the lack of a core virome in these mosquitoes from Belgium and caution the interpretation of other studies in this light. The discovery of new viruses in this study will aid our comprehension of ISVs and the mosquito virome in general in relation to mosquito physiology and mosquito population dynamics.