Malaria, which continues to cause major disease burden of human, is transmitted by the Anopheles mosquito[1]. Generally effective vaccines against malaria are not currently offered to the public. Subsequently, most intervention efforts focus on controlling mosquito populations, typically using chemical insecticides. However, widespread use of several pesticides has resulted in pesticide resistance in mosquito populations[2] which extends to employ alternative mosquito control strategies including mosquito-microbiome.
The microbiome is an ecosystem of commensal, symbiotic, and pathogenic bacteria that interact with a host[3]. Mosquitoes are act as natural hosts to a diverse range of microorganisms usually including bacteria, fungi, and viruses[4]. Among these, bacteria are continuously exposed to mosquitoes[5] and can influence nutrition, development, immune and behaviors of host mosquitoes[6, 7, 8]. For instance, infection with the bacterial endosymbiont Wolbachia pipientis prevents numerous arbovirus infections[9, 10]. Indeed, the introduction of wMel strain of Wolbachia pipientis into the Aedes aegypti population was effective in reducing the incidence of symptomatic dengue as well as the case of hospitalizations by dengue fever[11]. Also, Chromobacterium sp. exposure causes high mortality in larval and adult mosquitoes and reduces mosquitoes’ susceptibility to malaria and dengue infection[12]. These novel approach suggests that specific microbiome in mosquitoes can alter susceptibility to infection[13].
There is evidence that mosquitos have a core microbiome which is shared throughout populations of the same species[14, 15, 16]. For instance, Anopheles mosquitoes possess common bacterial genera such as Acinetobacter, Bacillus, Enterobacter, Staphylococcus, Pseudomonas, Chryseobacterium and Serratia[17, 18, 19, 20] and Aedes and Anopheles vectors share taxa including Pseudomonas, Asaia, Serratia and Enterobacter[21, 22]. Furthermore, microbiome investigations of Anopheles mosquitoes collected in the field reveal greater levels of inter-mosquito heterogeneity in community composition[23]. Previous studies have demonstrated the bacterial composition of mosquitoes collected from natural habitats is highly variable depending on the geographical origin and ecology[21, 24, 25, 26].
In this study, we focus on the regional difference of microbiome profiles in Anopheles sinensis mosquitoes, which is a major vector of Plasmodium vivax malaria in Republic of Korea. Republic of Korea was officially certified as a malaria-free country by the World Health Organization (WHO) in 1979[27], but Plasmodium vivax malaria re-emerged in 1993 in a soldier[28]. Indeed, malaria mainly occurs in border regions with North Korea where civilian access is restricted, such as Incheon, northern Gyeonggi, and Gangwon-do, where malaria patients were reported 300 to 500 cases every year. The sporadic malaria cases in this area may results from the most well-preserved natural habitats for wildlife and may be caused by long range migration from malaria hyperendemic area from the northern region. Therefore, it's worthwhile to investigate patterns of microbiome profiles in host mosquitoes, as this might be a key to figuring out where malaria vector insects come from.
In light of these observations, we identify the microbial diversity of Anopheles sinensis female from endemic malaria transmission region and non-endemic areas. By using metagenomics analysis, this study delves into determining whether this Anopheline mosquito in malaria endemic areas possesses distinct microbial profiles, which could be reliably linked to their habitats. Therefore, Investigating the microbiome profiles of female Anopheles sinensis might be a potential way to monitor malaria cases and develop effective vector control strategies[5, 29, 30].