Diverse novel residentWolbachiastrains in Culicine mosquitoes from Madagascar

Abstract

Wolbachia endosymbiotic bacteria are widespread throughout insect species and Wolbachia transinfected inAedes mosquito species has formed the basis for biocontrol programs as Wolbachia strains inhibit arboviral replication and can spread through populations. Resident strains in wild Culicine mosquito populations (the vectors of most arboviruses) requires further investigation given resident strains can also affect arboviral transmission. As Madagascar has a large diversity of both Culicine species and has had recent arboviral outbreaks, an entomology survey was undertaken, in five ecologically diverse sites, to determine the Wolbachia prevalence. We detected diverse novel resident Wolbachia strains within the Aedeomyia, Culex, Ficalbia, Mansonia and Uranotaenia genera. Wolbachia prevalence rates and strain characterisation through Sanger sequencing with multilocus sequence typing (MLST) and phylogenetic analysis revealed significant diversity and we detected co-infections with the environmentally acquired bacterial endosymbiont Asaia.Mosquitoes were screened for major arboviruses to investigate if any evidence could be provided for their potential role in transmission and we report the presence of Rift Valley fever virus in three Culex species:Culex tritaeniorhynchus, Culex antennatus and Culex decens. The implications of the presence of resident Wolbachia strains are discussed and how the discovery of novel strains can be utilized for applications in the development of biocontrol strategies.

Wolbachia Infection in Wild Mosquitoes (Diptera: Culicidae): Implications for Transmission Modes and Host-Endosymbiont Associations

“…Wolbachia detection in three medically important mosquito genera, Culex, Anopheles, and Aedes, was highly consistent with past studies. Among the Culex mosquitoes, Wolbachia infection has been reported to be variable across its member species [39,46,92,94]. Similarly, we observed infection only in ve out of 17 Culex species.…”

“…Detection in the gastrointestinal tract suggests horizontal transmission through uptake from the environment or host sharing [34,37,38], whereas a detection in non-gastrointestinal somatic tissues, such as the jointed appendages, could be a case of horizontal bacterial genome integration into the host genome [36]. Currently, most research on the detection of Wolbachia in mosquitoes adopts conventional PCR methods which extract DNA from the entire individual or its abdomen [39][40][41][42][43][44][45][46][47]. This limits our ability to identify the exact location of endosymbiont infection within an individual.…”

Wolbachia infection in wild mosquitoes (Diptera: Culicidae): implications for transmission modes and host-endosymbiont associations in Singapore

“…These genera are responsible for the transmission of vector-borne diseases such as lariasis, malaria, and arboviral diseases [86]. Among the Culex mosquitoes, Wolbachia infection has been reported to be variable across its member species [39,46,82,84]. Similarly, infections were observed only in ve out of 16 Culex species.…”

“…The detection of Wolbachia in the gastrointestinal tract suggests that it could be horizontally transmitted through uptake from the environment or host sharing [34,37,38], whereas a detection in non-gastrointestinal somatic tissues, such as jointed appendages, could be a case of horizontal bacterial genome integration into the host genome [36]. Currently, detection of Wolbachia in mosquitoes mostly adopts conventional PCR methods on DNA extracted from the entire individual or its abdomen [39][40][41][42][43][44][45][46][47]. This limits our ability to identify the site of endosymbiont infection within an individual (tissue tropism).…”

Wolbachia infection in wild mosquitoes (Diptera: Culicidae): implications for transmission modes and host-endosymbiont associations in Singapore

“…The detection of Wolbachia in the gastrointestinal tract suggests that it could be horizontally transmitted through uptake from the environment or host sharing [34,37,38], whereas a detection in non-gastrointestinal somatic tissues, such as the jointed appendages, could be a case of horizontal bacterial genome integration into the host genome [36]. Currently, detection of Wolbachia in mosquitoes mostly adopts conventional PCR methods on DNA extracted from the entire individual or its abdomen [39][40][41][42][43][44][45][46][47]. This limits our ability to identify the site of endosymbiont infection within an individual (tissue tropism).…”