Distribution and phylogeny of Wolbachia strains in wild mosquito populations in Sri Lanka

Abstract

Background Wolbachia are a group of maternally inherited intracellular bacteria known to be widespread among arthropods. Infections with Wolbachia cause declines of host populations, and also induce host resistance to a wide range of pathogens. Over the past few decades, researchers were curious to use Wolbachia as a biological tool to control mosquito vectors. During the present study, assessment of the prevalence of Wolbachia infections among wild mosquito populations in Sri Lanka where mosquito-borne diseases are a major health concern, was carried out for the first time. DNA was extracted from the abdomens of mosquitoes, collected from seven provinces, and screened for the presence of Wolbachia by PCR using wsp and groE primers. Group-specific and strain-specific primers were used to classify Wolbachia into the supergroups A and B, and into the strains Mel, AlbA and Pip. ResultsA total of 330 individual mosquitoes belonging to 22 species and 7 genera were screened. Eighty-seven mosquitoes (26.36%) belonging to four species (i.e. Aedes albopictus, Culex quinquefasciatus, Armigeres subalbatus and Mansonia uniformis) were positive for Wolbachia infections. Primary vector of the dengue fever, Ae. aegypti was negative for Wolbachia infections while the secondary vector, Ae. albopictus, showed a very high infection rate. The filarial vector C. quinquefasciatus had a relatively high rate of infection. Japanese encephalitis vectors C. gelidus and C. triteaneorynchus, and the Anopheles vectors of malaria were negative for Wolbachia infections. Nine sequences of Wolbachia-positive PCR products were deposited in the GenBank and compared with other available data. Aedes albopictus was infected with both Wolbachia strains A (AlbA) and B (Pip) supergroups. Phylogenetic analysis of the wsp sequences showed two major branches confirming identities obtained from the PCR screening with strain-specific primers.Conclusion Wolbachia infections were found only among four mosquito species in Sri Lanka: Aedes albopictus, Culex quinquefasciatus, Armigeres subalbatus and Mansonia uniformis. Sequence data showed high haplotype diversity among the Wolbachia strains.

Diverse novel residentWolbachiastrains in Culicine mosquitoes from Madagascar

“…Interestingly in Sri Lanka, 3/3 (100%) of Ma. uniformis individuals amplified the wsp gene 52 but in our study all seven individuals failed to amplify wsp. Ma.…”

Detection ofWolbachiain Field-Collected Mosquito Vector,Aedes aegypti

“…gambiae . Previous studies had reported no observed natural Wolbachia infection in this mosquito vector 26-31 ; however, the endosymbiont was successfully detected in An. gambiae from Burkina Faso, West Africa using an optimized wsp protocol 32,33 .…”

“…With the recognition of about 65% of known insects to be naturally infected with Wolbachia including those mosquito species from the genera of Aedes, Culex, Mansonia , major mosquito vectors of diseases such as Ae. aegypti and Anopheline mosquitoes were reported not to possess this endosymbiont 26-31 . It led to the belief that the presence of Wolbachia endosymbiont could be the reason why many of the mosquito species are considered to be weak vectors 23 .…”

Mosquito-Borne Diseases Emergence/Resurgence and How to Effectively Control It Biologically

“…The genus Asaia, first discovered in plant nectar, is an excellent candidate [166]; it is localized in many organs of mosquitoes, and can disperse inside the mosquito body through the haemolymph [165,167]. Its distribution in the mosquito population is made possible through several mechanisms (co-feeding, sexual mating, paternal, maternal, and horizontal transmission) [168][169][170]. Asaia bacteria may be genetically modified in order to be recolonised in a new host, resulting in spread within wild populations [166].…”