Wolbachia endobacterium in wild population of Aedes albopictus (Skuse) (Diptera: Culicidae) and phylogeny from Andaman and Nicobar Islands, India.

nally inherited intracellular alpha-proteobacteria, known to infect a wide range of invertebrates which include insects, mites, isopods, crustaceans and filarial nematodes1. Maternal inheritances have been detected in 20–75% of the invertebrate species. Among eight major clades (A–H) of Wolbachia clades, A, B, E, F, G and H have been detected in insects, arachnids and crustaceans; while C and D have been documented from filarial nematodes2–3. Effects of Wolbachia-host interactions are manifold, viz. mutualistic to pathogenic, parthenogenesis, cytoplasmic incompatibility, selective male killing and feminization1. Diversity of Wolbachia infection in mosquito genera has been reported from Southeast Asia, Europe and Africa4. Information on the association of Wolbachia with Aedes albopictus is limited. Recently, it is reported that Wolbachia clades wAlbA and wAlbB co-infect Aedes albopictus5–6. Aedes albopictus, the Asian tiger mosquito, native to Asia is an invasive species. Instances of introduction and establishment of Ae. albopictus are evident7 and in recent times the distribution has spread to Africa, Europe and Australia8. In addition to being an invasive species, this mosquito is an aggressive day time biter and has been implicated in the transmission of dengue9 and chikungunya10. It has been the premise that Wolbachia endosymbionts have a role in the host speciation through reproductive isolation which they cause in the infected hosts. Besides, they do provide an interesting and wide array of evolutionary signals to genetic conflicts11. The ability of Wolbachia to alter reproductive capabilities of its host enables it to suppress insect populations12. Against this background, Wolbachia is being explored as an alternative tool for the control of Ae. aegypti and Ae. albopictus. But before such an approach is explored, it becomes necessary to assess the presence of endosymbiont in Ae. albopictus. Hence, a preliminary study was undertaken to screen for the presence of these endosymbionts in the wild population of Ae. albopictus, from the Andaman and Nicobar archipelago, endemic for dengue13 and where sporadic cases of chikungunya are being observed since the first ever upsurge in 200614, hitherto reported for wide prevalence of Aedes spp15. We used polymerase chain reaction for detecting Wolbachia among Ae. albopictus, and determined its phylogenetic relationship with other known species using the partial genomic nucleotide sequence of Wolbachia surface protein (wsp) gene. The study was carried out in three localities, viz. Haddo, Old Pahargaon and Bambooflat in South Andaman district. In addition, one locality from Car Nicobar (Nicobar district), located at a distance of about 540 km from Port Blair was also included in the study. This island is geographically isolated and separated by vast stretch of sea. Larval and adult samples of mosquitoes were collected during November 2011. Specimens of mosquitoes were morphologically identified using standard taxonomic keys16. DNA extraction was carried out from individual mosquito sample using DNA extraction solution kit (Genie, Bengaluru, India), following manufacturer’s instructions and subjected to PCR amplification using Wolbachia specific primers to amplify the wsp gene (650 bp) using primers wsp 81F [5’-TGG TCC AAT AAG TGA TGA AGA AAC-3’] and wsp 691R [5’-AAA AAT TAA ACG CTA CTC CA-3’]17. Detection of Wolbachia species was carried out by PCR using the group specific wsp primers for A group; (136A; F5’-TGAAATTTTACCTCTTTTC-3 and 691R; 5-’AAAAATTAAACGC TACTCCA-3’) and for B group (81F; 5’-TGG TCCAATAAGTGATGAAG AAAC-3’ 522R; 5’-ACCAGCTTTT GCTTGATA-3’) following a method reported earlier18. J Vector Borne Dis 51, September 2014, pp. 235–238