Molecular evidence for the presence of malaria vector species a of the Anopheles annularis complex in Sri Lanka

Anopheline larvae were collected at a site in the Jaffna district, which lies within the dry zone of Sri Lanka, and reared in the laboratory. Emerged adults were identified using standard keys. DNA sequences of the D3 domain of 28S ribosomal DNA (rDNA) and the internal transcribed spacer-2 (ITS-2) of the morphologically identified An. annularis were determined. BLASTn searches against corresponding An. annularis sequences in GenBank and construction of phylogenetic trees from D3 and ITS-2 rDNA sequences showed that the Sri Lankan specimens, and An. annularis s.l. specimens from several Southeast Asian countries were closely related to species A of the Indian An. annularis complex.The results show the presence of the malaria vector An. annularis species A in Sri Lanka and Southeast Asia. Because An. annularis vectors have been long associated with malaria transmission in irrigated agricultural areas in the Sri Lankan dry zone, continued monitoring of An. annularis populations, and their sibling species status, in these areas need to be integral to malaria control and eradication efforts in the island.Anopheles (Cellia) annularis Van der Wulp is one of the species that form the "Annularis Group" that are classified under the Neocellia series of the subgenus Cellia [1]. The other members of this group are An. nivipes, An. philippinensis, An. pallidus and An. schueffneri. An. annularis s.l. is widespread in Asia from the Indian subcontinent to Southeast Asia, and has been incriminated as vector of malaria in India, Bangladesh, Myanmar, Malaysia and China [2-5]. The taxon An. annularis is reported to be a species complex comprising two sibling species viz. A and B in India [2,4]. The two sibling species can be distinguished through characteristic banding patterns in the polytene chromosome arm 2 [2]. They also possess different sequences in the D3 region of 28S RNA and the ITS-2 internally transcribed spacer region of ribosomal RNA [3]An. annularis s.l. was previously re