Morphological and mitochondrial cytochrome oxidase-I gene-based characterisation of Culex quinquefasciatus from central Kerala

Culex quinquefasciatus is a principal vector of filarial and viral infections and a key contributor to lymphatic filariosis transmission in Kerala, India. Accurate identification of mosquito vectors is crucial for surveillance and control and, morphological differentiation can be challenging among closely related species. This study characterised Culex quinquefasciatus from Thrissur and Ernakulam districts of Kerala using morphological and molecular approaches. A total of 6,421 mosquitoes were studies, with 271 specimens identified as Cx. quinquefasciatus and 42 as members of the Cx. vishnui group. Morphological features of Cx. quinquefasciatus included brown to golden-brown bodies, short palpi, unbanded proboscis and tarsi, and narrow pale abdominal bands. Molecular characterisation involved amplification of a 665 bp fragment of the mitochondrial COI gene with PCR yielding specific amplicons and sequencing confirming 100 per cent identity with published Cx. quinquefasciatus sequences. Phylogenetic analysis clustered the Kerala isolate with Indian and UK sequences, distinct from other Culex species, validating species identification and supporting its use in vector surveillance and control programs.