Abstract:
Leishmaniasis has been recognized in Sri Lanka
for many years and is becoming a serious public health threat.
Sandflies, the known vector of leishmaniasis, are also found
throughout the country. The presence of a species complex among
the potential vector species; Phlebotomus (Euphlebotomus)
argentipes sensu lato is one of the impediments to developing an
effective control strategy. The current study assessed the genetic
diversity of the species complex and compared the results to
morphology-based taxonomy. Sandflies were collected from
selected study sites in the Anuradhapura, Hambantota, Puttalam,
and Jaffna districts between 2015 and 2018. They were identified
morphologically using existing taxonomic keys. The PCR assay
and subsequent DNA sequence analysis were performed for the
cytochrome c oxidase subunit I (COI) gene. The morphological
analysis revealed that the species complex contains more than two
morphospecies. Nucleotide variation was observed in the COI
sequences that were aligned. The uncorrected p distances within
and between groups were 0.01%-0.08% and 2.1%, respectively.
The COI sequence-based phylogenetic tree revealed the presence
of two genetically distinct groups: one with a sensilla chaetica/
second antennal flagellomere length ratio of less than 0.4 and
another with a ratio of 0.45 and greater. This result contradicts
the existing taxonomic keys. A PCR-based assay is proposed to
differentiate the genetic groups based on the sequence variations.
