Unexpected diversity of sandflies (Diptera: Psychodidae) in tourist caves in Northern Thailand

Certain species of Phlebotomine sandflies (Diptera: Psychodidae) are vectors of the protozoa which causes leishmaniasis. Sandflies are found breeding in enclosed places like caves. Thailand is a popular tourist destination, including for ecotourism activities like caving, which increases the risk of contact between tourists and sandflies. Surveillance of sandflies is important for monitoring this risk but identification of species based on morphology is challenged by phenotypic plasticity and cryptic diversity. DNA barcodes have been used for the identification of sandflies in Thailand. We collected sandflies using CDC light trap from four tourist caves in Northern Thailand. Female sandflies were provisionally sorted into 13 morphospecies and 19 unidentified specimens. DNA was extracted from the thorax and legs of sandflies and the DNA barcode region of cytochrome c oxidase I mtDNA amplified and sequenced. The specimens were sorted into 22 molecular operational taxonomic units (MOTU) based on the 145 DNA barcodes, which is significantly more than the morphospecies. Several of the taxa thought to be present in multiple caves, based on morphospecies sorting, split into cave-specific MOTU which likely represent cryptic species. Several MOTU reported in an earlier study from Wihan Cave, Thailand, were also found in these caves. This supports the use of DNA barcodes to investigate species diversity of sandflies and their useful role in surveillance of sandflies in Thailand.