Molecular identification and genetic diversity of biting midges (Diptera: Ceratopogonidae) in the tropical environment on Hainan Island, China.

Background objectives: Biting midges are hematophagous arthropods responsible for zoonotic infectious diseases and have a wide distribution in temperate and tropical latitudes of the world.

Methods: The genomic DNA of midge samples was extracted using the Chelex method and the ITS1gene was amplified by PCR to identify the midge species via BLAST. The sequence characteristics and the genetic diversity were analyzed using ClustalOmega, DnaSP, Arlequin, PopART, and TCS software tool. The validity of the ITS1 gene as a DNA barcode marker was evaluated using DAMBE. The phylogenetic relationship was established in the MEGA software. The ABGD web determined the species boundary and the SDT software visualized the pairwise sequence comparisons.

Results: A total of 39 midge samples possessed the range from 364 to 429 bp of the ITS1 sequences. The midge samples were identified as Culicoides imicola, Culicoides oxystoma, Culicoides peregrinus, Culicoides jacobsoni, Forcipomyia peregrinator, and Culicoides fulvus, respectively. The ITS1 sequences had 288 conserved sites (60.25%), 167 variable sites (34.94%), 141 parsimony-informative sites (29.50%), and 26 singleton sites (5.44%), with a considerable sequence variation with a high haplotype diversity. Populations in Lingao, Haikou, Tunchang were relatively independent, with a low level of gene flow. A separate population of Forcipomyia genus in Danzhou was observed.

Interpretation conclusion: The biting midges in Hainan, a tropical island, had abundant genetic diversity. Timely surveillance is a crucial control measure for the spread of midge-borne diseases.