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Black flies (Simuliidae) are important biting insects and vectors of diseases agents of humans and livestock. Thus, understanding the taxonomy and biodiversity of these insects is crucial for control and management of these diseases. In this study, we used mitochondrial cytochrome c oxidase I sequences to examine genetic diversity of three human-biting and possible vector black fly taxa; the Simulium asakoae species-complex, S. chamlongi and S. nigrogilvum. High levels of genetic diversity (>3.5% intraspecific genetic divergence) were found in all three taxa. Phylogenetic analyses indicated that the S. asakoae complex can be divided into seven groups with the largest group consisting of specimens from Thailand, Malaysia and Myanmar. This group most likely represents true S. asakoae. The remaining haplotypes formed groups with conspecific haplotypes or with other closely related species. Among these groups, one including S. monglaense and another including S. myanmarense suggest that certain specimens identified as S. asakoae most likely belong to those species. Therefore, they constitute new locality records for Thailand and also represent new records of anthropophily. Members of S. chamlongi are not monophyletic as its clade also included S. hackeri. A median joining network revealed strong geographic associations of the haplotypes of S. nigrogilvum suggesting limitation of gene flow. Because this species occurs mainly in high elevation habitats, low land areas could present a barrier to gene flow., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Blackflies are an important medical and veterinary group of small blood-sucking insects. Ninety-three blackfly species have been reported in Thailand. However, information on their biodiversity and population dynamics in each region is lacking. The main aim of this study was to assess the regional biodiversity, seasonal abundance and distribution of blackflies in six eco-geographically different regions in the country., Methods: Blackfly larvae and pupae were sampled monthly from 58 sites between May 2011 and April 2013. Diversity parameters, seasonal abundance, regional distribution and frequency of species occurrence in stream sites were analyzed., Results: A total of 19,456 mature larvae representing 57 species, and belonging to six subgenera in the genus Simulium Latreille (s.l.), were found. The five predominant taxa were S. fenestratum (8.6%), the S. asakoae complex (8.3%), S. nakhonense (7.5%), the S. siamense complex (7.4%) and the S. doipuiense complex (6.7%). The most frequent taxa at all sites were the S. asakoae complex (84.5%), followed by S. fenestratum (82.8%), the S. siamense complex (75.9%), S. decuplum (60.3%), S. nakhonense (58.6%) and the S. tani complex (48.3%). The richness of regional species was highest (40 species) in the north and predominated in the cold season. However, blackflies in the south predominated during the hot season. The highest numbers of blackflies collected from central, northeastern, eastern and western regions of the country were observed in the rainy season. Overall, the mean number of blackflies collected across the six regions during the rainy and cold season had no statistically significant difference, but it differed significantly in the hot season., Conclusions: Blackflies in Thailand were surveyed in all three seasons across six geographical regions. These findings demonstrated that blackfly communities at each stream site varied with seasonality, and the regional relative abundance of blackflies differed markedly in the hot season. It was also found that the occurrence and distribution of blackflies in each region were associated strongly with elevation.

This is the first study on the seasonal biodiversity of black flies and evaluation of ecological factors influencing their distribution at Doi Pha Hom Pok National Park, northern Thailand. Larvae were collected from six fixed-stream sites in relation to altitude gradients from May 2011 to April 2013. The water temperature, water pH, conductivity, total dissolved solids (TDS), salt, water velocity, stream width and depth, streambed particle sizes, riparian vegetation, and canopy cover were recorded from each site. Monthly collections from the six sites yielded 5475 last-instar larvae, belonging to 29 black fly species. The most frequently found species from all sites were Simulium asakoae (100%) followed by Simulium yuphae (83.3%), and Simulium chiangdaoense, Simulium gombakense, Simulium phahompokense, Simulium fruticosum, Simulium maeaiense and Simulium fenestratum (66.6%). Of the 5475 last-instar larvae, S. maeaiense (19.3%), S. chiangdaoense (15.8%) and S. asakoae (14.8%), were the three most abundant species. The Shannon diversity index (H) at the six sites with different altitudes of 2100m, 2000m, 1500m, 1400m, 700m, and 500m above mean sea level, were 2.042, 1.832, 2.158, 2.123, 1.821 and 1.822, respectively. The Shannon index and number of taxa in the cold season were higher than those in the rainy and hot seasons. Principal component analysis (PCA) indicated that at least three principal components have eigen values >1.0 and accounted for 93.5% of the total variability of ecological factors among sampling sites. The Canonical correspondence analyses (CCA) showed that most species had a trend towards altitude, canopy cover, riparian vegetation and water velocity., (Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.)