Wichai Srisuka

Seasonal biodiversity of black flies (Diptera: Simuliidae) and evaluation of ecological factors influencing species distribution at Doi Pha Hom Pok National Park, Thailand

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.

Simulium (Asiosimulium) furvum, a New Species of Black Fly (Diptera: Simuliidae) From Thailand

ABSTRACT Simulium (Asiosimulium) furvum sp. nov. (Diptera: Simuliidae) is described from female, male, pupal, and larval specimens collected from Maewa National Park, Lampang Province, Thailand. This new species represents the fourth member of the subgenus Asiosimulium Takaoka & Chochoote, one of two small black fly subgenera endemic in the Oriental Region. It is characterized by a pear-shaped spermatheca in the female; a ventral plate in the male with a laterally compressed median keel directed ventrally and with a deep notch posteromedially, and aedeagal membrane with stout spines; and by 22 gill filaments in the pupa. Taxonomic notes are provided to separate this new species from three known species, Simulium (Asiosimulium) oblongum Takaoka & Choochote and Simulium (Asiosimulium) wanchaii Takaoka & Choochote, both from Thailand, and Simulium (Asiosimulium) suchitrae Takaoka from Nepal.

DNA barcoding for the identification of eight species members of the Thai Hyrcanus Group and investigation of their stenogamous behavior

Eight species members of the Thai Hyrcanus Group were identified based on the intact morphology and molecular analysis (COI barcoding, 658 bp) of F1-progenies. Five iso-female lines of each species were pooled in order to establish stock colonies. A stenogamous colony of each species was investigated by making 200 and 300 newly emerged adult females and males co-habit in a 30 cm cubic cage for one week. After ovipositon, the spermathecae of females were examined for sperms. The results revealed that Anopheles argyropus, Anopheles crawfordi, Anopheles nitidus, Anopheles pursati, Anopheles sinensis, Anopheles nigerrimus, Anopheles paraliae and Anopheles peditaeniatus yielded insemination rates of 0%, 0%, 0%, 31%, 33%, 42%, 50% and 77%, respectively. Continuous selection to establish stenogamous colonies indicated that An. sinensis, An. pursati, An. nigerrimus, An. paraliae and An. peditaeniatus provided insemination rates of 33-34%, 27-31%, 42-58%, 43-57% and 61-86% in 1, 2, 5, 6 and 20 generations of passages, respectively.

A New Species and Species-Group of Simulium (Simulium) (Diptera: Simuliidae) From Thailand

ABSTRACT Simulium (Simulium) atipornae sp. nov. is described from females, males, pupae, and larvae in Thailand. This new species is characterized in the female by the claw with a small subbasal tooth, ovipositor valve triangular with its inner margin nearly straight; in the male by the style with a short subbasal protuberance and ventral plate Y-shaped, with toothed posterior margin; and in the pupa by the head and thoracic integument almost bare and gill with six filaments. Taxonomic notes are given to compare this new species with nine related species. A new species-group, the christophersi species-group, is proposed to accommodate S. atipornae sp. nov. and nine related species.

Two new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Myanmar, and their phylogenetic relationships with related species in the S. asakoae species-group

Two new species of Simulium (Gomphostilbia), S. (G.) myanmarense and S. (G.) monglaense, are described from females, males, pupae and larvae from Myanmar. The two new species are placed in the S. asakoae species-group, and are similar to each other in the female and male but distinguished in the pupa by the presence or absence of an anterodorsal projection of the cocoon, and in the larva by a unique pattern of colored markings on the abdomen. Taxonomic notes are given to separate these species from related species. The COI gene sequences of both species are compared with those of eight species of the S. asakoae species-group and three species of the S. ceylonicum species-group. Both new species are most closely related to each other, further supporting their morphological classification in the S. asakoae species-group.

Comparative Studies on the Stenogamous and Eurygamous Behavior of Eight Anopheles Species of the Hyrcanus Group (Diptera: Culicidae) in Thailand.

Establishment of laboratory colony is essential for mosquito-borne-disease research. Mating behavior of stenogamous Anopheles peditaeniatus and seven eurygamous species (Anopheles argyropus, Anopheles crawfordi, Anopheles nigerrimus, Anopheles nitidus, Anopheles paraliae (=An. lesteri), Anopheles pursati and Anopheles sinensis), were investigated and compared in this study. The self-mating success of adult mosquitoes in different size cages at two density resting surface (DRS) values, 3.6 and 7.2, was statistically significant between stenogamous and eurygamous species. The results obtained from comparative measurements of specific characters in adult females (maxillary palpomere and antennal sensilla characters) and males (wing and genitalia) indicate those characters might influence the mating success of An. peditaeniatus in a small cage. The gonostylus of An. peditaeniatus was shorter than the eurygamous species. Additionally, the lower frequency of clasper movement and shorter mating time could be important mechanisms that control the stenogamous behavior of An. peditaeniatus. Interestingly, for the first time, a cluster of large sensilla coeloconica was recorded on the antenna of An. argyropus and An. peditaeniatus females. There was no statistically significant difference in the mean number per female of those large antennal sensilla coeloconica among six of the eurygamous species.

Development of a multiplex PCR assay for the identification of eight species members of the Thai Hyrcanus Group (Diptera: Culicidae)

The Hyrcanus Group comprises important vectors of malaria because of Plasmodium vivax Grassi and Feletti and filariasis caused by Brugia malayi Brug in many countries of South, Southeast and East Asian regions. In Thailand, eight species members (Anopheles argyropus Swellengrebel, An. crawfordi Reid, An. nigerrimus Giles, An. nitidus Harrison, Scanlon & Reid, An. paraliae Sandosham, An. peditaeniatus Leicester, An. pursati Laveran and An. sinensis Wiedemann) of the Hyrcanus Group have been recognized. Due to morphological overlap, adult females of the Hyrcanus Group in Thailand have been misidentified markedly among the eight species, particularly when using the traumatic scales of wild-caught specimens from epidemiology and control approaches. Therefore, this study first developed a simple and robust multiplex PCR assay, based on second internal transcribed spacer sequences of ribosomal DNA, for differentiating the eight species members of the Thai Hyrcanus Group.

Simulium maleewongae, a New Species of Simulium (Gomphostilbia) (Diptera: Simuliidae) From Thailand

Abstract Simulium (Gomphostilbia) maleewongae sp. nov. is described based on the adult males and females, their pupal exuviae, and larvae from Thailand. This new species is placed in the Simulium gombakense species-group of Simulium (Gomphostilbia). It is characterized by the female cibarium with a cup-like appendage, male ventral plate deeply depressed ventromedially, pupal gill composed of an inflated structure and eight slender filaments, cone-shaped pupal terminal hooks, and cocoon with an anterodorsal projection. Taxonomic notes are given to separate this new species from 10 other species of the same species-group known from China, India, Malaysia, Thailand, Nepal, and Vietnam. Keys to identify all 11 species of the S. gombakense species-group are provided for females, males, pupae, and larvae.

Descriptions of the female and larva of Simulium (Gomphostilbia) udomi (Diptera: Simuliidae) from Thailand, and its transfer to the Simulium asakoae species-group

The female and larva of Simulium (Gomphostilbia) udomi Takaoka & Choochote from Thailand are described for the first time. The female of this species is similar to those of S. (G.) asakoae Takaoka & Davies from Peninsular Malaysia, Thailand, Hong Kong and Vietnam, and S. (G.) chiangdaoense Takaoka & Srisuka from Thailand. The larva of this species is similar to S. (G.) curtatum Jitklang et al. and S. (G.) nr. asakoae 2 from Thailand in having a medium-long postgenal cleft. Taxonomic notes are given to separate this species from these related species. The COI gene sequence of S. (G.) udomi is compared with those of eight species of the S. asakoae species-group and three species of the S. ceylonicum species-group. This species is transferred from the S. ceylonicum species-group to the S. asakoae species-group based on the adult female and male morphological characters, comparisons of the genetic distances and phylogenetic relationships inferred from the COI gene sequences.

Scanning electron microscopy of Anopheles hyrcanus group (Diptera: Culicidae) eggs in Thailand and an ultrastructural key for species identification.

The eggs of Anopheles argyropus, Anopheles crawfordi, Anopheles nigerrimus, Anopheles nitidus, Anopheles paraliae, Anopheles peditaeniatus, Anopheles pursati, and Anopheles sinensis are described with the aid of scanning electron micrographs. Comparisons of the egg structure among the eight species showed that the eggs differed with respect to the following characteristics: the deck—complete (An. argyropus, An. nigerrimus, An. paraliae, An. peditaeniatus, and An. sinensis); variable (complete, split and incomplete decks found together within an egg batch/An. crawfordi); and division into an area at each end (An. nitidus and An. pursati). The ratios of the entire length per maximal deck width within the area covered by floats were 3.33–6.86 (An. sinensis), 8.78–18.20 (An. peditaeniatus), 13.67–22 (An. nigerrimus), 26.33–44.25 (An. paraliae), and 26.99–75.94 (An. argyropus). The numbers of float ribs were 21–27 (An. peditaeniatus) and 28–34 (An. nigerrimus), and the total numbers of anterior and posterior tubercles were 6–8 (An. paraliae) and 9–11 (An. argyropus). Exochorionic sculpturing was of reticulum type (An. argyropus, An. crawfordi, An. nigerrimus, An. nitidus, An. paraliae, An. peditaeniatus, and An. sinensis) and pure tubercle type (An. pursati). Attempts are proposed to construct a robust key for species identification based on the morphometrics and ultrastructures of eggs under scanning electron microscopy.