Displaying publications 1 - 20 of 131 in total

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  1. Fulltext Macrogenomic evidence for the origin of the black fly Simulium suzukii (Diptera: Simuliidae) on Okinawa Island, Japan
    Adler PH, Huang YT, Reeves WK, Kim SK, Otsuka Y, Takaoka H
    PLoS One, 2013;8(8):e70765.
    PMID: 23951001 DOI: 10.1371/journal.pone.0070765
    To determine the geographic origin of the black fly Simulium suzukii on Okinawa Island, Japan, macrogenomic profiles derived from its polytene chromosomes were compared with those of mainland and other insular populations of S. suzukii and of the isomorphic Simulium tani species complex. The Okinawan population is a chromosomally unique cytoform, designated 'D,' which is essentially monomorphic and differs by about 27 fixed rearrangements from the chromosomal standard sequence for the subgenus Simulium and by two fixed differences from its nearest known relative, representing the type of S. suzukii, on the main islands of Japan. Chromosomal band sequences revealed two additional, sympatric cytoforms of S. suzukii, designated 'A' and 'B,' each with species status, in Korea, and a third cytoform, designated 'C,' on Hokkaido, Japan. A new cytoform, 'K,' of S. tani from Malaysia, representing the type of S. tani, is more closely related to cytoforms in Thailand, as are populations from Taiwan previously treated as S. suzukii but more closely aligned with S. tani and newly recognized as cytoform 'L' of the latter nominal species. Rooting of chromosomal band sequences by outgroup comparisons allowed directionality of chromosomal rearrangements to be established, enabling phylogenetic inference of cytoforms. Of 41 macrogenomic rearrangements discovered in the five new cytoforms, four provide evidence for a stepwise origin of the Okinawan population from populations characteristic of the main islands of Japan. The macrogenomic approach applied to black flies on Okinawa Island illustrates its potential utility in defining source areas for other species of flies including those that might pose medical and veterinary risks.
  2. Evolutionary and biogeographic history of the black fly Simulium wayani (Diptera: Simuliidae) on the island of Timor
    Adler PH, Takaoka H, Sofian-Azirun M, Chen CD, Suana IW
    Acta Trop, 2019 May;193:1-6.
    PMID: 30772330 DOI: 10.1016/j.actatropica.2019.02.017
    A recently described species of black fly, Simulium wayani Takaoka and Chen, from the island of Timor was chromosomally mapped to provide insights into its evolutionary and biogeographic history. The morphologically based species status of S. wayani is supported by a suite of fixed chromosomal rearrangements and unique sex chromosomes derived primarily from a large pool of polymorphisms in the S. ornatipes complex in Australia. The banding patterns of its polytene chromosomes indicate that S. wayani is closely related to a pair of homosequential cryptic species (S. norfolkense Dumbleton and S. ornatipes cytoform A2) in the S. ornatipes Skuse complex on mainland Australia; all three species uniquely share the same amplified band in their chromosomal complement. The low level of polymorphism and heterozygosity in S. wayani, relative to Australian populations of the S. ornatipes complex, suggests few colonization events from the larger land mass.
  3. Fulltext Vietnam, a Hotspot for Chromosomal Diversity and Cryptic Species in Black Flies (Diptera: Simuliidae)
    Adler PH, Takaoka H, Sofian-Azirun M, Low VL, Ya'cob Z, Chen CD, et al.
    PLoS One, 2016;11(10):e0163881.
    PMID: 27695048 DOI: 10.1371/journal.pone.0163881
    The increasing attention on Vietnam as a biodiversity hotspot prompted an investigation of the potential for cryptic diversity in black flies, a group well known elsewhere for its high frequency of isomorphic species. We analyzed the banding structure of the larval polytene chromosomes in the Simulium tuberosum species group to probe for diversity beyond the morphological level. Among 272 larvae, 88 different chromosomal rearrangements, primarily paracentric inversions, were discovered in addition to 25 already known in the basic sequences of the group in Asia. Chromosomal diversity in Vietnam far exceeds that known for the group in Thailand, with only about 5% of the rearrangements shared between the two countries. Fifteen cytoforms and nine morphoforms were revealed among six nominal species in Vietnam. Chromosomal evidence, combined with available molecular and morphological evidence, conservatively suggests that at least five of the cytoforms are valid species, two of which require formal names. The total chromosomal rearrangements and species (15) now known from the group in Vietnam far exceed those of any other area of comparable size in the world, supporting the country's status as a biodiversity hotspot. Phylogenetic inference based on uniquely shared, derived chromosomal rearrangements supports the clustering of cytoforms into two primary lineages, the Simulium tani complex and the Southeast Asian Simulium tuberosum subgroup. Some of these taxa could be threatened by habitat destruction, given their restricted geographical distributions and the expanding human population of Vietnam.
  4. Revision of Simulium rufibasis (Diptera: Simuliidae) in Japan and Korea: Chromosomes, DNA, and Morphology
    Adler PH, Fukuda M, Takaoka H, Reeves WK, Kim SK, Otsuka Y
    J Med Entomol, 2020 02 27;57(2):388-403.
    PMID: 31746337 DOI: 10.1093/jme/tjz197
    The widespread nominal black fly Simulium (Simulium) rufibasis Brunetti was reexamined morphologically, chromosomally, and molecularly to determine the status of populations in Japan and Korea with respect to S. rufibasis from the type locality in India and to all other known species in the S. (S.) tuberosum species-group. Morphological comparisons established that the species previously known as S. rufibasis in Japan and Korea is distinct from all other species. Consequently, it was described and illustrated as a new species, Simulium (S.) yamatoense. Simulium yokotense Shiraki, formerly a synonym of S. rufibasis, was morphologically reevaluated and considered a species unplaced to species-group in the subgenus Simulium. Chromosomal analyses of S. yamatoense sp. nov. demonstrated that it is unique among all cytologically known species of the S. tuberosum group and is the sister species of the Taiwanese species tentatively known as S. (S.) arisanum Shiraki. Populations of S. yamatoense sp. nov. included two cytoforms, based on the sex chromosomes. Cytoform A, including topotypical representatives, was found in Kyushu, Japan, whereas cytoform B was found in Korea and Honshu, Japan. Molecular analysis based on the COI mitochondrial gene generally corroborated morphological and chromosomal data that S. yamatoense sp. nov. is a distinct species and, like the chromosomal data, indicate that it is most closely related to S. arisanum, with interspecific genetic distance of 2.92-4.63%.
  5. Fulltext Seasonal Filarial Infections and Their Black Fly Vectors in Chiang Mai Province, Northern Thailand
    Aupalee K, Saeung A, Srisuka W, Fukuda M, Streit A, Takaoka H
    Pathogens, 2020 Jun 25;9(6).
    PMID: 32630410 DOI: 10.3390/pathogens9060512
    The transmission of zoonotic filarial parasites by black flies has so far been reported in the Chiang Mai and Tak provinces, Thailand, and the bites of these infected black flies can cause a rare disease-human zoonotic onchocerciasis. However, species identification of the filarial parasites and their black fly vectors in the Chiang Mai province were previously only based on a morphotaxonomic analysis. In this study, a combined approach of morphotaxonomic and molecular analyses (mitochondrial cox1, 12S rRNA, and nuclear 18S rRNA (SSU HVR-I) genes) was used to clarify the natural filarial infections in female black flies collected by using human and swine baits from two study areas (Ban Lek and Ban Pang Dang) in the Chiang Mai province from March 2018 to January 2019. A total of 805 and 4597 adult females, belonging to seven and nine black fly taxa, were collected from Ban Lek and Ban Pang Dang, respectively. At Ban Lek, four of the 309 adult females of Simulium nigrogilvum were positive for Onchocerca species type I in the hot and rainy seasons. At Ban Pang Dang, five unknown filarial larvae (belonging to the same new species) were detected in Simulium sp. in the S. varicorne species-group and in three species in the S. asakoae species-group in all seasons, and three non-filarial larvae of three different taxa were also found in three females of the S. asakoae species-group. This study is the first to molecularly identify new filarial species and their vector black fly species in Thailand.
  6. Three new species of the Simulium (Simulium) striatum species-group (Diptera: Simuliidae) from Thailand, with their phylogenetic relationships
    Aupalee K, Saeung A, Srisuka W, Fukuda M, Junkum A, Pitasawat B, et al.
    Acta Trop, 2020 Nov;211:105625.
    PMID: 32649996 DOI: 10.1016/j.actatropica.2020.105625
    Three new species of black flies from Thailand, Simulium wangkwaiense, S. tadtonense and S. maeklongkeense, are described based on their adults, pupal exuviae and cocoons. All three new species are assigned to the Simulium (Simulium) striatum species-group, bringing its total number in Thailand to seven. Simulium wangkwaiense sp. nov. is the species formerly called S. quinquestriatum in Thailand. Certain male and pupal morphological characteristics are shown to separate all seven Thai species of this species-group. All of the three new species have been analyzed genetically for their phylogenetic relationships, with three known related species (except for S. thailandicum), by using the fast-evolving nuclear big zinc finger (BZF) gene.
  7. A new species of Simulium (Asiosimulium) (Diptera: Simuliidae) from northeastern Thailand, with its phylogenetic relationships with related species in the subgenus Asiosimulium
    Aupalee K, Srisuka W, Taai K, Takaoka H, Saeung A
    J Med Entomol, 2023 Nov 14;60(6):1330-1342.
    PMID: 37669777 DOI: 10.1093/jme/tjad118
    Simulium (Asiosimulium) khongchiamense sp. nov. is described based on females, males, pupae, and mature larvae collected from Khong Chiam District, Ubon Ratchathani Province, northeastern Thailand. It is characterized in the female by the medium-long sensory vesicle, scutum with 3 dark longitudinal vittae and elongate cercus; in the male by the number of upper-eye (large) facets in 17 or 18 vertical rows and 18 or 19 horizontal rows, hind basitarsus moderately enlarged and ventral plate with the posterior margin moderately concave medially; in the pupa by the head and thoracic integument sparsely covered with tubercles and gill of arborescent type with 32 or 33 filaments; and in the larva by the postgenal cleft deep, reaching the posterior margin of the hypostoma and sheath of the subesophageal ganglion dark pigmented. DNA analysis based on COI gene of all known species of the subgenus Asiosimulium, except for S. shanense and S. suchitrae, indicated that this new species can be clearly differentiated from all other related species (S. phurueaense, S. oblongum, S. saeungae, S. furvum, and S. wanchaii) with interspecific genetic distances ranging between 4.79% and 19.18%. This is the eighth species of the subgenus Asiosimulium. Taxonomic notes are given to distinguish this new species from the 7 known species members in its same subgenus. Additionally, keys to species of all members in the subgenus Asiosimulium are provided.
  8. A new case of zoonotic onchocercosis in northern Kyushu, Japan
    Fukuda M, Uni S, Otsuka Y, Eshita Y, Nakatani J, Ihara K, et al.
    Parasitol Int, 2015 Dec;64(6):519-21.
    PMID: 26209456 DOI: 10.1016/j.parint.2015.07.006
    A case of zoonotic onchocercosis has been found in a resident who lived in Iizuka City, Fukuoka Prefecture, Japan for some time. A 24-year-old male developed a painful nodule on the middle finger of his right hand. The nodule was surgically removed from the vagina fibrosa tendinis of the finger at Beppu Medical Center, Beppu City, Oita Prefecture in 2012. The causative agent was identified as a female Onchocerca dewittei japonica based on its histopathological characteristics. The identity of the filarioid has been confirmed by sequencing the cox1 gene. The present study indicates that the zoonotic onchocercosis caused by O. dewittei japonica has been concentrated in northeast Kyushu.
  9. Human case of Onchocerca dewittei japonica infection in Fukushima, Northeastern Honshu, Japan
    Fukuda M, Uni S, Igari T, Utsumi Y, Otsuka Y, Nakatani J, et al.
    Parasitol Int, 2019 Oct;72:101943.
    PMID: 31220633 DOI: 10.1016/j.parint.2019.101943
    A 73-year-old man living in Kawamata-machi, Fukushima Prefecture, Northeastern Honshu, Japan, visited a hospital with complaints of a subcutaneous swelling that had developed on the back of his left hand. The nodule was surgically removed from the vagina fibrosa tendinis of his left forefinger. Based on the histopathological characteristics, the causative agent of this nodule was identified as a female Onchocerca dewittei japonica (Spirurida: Onchocercidae). The species identification was confirmed by cox1 gene sequencing of the worm tissues from paraffin-embedded sections of the nodule. Although 11 cases of zoonotic onchocercosis have previously been recorded in Kyushu and Western Honshu, Japan, the present findings represent the first human case of infection with O. dewittei japonica in Northeastern Honshu, Japan.
  10. The biodiversity of black flies (Diptera: Simuliidae) in Indonesia
    Hadi UK, Takaoka H
    Acta Trop, 2018 Sep;185:133-137.
    PMID: 29452114 DOI: 10.1016/j.actatropica.2018.02.013
    Indonesia is one of the megadiversity country in the world endowed with rich and unique biodiversity insects such as blackflies species (Diptera: Simuliidae). Blackflies are found almost anywhere with running water suitable as habitat for the immature stages. This family is one of the most important groups of blood-sucking insects. This study collates the records of Simulium (Diptera: Simuliidae) in previous publications related fauna of Indonesia. Based on the results of this study, there were 124 species of blackflies in Indonesian Archipelago. All species are assigned to the genus Simulium Latreille s.l., and are placed into five subgenera, i.e. Gomphostilbia Enderlein, Morops Enderlein, Nevermannia Enderlein, Simulium Latreille s.str. and Wallacellum Takaoka. Further classification into 27 species groups within the subgenera were also made. Checklists of Indonesian Simuliidae are provided including data on the distribution of each species.
  11. Proteomes of the female salivary glands of Simulium nigrogilvum and Simulium nodosum, the main human-biting black flies in Thailand
    Hempolchom C, Reamtong O, Sookrung N, Srisuka W, Sakolvaree Y, Chaicumpa W, et al.
    Acta Trop, 2019 Jun;194:82-88.
    PMID: 30922801 DOI: 10.1016/j.actatropica.2019.03.026
    Although several studies have reported pharmacological and immunological activity, as well as the role of black flies in transmitting pathogens to vertebrate hosts through salivary glands (SG) during blood feeding, SG proteomes of the anthropophilic black flies in Thailand have never been reported. Therefore, this study determined the SG proteomes of female S. nigrogilvum and S. nodosum. Sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional (2-DE) gels containing separated SG proteins of individual species were subjected to liquid chromatography-tandem mass spectrometry (LCMS/MS) and an orthologous protein search from eukaryotic organism, nematocera and simuliidae databases for total protein identification. SDS-PAGE and protein staining revealed at least 13 and 9 major protein bands in the SGs of female S. nigrogilvum and S. nodosum, respectively, as well as several minor ones. The 2-DE demonstrated a total of 56 and 41 protein spots for S. nigrogilvum and S. nodosum, respectively. Most of the proteins obtained in both species were enzymes involved in blood feeding, including proteases, apyrases, hyaluronidases, aminopeptidase and elastase. The results obtained in this study provided a new body of knowledge for a better understanding on the role of salivary gland proteins in these black fly species in Thailand.
  12. Characterization of IgE-binding proteins in the salivary glands of Simulium nigrogilvum (Diptera: Simuliidae)
    Hempolchom C, Sookrung N, Srisuka W, Reamtong O, Sakolvaree Y, Chaicumpa W, et al.
    Parasitol Res, 2019 Aug;118(8):2353-2359.
    PMID: 31263951 DOI: 10.1007/s00436-019-06383-x
    Simulium dermatitis is an IgE-mediated skin reaction in animals and humans caused by the bites of black flies. Although Simulium nigrogilvum has been incriminated as the main human-biting black fly species in Thailand, information on its salivary allergens is lacking. Salivary gland extract of S. nigrogilvum females was subjected to sodium dodecylsulfate-polyacrylamide gel electrophoresis, and the separated components were applied onto nitrocellulose membranes for immunoblotting, which was performed by probing the protein blots with sera from 17 individuals who were allergic to the bites of S. nigrogilvum. IgE-reactive protein bands were characterized further by liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Nine protein bands (79, 42, 32, 25, 24, 22, 15, 13, and 11 kDa) were recognized in the serum of the subjects. Four of the nine protein bands (32, 24, 15, and 11 kDa) showed IgE reactivity in all (100%) of the tested sera, and they were identified as salivary secreted antigen 5-related protein, salivary serine protease, erythema protein, and hypothetical secreted protein, respectively. Three other proteins, salivary serine protease (25 kDa), salivary D7 secreted protein (22 kDa), and hypothetical protein (13 kDa), reacted with > 50% of the sera. The relevance of the identified protein bands as allergens needs to be confirmed by using pure recombinant proteins, either in the in vivo skin prick test or in vitro detection of the specific IgE in the serum samples of allergic subjects. This will be useful for the rational design of component-resolved diagnosis and allergen immunotherapy for the allergy mediated by the bites of black flies.
  13. Scanning electron microscopy of antennal sensilla of the eight Anopheles species of the Hyrcanus Group (Diptera: Culicidae) in Thailand
    Hempolchom C, Yasanga T, Wijit A, Taai K, Dedkhad W, Srisuka W, et al.
    Parasitol Res, 2017 Jan;116(1):143-153.
    PMID: 27752768
    Antennal sensilla were first investigated in the eight medically and veterinary important Anopheles mosquito species (Anopheles argyropus, Anopheles crawfordi, Anopheles nigerrimus, Anopheles nitidus, Anopheles paraliae (= Anopheles lesteri), Anopheles peditaeniatus, Anopheles pursati, and Anopheles sinensis) of the Hyrcanus Group in Thailand, using scanning electron microscopy (SEM). Four types of sensilla, including sensilla chaetica (large and small), sensilla trichodea (sharp- and blunt-tipped), sensilla basiconica or grooved pegs (types I, II, and III), and sensilla coeloconica (large and small), were observed on the female antennae of the eight species. The greatest number of sensilla found along the flagellum of all the Anopheles species consisted of sensilla trichodea. Grooved pegs type II were not found on the antennae of An. peditaeniatus. Interestingly, clusters of 10-15 grooved pegs type III, with blunt-tipped and unevenly grooved-lengthwise sensilla, and a sunken group of 7-12 grooved pegs type III, with slightly curved and point-tipped sensilla, were found distally on flagellomeres 3-7 of An. argyropus and An. peditaeniatus, respectively. In addition, the key for species identification, based on fine structure and morphometrics of antennal sensilla among the eight species, was constructed and differentiated successfully. However, in order to focus intensively on the exact function of these sensilla, further electrophysiological study is needed in understanding their significant role in mosquito behavior, especially when these insects seek hosts for transmitting pathogens to humans.
  14. DNA barcoding of black flies (Diptera: Simuliidae) in Indonesia
    Hew YX, Ya'cob Z, Adler PH, Chen CD, Lau KW, Sofian-Azirun M, et al.
    Parasit Vectors, 2023 Jul 22;16(1):248.
    PMID: 37480109 DOI: 10.1186/s13071-023-05875-1
    BACKGROUND: DNA barcoding is a valuable taxonomic tool for rapid and accurate species identification and cryptic species discovery in black flies. Indonesia has 143 nominal species of black flies, but information on their biological aspects, including vectorial capacity and biting habits, remains underreported, in part because of identification problems. The current study represents the first comprehensive DNA barcoding of Indonesian black flies using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences.

    METHODS: Genomic DNA of Indonesian black fly samples were extracted and sequenced, producing 86 COI sequences in total. Two hundred four COI sequences, including 118 GenBank sequences, were analysed. Maximum likelihood (ML) and Bayesian inference (BI) trees were constructed and species delimitation analyses, including ASAP, GMYC and single PTP, were performed to determine whether the species of Indonesian black flies could be delineated. Intra- and interspecific genetic distances were also calculated and the efficacy of COI sequences for species identification was tested.

    RESULTS: The DNA barcodes successfully distinguished most morphologically distinct species (> 80% of sampled taxa). Nonetheless, high maximum intraspecific distances (3.32-13.94%) in 11 species suggested cryptic diversity. Notably, populations of the common taxa Simulium (Gomphostilbia) cheongi, S. (Gomphostilbia) sheilae, S. (Nevermannia) feuerborni and S. (Simulium) tani in the islands of Indonesia were genetically distinct from those on the Southeast Asian mainland (Malaysia and Thailand). Integrated morphological, cytogenetic and nuclear DNA studies are warranted to clarify the taxonomic status of these more complex taxa.

    CONCLUSIONS: The findings showed that COI barcoding is a promising taxonomic tool for Indonesian black flies. The DNA barcodes will aid in correct identification and genetic study of Indonesian black flies, which will be helpful in the control and management of potential vector species.

  15. Co-occurrence of dual lineages within Simulium (Gomphostilbia) atratum De Meijere in the Indonesian Archipelago along Wallace's Line
    Hew YX, Ya'cob Z, Chen CD, Lau KW, Sofian-Azirun M, Muhammad-Rasul AH, et al.
    Acta Trop, 2024 Feb;250:107097.
    PMID: 38097150 DOI: 10.1016/j.actatropica.2023.107097
    Mitochondrial cytochrome c oxidase subunit I (COI) sequences were utilized to infer the population genetic structure of Simulium (Gomphostilbia) atratum De Meijere, an endemic simulid species to Indonesia. Both median-joining haplotype network and maximum-likelihood tree revealed two genetic lineages (A and B) within the species, with an overlap distribution in Lombok, which is situated along Wallace's line. Genetic differentiation and gene flow with varying frequencies (FST = 0.02-0.967; Nm = 0.01-10.58) were observed between populations of S. (G.) atratum, of which population pairs of different lineages showed high genetic differentiation. Notably, the high genetic distance of up to 5.92 % observed within S. (G.) atratum in Lombok was attributed to the existence of two genetically distinct lineages. The co-occurrence of distinct lineages in Lombok indicated that Wallace's line did not act as faunistic border for S. (G.) atratum in the present study. Moreover, both lineages also exhibited unimodal distributions and negative values of neutrality tests, suggesting a pattern of population expansion. The expansion and divergence time estimation suggested that the two lineages of S. (G.) atratum diverged and expanded during the Pleistocene era in Indonesia.
  16. Diversity of nematodes infecting the human-biting black fly species, Simulium nigrogilvum (Diptera: Simuliidae) in central Thailand
    Huang F, Srisuka W, Aupalee K, Streit A, Fukuda M, Pitasawat B, et al.
    Acta Trop, 2021 Dec;224:106140.
    PMID: 34562429 DOI: 10.1016/j.actatropica.2021.106140
    Black flies (Diptera: Simuliidae) are known as vectors of disease agents in humans and livestock, with some species being vectors of Onchocerca volvulus, the filarial nematode that is the causative agent of human onchocerciasis. Nematode infections in adult female black flies have been reported from some areas in northern and western Thailand, but not from other regions of Thailand. In this study, wild-caught adult female black flies from the central region of Thailand were examined for infections with nematodes. Collections of adult females were carried out at Khlong Lan district, Kamphaeng Phet province, central Thailand. A molecular approach, based on the mitochondrial (cox1, 12S rRNA) and nuclear (18S rRNA) genes, was used to identify the species of nematodes recovered from the specimens collected. A total of 911 wild-caught adult black flies were collected. Simulium nigrogilvum was the most abundant species (n = 708), followed by S. doipuiense complex (n = 179), S. chamlongi (n = 11), S. umphangense (n = 10), S. chumpornense (n = 1), S. multistriatum species-group (n = 1), and S. maewongense (n = 1). Nematode infections were detected in nine specimens of S. nigrogilvum, of which two were positive for filarial worms (one worm each, infection rate 0.28%) and seven were positive for non-filarial nematodes (11 worms in total, infection rate 0.99%). The two filarial nematodes (third-stage larvae) were identified molecularly as Onchocerca species type I, while the 11 non-filarial nematodes were classified into ascaridoid (n = 2), tylenchid (n = 6) and mermithid (n = 3) nematodes. The results of this study demonstrated that adult female S. nigrogilvum were parasitized with diverse nematodes (filarial and non-filarial). Detection of the infective larvae of Onchocerca sp. type I in S. nigrogilvum confirms that occurrence of zoonotic onchocerciasis is highly possible in Thailand. Additional in-depth investigation of the morphology, life cycle and host-parasite relationship of nematodes that parasitized this black fly host is still needed.
  17. Simulium (Gomphostilbia) aziruni: First record of a black fly (Diptera: Simuliidae) attracted to a human in Malaysia
    Izwan-Anas N, Ya'cob Z, Low VL, Lourdes EY, Ramli R, Bolongan G, et al.
    Acta Trop, 2021 Jun;218:105904.
    PMID: 33775626 DOI: 10.1016/j.actatropica.2021.105904
    Most female black flies in the genus Simulium are blood-sucking flies and they can cause various parasitic diseases in human and animal. A total of 94 species of black flies have been reported in Malaysia, however, their biting behavior and role as vector of infectious agents remain understudied. To fill in this knowledge gap, we attempted to survey adult black flies from field populations in Peninsular Malaysia. In a survey carried out in 2017 at Tasik Kenyir, Terengganu, three females were caught while attracted and landed on human skin. Further morphological and molecular analyses showed that the specimens were identical to Simulium (Gomphostilbia) aziruni Takaoka, Hashim & Chen of the Simulium gombakense species-group. This is the first report on a black fly species attracted to human in Malaysia which serves as a steppingstone towards in-depth studies for black flies in this region.
  18. Culturable bacteria in adults of a Southeast Asian black fly, Simulium tani (Diptera:Simuliidae)
    Lee HY, Loong SK, Ya'cob Z, Low VL, Teoh BT, Ahmad-Nasrah SN, et al.
    Acta Trop, 2021 Jul;219:105923.
    PMID: 33878305 DOI: 10.1016/j.actatropica.2021.105923
    Although the microbiome of blood-feeding insects serves an integral role in host physiology, both beneficial and pathogenic, little is known of the microbial community of black flies. An investigation, therefore, was undertaken to identify culturable bacteria from one of Malaysia's most common black flies, Simulium tani Takaoka and Davies, using 16S rDNA sequencing, and then evaluate the isolates for antibiotic resistance and virulence genes. A total of 20 isolates representing 11 bacterial species in four genera were found. Five isolates showed β-hemolysis on Columbia agar, and virulence genes were found in three of these isolates. Some degree of resistance to six of the 12 tested antibiotics was found among the isolates. The baseline data from this study suggest rich opportunities for comparative studies exploring the diversity and roles of the microbiome of S. tani and other Southeast Asian black flies.
  19. Occurrence of five distinct clades of mermithid nematodes (Nematoda: Mermithidae) infecting black fly larvae (Diptera: Simuliidae) in tropical streams in Malaysia
    Lourdes EY, Low VL, Izwan-Anas N, Dawood MM, Sofian-Azirun M, Takaoka H, et al.
    Parasitol Int, 2023 Jun;94:102733.
    PMID: 36693472 DOI: 10.1016/j.parint.2023.102733
    Mermithids are the most common parasites of black flies and are associated with host feminization and sterilization in infected hosts. However, information on the species / lineage of black fly mermithids in Southeast Asia, including Malaysia requires further elucidation. In this study, mermithids were obtained from black fly larvae collected from 138 freshwater stream sites across East and West Malaysia. A molecular approach based on nuclear-encoded 18S ribosomal RNA (18S rRNA) gene was used to identify the species identity / lineage of 77 nematodes successfully extracted and sequenced from the specimens collected. Maximum likelihood and neighbor-joining phylogenetic analyses demonstrated five distinct mermithid lineages. Four species delimitation analyses: automated simultaneous analysis phylogenetics (ASAP), maximum likelihood Poisson tree processes with Bayesian inferences (bPTP_ML), generalized mixed yule coalescent (GMYC) and single rate Poisson tree processes (PTP) were applied to delimit the species boundaries of mermithid lineages in this data set along with genetic distance analysis. Data analysis supports five distinct lineages or operational taxonomic units for mermithids in the present study, with two requiring further investigation as they may represent intraspecific variation or closely related taxa. One mermithid lineage was similar to that previously observed in Simulium nigrogilvum from Thailand. Co-infection with two mermithids of different lineages was observed in one larva of Simulium trangense. This study represents an important first step towards exploring other aspects of host - parasite interactions in black fly mermithids.
  20. Fulltext Mitochondrial DNA markers reveal high genetic diversity but low genetic differentiation in the black fly Simulium tani Takaoka & Davies along an elevational gradient in Malaysia
    Low VL, Adler PH, Takaoka H, Ya'cob Z, Lim PE, Tan TK, et al.
    PLoS One, 2014;9(6):e100512.
    PMID: 24941043 DOI: 10.1371/journal.pone.0100512
    The population genetic structure of Simulium tani was inferred from mitochondria-encoded sequences of cytochrome c oxidase subunits I (COI) and II (COII) along an elevational gradient in Cameron Highlands, Malaysia. A statistical parsimony network of 71 individuals revealed 71 haplotypes in the COI gene and 43 haplotypes in the COII gene; the concatenated sequences of the COI and COII genes revealed 71 haplotypes. High levels of genetic diversity but low levels of genetic differentiation were observed among populations of S. tani at five elevations. The degree of genetic diversity, however, was not in accordance with an altitudinal gradient, and a Mantel test indicated that elevation did not have a limiting effect on gene flow. No ancestral haplotype of S. tani was found among the populations. Pupae with unique structural characters at the highest elevation showed a tendency to form their own haplotype cluster, as revealed by the COII gene. Tajima's D, Fu's Fs, and mismatch distribution tests revealed population expansion of S. tani in Cameron Highlands. A strong correlation was found between nucleotide diversity and the levels of dissolved oxygen in the streams where S. tani was collected.
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