Displaying publications 81 - 100 of 131 in total

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  1. Fulltext Distribution pattern of black fly (Diptera: Simuliidae) assemblages along an altitudinal gradient in Peninsular Malaysia
    Ya'cob Z, Takaoka H, Pramual P, Low VL, Sofian-Azirun M
    Parasit Vectors, 2016 Apr 19;9:219.
    PMID: 27094088 DOI: 10.1186/s13071-016-1492-7
    BACKGROUND: Preimaginal black flies (Diptera: Simuliidae) are important components of the stream ecosystem. However, there has been limited research undertaken on the vertical distribution of preimaginal black flies and their associated ecological factors. Stream conditions are generally variable along the altitudinal gradient. Therefore, we conducted an in-depth entomological survey to investigate the simuliid distribution pattern along an altitudinal gradient in Peninsular Malaysia.

    METHODS: A total of 432 collections were performed in this study (24 samplings at each of 18 fixed-streams at monthly intervals) from February 2012 to January 2014. Larvae and pupae attached on aquatic substrates such as grasses, leaves and stems, twigs, plant roots and rocks were collected by hand using fine forceps. Stream depth (m), width (m), velocity (m/s), water temperature (°C), acidity (pH), conductivity (mS/cm) and dissolved oxygen (mg/L) were measured at the time of each collection.

    RESULTS: A total of 35 black fly species were recorded in the present study. The most frequently collected species were Simulium tani (31.7%) and S. whartoni (21.5%), while the relatively common species were Simulium sp. (nr. feuerborni) (16.2%), S. decuplum (15.5%), S. angulistylum (14.8%), S. bishopi (13.2%) and S. izuae (11.8%). Total estimated species richness ranged between 39.8 and 41.3, which yielded more than 80% of sampling efficiency. Six simuliid species were distributed below 500 m, whereas eight species were distributed above 1400 m. Simulium sp. (nr. feuerborni) and S. asakoae were found from middle to high altitudes (711-1813 m). Simulium whartoni, S. brevipar and S. bishopi were distributed widely from low to high altitudes (159-1813 m). Regression analysis between species richness and PCs revealed that the species richness was significantly associated with wider, deeper and faster streams at low altitude, normal water temperature (23-25 °C), low conductivity, higher discharge, more canopy cover and riparian vegetation and with larger streambed particles (F = 20.8, df = 1, 422, P 

  2. Acanthocheilonema delicata n. sp. (Nematoda: Filarioidea) from Japanese badgers (Meles anakuma): description, molecular identification, and Wolbachia screening
    Uni S, Bain O, Suzuki K, Agatsuma T, Harada M, Motokawa M, et al.
    Parasitol Int, 2013 Feb;62(1):14-23.
    PMID: 22926421 DOI: 10.1016/j.parint.2012.08.004
    Acanthocheilonema delicata n. sp. (Filarioidea: Onchocercidae: Onchocercinae) is described based on adult filarioids and microfilariae obtained from subcutaneous connective tissues and skin, respectively, of Japanese badgers (Meles anakuma) in Wakayama Prefecture, Japan. No endemic species of the genus had been found in Japan. Recently, some filarioids (e.g., Acanthocheilonema reconditum, Dirofilaria spp., and Onchocerca spp.) have come to light as causative agents of zoonosis worldwide. The new species was readily distinguished from its congeners by morphologic characteristics such as body length, body width, esophagus length, spicule length, and the length of microfilariae. Based on the molecular data of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene, A. delicata n. sp. was included in the clade of the genus Acanthocheilonema but differed from two other congeneric species available for study, A. viteae and A. reconditum. Acanthocheilonema delicata n. sp. did not harbor Wolbachia. It is likely that the fauna of filarioids from mammals on the Japanese islands is characterized by a high level of endemicity.
  3. Onchocerca takaokai n. sp. (Nematoda: Filarioidea) in Japanese wild boars (Sus scrofa leucomystax): Description and molecular identification of intradermal females
    Uni S, Fukuda M, Agatsuma T, Bain O, Otsuka Y, Nakatani J, et al.
    Parasitol Int, 2015 Dec;64(6):493-502.
    PMID: 26165205 DOI: 10.1016/j.parint.2015.07.001
    Human zoonotic onchocercosis is caused by Onchocerca dewittei japonica, parasitic in wild boars (Sus scrofa leucomystax) in Japan. Previously, microfilariae longer than those of Onchocerca dewittei japonica were observed in skin snips from wild boars during the study of O. dewittei japonica. Moreover, the third-stage larvae (L3) of these longer microfilariae were obtained from the blackfly Simulium bidentatum after experimental injections. Based on morphometric and molecular studies, similar L3 were found in blackflies during fieldwork in Oita, Japan. However, except for O. dewittei japonica, adult worms of Onchocerca have not been found in wild boars. In this study, we discovered adult females of a novel Onchocerca species in the skin of a wild boar in Oita, and named it Onchocerca takaokai n. sp. Females of this new species had longer microfilariae and differed from O. dewittei japonica in terms of their morphological characteristics and parasitic location. The molecular characteristics of the cytochrome c oxidase subunit 1 and 12S rRNA genes of the new species were identical to those of the longer microfilariae and L3 previously detected, but they differed from those of O. dewittei japonica at the species level. However, both species indicated a close affinity among their congeners and Onchocerca ramachandrini, parasitic in the warthog in Africa, was basal in the Suidae cluster of the 12S rRNA tree.
  4. 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.
  5. Prevalence of Onchocerca japonica and O. takaokai infections in the Japanese wild boar, Sus scrofa leucomystax, and the Ryukyu wild boar, S. s. riukiuanus, in Japan
    Uni S, Fukuda M, Uga S, Agatsuma T, Nakatani J, Suzuki K, et al.
    Parasitol Int, 2021 Aug;83:102313.
    PMID: 33662527 DOI: 10.1016/j.parint.2021.102313
    Reports of zoonotic infections with Onchocerca japonica (Nematoda: Filarioidea), which parasitizes the Japanese wild boar, Sus scrofa leucomystax, have recently increased in Japan. To predict the occurrence of infection in humans, it is necessary to determine the prevalence of O. japonica infection in the natural host animals. We investigated the presence of adult worms in the footpads, and of microfilariae in skin snips, taken from the host animals, between 2000 and 2018. Onchocerca japonica was found in 165 of 223 (74%) Japanese wild boars in Honshu and Kyushu. Among the nine regions studied, the highest prevalence of O. japonica infection was found in Oita, Kyushu, where 47 of 52 (90.4%) animals were infected. The ears were the predilection sites for O. japonica microfilariae. Adult worms of O. japonica were found more frequently in the hindlimbs than in the forelimbs of the host animals. Onchocerca takaokai was found in 14 of 52 (26.9%) Japanese wild boars in Oita. In Kakeroma Island among the Nansei Islands, both O. japonica and O. takaokai were isolated from the Ryukyu wild boar, S. s. riukiuanus. These observations could help predict future occurrences of human zoonotic onchocercosis in Japan.
  6. Zoonotic infection with Onchocerca dewittei japonica in an 11-year-old boy in Kansai Region, Western Honshu, Japan
    Uni S, Fukuda M, Ogawa K, Lim YA, Agatsuma T, Bunchom N, et al.
    Parasitol Int, 2017 Oct;66(5):593-595.
    PMID: 28648713 DOI: 10.1016/j.parint.2017.06.006
    An 11-year-old boy living in Otsu City, Shiga Prefecture, Kansai Region, Western Honshu, Japan had zoonotic onchocercosis. The patient developed a painful swelling on the little finger of his left hand. The worm detected in the excised mass had external transverse ridges but did not have inner striae in the cuticle. On the basis of the parasite's histopathological characteristics, the causative agent was identified as a female Onchocerca dewittei japonica (Spirurida: Onchocercidae). The species of the filarial parasite was confirmed by sequencing the cox1 gene of the parasite. The Japanese wild boar Sus scrofa leucomystax is a definitive host for O. dewittei japonica, which is then transmitted by blackflies as the vector to humans. The current case described occurred in the Kansai Region, Western Honshu, where such infections were previously not reported.
  7. Description and molecular characteristics of Morishitium polonicum malayense Urabe, Nor Hashim & Uni, n. subsp. (Trematoda: Cyclocoelidae) from the Asian glossy starling, Aplonis panayensis strigata (Passeriformes: Sturnidae) in Peninsular Malaysia
    Urabe M, Nor Hashim NE, Uni S, Iwaki T, Abdullah Halim MR, Marzuki ME, et al.
    Parasitol Int, 2020 Jun;76:102074.
    PMID: 32057926 DOI: 10.1016/j.parint.2020.102074
    We describe Morishitium polonicum malayense n. subsp. from Asian glossy starlings (Aplonis panayensis strigata) (Horsfield, 1821) (Passeriformis: Sturnidae) caught in Malaysia. The trematodes had parasitized the air sacs and the thoracic and body cavities of 40 out of 67 (59.7%) birds examined. The specimens each had an oral sucker, a postpharyngeal genital pore, and tandem testes, but lacked a ventral sucker. The morphological characteristics of our specimens were similar to those of M. polonicum polonicum (Machalska, 1980) from Poland. However, the anterior extremity of vitelline follicles of the present specimens sometimes extended to the level of pharynx. The oral sucker width, oral sucker width/pharynx width ratio, and intertesticular space metrics differed from those of M. p. polonicum. The maximum-likelihood trees based on the cytochrome c oxidase subunit I (COI) and the internal transcribed spacer 2 (ITS2) sequences indicated that the species from the present study formed a sister group with M. p. polonicum from the Czech Republic. The p-distances of COI and ITS2 sequences between the present specimens and M. p. polonicum from the Czech Republic were 6.9-7.5% and 0.6%, respectively. These genetic divergences indicate the border for intra- or interspecific variation of digeneans. The definitive host species and geographical distribution of the current specimens were distinct from those of M. p. polonicum from Europe. We thus concluded that the present specimens are ranked as a new subspecies of M. polonicum, namely M. polonicum malayense n. subsp.
  8. 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.
  9. 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.
  10. Sexually anomalous individuals of the black fly Simulium trangense (Diptera: Simuliidae) infected with mermithid parasites (Nematoda: Mermithidae)
    Ya'cob Z, Low VL, Tan TK, Noor-Izwan A, Lourdes EY, Ramli R, et al.
    Parasitol Res, 2021 May;120(5):1555-1561.
    PMID: 33655351 DOI: 10.1007/s00436-021-07087-x
    Sexually anomalous individuals, typically intersexes or gynandromorphs, bear a mixture of male and female traits. Twelve sexually anomalous individuals of the black fly Simulium (Gomphostilbia) trangense Jitklang, Kuvangkadilok, Baimai, Takaoka & Adler were discovered among 49 adults reared from pupae. All 12 sexually anomalous adults were parasitized by mermithid nematodes, although five additional parasitized adults had no overt external anomalies. Sequence analysis of the 18S rRNA gene revealed that the mermithids, possibly representing a new species, are related to Mesomermis spp., with genetic distances of 5.09-6.87%. All 12 anomalous individuals had female phenotypical traits on the head, thorax, forelegs, midlegs, and claws, but male features on the left and right hind basitarsi. One individual had mixed male and female genitalia. The findings are in accord with the trend that mermithid infections are associated with sexually anomalous adult black flies.
  11. A novel molecular and chromosomal lineage of the anthropophilic Simulium (Simulium) rufibasis subgroup (Diptera: Simuliidae) in Taiwan
    Low VL, Takaoka H, Adler PH, Tan TK, Weng FC, Chen CY, et al.
    Parasitol Res, 2018 Oct;117(10):3137-3143.
    PMID: 30006809 DOI: 10.1007/s00436-018-6011-7
    The Simulium rufibasis subgroup is one of three subgroups of the Simulium (Simulium) tuberosum species-group; it is characterized by a pair of clustered stout hairs on the ventral surface of female abdominal segment 7. A member of the S. rufibasis subgroup in Taiwan was investigated morphologically and genetically using the universal cytochrome c oxidase subunit I (COI) barcoding gene and polytene chromosomal banding pattern. The Taiwanese material is morphologically similar to S. rosliramlii Takaoka & Chen from Vietnam and represents the second species of the S. rufibasis subgroup known from Taiwan. It also represents a novel molecular lineage that is distinct from three other primary lineages identified as S. doipuiense, S. doipuiense/S. rufibasis, and S. weji previously reported from Thailand. The mitochondrial evidence for a distinct lineage in Taiwan is supported by chromosomal analysis, which revealed unique sex chromosomes. For nomenclatural stability, we associate the name S. arisanum Shiraki with the Taiwanese entity. Originally described from females from Taiwan, S. arisanum until now has remained an enigmatic species.
  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. 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.
  15. 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.
  16. 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.
  17. 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.
  18. Fulltext Delineating taxonomic boundaries in the largest species complex of black flies (Simuliidae) in the Oriental Region
    Low VL, Takaoka H, Pramual P, Adler PH, Ya'cob Z, Huang YT, et al.
    Sci Rep, 2016 Feb 03;6:20346.
    PMID: 26839292 DOI: 10.1038/srep20346
    Perspicuous assessments of taxonomic boundaries and discovery of cryptic taxa are of paramount importance in interpreting ecological and evolutionary phenomena among black flies (Simuliidae) and combating associated vector-borne diseases. Simulium tani Takaoka & Davies is the largest and perhaps the most taxonomically challenging species complex of black flies in the Oriental Region. We use a DNA sequence-based method to delineate currently recognized chromosomal and morphological taxa in the S. tani complex on the Southeast Asian mainland and Taiwan, while elucidating their phylogenetic relationships. A molecular approach using multiple genes, coupled with morphological and chromosomal data, supported recognition of cytoform K and morphoform 'b' as valid species; indicated that S. xuandei, cytoform L, and morphoform 'a' contain possible cryptic species; and suggested that cytoform B is in the early stages of reproductive isolation whereas lineage sorting is incomplete in cytoforms A, C, and G.
  19. Fulltext Description of male, pupa and larva of Simulium (Asiosimulium) wanchaii (Diptera: Simuliidae) from Thailand, with keys to identify four species of the subgenus Asiosimulium
    Srisuka W, Takaoka H, Saeung A
    Trop Biomed, 2015 Sep;32(3):504-10.
    PMID: 26695212 MyJurnal
    The male, pupa and mature larva of Simulium (Asiosimulium) wanchaii Takaoka & Choochote, one of the four species of the small Oriental black fly subgenus Asiosimulium, are described for the first time based on samples collected from Thailand. The male S. (A.) wanchaii is characterized based on the enlarged hind basitarsus and the ventral plate which is much wider than long. The pupa and larva are characterized by the gill with 19 filaments and the deep postgenal cleft, respectively. Keys are provided to identify all the four species of the subgenus Asiosimulium for females, males, pupae and mature larvae.
  20. Fulltext Female black flies of Simulium (Diptera: Simuliidae) collected on humans in Tam Dao National Park, Vietnam: description of a new species and notes on four species newly recorded from Vietnam
    Takaoka H, Sofian-Azirun M, Ya'cob Z, Chen CD, Lau KW, Pham HT
    Trop Biomed, 2014 Dec;31(4):742-8.
    PMID: 25776600 MyJurnal
    A total of 29 female black flies were captured by a hand net as they swarmed around humans in Tam Dao National Park, Vinh Phuc Province, Vietnam. They included one species of the subgenus Gomphostilbia (Simulium (Gomphostilbia) asakoae Takaoka & Davies) and five species of the subgenus Simulium, of which one species is described as Simulium (Simulium) vietnamense sp. nov. and the other four species (S. (S.) chungi Takaoka & Huang, S. (S.) grossifilum Takaoka & Davies, S. (S.) maenoi Takaoka & Choochote, and S. (S.) rufibasis Brunetti) are newly recorded from Vietnam.
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