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• First survey on wild adult black flies in Malaysia using malaise trap. • 14.7 % of black flies species in Malaysia were caught including a few unknown species. • Adult female of Simulium tanahrataense was discovered for the first time. • Adult S. pahangense was caught for first time after 20 years. Most studies on black flies focus on the taxonomy and ecology of their aquatic stages. Despite posing a public health threat, the adults remain poorly studied in many countries, including Malaysia. The present study represents the first investigation of the distribution of wild-caught black flies from various ecological landscapes and climatic conditions in Malaysia. CO 2 -baited Malaise traps were set randomly at 41 sampling sites across Peninsular Malaysia from 2020 to 2023. In total, 532 black flies belonging to 14 species of four subgenera were captured. To ensure taxonomic rigor, specimens were identified to species morphologically and molecularly. The subgenus Gomphostilbia was the most abundant (71.43 %), followed by Simulium (14.28 %) and Davieselleum and Nevermannia each representing 7.14 % of the total captures. These species represented 14.74 % of the total species recorded from Malaysia. The most frequently collected species were Simulium roslihashimi (24.39 %), followed by S. aureohirtum, S. vanluni , and S. (Gomphostilbia) sp. 1 with 7.32 % each. The highest relative abundance was found for S. vanluni (86.09 %) and S. roslihashimi (7.14 %). Most species were found at elevation below 300 m (78.57 %); fewer were at elevation higher than 1,000 m (21.43 %). Two principal components accounted for 85.3 % of the total intersite variance. Simulium roslihashimi was found at almost every site, with a maximum relative humidity of 90 %. Simulium aureohirtum and S. vanluni were found at sites with relative humidity up to 73 %, but S. aureohirtum was found at higher temperatures (31 °C) compared with S. roslihashimi (28 °C) and S. vanluni (29 °C). The present study establishes the groundwork for further studies of wild adults in Malaysia and identifies the need to use more traps over the range of seasons and environmental conditions, particularly near breeding sites. [ABSTRACT FROM AUTHOR]

• Genetic diversity of three human-biting black fly species was examined. • DNA barcoding sequences indicate cryptic diversity in these human-biting black flies. • New records for human-biting black fly species in Thailand were revealed based on DNA barcode. 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. [ABSTRACT FROM AUTHOR]

Abstract Simulium (Gomphostilbia) aziruni Takaoka, Hashim & Chen was described initially based only on a pupa and a mature larva collected from Peninsular Malaysia. Herein, we describe the morphological characters of the female of S. aziruni for the first time. It resembles those of the other members of the Simulium gombakense species-group by the genital fork with a distinct projection directed medioposteriorly from each arm and claw with a large basal tooth. Cytochrome c oxidase I (COI) barcoding analysis indicates that S. aziruni is the sister species of S. maleewongae , but both are distantly separated by a genetic distance of 4.9%. [ABSTRACT FROM AUTHOR]

Abstract A new species of black fly, Simulium (Simulium) luculentum , is described from specimens collected in Thailand, and is assigned to the Simulium variegatum species-group of the subgenus Simulium Latreille. This new species is distinguished from most members of this species group in the female by the mid femur and tibia entirely yellowish; and in the pupa by the gill with six filaments, which are somewhat inflated basally. This species represents the fifth member of the S. variegatum species-group recorded from Thailand. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A total of 404 black flies from Thailand were molecularly screened for Leucocytozoon. • Leucocytozoon was detected in approximately 10% of the examined black flies. • Most of Leucocytozoon found are genetically similar to those in domestic chickens. • Black flies are potentially vectors of Leucocytozoon in domestic chicken. Abstract Information regarding vector-parasite association is necessary for fully understanding the epidemiology of vector borne diseases yet, this information is lacking in the case of Leucocytozoonosis in the Oriental region, despite a high incidence of the disease. In this study, we used a molecular approach based on mitochondrial cytochrome b (cyt b) sequence to detect the parasite, Leucocytozoon , in potential black fly (Simuliidae) vectors in Thailand. A total of 404 wild caught black flies representing six morphological species of two subgenera were examined.- Gomphostilbia (Simulium asakoae complex, S. chumpornense) and Simulium (S. chamlongi , S. nodosum , S. nigrogilvum). Forty-four black fly specimens from two species of the Gomphostilbia were positive for Leucocytozoon. Most (35) of these were found in a village where high numbers of domestic chicken were kept, consistent with the possibility that chickens are a host of Leucocytozoon species found in black flies. Sixteen haplotypes were identified among 44 cyt b sequences. Comparisons of the sequences with previous reports revealed that the 11 haplotypes obtained in this study were identical or very similar to unknown Leucocytozoon found in infected domestic chickens. Four haplotypes are genetically similar to L. schoutedeni and one haplotype is genetically very different from existing cyt b sequences in public database. Our results indicate that two black fly species of the subgenus Gomphostilbia in Thailand are possible vectors of Leucocytozoon transmitted among poultry and wild birds in the country. [ABSTRACT FROM AUTHOR]

Abstract Simulium pumatense sp. nov. is described from Vietnam, and is placed in the Simulium feuerborni species-group of the subgenus Simulium (Nevermannia) Enderlein. Its morphological characteristics include the relatively smaller numbers of the following three numerical features: inner teeth of the female mandible (15–18), minute conical processes (16) on the female cibarium, and male upper-eye facets (in 15 vertical columns and 16 horizontal rows). Keys are constructed to distinguish this species from four species of the same group in Vietnam. Our molecular analysis of the DNA barcoding COI gene shows that this species is most closely related to cytoform A of the S. feuerborni complex from Thailand. [ABSTRACT FROM AUTHOR]

Simulium ( Simulium ) hackeri Edwards, 1928 of the Simulium variegatum species-group from Malaysia was described initially based on the female specimen from Cameron Highlands, Pahang. In the present study, the pupa and larva of this species are described for the first time. Their morphological characters resemble those of the Simulium variegatum species-group by having six gill filaments per side, abdomen with dorsal spine-combs at least on segments 7 and 8, cocoon with wall-pocket shaped and with or without an anterodorsal projection. Postgenal cleft of the larva medium-sized, rarely small, ventral papillae small or absent. The DNA barcode of this species is also reported herein. [ABSTRACT FROM AUTHOR]

Larvae and adults reared from pupae of Simulium ( Gomphostilbia ) gombakense Takaoka & Davies from eight streams in five provinces of Thailand were genetically analyzed by using cytochrome c oxidase subunit 1 sequences. The material was composed of four lineages, of which lineages 2, 3 and 4 are genetically closely related to one another, but more distantly related to lineage 1, which is equivalent to typical S . ( G .) gombakense from Peninsular Malaysia. Lineages 2, 3 and 4, which are morphologically indistinguishable, are designated as genoforms A, B and C within a species complex of S . ( G .) paiense sp. nov., which is described based on specimens of lineage 2 (=genoform A). Simulium ( G .) paiense sp. nov. is similar to S . ( G .) gombakense from Peninsular Malaysia but appears to be barely distinguished by the relative length of the female fore basitarsus. Simulium ( G .) thuathienense Takaoka & Sofian-Azirun is newly recorded from Thailand and its male is described for the first time. The female of S . ( G .) gombakense is briefly described based on females reared from pupae collected from Peninsular Malaysia. [ABSTRACT FROM AUTHOR]

Five new species of black flies, Simulium ( Gomphostilbia ) chiangraiense , S . ( G .) huaikaeoense, S . ( G .) khaokhoense, S . ( G .) maeklangense, and S . ( G .) pamiangense, are described based on adults, pupae and mature larvae from Thailand. These five species are similar to one another and are placed in the S. decuplum subgroup of the S. batoense species-group by having the male fore coxae darkened, ventral plate flat and transverse; pupal gill with 10 short filaments; and larval postgenal cleft deep approaching or reaching the posterior margin of the hypostoma. Simulium ( G .) chiangraiense sp. nov. and S . ( G .) pamiangense sp. nov. differ from the three other new species by the much longer pupal gill filaments and darkened dorsal surface of abdominal segments 1 and 2. Taxonomic notes are provided to distinguish these five new species from five other related species. The phylogenetic positions of these new species in the S. decuplum subgroup are presented based on the mitochondrial COI gene. Simulium ( G .) pamiangense sp. nov. and S . ( G .) huaikaeoense sp. nov. are highly similar to each other genetically, showing a sister relationship, though they are clearly different morphologically. On the contrary, S . ( G .) khaokhoense sp. nov. is distantly positioned from S . ( G .) huaikaeoense nov., though it is almost indistinguishable morphologically from the latter. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A new species of black fly, Simulium ( Gomphostilbia ) isanense, is described based on females, males, pupae and mature larvae from Thailand. This new species is placed in the Simulium epistum species-group of the subgenus Gomphostilbia Enderlein. It is characterized by the pupal gill with eight filaments arranged as 3 + 3 + 2 from dorsal to ventral, of which an inner filament of the ventral pair is slightly longer than its counter filament. Taxonomic notes are provided to distinguish this new species from S . ( G .) angulistylum Takaoka & Davies from Peninsular Malaysia, and three other related species. The difference between this new species and S . ( G .) angulistylum is supported by genetic distances using the mitochondrial COI gene. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Twenty-nine taxa of Simulium were identified amongst 527 collections of larvae and pupae from untreated rivers and streams in Liberia (362 collections in 1967–71 & 1989), Togo (125 in 1979–81), Benin (35 in 1979–81) and Ghana (5 in 1980–81). Presence or absence of associations between different taxa were used to group them into six clusters using Ward agglomerative hierarchical cluster analysis. Environmental data associated with the pre-imaginal habitats were then analysed in relation to the six clusters by one way ANOVA. The results revealed significant effects in determining the clusters of maximum river width (all P < 0.001 unless stated otherwise), water temperature, dry bulb air temperature, relative humidity, altitude, type of water (on a range from trickle to large river), water level, slope, current, vegetation, light conditions, discharge, length of breeding area, environs, terrain, river bed type (P < 0.01), and the supports to which the insects were attached (P < 0.01). When four non-significant contributors (wet bulb temperature, river features, height of waterfall and depth) were excluded and the reduced data-set analysed by principal components analysis (PCA), the first two principal components (PCs) accounted for 87% of the variance, with geographical features dominant in PC1 and hydrological characteristics in PC2. The analyses also revealed the ecological characteristics of each taxon’s pre-imaginal habitats, which are discussed with particular reference to members of the Simulium damnosum species complex, whose breeding site distributions were further analysed by canonical correspondence analysis (CCA), a method also applied to the data on non-vector species. [ABSTRACT FROM AUTHOR]

Uganda is the only country in sub-Saharan Africa whose onchocerciasis elimination programme extensively uses vector control and biannual treatment with ivermectin. The purpose of this study was to assess the impact of combined strategies on interrupting onchocerciasis transmission in the Kashoya-Kitomi focus. Mass Drug Administration annually (13 years) followed by biannual treatments (6 years) and ground larviciding (36 cycles in 3 years) with temephos (Abate ® , EC500) against Simulium neavei were conducted. Routine fly catches were conducted for over seven years in six catching sites and freshwater crabs Potamonautes aloysiisabaudiae were examined for immature stages of Simulium neavei . Epidemiological assessments by skin snip were performed in 2004 and 2013. Collection of dry blood spots (DBS) from children <10 years for IgG4 antibodies analysis were done in 2010 and 2013. Treatment coverage with ivermectin improved with introduction of biannual treatment strategy. Microfilaria prevalence reduced from 85% in 1991 to 62% in 2004; and to only 0.5% in 2013. Crab infestation reduced from 59% in 2007 to 0% in 2013 following ground larviciding. Comparison of total fly catches before and after ground larviciding revealed a drop from 5334 flies in 2007 to 0 flies in 2009. Serological assays conducted among 1,362 children in 2010 revealed 11 positive cases (0.8%; 95% CI: 0.4%–1.2%). However, assessment conducted on 3246 children in 2013 revealed five positives, giving point prevalence of 0.15%; 95% CI: 0.02%-0.28%. Four of the five children subjected to O-150 PCR proved negative. The data show that transmission of onchocerciasis has been interrupted based on national and WHO Guidelines of 2012 and 2016, respectively. [ABSTRACT FROM AUTHOR]

In recent decades, the numbers of cryptic taxa have increased significantly with current progress in DNA barcoding, yet, most of these cryptic taxa have not been formally named and recognized as valid species. To address this issue, we provide a guide for applying the procedure of describing new cryptic species in the family Simuliidae. Simulium ( Simulium ) vanluni from Pahang, Peninsular Malaysia, previously treated as S. nobile De Meijere, is described as a new species by using an integrated morpho-taxonomical and genetic approach. This new species is morphologically identical to S. nobile from Java and S. kiuliense Smart & Clifford from Borneo, but their distinctiveness is supported by an expanded multigene phylogeny analysis. [ABSTRACT FROM AUTHOR]

The simuliid fauna of the Oriental Region is reviewed in comparison with those in five other zoogeographical regions. It is relatively young, represented by only one genus Simulium , which is regarded as the most specialized among 26 genera of the family Simuliidae. The Oriental Region has the second largest simuliid fauna with 524 species or 23.8% of the world total of 2204 extant species. This species richness is associated with a high speciation index (15.4), reflected especially by the high speciation rates of two dominant subgenera Gomphostilbia and Simulium although the number of lineages in the Oriental Region is moderate (34 or 20.6% of the total 165). The Oriental fauna has relationships with all other zoogeographical regions at the lineage level, having the highest affinity index (31.9) with the Palearctic Region. It is inferred that eight of 10 Oriental subgenera moved during the ice ages from the Palaearctic to the Oriental Regions; the subgenus Gomphostilbia evolved into 11 species-groups and underwent species radiation in the Oriental Region. On the other hand, two other subgenera, Nevermannia and Simulium , moved southward during the ice ages after evolving into species-groups. In the post-ice ages, most lineages retreated northward, with different portions of species left in the Oriental Region, although some lineages failed to retreat and survived as relict lineages in the Oriental Region. [ABSTRACT FROM AUTHOR]

Black flies (Diptera: Simuliidae) are important insect vectors and pests of humans and animals. Accurate identification, therefore, is important for control and management. In this study, we used mitochondrial cytochrome oxidase I (COI) barcoding sequences to test the efficiency of species identification for the human-biting black flies in Thailand. We used human-biting specimens because they enabled us to link information with previous studies involving the immature stages. Three black fly taxa, Simulium nodosum , S. nigrogilvum and S. doipuiense complex, were collected. The S. doipuiense complex was confirmed for the first time as having human-biting habits. The COI sequences revealed considerable genetic diversity in all three species. Comparisons to a COI sequence library of black flies in Thailand and in a public database indicated a high efficiency for specimen identification for S. nodosum and S. nigrogilvum, but this method was not successful for the S. doipuiense complex. Phylogenetic analyses revealed two divergent lineages in the S. doipuiense complex. Human-biting specimens formed a separate clade from other members of this complex. The results are consistent with the Barcoding Index Number System (BINs) analysis that found six BINs in the S. doipuiense complex. Further taxonomic work is needed to clarify the species status of these human-biting specimens. [ABSTRACT FROM AUTHOR]

Onchocerciasis is a neglected parasitic disease affecting the poorest underserved people in Yemen. A national control programme with goals to eliminate onchocerciasis has yet to be launched due to the current upheaval and social unrest in the country. The disease, locally termed as sowda, is unique in its clinicopathologic pattern, being of the localized, non-blinding, hyperreactive onchocercal skin disease. Although early reports identified endemic foci along seasonal watercourses, there is a need to redefine its epidemiologic patterns as well as health and socioeconomic impacts. Laboratory diagnosis of sowda among Yemeni patients is difficult due to the low load of microfilariae in skin snips and the presence of asymptomatic itching-free microfilaria carriers. Adoption of ivermectin use at three-month intervals as a control strategy has not been evaluated because the drug is mostly used in clinics and distributed to only a few affected communities. This paper addresses key aspects of onchocerciasis in Yemen and highlights the need for screening at-risk populations using highly sensitive techniques and mapping the distributions of the parasite in human and vector populations of blackflies. The new research should be integrated with the launch of a national onchocerciasis control programme to achieve onchocerciasis elimination. [ABSTRACT FROM AUTHOR]

To investigate the breeding habitat preference of black flies, a comprehensive black fly survey was conducted for the first time in Peninsular Malaysia. Preimaginal black flies (pupae and larvae) were collected manually from 180 stream points encompassing northern, southern, central and east coast of the Peninsular Malaysia. A total of 47 black fly species were recorded in this study. The predominant species were Simulium trangense (36.7%) and Simulium angulistylum (33.3%). Relatively common species were Simulium cheongi (29.4%), Simulium tani (25.6%), Simulium nobile (16.2%), Simulium sheilae (14.5%) and Simulium bishopi (10.6%). Principal Component Analysis (PCA) of all stream variables revealed four PCs that accounted for 69.3% of the total intersite variance. Regression analysis revealed that high species richness is associated with larger, deeper, faster and higher discharge streams with larger streambed particles, more riparian vegetation and low pH ( F = 22.7, d.f. = 1, 173; P < 0.001). Relationship between species occurrence of seven common species (present in >10% of the sampling sites) was assessed. Forward logistic regression analysis indicated that four species were significantly related to the stream variables. S . nobile and S. tani prefer large, fast flowing streams with higher pH, large streambed particles and riparian trees. S . bishopi was commonly found at high elevation with cooler stream, low conductivity, higher conductivity and more riparian trees. In contrast, S. sheilae was negatively correlated with PC-2, thus, this species commonly found at low elevation, warmer stream with low conductivity and less riparian trees. The results of this study are consistent with previous studies from other geographic regions, which indicated that both physical and chemical stream conditions are the key factors for black fly ecology. [ABSTRACT FROM AUTHOR]

Simulium ( Simulium ) rasuli sp. nov. is described from two females collected by a Malaise trap in Genting Highlands, Peninsular Malaysia. This new species is placed in the Simulium christophersi species-group of the subgenus Simulium . The female of this new specie is characterized by the scutum with three longitudinal vittae, dark legs, claw with a small subbasal tooth, and ovipositor valve triangular with its inner margin nearly straight. This new species is distinguished in the female from all the six named species of the species-group by the entirely brownish-black femora and tibiae. [ABSTRACT FROM AUTHOR]

Simulium ( Chirostilbia ) vitribasi n. sp. from the Mantiqueira mountain range, in São Paulo and Minas Gerais states, southeastern Brazil, is described and illustrated based on male, female, pupal and larval morphologies. The pupae of the new species is similar to the one of Simulium pertinax Kollar, one of the most voracious black fly species in the South and Southeast regions of Brazil and a target of control programs in these regions. But the pupa of the new species has a large basal fenestra in the gills that distinguishes it from all other S . ( Chirostilibia ) species. The other life stages of the new species also have morphological characters that distinguish it from the other species in the subgenus: male has scutum black, with patches of thick, golden hairs; female has scutum similar to that of the male, without banding or other markers, abdominal tergites I and II whitish and sternite VIII dark, heavily sclerotized; anal lobe almost as wide as long, with thin, long hairs on its outer margin; larva body cuticle has wide scale-like setae, with lobulated distal margins. Females were not observed biting humans during the fieldwork. [ABSTRACT FROM AUTHOR]

Two new species of Simulium ( Gomphostilbia ) (Diptera: Simuliidae) are described on the basis of reared adult, pupal and larval specimens collected from Southern Western Ghats India. The morphological data of two new species S . ( Gomphostilbia ) panagudiense sp. n. and S . ( Gomphostilbia ) kottoorense sp. n. are assigned to the batoense species group in the subgenus Gomphostilbia. S . ( Gomphostilbia ) panagudiense sp.n. is characterized in the female by having the scutum without longitudinal vitta and arms of the genital fork wide basally and in the pupa by the stalk of ventral pair medium-long. S. ( Gomphostilbia ) kottoorense sp.n. is characterized by the arm of genital fork tapered near apex in the female and style in medial view 0.63 times as long as coxite in the male. Phylogeny of members in the genus Simulium was reconstructed based on DNA barcoding gene ( cytochrome oxidase c subunit I). Tree analysis using new technology and maximum likelihood analyses are congruent with evidence of two new species in the subgenus Gomphostilbia and separated from other species. [ABSTRACT FROM AUTHOR]

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 2100 m, 2000 m, 1500 m, 1400 m, 700 m, and 500 m 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. [ABSTRACT FROM AUTHOR]

Highlights: [•] First evidence that Simulium guianense DNA escapes the effects of concerted evolution. [•] New ribosomal DNA barcoding tool for the onchocerciasis vector Simulium guianense. [•] New ribosomal mitochondrial barcoding tool for Simulium guianense. [•] Important Insights into the biology and evolution of Simulium guianense. [•] Important Insights for development of further subspecies Simulium guianense identification tools. [ABSTRACT FROM AUTHOR]

• Nine of 42 simuliid species in Malaysia were parasitized by mermithid nematodes. • The number of mermithids per simuliid host larva was 1–3, with a mean of 1.10. • Mermithid distributions were patchy among simuliid hosts and streams. • Parasitism was significantly associated with environmental factors, e.g. temperature. • Patchy parasite distributions suggest strong host–parasite–environment interactions. Mermithids are parasites of black flies that cause host mortality along with physical and behavioural changes in infected hosts. However, there is a lack of knowledge on the distribution of mermithids infecting black fly larvae and the factors that influence these distributions in Asia, including Malaysia. A total of 13,116 mid- to late-instar black fly larvae belonging to 42 species were collected from 138 streams across East and West Malaysia and screened for the presence of mermithid parasites. Overall, 121 mermithids were obtained from 107 (0.82%) larvae of nine (21.4%) black fly species. The average number of mermithids per black fly host was 1.10 ± 0.04 (SE), ranging from one to three mermithids per host. Mermithid infection was highest in Simulium trangense , with a frequency of occurrence of 6.5%, followed by S. cheongi (5.8%) and S. angulistylum complex (2.9%). Infection was lowest in S. brevipar and S. tahanense , with a frequency of occurrence of 0.7% each. Regression analysis indicated that mermithid infections in larval black flies were significantly associated with cooler and shallower streams with more canopy cover, dense riparian vegetation, high dissolved oxygen, and lower conductivity and complete pH. Forward logistic regression further indicated that infections in S. cheongi were associated with shaded, cooler, slightly acidic streams with higher conductivity and dissolved oxygen. These findings suggest that mermithid infections in larval black flies in Malaysia are not randomly distributed and are influenced by the breeding habitat of their hosts. [ABSTRACT FROM AUTHOR]

• Simulium (Gomphostilbia) mokroense is described from Western Thailand. • It is the 30th species of the S. asakoae species-group recorded from Thailand. • The color of the tuft hairs at the base of the radius is the diagnostic character. Adult females and males reared from pupae of Simulium sp. from Tak Province and those of S. chiangdaoense Takaoka & Srisuka from four localities in Chiang Mai and Lampang Provinces, northern Thailand, were molecularly and morphologically compared. Simulium sp. is morphologically almost indistinguishable from S. chiangdaoense except the hair tuft at the base of the radius of the adult female and male, which is composed of yellow and dark hairs (in place of yellow hairs only). Molecular analysis using COI gene sequences shows that S. sp. formed a distinct clade and was separated from S. chiangdaoense by a genetic distance of 1.56–2.44%. Based on the results of morphological and molecular analyzes, S. sp. is described as a new species, S. mokroense , from females, males, pupae and mature larvae. It is also found that S. chiangdaoense is genetically diverse, with five lineages, and is morphologically variable in the number of male upper-eye (large) facets, which are in 13 to 17 vertical columns and 14 to 17 horizontal rows on each side. This is a first case, in which the difference in the color of the wing tuft hairs is a clue leading to the discovery of a new cryptic species close to S. chiangdaoense. [ABSTRACT FROM AUTHOR]

Highlights: [•] CO1 barcodes for Simulium limbatum and Simulium incrustatum. [•] Novel ecotypes recorded. [•] Implications for onchocerciasis. [Copyright &y& Elsevier]

Abstract: The Itwara focus of onchocerciasis covers an area of approximately 600km2 in western Uganda about 20km north of Fort Portal. The vector is Simulium neavei, whose larvae and pupae live in a phoretic association on freshwater crabs. The phoretic host in the Itwara focus is the crab Potamonautes aloysiisabaudiae. Before any onchocerciasis control, ATPs were estimated to reach between 4500 and 6500 infective larvae per person per year. S. neavei was found to be a very efficient vector with 40% of parous flies harbouring developing larvae of Onchocerca volvulus. After 4 years of community-based distribution of ivermectin transmission was still considerable and in 1995 monthly treatment of streams with the larvicide temephos commenced in the first of three sub-foci, and was gradually extended to the whole focus. Biting S. neavei disappeared from the first sub-focus (Itwara main) in June 1996, and the last infested crab was caught in November 1996. In the second sub-focus (Siisa) treatment commenced towards the end of 1995, and the last biting fly was caught in March 1997, but a deterioration in the security situation interrupted the programme (after only three treatments in the third sub-focus). Monthly treatments restarted in the second and third sub-foci (Aswa) in September 1998, and when the situation was reassessed in 2003 no biting flies were found anywhere, and the flies had not reinvaded the first sub-focus, but infected crabs were found in the second and third sub-foci. The last treatments were carried out in April–June 2003, and since then no infested crabs have been found. In summary, no S. neavei-infested crabs have been found anywhere in the focus since June 2003 and the vector is considered eliminated from that date. However, transmission had already been halted since February 2001, when the last biting flies had been collected. The parasite reservoir should die out in the human population by 2016. [Copyright &y& Elsevier]

Abstract: Although it is now well established that in the Amazonian onchocerciasis focus, straddling between Venezuela and Brazil, the main vectors in the highland (hyperendemic) and lowland (hypoendemic) areas, are respectively Simulium guianense sensu lato Wise and S. oyapockense s.l. Floch and Abonnenc, investigation of the vectorial role of a third anthropophagic species, Simulium incrustatum Lutz has remained inconclusive. Here we compare the vector competence of S. incrustatum with that of S. oyapockense s.l. by conducting, in the Venezuelan part of the focus, a series of feeding experiments designed to analyze their relative: (a) microfilarial intakes when fed upon the same skin load; (b) proportions of microfilariae (mf) surviving damage inflicted by the cibarial armature (present in both species); and (c) infective (L3) larval outputs. Although the ability of S. oyapockense s.l. to ingest mf, for a given microfilaridermia, was markedly higher than that of S. incrustatum, the (density-dependent) proportions of those ingested mf that were damaged by the armature were also consistently higher, with the resulting output of L3 larvae being significantly lower in S. oyapockense s.l. than in S. incrustatum. These results indicate that S. incrustatum plays a more important role in onchocerciasis transmission in the Amazonian focus than previously realized. We discuss the implications of our findings for the control and elimination of onchocerciasis with mass administration of ivermectin in this focus, where the three main anthropophagic species often co-occur. [Copyright &y& Elsevier]

Abstract: Although Simulium exiguum Roubaud s.l. is present in all South American onchocerciasis foci, it is a significant vector only in Colombia and Ecuador. This variable vectorial role has been attributed to sibling forms that differ in their ability to allow Onchocerca volvulus larval development and their preferred bloodmeal hosts. Here we evaluate the relationship between parasite availability in human skin and infective larval output measured as (a) number of L3 larvae and (b) proportion of surviving flies with L3s in the Cayapa form of S. exiguum s.l. from Ecuador, taking into account the variation in counts of microfilariae (mf) from 6skin snips/patient. Comparisons with other cytoforms (Aguarico, Bucay and Quevedo, absent in the main Ecuadorean onchocerciasis foci) are made to suggest the relative roles of intrinsic susceptibility or co-adaptation versus density-dependent parasite uptake. A nonlinear (limitation) relationship, characterised by an initial rapid increase in infective larvae with increasing mf skin density was confirmed for the Cayapa cytoform. The proportion of infective Cayapa flies increased and saturated rapidly (reaching 80% for ≥ 20mf/mg skin). After adjusting for density dependence, non-Cayapa cytoforms exhibited significantly lower L3 loads and proportions of infective flies for a given mf skin density than Cayapa flies, indicating that the susceptibility of those cytoforms is intrinsically lower than that of the Cayapa cytoform and that the differences observed are not due to density-dependent effects. [Copyright &y& Elsevier]