Species Of Simulium Research Articles

Evaluation of <i>Onchocerca volvulus</i> infectivity status of black flies in post-ivermectin regime in Kachia, Kaduna State, Nigeria

The infectivity status of Simulium species is an important factor in assessing the transmission of Onchocerca species. In this study, we determined the biting rate and presence of the larval stage of the parasite to determine the status of onchocerciasis in the post-ivermectin era in the study area. A total of 1.063 black flies were collected in September and October 2023. Dissection was carried out under a microscope to examine the internal organs for the presence of microfilaria and record their condition. The findings indicated that parous flies 311(29.3%) were markedly less prevalent compared to nulliparous flies 752(70.7%). Among the dissected flies, a total of 14 (1.3%) were found to be infected with Onchocerca species. The flies exhibited a bimodal biting pattern, with a peak in the morning occurring between 9 and 10 am and afternoon between 4:00 and 5:00 pm. The monthly biting rates of 5177.0 and 5807.3 in September and October respectively exceeded the World Health Organization's threshold of 1,000 bites per person per month. It is essential to investigate the potential resurgence of onchocerciasis in the study area, which may be attributed to the overlapping presence of cattle, Simulium vectors, and humans.

Repellent activity of Vitex negundo and Curcuma longa herbal extract against Simulium species in India.

At present, use of synthetic pesticides to manage insects and other arthropods creates a number of issues that are related to the environment and public health. The goal of the present study is to find repellent activity of Vitex negundo and Curcuma longa herbal extracts against the wild species Simulium (blackfly) bite. We have studied Simulium biting behavior and tested the repellency of herbal extract obtained from Vitex negundo L. (Lamiales: Lamiaceae) and Curcuma longa L. (Zingiberal: Zingiberaceae) along with their essential oils in three locations in Arunachal Pradesh, India on human volunteers' resistance to Simulium (blackflies). The reported herbal extracts were incorporated to topical drug delivery vehicle as a cream and gel. The methanolic extract of Vitex negundo cream and gel formulation showed >2 h safety at 5% concentration and >5 h safety at 10% concentration in all the testing sites followed by ethyl acetate extract. Whereas, chloroform extract of Curcuma longa cream and gel formulation provided >1 h safety at 5% concentration and >4 h safety at 10% concentration. At an optimum concentration of 10%, the methanolic extract of Vitex negundo cream provided complete protection times (CPTs) 320.4, 358.6, and 346.4 min, respectively. These findings offer confirmation of the methanolic extract and chloroform extract potential for use in new blackfly repellents.

A new species of Simulium (Asiosimulium) (Diptera: Simuliidae) from northeastern Thailand, with its phylogenetic relationships with related species in the subgenus Asiosimulium.

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.

From bites to barcodes: uncovering the hidden diversity of black flies (Diptera: Simuliidae) in Vietnam

BackgroundPrompt and precise identification of black flies (Simuliidae) is crucial, given their biting behaviour and significant impact on human and animal health. To address the challenges presented by morphology and chromosomes in black fly taxonomy, along with the limited availability of molecular data pertaining to the black fly fauna in Vietnam, this study employed DNA-based approaches. Specifically, we used mitochondrial and nuclear-encoded genes to distinguish nominal species of black flies in Vietnam.MethodsIn this study, 135 mitochondrial cytochrome c oxidase subunit I (COI) sequences were established for 45 species in the genus Simulium in Vietnam, encompassing three subgenera (Gomphostilbia, Nevermannia, and Simulium), with 64 paratypes of 27 species and 16 topotypes of six species. Of these COI sequences, 71, representing 27 species, are reported for the first time.ResultsCombined with GenBank sequences of specimens from Malaysia, Myanmar, Thailand, and Vietnam, a total of 234 DNA barcodes of 53 nominal species resulted in a 71% success rate for species identification. Species from the non-monophyletic Simulium asakoae, S. feuerborni, S. multistriatum, S. striatum, S. tuberosum, and S. variegatum species groups were associated with ambiguous or incorrect identifications. Pairwise distances, phylogenetics, and species delimitation analyses revealed a high level of cryptic diversity, with discovery of 15 cryptic taxa. The current study also revealed the limited utility of a fast-evolving nuclear gene, big zinc finger (BZF), in discriminating closely related, morphologically similar nominal species of the S. asakoae species group.ConclusionThis study represents the first comprehensive molecular genetic analysis of the black fly fauna in Vietnam to our knowledge, providing a foundation for future research. DNA barcoding exhibits varying levels of differentiating efficiency across species groups but is valuable in the discovery of cryptic diversity.Graphical abstract

Autoimmune disorders in horses: the role of Insect Bite Hypersensitivity

Autoimmune disorders are exaggerated immunologic responses to harmless antigens. The incidences of these conditions in animals specifically horses are on the increase. Autoimmune skin disorders of horses such as multi-systemic eosinophilic epitheliotrophic disease (MEED) and Pemphigus foliaceus (PF) are triggered by insect bite hypersensitivity principally due to Culicoides and Simulium species respectively. Other relatively uncommon skin disorders of horses include pemphigus vulgaris, cutaneous lupus erythematosus, bullous pemphigoid, systemic lupus erythematosus, and erythema multiforme. The roles of risk factors such as autoantibodies and changes associated with age in the immune system of equines such as immunosenescence and inflamm-aging, and the diagnosis, treatment, and management of some major autoimmune diseases of horses are discussed in this review. Additionally, we reviewed recent information on autoimmune thrombocytopenia in equines

Testing the susceptibility of larval stages of Simulium to temephos and Bacillus thuringiensis var israelensis in Germany and Northern Cameroon.

Assays to evaluate the susceptibility of Simulium larvae to temephos and Bacillus thuringiensis var israelensis (Bti) were carried out by setting-up an in vitro laboratory test ('bio assay') and a semi-natural test ('système de goutières') to assess the LC50/LC90 values. Larvae of Simulium species in Cameroon (S. damnosum s.l., S. hargreavesi, S. vorax and S. cervicornutum) and (S. (Odagmia) ornatum and S. latipes) in Germany were identified and tested. In the bio-assay, 50 larvae were exposed for 10min to concentrations from 0.01 to 10ppm. For the Simulium from Germany, the LC50 (LC90) values after 3 and 6h were 3.1 (27.9) and 0.14 (1.26) ppm for temephos and for Bti 7.8 (70.2) and 1.7 (15.3) ppm, respectively. For Cameroonian species, the values of LC50 (LC90) were lower, that is, 0.42 (8.04), 0.14 (2.70) and 0.073 (1.38) ppm, respectively, after 3, 6 and 12 h for temephos. In a semi natural condition, the LC50 of 10min of application of temephos was 0.84 ppm after 3h and a working solution (2.6 L) of Bti killed 50% after 6h. To detect an upcoming of any resistance as it happened in Ivory Coast, a study of the occurrence resistance genes should be implemented.

Chromosomes as Barcodes: Discovery of a New Species of Black Fly (Diptera: Simuliidae) from California, USA.

Simple SummaryThe discovery and elucidation of species, especially those that are structurally similar, often require special tools and approaches. The basic principle of a unique barcode, as used in retail stores and more recently as DNA sequences in taxonomy, is also inherent in the giant banded chromosomes of flies (Diptera). We used the sequence of chromosome bands—the barcode—in the discovery of a new species of black fly from California, USA. The chromosomal barcode indicates this species is unique among all others in the Simulium (Boreosimulium) annulus group to which it belongs. To provide an integrated taxonomic approach, we analyzed and described the larvae, pupae, males, and females of this new species and assigned the formal name Simulium ustulatum n. sp. We also provided a traditional DNA barcode using the cytochrome c oxidase I (COI) gene. The new species has the most rearranged chromosomes of all North American members of its species group and differs most conspicuously by having a large chromocenter from which all six chromosome arms radiate. The species is structurally unique in the larva and male. The COI barcode enables identification of the female and pupa, which are structurally similar to other species in the group. The new species is the only western North American member of the Simulium annulus group that inhabits low-elevation, disturbed landscapes.One of the most popular tools for species discovery and resolution is the DNA barcode, typically based on the cytochrome c oxidase I (COI) gene. However, other non-genic barcodes are available for Diptera. The banding sequence of polytene chromosomes in some dipteran cells, particularly of the larval silk glands, can provide a unique species barcode. We used the sequence of bands to reveal a new species of black fly in the Simulium (Boreosimulium) annulus species group from California, USA. To further characterize the species and provide more integrated taxonomy, we morphologically described all life stages above the egg, formally named the species Simulium ustulatum n. sp., and provided a conventional COI barcode. The COI barcode confirmed the chromosomal and morphological evidence that the species is a new member of the S. annulus group, and enabled identification of the larva and female, which are structurally similar to those of other species. The chromosomal barcode shows that this species has the most rearranged complement, compared with the eight other North American members of its species group, with up to 12 times the number of fixed rearrangements. Up to six chromosomal rearrangements, including autosomal polymorphisms and sex-linked phenomena, are shared with other members of the group. The most unique and conspicuous chromosomal feature of this new species is a large, pale-staining chromocenter from which the six chromosomal arms radiate. The distribution of this univoltine species in lowland rivers of California’s Central Valley could make it vulnerable, given climate change and increasing land development.

A checklist of black flies (Diptera, Simuliidae) from India.

An updated checklist of the family Simuliidae from India is presented. A total of 79 species of Simulium belonging to eight different subgenera are listed. Eleven species that were not reported in the previous checklist are added here. The present list contributes to a better understanding of the diversity of Simuliidae in India, as well as the impact of Simulium species on the public health of this mega-diverse country.

Molecular genetics of Simulium (Wilhelmia) equinum (Linnaeus) (Diptera: Simuliidae) from West Siberia.

The medico-parasitological importance of bloodsucking black flies is high. To assess potential epidemiological risks and develop biological control programs for these bloodsucking Diptera, it is necessary to be informed of their diversity, community structure and the most common and dominant species. The degree of homogeneity of molecular genetic characteristics of one of the most widespread black fly species Simulium (W.) equinum (Linnaeus) in different parts of its range was investigated. The features of S. equinum from West Siberia where the species has become an abundant ecosystem component in recent years have been revealed. Analysis of species-diagnostic DNA-fragments (COI, ITS2 and D2 28S) in the specimens studied from this region, from the Novosibirsk Oblast (Russia) and data from the DNA database revealed four distinct branches tentatively referred to as West-European, East-European, Finland-Turkish, and Novosibirsk. Specimens from the Novosibirsk Branch were closer to the Finland-Turkish branch. We simulated restriction patterns of the standard COI fragment for all the branches. Substantial level of differences among the branches (4.114.8 % by COI sequences) raised the issue of their species status. A further study of S. equinum from West Siberia may clarify the ecological and medico-parasitological features of the Novosibirsk Branch of the species.

The Palearctic blackfly Simulium equinum (Diptera: Simuliidae) as a biting pest of captive nyala antelopes (Tragelaphus angasii).

Blackflies (Diptera: Simuliidae) are cosmopolitan nuisance pests of great economic importance as well as vectors of many pathogens. After reports of massive blackfly biting of captive nyala antelopes in the Vienna Zoo, Austria, this study aimed to identify the species causing multiple skin lesions on the antelope hosts. The Palearctic species Simulium equinum, belonging to the medically and veterinary important Wilhelmia subgenus, was identified as the most likely causative agent. Barcoding and maximum likelihood analysis supported morphological species identification and highlighted the complex phylogeny of the subgenus Wilhelmia. Our study gives first evidence of the multi-host feeding blackfly S. equinum in the Vienna Zoo, thereby raising the question whether other hosts could also be bitten on a regular basis. The preliminary results urge for further analysis of blackfly breeding sites as well as the clarification of the host spectrum to assess the medical and veterinary importance of blackflies in the Zoo.

Chironomids are commensals of the larvae and pupae of Blephariceridae and Simuliidae from the North Caucasus (Diptera: Chironomidae: Orthocladiinae)

Illustrated morphological descriptions of chironomid larvae from subfamily Orthocladiinae Cardiocladius sp. 1, which as commensals live between ventral suckers of Blephariceridae larvae, as well as larvae and pupae of Eukiefferiella claripennis group inhabited of Simuliidae pupal cocoons, are given. DNA barcodes of these chironomid species and sequences of their hosts, three species of Liponeura Loew (Blephariceridae) and one species of Simulium aff. variegatum (Simuliidae), are provided.

Contribution to the knowledge on black flies (Diptera: Simuliidae) as vectors of Leucocytozoon (Haemosporida) parasites in Lithuania.

Black flies (Diptera: Simuliidae) are among the most bothersome blood-sucking dipterans causing severe irritation and distress to poultry, wild birds, animals, and humans globally. These insects are vectors of viruses, bacteria, parasitic protozoans, and nematodes of humans and animals. Parasitic protozoa belonging to Haemosporida (Apicomplexa) are distributed worldwide and black flies are the principal vectors of avian haemosporidian parasites of the genus Leucocytozoon, a common parasite of birds. Based on the detection of parasite DNA in insects, 13 black fly species were reported to be potential vectors of Leucocytozoon in Europe. Information about which species of Simulium can play a role in the transmission of Leucocytozoon parasites is insufficient and needs to be developed. The aim of our study was to determine which black fly species are involved in the transmission of Leucocytozoon parasites in the Eastern Europe. The black fly females were collected in Lithuania using entomological net. They were morphologically identified, dissected to prepare salivary glands preparations, and then screened for the presence of Leucocytozoon parasites using microscopy and PCR-based methods. In all, we collected 437 black fly females belonging to eight species. The DNA of Leucocytozoon (genetic lineage lCOCO18) was detected in one of analysed females identified as Simulium maculatum. All salivary gland preparations were negative for the presence of Leucocytozoon sporozoites. Our results included S. maculatum as a potential vector of Leucocytozoon parasites. Increasing the knowledge on vector ecology, behaviour and improving collection methods may be the key to understand the evolution and diversity of these parasites.

Molecular detection of Mansonella mariae incriminates Simulium oyapockense as a potentially important bridge vector for Amazon-region zoonoses.

To assess the emergent zoonotic disease risk posed by the voracious human-biting blackfly species Simulium oyapockense in the peripheral regions of an expanding urban centre situated deep in the Brazilian Amazon rainforest. We performed nine human landing catches at three periurban sites surrounding the Brazilian Amazon town of São Gabriel da Cachoeira. Using the detection of non-human primate filarial parasites as an indicator of the zoonotic disease threat posed by a biting insect, we screened 3328S. oyapockense blackflies for the presence of zoonotic filarial DNA with an ITS-1 PCR assay and Sanger sequencing. Between 98 and 100% of the biting insects captured during our nine collections were identified as S. oyapockense; at our three collection sites and during our three seasonally-distinct collections this species was captured at rates between 28 and 294 blackflies per hour. PCR screening of the march-collected S. oyapockense detected infectious-stage (L3) Mansonella mariae parasites (which are only known to infect non-human primates) in >0.15% of the tested head samples. Our results show that residents of the periurban regions of São Gabriel da Cachoeira are routinely exposed to the bites of S. oyapockense blackflies which have previously fed on non-human primates.

Blackflies (Simulium spp.) attacks on humans and animals in Rome and surrounding areas (Central Italy).

Due to their abundance in some environments, the blood-sucking habit and the involvement in the transmission of several diseases, blackflies of the genus Simulium (Diptera: Simuliidae) can be considered among the most annoying biting arthropods. Following repeated attacks to humans and animals, entomological investigations were carried out in green areas of Rome and surroundings. Site and period of attacks were reported, together with the human and animal reactions to the bites. Four Simulium species have been identified through morphological or molecular analysis: Simulium intermedium, Simulium lineatum, Simulium lundstromi and Simulium ornatum (complex). Larval breeding sites were identified in small moats, where a high density of blackflies larvae and pupae was revealed. Being able to thrive in highly polluted water, even in few mm depth watercourses, some blackfly species are widely distributed in the area and their bites caused mild to severe reactions to humans and animals.

Potential phenotypic plasticity within Simulium nigrimanum Macquart, 1838 (Diptera: Simuliidae) larvae

Black fly larvae (Diptera: Simuliidae) are suspension filter-feeders which strongly depend on water velocity for proper feeding. Black fly species feature different microhabitat preferences. Studies of Holarctic black fly larvae revealed their phenotypic plasticity in response to water current velocity variation, but such studies have been rarely undertaken with Neotropical black flies. The current work presents results on the phenotypic plasticity of the black fly species Simulium nigrimanum Macquart. Twelve last instar larvae, sampled from the Brazilian Cerrado, were photographed under a stereoscopic microscope and measured using the CMEIAS Image tool software. Linear regressions with water velocity as the independent variable were performed, indicating that while body size and anal disk diameter correlated positively with water velocity, labral fan length correlated negatively. The observed relationships between water velocity and labral fan length and anal disk diameter were consistent with the literature, while the pattern of body size variation partially corroborated previous studies. The present work results suggest that potential phenotypic plasticity can be observed in black fly larvae within one population distributed in different microhabitats of the same stream section, as opposed toprevious reports implying that such variation is only found among population from different streams.

A new species and four newly recorded species of black flies (Diptera: Simuliidae) from Bhutan.

Simulium (Simulium) thimphuense sp. nov. is described from a pupa and a mature larva in Bhutan. This new species is placed in the S. multistriatum species-group, and is characterized by the pupal gill with eight thread-like filaments divergent basally at an acute angle when viewed laterally and the cocoon slipper-shaped with several small openings anterolaterally. Four species of Simulium (Simulium) are newly recorded from Bhutan: S. barraudi Puri in the S. multistriatum species-group, S. nodosum Puri in the S. nobile species-group, S. chiangmaiense Takaoka & Suzuki in the S. striatum species-group and S. himalayense Puri in the S. variegatum species-group. Our study increases the number of black fly species known from Bhutan from 18 to 23.

A new species of Simulium (Gomphostilbia) (Diptera: Simuliidae) from Northern Thailand, with its genetic relationship in the S. asakoae species-group

A new black fly species, Simulium (Gomphostilbia) kiewlomense, is described from females, males, pupae and mature larvae in Thailand. This new species is placed in the S. asakoae species-group and is characterized by having a combination of the elongate female sensory vesicle, widened male hind basitarsus, which is much wider than the hind femur, small pupal terminal hooks, and light greenish larval abdominal segments 1–3. Taxonomic notes are given to separate this new species from other related species. A DNA analysis using the COI gene shows that this new species has two genoforms with 1.21% difference. This is the 28th species of the S. asakoae species-group in Thailand, strengthening the evidence for high species diversity of this species-group.

Black flies (Diptera: Simuliidae) of the Aras River Basin: Species composition and floral visitation

Black flies are insects of medical, veterinary, and environmental significance. Historically, they have attacked humans and caused simuliotoxicosis in livestock in the Aras River Basin in northwest Iran. However, information on the species and their bionomics is limited in the region. Adult flies were collected from diverse ecotopes of the Aras River Basin. After morphological identification, representative specimens of each morphological group were subjected to mtDNA COI gene sequence analysis for species diagnosis and to infer relationships. Flies also were examined for pollinia. A total of 1880 specimens representing 12 morphotaxa in two genera (Simulium and Metacnephia) were identified: Simulium turgaicum (n=1834), S. kiritshenkoi (n=12), S. bezzii (n=7), S. brevitarse (n=7), S. pseudequinum (n=5), S. aureum species group (n=4), S. vernum species group (n=3), S. transcaspicum (n=1), three unidentified species of the subgenus Simulium (n=5), and Metacnephia possibly persica (n=2). Fifty two haplotypes were detected for the 65 COI sequences analyzed. Intraspecific genetic divergence was 0.19-8.83%, whereas the mean interspecific genetic distances among the morphotaxa were 1.41-19.58%. Molecular analyses recovered three well-supported lineages within S. turgaicum. One lineage included black flies collected from agricultural fields, a second lineage involved black flies captured from animals, and a third lineage included specimens that had visited flowers, as evidenced by presence of pollinia. The relative abundance (97%) and observations of the S. turgaicum complex biting humans are important epidemiological factors. Future studies are needed to define the potential epidemiological risk of simulids in Khoda-Afarin County of Iran.

Biting rates and relative abundance of Simulium flies under different climatic conditions in an onchocerciasis endemic community in Ghana

BackgroundKnowledge of the relative abundance and biting rates of riverine blackflies (vectors of onchocerciasis) is essential as these entomological indices affect transmission of the disease. However, transmission patterns vary from one ecological zone to another and this may be due to differences in species of blackfly vectors and the climatic conditions in the area. This study investigated the effects of climate variability on the relative abundance and biting rates of blackflies in the Tanfiano community (Nkoranza North District, Bono East Region, Ghana). Such information will help to direct policy on effective timing of the annual mass drug administration of ivermectin in the area.MethodsThe study employed human landing collections and locally built Esperanza window traps to collect blackflies from March 2018 to February 2019. The relative abundance and biting rates of the Simulium vectors as well as the monthly climatic conditions of the study area were monitored. Correlation analysis and Poisson regression were used to establish the relationships between the variables.ResultsThe relative abundance and biting rates of the Simulium vectors were highest in the drier months of March, April and August, characterized by high temperatures, low humidity, longer hours of sunshine and stronger winds. The rainy months of May, June and July, characterized by low temperatures, high humidity, few hours of sunshine and weaker winds, had relatively low blackfly abundance and biting activity. Correlation analysis showed that only temperature was significantly, positively correlated with the relative abundance of blackflies (r = 0.617, n = 12, P = 0.033) and monthly biting rates (r = 0.612, n = 12, P = 0.034). A model to predict relative abundance and monthly biting rates using climatological variables was developed.ConclusionsThis study demonstrated that Simulium species in the study area preferred higher temperature, lower humidity and rainfall, more hours of sunshine and relatively stronger winds for survival. It is thus recommended that for the study district and others with similar climatological characteristics, mass drug administration of ivermectin should take place in April and September when the abundance of vectors has begun to decline after peaking.

Ecology of black flies (Diptera: Simuliidae) in streams of northern and southern Thailand: Factors associated with larval and pupal distributions

The ecology of black flies in Thailand was investigated, based on 19,451 larvae and pupae collected from 65 stream sites in 10 northern provinces during the rainy, cool, and hot seasons, and 1,906 larvae and pupae collected from 18 sites in 9 southern provinces during the cool season. Twenty-seven black fly species were identified from northern Thailand, of which 26 were found in the cool season, when richness was greatest. Significant regressions between species richness and elevation fit a unimodal model in the rainy season but a linear model in the cool and hot seasons. Twenty-two species occurred in all seasons. Species in the subgenera Gomphostilbia and Nevermannia were most common in the hot season, whereas species in the subgenus Simulium were predominant in the cool season. Some species (e.g., S. nakhonense) were geographically widespread, whereas others (e.g., S. chaliowae and S. weji) were restricted to particular localities. Eighteen species and species complexes were found in southern Thailand. The S. tani complex was the most widely distributed taxon, occurring at 66.7% of the sites in the South. Ecological analyses revealed that water temperature, elevation, conductivity, dissolved oxygen, and stream size were among the significant factors associated with the distributions of black flies in both regions of Thailand—the same factors associated with simuliid distributions in other areas of the world.