Search Results (103)

Culicoides (Diptera, Ceratopogonidae) are small biting midges and are known as vectors for many arboviruses, including bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV). Tengchong County of Yunnan Province, China, which borders Myanmar, has many private farms with goats, sheep, and cattle. To estimate the risk of Culicoides-borne viral diseases such as bluetongue (BT) and epizootic hemorrhagic disease (EHD) in this area, an investigation of the diversity and abundance of Culicoides in Tengchong between May 2024 and April 2025 was performed. As a result, 70 collections totaling approximately 93,000 Culicoides were carried out at five farms (cattle + Asian buffaloes, goats, and sheep, respectively). Nineteen species were identified, and eight potential cryptic species were found. A total of 13 cox1 sequences and 4 28S sequences for 13 specimens were generated. The most dominant species were Obsoletus (44.1%), C. homotomus (23.3%), and C. arakawae (12.9%) at the bovine farm; C. tainanus (68.0%), C. orientalis (12.6%), and C. newsteadi (Asia) (6.3%) at the goat farm; and C. tainanus (73.6%), C. fenggangensis (7.3%), and C. sp. nr palpifer (6.3%) at the sheep farm. In this investigation, C. tainanus, Obsoletus, and C. orientalis were the most dominant potential BTV vectors, and the period between July and October may be the main period for epidemics of Culicoides-borne viruses in Tengchong. Full article

Information on Culicoides transmitted parasites, especially trypanosomatids, infecting animals and insects, is scarce. Our goal was to clarify the seasonal patterns of both Culicoides and trypanosomatids detected in these insects and the relationships between Culicoides abundance and meteorological parameters. UV light traps were used to collect biting midges in four study sites in 2022–2023; collected Culicoides females were dissected and analyzed using microscopy and PCR-based methods. Out of 1631 parous Culicoides females belonging to 14 different species, 6.5% were found to be infected with trypanosomatids (5.0% with at least three Trypanosoma species and 1.5% with monoxenous parasites). The highest Culicoides abundance was detected in June. The prevalence of trypanosomatids in biting midges increased during the summer (5.3% in June, 8.8% in July, and 11.2% in August). Temperature was recorded to be a presiding environmental gradient structuring Culicoides species composition, while wind speed and precipitation explained little of the variation. Our results indicate that both avian and mammalian trypanosomes can be found in these insects, although further research is needed to better understand the development of these parasites in biting midges and Culicoides vectorial capacity. Full article

Arthropod-borne viruses (arboviruses) significantly impact human, domestic animal, and wildlife health. While most arboviruses are transmitted to vertebrate hosts by blood-feeding mosquitoes and ticks, a growing body of evidence highlights the importance of other hematophagous arthropods in arboviral transmission. These lesser-known vectors, while often overlooked, can play crucial roles in the maintenance, amplification, and spread of arboviruses. This review summarizes our understanding of hematophagous arthropods, other than mosquitoes and ticks, in arboviral transmission, as well as their associations with non-arboviral viruses. Thirteen arthropod groups are discussed: bat flies, blackflies, cimicids (bat bugs, bed bugs, and bird bugs), Culicoides midges, fleas, hippoboscid flies, lice, mites, muscid flies (including horn flies and stable flies), phlebotomine sandflies, tabanids (including deer flies and horse flies), triatomines, and tsetse flies. Some of these arthropods are regarded as known or likely arboviral vectors, while others have no known role in arbovirus transmission. Particular attention is given to species associated with arboviruses of medical and veterinary significance. As the burden of arboviruses continues to grow, it is critical not to overlook the potential contribution of these lesser-known vectors. Full article

Biting midges, Culicoides spp. (Diptera: Ceratopogonidae), are significant vectors capable of transmitting arboviruses, such as bluetongue virus, to livestock. New Zealand is free of Culicoides, and a national surveillance programme is in place for the early detection of an incursion. Traditionally, insect trap samples from the surveillance programme are analyzed using morphology-based diagnostics under microscopes, which is time-consuming and relies on specialized taxonomic expertise. Here, we assessed the effectiveness of DNA metabarcoding using insect bulk samples and environmental DNA (eDNA) from liquid samples collected in surveillance traps. Two Cytochrome oxidase I (COI) barcoding primer sets were employed to study biodiversity and detect exotic species. The results indicated that DNA metabarcoding with homogenized insect bulk samples had a higher overall detection accuracy rate (over 81% for both primer pairs) compared to ethanol fluid-derived eDNA samples from traps (68.42% and 55.26% for the primer sets LCO1490/HCO2198 and mlCOIintF/jgHCO2198, respectively) based on congruence with morphological identification. Detection failures were likely due to eDNA extraction issues or low target species abundance. Both approaches showed similar insect community composition and diversity in the surveillance trap samples, suggesting the potential of DNA metabarcoding for biosecurity surveillance and biodiversity assessments. Overall, DNA metabarcoding using bulk insect samples could enhance the efficiency of Culicoides surveillance, reducing workload and screening time. Full article

Culicoides biting midges (Diptera: Ceratopogonidae) are important vectors of avian haemosporidian parasites. Understanding their host preferences is crucial for elucidating transmission routes of vector-borne pathogens. In Slovakia, such knowledge is limited, particularly in forested wetlands. This study aimed to identify Culicoides species, their host preferences, and haemosporidian parasites in a wetland ecosystem at the Bird Ringing Station in Drienovec. Midges were collected in 2022 using UV light traps at two sites. In total, 2344 Culicoides individuals of 19 species were collected. Host blood was identified and DNA subsequently extracted from 36 engorged females, revealing feeding on three mammal and five bird species. The most frequently identified host was roe deer (Capreolus capreolus), predominantly fed upon by Culicoides obsoletus (Meigen 1818). Notably, avian haemosporidian DNA was detected for the first time in Slovakia in three Culicoides females. In two Culicoides alazanicus Dzhafarov 1961 individuals, DNA of Haemoproteus asymmetricus (TUPHI01) and Plasmodium matutinum (LINN1) was confirmed, both associated with avian blood from Turdus sp. One Culicoides festivipennis Kieffer 1914 female carried Haemoproteus tartakovskyi (HAWF1) and fed on Coccothraustes coccothraustes. These findings highlight the potential role of local Culicoides species in transmitting avian pathogens and underscore the importance of monitoring their ecology. Full article

Species of the widespread Obsoletus Complex (Culicoides subgenus Avarita Fox, 1955) have been implicated as potential key vectors during the bluetongue and Schmallenberg epidemics in Central Europe in 2006 and 2012. Although extensive efforts have been made to clarify vector–pathogen relationships, one of the most important steps in this process—correct species identification—remains difficult, due to the presence of isomorphic species within the Obsoletus Group. To overcome the difficulties in morphological species identification, several PCR tests were developed. With the aim of developing a high-throughput PCR, capable of differentiating all putative vector species and newly described haplotypes of the subgenus Avaritia present in Europe, a dataset of 4407 published sequences of the mitochondrial (mt) cytochrome c oxidase subunit I (COI) was used to develop specific primers and probes, which can either be applied in a singleplex PCR or in different multiplex PCR approaches. The real-time PCR achieved very high diagnostic sensitivity (100%) and specificity (91.7%) and reliably detected the three clades of C. obsoletus sensu stricto (s.s.) in a pool of specimens. Thus, the new real-time PCR approach will provide an excellent tool for large-scale monitoring, which could improve the understanding of the biology, geographical distribution, and habitat preference of European biting midge species involved in the transmission of bluetongue, Schmallenberg, and epizootic hemorrhagic disease viruses. Full article

Background: Oropouche virus (OROV), part of the Peribunyaviridae family, is an emerging pathogen causing Oropouche fever, a febrile illness endemic in South and Central America. Transmitted primarily through midge bites (Culicoides paraensis), OROV has no specific antiviral treatment or vaccine. This study aims to identify host-targeted therapeutics against OROV using computational approaches, offering a potential strategy for sustainable antiviral drug discovery. Methods: Virus-associated host targets were identified using the OMIM and GeneCards databases. The Enrichr and DSigDB platforms were used for drug prediction, filtering compounds based on Lipinski’s rule for drug likeness. A protein–protein interaction (PPI) network analysis was conducted using the STRING database and Cytoscape 3.10.3 software. Four key host targets—IL10, FASLG, PTPRC, and FCGR3A—were prioritized based on their roles in immune modulation and OROV pathogenesis. Molecular docking simulations were performed using the PyRx software to evaluate the binding affinities of selected small-molecule inhibitors—Acetohexamide, Deptropine, Methotrexate, Retinoic Acid, and 3-Azido-3-deoxythymidine—against the identified targets. Results: The PPI network analysis highlighted immune-mediated pathways such as Fc-gamma receptor signaling, cytokine control, and T-cell receptor signaling as critical intervention points. Molecular docking revealed strong binding affinities between the selected compounds and the prioritized targets, suggesting their potential efficacy as host-targeting antiviral candidates. Acetohexamide and Deptropine showed strong binding to multiple targets, indicating broad-spectrum antiviral potential. Further in vitro and in vivo validations are needed to confirm these findings and translate them into clinically relevant treatments. Conclusions: This study highlights the potential of using computational approaches to identify host-targeted therapeutics for Oropouche virus (OROV). By targeting key host proteins involved in immune modulation—IL10, FASLG, PTPRC, and FCGR3A—the selected compounds, Acetohexamide and Deptropine, demonstrate strong binding affinities, suggesting their potential as broad-spectrum antiviral candidates. Further experimental validation is needed to confirm their efficacy and potential for clinical application, offering a promising strategy for sustainable antiviral drug discovery. Full article

The biting midges Culicoides Latreille, 1809 (Diptera: Ceratopogonidae) is highly relevant to epidemiology and public health, as it includes species that are potential vectors of human and animal arboviruses. The aim of this study was to investigate the presence of RNA viruses in species of the genus Culicoides collected in the Carajás mining complex in the state of Pará. The biting midges were collected in the municipalities of Canaã dos Carajás, Curionópolis and Marabá and morphologically identified. A total of 1139 specimens of seven Culicoides species were grouped into eight pools and subjected to metagenomic analysis. Eight new insect-specific viruses (ISVs) were characterized and assigned to the order Tolivirales, the families Chuviridae, Nodaviridae, Iflaviridae, Mesoniviridae, and Flaviviridae, and the taxon Negevirus. All viruses identified were assigned to clades, families and taxa never reported in Culicoides in Brazil. This study demonstrated that biting midges harbor a significant diversity of RNA viruses, many of which are still unknown, highlighting the importance of studies aiming at virome of these insects. Full article

The part of the life cycle concerning the vectors of avian haemosporidians of the genus Haemoproteus remains only partially studied. This work presents the results of capturing and analyzing female Culicoides biting midges for Haemoproteus infection, collected on the Curonian Spit of the Baltic Sea. The midges were collected from April to August 2023 in dry and wet habitats of the Spit using light traps. Each parous female midge was identified to the species level and then its salivary glands were isolated to prepare a thin smear. The preparation was examined under a light microscope for the presence of parasite stages infecting the birds (sporozoites). PCR analysis was also conducted to assess the prevalence of infection in the midges and the genetic diversity of Haemoproteus spp. among vectors on the Curonian Spit. As a result, 995 Culicoides females belonging to 12 species were collected over the course of 4 months. The highest number of midges was recorded in June. The dominant species were Culicoides kibunensis and Culicoides pictipennis. Molecular analysis showed that 2.71% (n = 27) of the examined individuals contained DNA of Haemoproteus spp. Parasites were found in midges of C. pictipennis, C. kibunensis, C. segnis, C. obsoletus, C. punctatus, C. reconditus, C. festivipennis, and C. pallidicornis from May 15 to July 13. The DNA of the identified parasites belonged to six genetic lineages of Haemoproteus—Haemoproteus parabelopolskyi hSYAT02, H. asymmetricus hTUPHI01, H. minutus hTURDUS2, H. spp. hBRAM1, hHAWF6, and hHIICT1. Sporozoites of H. parabelopolskyi hSYAT02 were detected in two individuals of C. pictipennis and one of C. kibunensis. Thus, taking into account the previous results of other studies, we have assumed that these two midge species are competent vectors for Haemoproteus parasites on the Curonian Spit. Full article

Bluetongue (BT) is a Culicoides midge-borne hemorrhagic disease affecting cervids and ruminant livestock species, resulting in significant economic losses from animal production and trade restrictions. Experimental animal infections using the α/β interferon receptor knockout IFNAR mouse model and susceptible target species are critical for understanding viral pathogenesis, virulence, and evaluating vaccines. However, conducting experimental vector-borne transmission studies with the vector itself are logistically difficult and experimentally problematic. Therefore, experimental infections are induced by hypodermic injection with virus typically derived from baby hamster kidney (BHK) cells. Unfortunately, for many U.S. BTV serotypes, it is difficult to replicate the severity of the disease seen in natural, midge-transmitted infections by injecting BHK-derived virus into target host animals. Using the IFNAR BTV murine model, we compared the virulence of traditional BHK cell-derived BTV-17 with C. sonorensis midge (W8) cell-derived BTV-17 to determine whether using cells of the transmission vector would provide an in vitro virulence aspect of vector-transmitted virus. At both low and high doses, mice inoculated with W8-BTV-17 had an earlier onset of viremia, earlier onset and peak of clinical signs, and significantly higher mortality compared to mice inoculated with BHK-BTV-17. Our results suggest using a Culicoides W8 cell-derived inoculum may provide an in vitro vector-enhanced infection to more closely represent disease levels seen in natural midge-transmitted infections while avoiding the logistical and experimental complexity of working with live midges. Full article

Culicoides biting midges are small dipterous insects known as biological vectors of arboviruses, protozoa, and filaria parasites worldwide. Many studies on Culicoides focus on trapping them at ground level, without considering the best trap heights for different vector species. This implies that we might overlook insects positioned higher in the canopy. From June to August, we used UV traps to catch Culicoides biting midges at three different heights in three temperate mature forest areas in east Lithuania, Baltic region of Europe. We conducted this study to test the differences in midge numbers, male and female proportions, and female parity at each height. We caught the majority of biting midges (80.6%) at the mid-canopy and high-canopy. A higher number of female Culicoides midges than males was caught, with the proportion of males varying based on height and reaching its lowest point at ground level. No significant difference between the proportion of nulliparous and parous females caught at different height was detected. Culicoides pictipennis and C. festivipennis were the most common species of biting midge we found. They were found in the mid-canopy (86.8%) and the high-canopy (50.0%), respectively. Culicoides kibunensis was next, found at ground level (66.2%), and C. punctatus was found at the high canopy strata (63.0%). Each species’ abundance was seasonal dependent. Information on the vertical distribution of vector species in the temperate forest ecosystem is an important step in understanding patterns of vector borne disease transmission in wildlife. Full article

Culicoides biting midges were collected using UV light traps from nine livestock farms in Kanchanaburi Province, Thailand. Collections were made one night per month from June 2020 to May 2021 to determine the seasonal changes and spatial distribution of the Culicoides assemblage. The influence of four environmental factors (temperature, rainfall, humidity, and wind speed), types of animals in each shed (cattle, pigs, and avians), and neighboring animals (those in the other sheds and their proximity) were assessed. A subsample of 130,670 out of a total of 224,153 specimens collected was identified and counted. The collections were predominantly female (76.9%), though males were also commonly collected (23.1%). The dominant species included C. peregrinus (97,098 individuals; 43.0%), C. oxystoma (55,579; 24.6%), C. arakawae (45,996; 20.4%), and C. imicola (15,703; 7.0%), while other species accounted for the remaining 9777 individuals (4.4%). Trap captures were strongly influenced by seasons and animal sheds. Cattle exhibited the greatest effect on the community, likely due to their large biomass. Humidity and temperature had a positive effect on trap captures, whereas wind speed exhibited a negative effect. Cattle positively influenced all major species, except for C. arakawae, which showed a positive association with avians. A “neighboring effect” was also observed. Additionally, the lowest dispersal ability of C. arakawae was suggested. Full article

Vesicular stomatitis (VS) is a viral disease that affects horses, cattle, and swine that is transmitted by direct contact and hematophagous insects. In 2023, a multi-state outbreak of vesicular stomatitis New Jersey virus (VSNJV) occurred in California, Nevada, and Texas, infecting horses, cattle, and rhinoceros. To identify possible insect vectors, we conducted insect surveillance at various locations in San Diego County, CA, including at a wildlife park. CO₂ baited traps set from mid-May to mid-August 2023 collected 2357 Culicoides biting midges and 1215 Simulium black flies, which are insect genera implicated in VSNJV transmission. Insects were pooled by species, location, and date, then tested for viral RNA. Nine RNA-positive pools of Culicoides spp. and sixteen RNA-positive pools of Simulium spp were detected. Infectious virus was detected by cytopathic effect in 96% of the RNA-positive pools. This is the first report of VSNJV in wild-caught C. bergi, C. freeborni, C. occidentalis, S. argus, S. hippovorum, and S. tescorum. The vector competency of these species for VSNJV has yet to be determined but warrants examination. Active vector surveillance and testing during disease outbreaks increases our understanding of the ecology and epidemiology of VS and informs vector control efforts. Full article

Species delimitation of Culicoides complex species can be challenging. Among species within the Culicoides variipennis complex, C. sonorensis is considered the primary vector of bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) in North America. Morphological identification of C. sonorensis within the C. variipennis complex is laborious, time-consuming, and requires entomology expertise. Therefore, in this study we developed and validated a multiplex real-time PCR for rapid detection and differentiation of C. sonorensis from the two other main cryptic species (C. variipennis and C. occidentalis) within the C. variipennis complex. The assay targets the EF1α gene and has a built-in internal control targeting 18 S. The specificity and the sensitivity of the multiplex real-time PCR were evaluated using morphologically identified reference and field-collected specimens. The multiplex PCR was 100% specific when nucleic acid extracted from C. variipennis, sonorensis, and occidentalis specimens was tested. When nucleic acid extracted from pools of midges was tested, the multiplex PCR was able to detect all three Culicoides species with comparable sensitivity. The multiplex assay, however, failed to detect eight morphologically identified C. sonorensis specimens collected from Alberta in 2014. The EF1α gene sequences of these specimens formed a distinct phylogenetic cluster, amongst those from C. variipennis, sonorensis, and occidentalis, suggesting that they belong to a different species. We hypothesize that those specimens might be C. albertensis, the only other species remaining in the C. variipennis complex with known geographical distribution in North America. We believe that this highly sensitive and specific multiplex real-time PCR assay could be an effective tool for rapid detection and differentiation of C. sonorensis, the known vector of BTV and EHDV, in trap collections in future vector surveillance programs. Full article

Biting midges (Culicoides) are vectors of many pathogens of medical and veterinary importance, but their viromes are poorly characterized compared to certain other hematophagous arthropods, e.g., mosquitoes and ticks. The goal of this study was to use metagenomics to identify viruses in Culicoides from Mexico. A total of 457 adult midges were collected in Chihuahua, northern Mexico, in 2020 and 2021, and all were identified as female Culicoides reevesi. The midges were sorted into five pools and homogenized. An aliquot of each homogenate was subjected to polyethylene glycol precipitation to enrich for virions, then total RNA was extracted and analyzed by unbiased high-throughput sequencing. We identified six novel viruses that are characteristic of viruses from five families (Nodaviridae, Partitiviridae, Solemoviridae, Tombusviridae, and Totiviridae) and one novel virus that is too divergent from all classified viruses to be assigned to an established family. The newly discovered viruses are phylogenetically distinct from their closest known relatives, and their minimal infection rates in female C. reevesi range from 0.22 to 1.09. No previously known viruses were detected, presumably because viral metagenomics had never before been used to study Culicoides from the Western Hemisphere. To conclude, we discovered multiple novel viruses in C. reevesi from Mexico, expanding our knowledge of arthropod viral diversity and evolution. Full article