Serological evidence of bluetongue virus exposure in domestic ruminants at altitudes above 4500 m (Ali Prefecture, Tibetan Plateau, China).

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are key arbovirus vectors of human and animal health relevance. Understanding the biological and molecular factors influencing arbovirus transmission is essential for informing effective mitigation strategies. Culicoides brevitarsis Kieffer is of particular importance due to its close relationship to cattle, high population abundance in suitable sites, and demonstrated vector capacity for arboviruses. However, limited genomic resources have constrained investigation into its molecular and evolutionary biology, necessitating a chromosome-level genome assembly and comparative genomic analyses. A chromosome-level genome assembly of C. brevitarsis was generated using Oxford Nanopore long reads, polished with Illumina short reads, and scaffolded using Hi-C sequencing, followed by genome annotation, comparative dipteran genomics, immune gene characterisation, and evolutionary analyses of vector competence-associated genes. A 129.5Mb genome was assembled into three chromosomes with high contiguity (N50 = 43Mb, L50 = 2) and high completeness (98% for Arthropoda BUSCO odb10 lineage). Genome annotation identified 11,708 genes, including 661 immunity-related genes, as well as genes associated with key functional categories such as metabolism, sensory perception, and host-pathogen interactions. Comparative gene family analyses across 12 dipteran genomes revealed strong family-level (Ceratopogonidae) and genus-level (Culicoides) evolutionary signatures. In C.brevitarsis, 405 expanded and 262 contracted gene families were enriched for functions associated with metabolism, regulation, locomotion, and stimulus response. Integration of transcriptomic datasets from C.sonorensis Wirth and Jones identified 82 orthologous genes in C.brevitarsis corresponding to genes previously associated with differential responses to bluetongue virus infection, including lineage-specific patterns of conservation and selection. The genome provides a foundational resource to understand the molecular biology and evolutionary features of C.brevitarsis. Integration of immune, sensory, metabolic, and evolutionary analysis provides a framework for future functional and comparative studies aimed at understanding variation in arbovirus transmission among Culicoides species.

Assessing permethrin susceptibility of field-collected biting midges in Florida and evidence for resistance evolution using laboratory selections.

Culicoides biting midges are a major nuisance in coastal residential areas of Australia, yet effective control strategies remain limited. This study evaluated the effectiveness of a residual insecticide treatment applied to a purpose-grown vegetation barrier in reducing biting midge nuisance in adjacent coastal residences, with secondary effects on mosquito abundance also monitored. Biting midge and mosquito populations were monitored continuously using automated smart traps (BG-Counter®) over 18 wk, including 11 wk of pretreatment and 7 wk posttreatment surveillance. During the pretreatment surveillance period, properties adjacent to the vegetation barrier (n = 4) recorded 71% fewer biting midges than nonadjacent properties (n = 2), although this effect was temporally variable (95% confidence interval [CI]: -95% to +55%) and not significant. No reduction in mosquito abundance was observed during the same period. Following treatment of the barrier with a residual insecticide (BiFlex AquaMax®, bifenthrin 100 g/liter), biting midge and mosquito populations declined by 86% (95% CI: 77-92%) and 79% (95% CI: 68-86%), respectively, across the study landscape, including in areas with and without the vegetation barrier. A significant barrier-insecticide interaction for both groups indicated that reductions were greatest in residences adjacent to the vegetation barrier. Decreases in mosquito abundance following application of the residual spray suggests that the vegetation barrier functioned as important harborage habitat, enabling targeted control within and beyond its immediate boundary. These findings support the integration of insecticide-treated vegetation barriers into pest management programs targeting nuisance biting midge and mosquito populations in coastal residential environments.

Biting midges of the genus Culicoides Latreille (Ceratopogonidae) pose a significant threat to veterinary health as vectors of over 60 viruses, most of which affect livestock. In this study, we used light traps to sample Culicoides populations on cattle and goat farms from May to October 2023 at 15 sites in Gyeongsangnam-do, Jeollanam-do, and Jeju Island, South Korea. Diversity and abundance were analysed based on the collection date, environmental conditions, and host species. A total of 124,055 individuals were collected, comprising 14 previously recorded and two newly recorded species: C. asiana and C. palawanensis. The dominant species was C. arakawae, which accounted for 80.60% of the total collected individuals, followed by C. punctatus (10.25%), and C. tainanus (3.36%), while the remaining 13 species constituted 5.80% of the collection. Total Culicoides abundance peaked in August (40.15%), driven largely by fluctuations in C. arakawae abundance, but the seasonal abundances of individual species varied. Culicoides arakawae and C. punctatus were dominant on the mainland, while C. matsuzawai, C. lungchiensis, and C. tainanus were dominant on Jeju Island. The dominant species on cattle farms were C. arakawae and C. punctatus, while C. arakawae dominated in collections from goat farms. The detection of two new species records suggests that the fauna of South Korea is still incompletely understood.

Gut microbiome diversity and functional profiles of Culicoides across Sanya, Ruili, and Linyi, China.

Oropouche virus (OROV) is an emerging vector-borne pathogen in the American tropics that is a significant cause of human disease. Over 100 traveler imported cases of OROV were recorded in the continental USA in 2024 (103 in Florida), elevating the risk of local transmission of OROV should competent insect vectors feed upon viremic humans. The only confirmed natural vector of OROV is Culicoides paraensis (Goeldi), a biting midge species that occurs throughout forested areas of the New World, including the eastern USA, Central America and most of northern South America. Anthropophagic mosquito species, especially Culex quinquefasciatus Say and Aedes aegypti L. have been suspected of transmitting emerging lineages of OROV in areas where C. paraensis had not been reported (Cuba). Recent laboratory studies have shown that emerging strains of OROV replicate to higher titers in human cell lines than ancestral strains, raising the possibility that these strains may also be transmitted by select mosquito species that feed on humans. To assess the potential for anthropophagic mosquitoes in the southern USA to transmit OROV, we evaluated the vector competence (based on viral RNA detection) of lab-adapted Cx. quinquefasciatus and Ae. aegypti, along with an F1 generation of Ae. aegypti from field-collected mosquitoes in Florida, using prototype (TRVL9760, Trinidad 1955) and emerging (240023, Cuba 2024) OROV genotypes across two incubation periods in cell culture (5 and 7 days) and three extrinsic (7, 14, and 21 days) incubation periods. Both mosquito species exhibited moderate susceptibility to infection (24.2-43.2%) and disseminated infection (23.0-57.5%), but low competence to transmit OROV. Transmission was observed in Ae. aegypti (2.5% in the Lower Keys strain and 1.8% in the Orlando strain) and Cx. quinquefasciatus (0.7%). When the two viral genotypes (TRVL9760 vs 240023) were compared at the same incubation conditions (IP/EIP), the emergent genotype did not exceed the prototype in infection, dissemination, or transmission. Our data indicates that these two relatively anthropophagic mosquito species are unlikely to serve as competent vectors of OROV in Florida, attributable to substantial midgut and salivary gland barriers.

Oropouche virus (OROV) is mainly transmitted to humans by Culicoides paraensis, a biting midge widely distributed across the Americas. In this study, we modeled the potential distribution of C. paraensis in Brazil using environmental variables and found that temperature-related factors, particularly minimum temperature and annual temperature range, were the strongest predictors of its occurrence. Comparison of the predicted distribution with confirmed autochthonous OROV cases revealed several areas of mismatch, suggesting either underreporting of C. paraensis or the involvement of additional vector species in transmission. These findings highlight the need to integrate C. paraensis into Brazil’s arbovirus surveillance systems and to strengthen entomological monitoring with the support of remote sensing, climate data, and ecological research to better anticipate and mitigate future transmission risks.Graphical

Biting midges, commonly known as no-see-ums, are year-round pests found in Florida and the southeastern United States that cause disruption of outdoor activities and tourism. Despite their frustrating bites and impact on skin health, dermatology literature on no-see-ums is scarce. We present a case report and dermoscopic description of a no-see-um bite and review its management.

Biting midges (also known as no-see-ums, sand flies, or sand gnats) are tiny bloodsucking flies that are important for several reasons. In the United States, especially in coastal areas, these biting insects are often abundant and persistent pests of campers, beachgoers, fishers, and anyone desiring to enjoy the outdoors. Biting midges are also important as vectors (transmitters) of deadly and debilitating pathogens that affect wild and domesticated animals, especially livestock and game animals. Biting midges can even transmit pathogens like Oropouche virus and filarial worms that affect humans in many parts of the world, especially in South America and Africa. This revision of the Featured Creature document on biting midges provides detailed information on biting midges' diversity, distribution, description, life cycle, ecology, medical and veterinary significance, management, and prevention.

Oropouche virus (OROV) is an emerging arbovirus primarily endemic to South America, capable of infecting humans, diverse animals, and multiple vector species. Although its ecology remains poorly understood, increased globalisation and human mobility raise concerns regarding potential introduction into Europe. To evaluate European risk, vector competence trials were conducted using Italian Culicoides obsoletus/scoticus and C. imicola, major vectors of livestock orbiviruses, orally exposed to a 2024 Cuban reassortant OROV strain. Of 260 surviving C. obsoletus/scoticus and 65 C. imicola midges, all samples tested negative for OROV RNA, suggesting limited vector competence. These findings indicate that tested European Culicoides populations are unlikely to support OROV transmission. Nevertheless, the virus's broad host and vector range, reassortment potential, and presence of anthropophilic midges in Europe warrant continued surveillance and vector competence studies. Improved understanding of transmission dynamics, reservoir hosts, and potential vectors is critical for preparedness against Oropouche virus introduction and spread in non-endemic regions.

Culicoides species involved in the BTV‐3 epidemic, the Netherlands, 2023–2024

Soil is an important non-aqueous habitat for algae. Algal mats, a type of microbial mat, oft en on the surface of soil. These mats can become a significant ecological problem if they grow too large or thick, potenti ally disrupting underground life by blocking sunlight or producing toxic compounds. Fungi may serve as affective biological control agents against such harmful algae. In this study, fungi were isolated from the larvae of a biting midge, Forcipomyia taiwana, which feeds primarily on algae. These fungal isolates were evaluated for their anti-algal activity against Coelastrella and Desmodesmus species. Here, we reported two fungal isolates, Vishniacozyma victoriae strain JYC1105 and Kwoniella pini strain JYC1032, were capable of inhibiti ng algal growth when treated with their cell-free supernatant. Both fungal strains exhibited strong algicidal activity, achieving over 99% inhibition of algal growth within three days, even when the supernatant was diluted to one-tenth of its original concentration. Algal cell death was assessed by direct cell counts and SYTOX Green staining, revealing inhibitory effects within just half a day. These results highlight the potential of these fungal metabolites as rapid and effective biocontrol agents against nuisance algae in terrestrial environments.

We detected Shuni virus in horses and ovine fetuses and Shamonda virus in a caprine fetus in South Africa. We identified a Shuni/Shamonda virus reassortant in a horse and Shuni/Caimito, Shamonda/Caimito, and Shamonda/Sango virus reassortants in Culicoides midges. Continued genomic surveillance will be needed to detect orthobunyavirus infections in Africa.

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.

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.

Biting midges of the genus Culicoides (Diptera: Ceratopogonidae) are known for their medical and veterinary importance. The presence of these insects in domestic animal shelters can pose significant risks to animal and public health. This study aimed to assess the richness, abundance, and seasonal frequency of Culicoides biting midges in domestic animal shelters located in the backyards of human residences. Insects were collected once a month from August 2016 to July 2018 in pigsties, chicken coops, corrals, sheep pens, and goat pens in three rural villages in Vitória do Mearim, Maranhão State, Brazil. The data were subjected to one-way analysis of variance and Tukey's post hoc test to verify differences in infestation between shelters and determine which shelter types were most attractive to midges. A total of 2801 individuals belonging to 13 species of Culicoides were captured. Richness was highest in pigsties (11 species) and chicken coops (10), whereas abundance was highest in chicken coops (45.6%), cattle corrals (27.7%), and pigsties (19.7%). Biting midges occurred throughout the year but prevailed in the rainy season (13 species, 64.4% of individuals), when humidity is high and temperatures and winds are milder. Backyard infestations demonstrate the important role of domestic animals and their shelters in attracting biting midges. This study recommends implementing backyard cleaning efforts focused on animal shelters as part of an environmental management strategy to prevent midge infestations. Additionally, conservation actions should be undertaken in adjacent forest areas to preserve the environmental conditions that support these insects in their natural habitats.

Biting midges are key vectors that can transmit different pathogens to mammals and birds. In Ethiopia, two studies showed the diversity of Culicoides species in several districts based on morphological characters. For this, the same identification key was used for Afrotropical and Palaearctic Culicoides fauna. Consequently, results are incomplete and erroneous. It is misleading to state that a universal identification key is available.

Biting midges, Culicoides spp. (Diptera: Ceratopogonidae) are significant insect 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 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 oxidate I (COI) barcoding primer sets were employed to study biodiversity and detect exotic species. 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.

Culicoides are small hematophagous biting midges belonging to the family Ceratopogonidae. The genus is distributed worldwide yet remains poorly studied. This study investigated the vector and host specificity of Culicoides oxystoma, a species of significant relevance to the surveillance of vector-borne diseases in Tunisia and globally. The research was conducted in two Tunisian governments: Tozeur and Kairouan. A total of 24,366 adult midges were collected using two types of suction traps: the Center for Disease Control trap and the Onderstepoort Veterinary Institute trap. Females of Culicoides oxystoma were isolated, carefully dissected, and slide mounted in a phenol alcohol balsam mixture. A portion of the abdomen was excised for total DNA extraction to identify the origin of the blood meal. A total of 108 engorged females were analyzed using polymerase chain reaction (PCR) to amplify specific fragments of the cytochrome b gene, followed by sequencing and sequence analysis. However, DNA sequences were successfully obtained for only 56 individuals. Sequence analysis revealed that the midges fed on a variety of mammalian hosts, including humans, with a prevalence of Mus musculus and Bos taurus. This represents the first study aiming to identify a wide range of hosts in Tunisia and North Africa, providing valuable insights into the hosts utilized by Culicoides oxystoma for blood feeding.