Medical and Veterinary Entomology最新文献

African horse sickness virus (AHSV: Sedoreoviridae; Orbivirus) causes a severe and often fatal disease in horses (African horse sickness: AHS) and is transmitted almost exclusively by Culicoides biting midges (Diptera: Ceratopogonidae). In recent years, unprecedented outbreaks of AHSV have occurred in new geographical foci in Thailand and other related Culicoides-borne viruses continue to emerge unexpectedly, causing disease outbreaks in northern Europe. This study investigated Culicoides abundance and diversity at a donkey (Equus asinus) sanctuary in southern England. The incidence and severity of AHS in infected donkeys are lower than in horses, with concerns, therefore, that these species could act as potential reservoirs in the event of an incursion of AHSV. A total of 21,350 Culicoides of 20 species were collected over 14 nights during spring and summer 2019 using three Onderstepoort Veterinary Institute ultraviolet light-suction traps. The most abundant species were identified within the subgenus Avaritia (19,574; 91.7%), which are known vectors of other Orbiviruses in northern Europe and have been previously identified as putative vectors of AHSV in southern Europe. Furthermore, Culicoides blood-feeding on donkeys was confirmed for the subgenus Avaritia through polymerase chain reaction of blood-fed female Culicoides using a 685 bp region of the cytochrome c oxidase subunit 1 gene. Data on the size and distribution of the donkey population and the potential impact of infection with AHSV on donkeys within the United Kingdom are scarce. This study demonstrates that large populations of Culicoides can exist near these hosts and that they regularly take blood meals from them. There is a potential risk that donkeys could play a significant role in transmission and persistence of AHSV in the event of an incursion into the United Kingdom, which could complicate disease control.

Stable flies, Stomoxys calcitrans, blood-feed daily on livestock hosts. The presence of conspecific flies on host animals may signify host suitability ('conspecific cueing') or may signal density-dependent feeding benefits ('Allee effects'). However, stable flies captured on sticky traps reportedly render traps less attractive to conspecifics. We investigated whether this deterrent effect is context-dependent, and whether host-foraging stable flies are attracted to, rather than deterred by, conspecifics. In two-choice laboratory bioassays, we offered food-deprived, CO₂-stimulated stable flies a choice between paired landing platforms that were baited or not (control) with conspecific flies ('bait flies'). The presence of bait flies-irrespective of their abundance, sex or relative position on the platform-prompted attraction and landing of foraging flies. Even heterospecific flies and fly-look-alike decoys were attractive, provided they visually resembled stable flies. As shown in separate bioassays, chemical cues of bait flies on their own were not attractive to foraging flies. Our data suggest that foraging stable flies may aggregate on hosts. Aggregated blood-feeding may be adaptive in that aggregated conspecifics on a host animal may signal the presence of a suitable food resource, and group-feeding may help suppress immune responses of host animals.

Ticks of the genus Haemaphysalis, akin to other tick genera, are obligate hematophagous ectoparasites of medical and veterinary importance, serving as vectors for various pathogens. Haemaphysalis ticks, like Haemaphysalis muhsamae (H. muhsamae) within the Haemaphysalis leachi group, have previously had taxonomic uncertainties, which recent revisions have validated. Historically restricted to Eastern and Southern Africa, knowledge of their presence in West Africa has remained uncertain. This study aimed to confirm the presence of H. muhsamae in Ghana and to investigate its distribution, host associations and infestation patterns across ecological zones and seasons. A total of 3816 ticks were collected from wild mammal carcasses at two bushmeat markets between 2020 and early 2021. Morphological examination and molecular analysis targeting the mitochondrial cytochrome oxidase I (COI) gene confirmed the presence of H. muhsamae in Ghana for the first time. Of the total, 140 ticks (3.7%) were identified as H. muhsamae, predominantly infesting the African civet (Civettictis civetta), striped ground squirrel (Xerus erythropus) and Kusimanse mongoose (Crossarchus obscurus). The species occurred in both forest (3.9%) and coastal savannah (3.5%) zones, with infestation intensity highest on African civets (p = 0.0032) and significantly greater during the wet season in the coastal savannah (p = 0.0213). Phylogenetic analysis showed close genetic similarity between Ghanaian specimens and those from the Democratic Republic of the Congo, suggesting a shared evolutionary lineage. These findings expand the known distribution of H. muhsamae and underscore the importance of ongoing tick surveillance and molecular characterization to better understand tick-borne disease risks in West Africa.

Tabanid flies are gaining high medical and veterinary importance due to their role as a vector of many pathogens. In the present study, a total of 3760 female tabanid flies were collected from Narathiwat and Phayao provinces of Thailand. All were identified using the morphological method, DNA barcoding and wing geometric morphometric (WGM) analysis. Eight species were identified, and among them, Tabanus tenens is a new recorded Thai horse fly. Morphologically, 2178 and 1559 females from Narathiwat and Phayao were identified at the species level, including Chrysops dispar, Chrysops fasciatus, Tabanus griseilineis, Tabanus rufiscutellatus and Tabanus minimus. The other 23 females were identified at the level of the genus (Tabanus spp.) only. Among these, DNA barcoding was further identified as Tabanus tenens, Tabanus rubidus and Tabanus striatus. The landmark-based WGM analysis was used to differentiate the samples from Narathiwat, and the results showed the efficacy of this approach in differentiating the four species of tabanids, achieving an overall accuracy score of 99%. Additionally, the data derived from wing landmarks of samples collected in Narathiwat were used as reference materials for identification of the tabanid fly collected from Phayao, and the finding revealed efficacy of the reference materials. Together, this study demonstrated that DNA barcoding is a reliable tool for the identification of tabanid fly species, while WGM analysis could be a complementary tool. The barcode sequences and WGM data generated in this study can serve as a valuable reference material to identify new field samples from other regions of Thailand. Altogether, this study updated the species list of tabanid flies in Thailand, particularly in the Narathiwat and Phayao provinces, using various integrative identification tools.

Many mosquito species act as vectors for zoonotic pathogens, transmitting them between natural amplifying hosts and dead-end hosts. Determining the relationship between mosquitoes and their hosts is crucial for understanding the lifecycle dynamics of such pathogens. The aim of this research was to assess the host-feeding patterns of mosquitoes inhabiting natural and semi-natural environments of Vojvodina Province, Serbia, using the invertebrate-derived DNA (iDNA) from blood-fed female mosquitoes. Mosquito species (Diptera: Culicidae) belonging to four genera were identified, based upon morphological characteristics. A segment of the 16S rRNA gene was amplified and sequenced, allowing for 10 different vertebrate host species to be identified. Culex specimens collected in this study primarily fed on birds, while mammal species constituted about a third of their bloodmeals. Species of Anopheles and Aedes overwhelmingly took bloodmeals from a single host species, the red deer, but also fed on other mammal species from diverse families. Our results indicate that enzootic and bridge vectors are active in the study area, feeding upon the respective host groups that could sustain transmission of mosquito-transmitted viruses, highlighting the need for continued surveillance of the region.

Multiple species of Anopheles mosquitoes transmit malaria-causing Plasmodium around the world. Molecular methods are often employed to confirm vector species, detect parasites and determine bloodmeal host sources; these assays are often performed separately and can be time-consuming and expensive. However, in this study, we show that the Oxford Nanopore Technologies (ONT) MinION Sequencer offers a cost-effective and efficient alternative to accurately identify mosquito species, host bloodmeal sources and detect parasites simultaneously in malaria vectors. We sequenced 150 insectary-reared mosquitoes representing nine species and 150 blood-fed mosquitoes with one of five vertebrate blood sources. We also analysed the presence of Plasmodium falciparum (Welch, 1897) in 40 infected mosquito samples. A final combined assay integrated all three previously optimized assays into a single sequencing run, demonstrating the high-throughput capability of the Nanopore sequencing platform. This run included 32 samples for each targeted amplicon, totalling 96 samples. For comparison, we sequenced all samples using a standard Sanger sequencing protocol. Our results showed that the MinION sequencing platform accurately identified all nine mosquito species, five different bloodmeal hosts from the blood-fed mosquitoes up to 48 h post blood feed, and detected P. falciparum in the 40 positive controls. The sequencing results obtained using the MinION platform exhibited high concordance with those from standard Sanger sequencing, as demonstrated by comparable similarity scores and correct mosquito species identification. This demonstrates that our MinION sequencing and analysis protocol offers a novel, highly precise, cost-effective solution for combined mosquito species identification, bloodmeal analysis and parasite detection.

Effective surveillance of mosquito populations is critical to monitoring and mitigating the spread of mosquito-borne diseases (MBDs). This study evaluated the relative trapping efficiency of two widely used adult mosquito traps-the Biogents BG-Sentinel (BGS) and the Mosquito Magnet® Executive (MM)-on British mosquitoes across four wetlands in south-east England over a 12-week period. A third trap, a Box-Gravid trap fitted with an FTA™ card, was deployed to detect arboviruses such as West Nile virus (WNV) via saliva collection. A total of 11,584 adult female mosquitoes representing 15 species were collected. The MM trap captured a significantly higher total number of mosquitoes, while the BGS trap demonstrated greater species evenness and was significantly more effective at catching Culex (Culex) pipiens L., 1758. Spatial variation strongly influenced catch rates, with significant differences between wetlands. No evidence of WNV was detected in any mosquito pools or FTA™ cards. While both trap types yielded similar species richness, the MM trap may be optimal for collecting large sample sizes of mammalophagic species, whereas the BGS is better suited for capturing enzootic vectors such as Culex pipiens s.l., and a broader spectrum of species. These findings provide evidence-based recommendations for future UK wetland surveillance and enhance preparedness for emerging vector-borne disease risks.

The highlands of the eastern Democratic Republic of the Congo (DRC) are home to critically endangered eastern gorillas (Gorilla beringei). Concerns have been raised that the increased temperatures and extreme weather conditions associated with climate change will lead to an increase in the abundance and distribution of Culicoides-borne diseases. Here, we utilized an integrated morphological and molecular approach to identify Culicoides species in a small but significant collection of Culicoides captured from highland eastern gorilla habitat and surrounding areas and updated the Culicoides spp. reported from the highlands of the eastern DRC. A review of the literature related to Culicoides collections in the DRC was conducted in French and English. Recent worldwide checklists were consulted to rectify synonyms and other discrepancies found in the literature for the region. Fresh Culicoides specimens were collected, wings slide-mounted and remaining carcasses subjected to DNA extraction. A total of 82 Culicoides specimens were collected. From these, 75 high-quality DNA barcodes (658-bp of the mtDNA COI gene) were obtained, belonging to 14 distinct taxa, 11 of which were new records for the DRC, including C. bolitinos Meiswinkel, 1989, C. hortenis Khamala & Kettle, 1971, C. citroneus Carter, Ingram & Macfie, 1920, and C. radiomaculatus Khamala & Kettle, 1971, and seven species new to science (C. sp. nr. citroneus, C. sp. nr. glabripennis 1, C. sp. nr. glabripennis 2, C. sp. nr. kibatiensis 1, C. sp. nr. kibatiensis 2, C. sp. nr. neavei 1 and C. sp. nr. neavei 2), increasing the known Culicoides fauna of the DRC from 20 to 31. The presence of C. imicola Kieffer, 1913, C. enderleini Cornet & Brunhes, 1994 and C. neavei Austin, 1912, was confirmed. The potential health impact of the association of known Culicoides pathogen vectors with endangered gorillas is discussed.

In District Faisalabad, ticks, such as Hyalomma (H) anatolicum Koch and Rhipicephalus (Boophilus) microplus Canestrini (Ixodida: Ixodidae), are significant ectoparasites impacting livestock and wildlife, transmitting pathogens that lead to substantial economic losses. The increasing resistance of tick populations to conventional acaricides necessitates te exploration of potential complementary approaches as control strategies, including nanoparticle formulations. The acaricidal effect of sulfur (S) and copper (Cu) nanoparticles was evaluated against various life stages (eggs, larvae, and adults) of R. (B.) microplus. Nanoparticles were synthesized and characterized using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The susceptibility of ticks to nanoparticles was evaluated by adult and larval immersion tests and larval hatch tests. Ivermectin was used as a positive control. The lethal concentration to 50% mortality (LC₅₀) values for Cu and S nanoparticles against adult R. (B.) microplus were 22.3 ± 3.44 mg/L and 36.16 ± 6.19 mg/L, respectively. At higher concentrations of 80 mg/L (Cu) and 150 mg/L (S), both nanoparticles achieved 99.17% adult tick mortality. S and Cu nanoparticles demonstrated 99.87% and 98.50% larval mortality at concentrations of 150 mg/L and 80 mg/L, respectively. Lower mortality was observed with Ivermectin at 30 mg/L, with 66.67% adult mortality and 61.50% larval mortality. Cu and S also resulted in 99.87% unviable eggs at concentrations of 80 mg/L and 150 mg/L, respectively, while Ivermectin led to only 90.63% unviable eggs. S and Cu nanoparticles exhibited significant potential as effective complementary agents to traditional acaricides, disrupting the life cycle of R. (B.) microplus. Further research is essential to assess their long-term ecological impacts and safety for non-target organisms.

In recent years, a consortium of research institutes and a private partner (AtoZ Group Ltd, Arusha, Tanzania) have developed a new technology called 'multi-layer, multi-functionalized polyethylene films', which can be used to produce insecticide-impregnated screens in different colours, at low manufacturing cost, which are robust and easy to use. In a first step, a comparative study of the material and shape of candidate white and blue polyethylene (PE) screens was carried out on Glossina tachinoides and G. palpalis gambiensis in Burkina Faso, West Africa. In a second step, four candidate PE screens were compared with a reference polyester screen, the west African tiny target commonly used in control campaigns. No significant difference in terms of attractiveness was observed between PE screens and fabric screens (p > 0.05) for the two riparian species. The vertical shape of the screen (PE and fabric) attracted significantly more G. tachinoides (p < 0.001). The white and blue vertical PE screen and the blue horizontal PE screen attracted more tsetse flies than the WATT reference screen, but none of these comparisons were significant. This study opens up new prospects for the application of multi-layer, multi-functionalized polyethylene film technology against riverine tsetse flies.