Medical and Veterinary Entomology最新文献

The simuliid fauna of Laos is among the most poorly known of any country in the world, only seven species having been recorded. We explored the Laotian simuliid fauna as an opportunity to test reproductive isolation and the minute morphological differences between two of the country's common isomorphic nominal species-Simulium chamlongi Takaoka & Suzuki (Diptera: Simuliidae) and Simulium luculentum Takaoka, Srisuka & Saeung (Diptera: Simuliidae). Both are members of the widespread Simulium variegatum group. Using the band patterns of the giant chromosomes in the larval silk glands, we showed that S. chamlongi and S. luculentum are reproductively isolated, no hybrids having been found. Molecular analyses indicated that the two species are genetically distinct, with a minimum genetic divergence of 2.91%. Analysis of a fragment of the vertebrate cytochrome b gene revealed that the blood hosts of S. chamlongi and S. luculentum in Laos include humans and water buffaloes (Bubalus bubalis Linnaeus) (Artiodactyla: Bovidae), respectively. Diagnostic morphological characters provided in the original species descriptions were substantiated for pupae and females but not for larvae or males. Our chromosomal analyses also revealed a third reproductively isolated species, possibly new, with a unique IIS chromosomal sequence. The absence of a uniquely shared inversion among the three species indicates that the S. variegatum group lacks a defining chromosomal synapomorphy.

Fleas are important for their role as parasites causing pulicosis or tungiasis, and as vectors of pathogens that can cause diseases in humans and other animals, in tropical and subtropical regions, with a disproportionate effect linked to contexts of structural poverty and social exclusion. This study evaluated the risk factors for flea parasitism in dogs and cats from urban (Ur) and rural (Ru) households in Puerto Iguazú, Argentina, through seasonal sampling between March 2017 and February 2018. Prevalence (P), mean intensity, and mean abundance of the host-associated variable were calculated. To identify associations between the presence/pseudoabsence of fleas and the explanatory variables, a generalized linear mixed model was constructed. A total of 1932 fleas, identified as Ctenocephalides felis felis (Bouché) (Siphonaptera: Pulicidae), were collected from 402 dogs (P_Ur = 79.8%; P_Ru = 88.4%) and 87 cats (P_Ur = 77.6%; P_Ru = 66.7%). The prevalence was higher in rural dogs. Regarding host species, the prevalence in dogs was higher than in cats in rural areas. Tunga penetrans L. (Siphonaptera: Tungidae) was observed in 195 dogs (P_Ur = 31.97%; P_Ru = 70.48%) and 29 cats (P_Ur = 4.46%; P_Ru = 59.46%), which was also more common in rural areas. Risk factors for C. f. felis presence in dogs included young age, lack of antiparasitic treatment, peridomestic fumigation, bare soil and lower humidity and temperature four weeks prior to sampling (w-4). In cats, infestation was associated with young age, the presence of infested dogs in the same household, and higher vegetation coverage. In both hosts, T. penetrans infestation was positively associated with no antiparasitic treatment, lower humidity in w-3, and higher humidity in w-1 and higher temperature in w-2. The findings indicate that the factors influencing the presence, prevalence and abundance of C. f. felis and T. penetrans may differ according to host, socio-environmental, climatic and soil conditions in each locality. The establishment of institutional policies is imperative to effectively manage flea parasitosis, particularly in regions of socio-environmental heterogeneity.

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.

Filth flies pose a health risk because of the microbes they carry outside and inside of their bodies to humans and animals. Mostly synthetic chemical insecticides are used for fly control. Alternative approaches with a different mode of action are needed because of increasing fly resistance to pesticides. We used a modified World Health Organization cone test to determine the efficacy of the minerals produced by diatoms (diatomaceous earth) as a mechanical insecticide against adults of the house fly, Musca domestica, the secondary screwworm, Cochliomyia macellaria, and the grey flesh fly, Sarcophaga bullata, under low and high humidity. The use of mechanical insecticides as an alternative to kill filth flies has received minimal consideration. However, recent research showed that expanded perlite, a new mechanical insecticide made from volcanic rock, was highly efficacious against mosquitoes and flies. Mortality for diatomaceous earth in this paper at 30°C and 50% relative humidity was observed as early as 2 h after exposure with 50% and 90% mortality observed at 3.5 and 4.6 h (the LT₅₀ and LT₉₀, respectively) in M. domestica. The LT₅₀ and LT₉₀ increased as the size of the fly species increased (M. domestica to C. macellaria to S. bullata) and increased for all three species when the relative humidity increased from 50 to 70%. These results suggest dehydration was the mode of action. Scanning electron micrographs of C. macellaria adults 2 h after diatomaceous earth exposure, showed the flies were evenly self-covered with the mineral with no obvious damage to the cuticle. Proof of concept was demonstrated that diatomaceous earth as a residual surface treatment could be used as an alternative for filth fly control.

Some species of the genus Chrysomya, known as hairy maggot blowflies (Diptera: Calliphoridae), are medically and forensically important insects worldwide. However, identifying these species can be challenging due to morphological characteristics overlapping. In this study, we investigated morphological and molecular differences among three hairy maggot blowflies: Chrysomya rufifacies Macquart, 1843, Chrysomya albiceps (Wiedemann, 1819), which are widely distributed throughout the Old World, respectively; and Chrysomya villeneuvi Patton, 1922, which is restricted to Asia. Morphological analysis revealed overlapping characters in larval and adult stages of C. rufifacies and C. albiceps based on traditional diagnostic characters, confirming phenotypic polymorphism in both species. Due to the global spread of these species, likely by human activity and climate change, a morphological and phylogenetic investigation was underway. A revision of the established morphological keys was proposed, and the phylogenetic analysis supported a sister relationship among the three species, with C. rufifacies more closely related to C. albiceps (genetic distances of 2.42%-3.13%) than to C. villeneuvi (3.49%-4.40%). Notably, C. albiceps differed from C. villeneuvi (3.31%-3.48%), suggesting that C. albiceps, occupies an intermediate evolutionary position between C. rufifacies and C. villeneuvi.

Houseflies (Musca domestica L.), a widespread pest in livestock facilities, have developed resistance to commonly utilized insecticides, including pyrethroids, organophosphates and carbamates. However, the genetic status of insecticide resistance in Japanese housefly populations remains largely elusive. We used hybridization probe capture and next-generation sequencing (NGS) to examine the mutations across the entire coding sequence of two insecticide target genes, voltage-gated sodium channel (VGSC) and acetylcholinesterase (AChE), from 240 individual M. domestica collected from 14 livestock facilities in Japan between 2013 and 2024. This study is the first to utilize these molecular methods to examine insecticide resistance in houseflies collected from the field. Resistance-related mutations in VGSC (e.g., super-kdr [M918T + L1014F], kdr-His [L1014H] and L1014F) were detected in most wild populations, with differing allele frequencies. Notably, super-kdr was widespread (12/15 populations) with frequencies ranging from 0.06 to 1.00, whereas kdr-His was observed in 8/15 populations with 0.03-0.70 frequencies. For AChE, three known resistance mutations (V260L, G342A/V and F407Y) were observed in all populations, with at least one resistance allele present at 0.65-1.00 frequencies. An elevation in NGS read counts for AChE was noted in several populations, along with the presence of three distinct alleles at amino acid position 342, suggesting AChE gene duplication. These duplications may help in mitigating the fitness costs linked to AChE resistance. Our results show the widespread presence and complexity of insecticide resistance mutations in Japanese M. domestica populations and underscore the use of NGS-based probe capture techniques for monitoring the evolution of resistance.