Medical and Veterinary Entomology最新文献

Mansonia mosquito species are recognised as a significant vector of human pathogens, primarily transmitting the filarial nematode, Brugia malayi. In central Thailand, the three most prevalent Mansonia species are Mansonia annulifera, Mansonia indiana and Mansonia uniformis. This study explored the influence of seasonal changes on the phenotypic variation of these Mansonia species in central Thailand using the geometric morphometrics (GM). To ensure accurate species identification, we integrated GM techniques with DNA barcoding, examining distinctions in both phenotype and genotype among the species. The intraspecific genetic divergence ranged from 0.00% to 1.69%, whereas the interspecific genetic divergence ranged from 10.52% to 16.36%. The clear distinction between intra- and interspecific distances demonstrated the presence of a barcoding gap, confirming the successful differentiation of the three Mansonia mosquito species through DNA barcoding. Similarly, the interspecies GM assessment for classifying Mansonia species demonstrated a high degree of accuracy, with an overall performance of 98.12%. Exploring seasonal variation in the three Mansonia species revealed wing variations across different seasons, and pronounced variations appearing in the cool season. Regarding their association with meteorological factors, Ma. annulifera and Ma. uniformis showed significant positive correlations with temperature (p < 0.05), and Ma. uniformis also displayed a significant negative correlation with atmospheric pressure (p < 0.05). The insights from this study will deepen our understanding of the adaptive patterns of Mansonia mosquitoes in Thailand's central region, paving the way for enhanced disease surveillance related to these vectors.

Geographically expanding and invading ticks are a global concern. The Asian longhorned tick (ALT, Haemaphysalis longicornis) was introduced to the mid-Atlantic US between 2010 and 2017 and recently invaded Ohio, an inland state. To date, ALTs in the US have been associated with livestock exsanguination and transmission of the agent of bovine theileriosis. To inform management, studies describing tick ecology and epidemiology of associated disease agents are critical. In this study, we described phenology, habitat and host associations, and tested for agents of medical and veterinary concern at the site of the first known established ALT population in Ohio, where pesticide treatment was applied in early fall 2021. In spring–fall 2022, we sampled wildlife (small mammals) and collected ticks from forest, edge, and grassland habitats. We also opportunistically sampled harvested white-tailed deer at nearby processing stations and fresh wildlife carcasses found near roads. Field-collected ALTs were tested for five agents using real-time PCR. We found that ALT nymphs emerged in June, followed by adults, and concluded with larvae in the fall. ALTs were detected in all habitats but not in wildlife. We also found a 4.88% (2/41) prevalence of Anaplasma phagocytophilum across ALT adults and nymphs. Host and habitat associations were similar to other studies in the eastern United States, but two potential differences in phenology were identified. Whether ALTs will acquire more endemic disease agents requires further investigations. Our findings provide the first evidence regarding ALT life history from the Midwest region of the United States and can inform exposure risk and guide integrated management.

Sarcophaga (=Parasarcophaga) (Liopygia) ruficornis (Fabricius, 1794) is a species of medical–veterinary and forensic importance, as its immatures cause myiasis in humans and animals and colonize carcasses and cadavers. Therefore, investigations into the biology and morphology of this species, with a particular focus on pupae that constitute ≥50% of the developmental period for the immatures, are pertinent. Although there are biological and morphological studies of pupae, the intrapuparial development at different temperatures has not yet been analysed. Therefore, the present study aimed to describe how temperature (22, 27 and 32 ± 1°C) affects the development and morphology of S. (L.) ruficornis pupae at 60 ± 10% relative humidity and a 12-h photoperiod. Ten pupae were collected, euthanized and fixed every 4 h from pupariation until 24 h and every 8 h until the emergence of the first adult. Emergence occurred at 440, 272 and 232 h at 22, 27 and 32°C, with 590, 380 and 330 pupae, respectively. The highest mortality occurred at 32°C. Eight periods were defined, and sex was determined in pharate adult stage; in addition, 40 key morphological characteristics to estimate pupal age were presented. These findings can serve as a basis for studies on the biology and morphology of the pupa of S. (L.) ruficornis, particularly in bionomics, control and forensics, helping researchers and experts.

Vector control remains one of the best strategies to prevent the transmission of trypanosome infections in humans and livestock and, thus, a good way to achieve the elimination of human African trypanosomiasis and animal African trypanosomiasis. A key prerequisite for the success of any vector control strategy is the accurate identification and correct mapping of tsetse species. In this work, we updated the tsetse fly species identification and distribution in many geographical areas in Cameroon. Tsetse flies were captured from six localities in Cameroon, and their species were morphologically identified. Thereafter, DNA was extracted from legs of each tsetse fly and the length polymorphism of internal transcribed spacer-1 (ITS1) region of each fly was investigated using PCR. ITS1 DNA fragments of each tsetse species were sequenced. The sequences obtained were analysed and compared to those available in GenBank. This enabled to confirm/infirm results of the morphologic identification and then, to establish the phylogenetic relationships between tsetse species. Morphologic features allowed to clearly distinguish all the tsetse species captured in the South Region of Cameroon, that is, Glossina palpalis palpalis, G. pallicera, G. caliginea and G. nigrofusca. In the northern area, G. morsitans submorsitans could also be distinguished from G. palpalis palpalis, G. tachinoides and G. fuscipes, but these three later could not be distinguished with routine morphological characters. The ITS1 length polymorphism was high among most of the studied species and allowed to identify the following similar species with a single PCR, that is, G. palpalis palpalis with 241 or 242 bp and G. tachinoides with 221 or 222 bp, G. fuscipes with 236 or 237 bp. We also updated the old distribution of tsetse species in the areas assessed, highlighting the presence of G. palpalis palpalis instead of G. fuscipes in Mbakaou, or in sympatry with G. morsitans submorsitans in Dodeo (northern Cameroon). This study confirms the presence of G. palpalis palpalis in the Adamawa Region of Cameroon. It highlights the limits of using morphological criteria to differentiate some tsetse species. Molecular tools based on the polymorphism of ITS1 of tsetse flies can differentiate tsetse species through a simple PCR before downstream analyses or vector control planning.

Scorpionism is an increasing public health problem in the world. Although no specific methodology or product is currently available for the control of those arachnids, the use of insecticides could be an effective tool. Chlorpyrifos is one of the insecticides used, but to date, whether scorpions recognise surfaces with that insecticide and how it affects their physiology and/or biochemistry is unknown. In the present study, we observed that scorpions recognise surfaces with 0.51 and 8.59 μg/cm² of chlorpyrifos and avoid those areas. The 0.51 μg/cm² concentration produced a decrease in acetylcholinesterase and an increase in catalase, superoxide dismutase and glutathione S-transferase, whereas the 8.59 μg/cm² concentration evoked a decrease in acetylcholinesterase and an increase in catalase and glutathione S-transferase. Using the comet assay, we observed that the insecticide at 0.17, 0.51 and 8.59 μg/cm² caused DNA damage. Finally, we found that the insecticide does not generate significant variations in glutathione peroxidase, glutathione reductase, the amount of protein or lipid peroxidation. The present results offer a comprehensive understanding of how scorpions respond, both at the biochemical and behavioural levels, when exposed to insecticides.

Among gastrointestinal nematodes, Haemonchus contortus (Rudolphi) Cobb (order Strongylidae; family Trichostrongylidae) is one of pathogenic and economic importance in domestic and wild ruminants, including the European bison, Bison bonasus Linnaeus (order Cetartiodactyla; family Bovidae); a species on the International Union for Conservation of Nature's Red List of Threatened Species. Carabus granulatus Linnaeus (order Coleoptera; family Carabidae) is one of the most prevalent species of ground beetle, inhabiting a wide range of terrestrial ecosystems in Poland. Twenty-six ground beetles of this species inhabiting the Białowieża Primeval Forest in eastern Poland were screened for the presence of DNA of pathogenic gastrointestinal nematodes of ruminants. Extracted DNA was sequenced and compared to reference sequences. In six insects, the presence of H. contortus DNA was detected. The obtained nucleotide sequences were homologous to each other and to the majority of the published DNA sequences of H. contortus isolates. The sequences were also identical to a sequence of H. contortus isolated from European bison in Poland. The study provides the first molecular evidence of the presence of H. contortus DNA in C. granulatus. The finding suggests that ground beetles may play a role in the transmission dynamics of this parasite.

The relationship between the incidence of bovine teat papillomatosis and the activity of haematophagous flies was investigated in Japan. A total of 15,737 flies consisting of 33 species were collected by dry ice-baited mosquito net (DMN) trap and a sweep net from udders of cattle. Simulium aokii (Takahasi) of Simuliidae (black flies) was the predominant species, followed by S. tobetsuense Ono and S. iwatense (Shiraki). Simulium aokii had the highest peak in October, followed by September. Numbers of blood spots from the bites per teat in nulliparous cattle were significantly correlated with numbers of S. aokii collected by DMN trap. Numbers of teats with warts and spots of blood from the bites per teat were significantly more abundant in anterior teats than posterior teats. The average incidence of teat papillomatosis in nulliparous cattle was significantly higher than that in parous cattle, and the highest incidence by month was in May, followed by April. Although bovine papillomavirus (BPV) DNA was not detected in flies examined, the presence of black flies and blood spots from their bites were associated with subsequent high incidence of growing warts. In particular, it would pay to give attention to species such as S. aokii that severely attack udders in the present locality. Further investigations for the detection of BPV DNA from flies parasitizing on teats are needed.

Mayaro virus (MAYV; Alphavirus: Togaviridae) is an emerging pathogen in Latin America, causing fever and polyarthritis. Sporadic outbreaks of MAYV have occurred in the region, with reported human cases being imported to Europe and North America. Although primarily a risk for those residing in the Amazon basin's tropical forests, recent reports highlight that urbanization would increase the risk of MAYV transmission in Latin America. Urban emergence depends on human susceptibility and the ability of mosquitos like Aedes aegypti  (Linnaeus, 1762) (Diptera: Culicidae) to transmit MAYV. Despite the absence of active MAYV transmission in Argentine, the risk of introduction is substantial due to human movement and the presence of Ae. aegypti in the region. This study aimed to evaluate the susceptibility of different Argentine Ae. aegypti populations to MAYV genotype L (MAYV-L) using dose–response assays and determine barriers to virus infection, dissemination and transmission. Immature mosquito stages were collected in Buenos Aires, Córdoba and Rosario cities. Female Ae. aegypti (F2) were orally infected by feeding on five concentrations of MAYV-L, ranging from 1.0 to 6.0 log₁₀ PFU/mL. Abdomens, legs and saliva were analysed using viral plaque assays. Results revealed that MAYV-L between infection and dissemination were associated with viral doses rather than the population origin. Infection rates varied between 3% and 65%, with a 50% infectious dose >5.5 log₁₀ PFU/mL. Dissemination occurred at 39%, with a 50% dissemination dose of ~6.0 log₁₀ PFU/mL. Dissemination among infected mosquitoes ranged from 60% to 86%, and transmission from disseminated mosquitoes ranged from 11% to 20%. Argentine Ae. aegypti populations exhibited a need for higher viral doses of MAYV-L than those typically found in humans to become infected. In addition, only a small proportion of infected mosquitoes were capable of transmitting the virus. Understanding MAYV transmission in urban areas is crucial for public health interventions.

Aedes albopictus is highly prevalent in the northern part of West Bengal and is considered to be responsible for the recent dengue outbreaks in this region. Control of this vector is largely relied on the use of synthetic pyrethroids, which can lead to the development of resistance. In the present study, larvae of three wild Ae. albopictus populations from the dengue-endemic regions were screened for deltamethrin resistance, and the role of cytochrome P450 monooxygenases (CYPs) was investigated in deltamethrin exposed and unexposed larvae. Two populations were incipient resistant, and one population was completely resistant against deltamethrin. Monooxygenase titration assay revealed the involvement of CYPs in deltamethrin resistance along with an induction effect of deltamethrin exposure. Gene expression studies revealed differential expression of five CYP6 family genes, CYP6A8, CYP6P12, CYP6A14, CYP6N3 and CYP6N6, with high constitutive expression of CYP6A8 and CYP6P12 in all the populations before and after deltamethrin exposure. From these findings, it was evident that CYPs play an important role in the development of deltamethrin resistance in the Ae. albopictus populations in this region.

We used entire mitochondrial (mt) genome sequences (14.5–15 kbp) to resolve the phylogeny of the four main lineages of the Haematobothrion ticks: Alloceraea, Archaeocroton, Bothriocroton and Haemaphysalis. In our phylogenetic trees, Alloceraea was the sister to Archaeocroton sphenodonti, a tick of an archetypal reptile, the tuatara, from New Zealand, to the exclusion of the rest of the species of Haemaphysalis. The mt genomes of all four of the Alloceraea species that have been sequenced so far had a substantial insert, 132–312 bp, between the tRNA-Glu (E) gene and the nad1 gene in their mt genomes. This insert was not found in any of the other eight subgenera of Haemaphysalis. The mt genomes of 13 species of Haemaphysalis from NCBI GenBank were added to the most recent data set on Haemaphysalis and its close relatives to help resolve the phylogeny of Haemaphysalis, including five new subgenera of Haemaphysalis not previously considered by other authors: Allophysalis (structurally primitive), Aboimisalis (structurally primitive), Herpetobia (structurally intermediate), Ornithophysalis (structurally advanced) and Segalia (structurally advanced). We elevated Alloceraea Schulze, 1919 to the status of genus because Alloceraea Schulze, 1919 is phylogenetically distinct from the other subgenera of Haemaphysalis. Moreover, we propose that the subgenus Allophysalis is the sister to the rest of the Haemaphysalis (14 subgenera) and that the ‘structurally primitive’ subgenera Hoogstraal and Kim comprise early diverging lineages. Our matrices of the pairwise genetic difference (percent) of mt genomes and partial 16S rRNA sequences indicated that the mt genome sequence of Al. kitaokai (gb# OM368280) may not be Al. kitaokai Hoogstraal, 1969 but rather another species of Alloceraea. In a similar way, the mt genome sequence of H. (Herpetobia) nepalensis Hoogstraal, 1962 (gb# NC_064124) was only 2% genetically different to that of H. (Allophysalis) tibetensis Hoogstraal, 1965 (gb# OM368293): this indicates to us that they are the same species. Alloceraea cretacea may be better placed in a genus other than Alloceraea Schulze, 1919. Reptiles may have been the host to the most recent common ancestor of Archaeocroton and Alloceraea.