Medical and Veterinary Entomology最新文献

The critical impact of mosquito-borne diseases on public health, along with the failure of current control strategies, highlights the need for novel mosquito control approaches mainly in tropical countries. This study explored the larvicidal properties of bacterial isolates from the egg surfaces of Aedes aegypti L. and Aedes albopictus Skuse (Diptera: Culicidae), the primary and secondary dengue vector mosquitoes in Sri Lanka. Among 30 bacterial isolates, a local strain of Pseudomonas mosselii Quesnel isolated from the egg surfaces of the dengue vectors demonstrated strong larvicidal activity against Ae. aegypti. Larvicidal assays using the bacterial supernatant (OD 1.7) and freeze-dried products were performed across concentrations ranging from 80 to 2.1 mg/mL. The LC₅₀ values for the supernatant were 55, 54 and 52 mg/mL at 24, 48 and 72 h, respectively, with corresponding LC₉₀ values of 91, 89 and 86 mg/mL. Freeze-dried supernatant showed LC₅₀ values of 2.73, 2.64 and 2.63 mg/mL, while freeze-dried bacterial culture showed higher toxicity with LC₅₀ values of 2.57, 2.51 and 2.44 mg/mL. Strong larvicidal activity was observed against Culex quinquefasciatus Say (Diptera: Culicidae), a primary vector of filariasis. The freeze-dried products retained their efficacy for up to 2 months. Ovicidal and adulticidal assays indicated no significant effects on mosquito eggs or adults. However, the active components of bacterial metabolites significantly impacted the development of Aedes larvae. Toxicity effects were observed in non-target organisms, including zooplankton and tadpoles. These findings suggest the local Ps. mosselii strain as a potential bio-larvicide against dengue vectors while underscoring the need for further environmental assessment.

Lizama-Schmeisser, N., Castro, E.S., Espinoza-Carniglia, M., Herrera, Y., Silva-de La Fuente, M.C., Lareschi, M. et al. (2024) Are Rattus rattus fleas invasive? Evaluation of flea communities in invasive and native rodents in Chile. Medical and Veterinary Entomology, 38(4), 599–613. Available from: https://doi.org/10.1111/mve.12739

The paper by Lizama-Schmeisser et al. (2024) appeared in a regular issue in error. It should be part of the Special Issue: Mammalian ectoparasite threats and management under a changing climate in the Global South.

We apologize for this error.

Records of infections by Leishmania spp. (Kinetoplastida: Trypanosomatidae) have been occurring in the last decade in Sergipe, Brazil. The capital, Aracaju, alone accounted for 44% of the total cases of the state for the visceral form between 2007 and 2016, with high numbers also in other municipalities that make up the metropolitan region. In this sense, this work aimed to carry out entomological surveillance actions in the municipalities of the Metropolitan Region of Aracaju and evaluate the characteristics of the peri-domestic environments that contribute to the maintenance of species richness and abundance. Entomological captures were carried out between 2021 and 2022 with Centers for Disease Control and Prevention (CDC)-type traps for three consecutive nights between twilight and dawn at the beginning of the dry and rainy periods in the peri-domestic area of residences in neighbourhoods peri-urban in the municipalities in the metropolitan region: Aracaju, Barra dos Coqueiros, Nossa Senhora do Socorro and São Cristóvão. The characteristics around the houses were also recorded in a field diary. Constancy, dominance for all species, the household infestation rate and the relative abundance index of the vector for epidemiologically interesting species were calculated. Chi-square tests and multivariate analyses of variance were also performed to search for associations between the vectors and aspects of the dwellings. In total, 752 phlebotomines were captured at 64 collection points. Seven species of phlebotomines were identified, including Lutzomyia longipalpis (Lutz & Neiva, 1912), Evandromyia lenti (Mangabeira, 1938) and Migonemyia migonei (França, 1920). The vector Lu. longipalpis was the species that showed the highest infestation in residences. The results also reveal a sex-specific association influenced by vegetation size, suggesting that denser vegetation may promote male aggregation, a behavioural trait that could be explored in the development of targeted vector control strategies. No significant association was recorded between abundance and environmental factors, which may be related to the difficulty of measuring this association in a heterogeneous environment with so many anthropic interferences in the urbanisation process. By evidencing the influence of ecological factors such as vegetation size on vector behaviour, this study offers insights to enhance leishmaniasis control strategies in Sergipe.

This study reports the first detection of Babesia aktasi and Anaplasma phagocytophilum in a bezoar goat (Capra aegagrus), providing insight into the presence of these pathogens in wild caprinae. The infected goat exhibited a localised ocular infection but showed no clinical signs of acute piroplasmid or Anaplasma infections. Microscopic examination of blood smears revealed low parasitemia of intra- and extraerythrocytic piroplasms and intragranulocytic morulae, consistent with chronic infection. PCR and sequence analysis confirmed that the Babesia species detected was B. aktasi, a recently described piroplasmid previously reported in domestic goats. Phylogenetic analysis placed the B. aktasi haplotype within the Babesia sensu stricto clade, closely related to sequences from domestic goats in Türkiye and an uncharacterised Babesia sp. from a red deer. The A. phagocytophilum strain detected in this study belonged to ecotype 1, which includes human pathogenic strains. These findings raise the possibility that bezoar goats may contribute to the natural maintenance of B. aktasi and A. phagocytophilum, highlighting their potential involvement in the enzootic cycles of these pathogens alongside domestic caprinae. Given that bezoar goats are the ancestors of modern domestic goats and that their habitats overlap in Anatolia, further research is needed to better understand the transmission dynamics, vector associations and zoonotic potential of these pathogens.

Culicoides biting midges (Diptera: Ceratopogonidae) are economically important biting flies known for transmitting pathogens like bluetongue virus to livestock. In order to control these insects and the diseases they are associated with, livestock producers employ a variety of preventive practices which commonly include insecticide use. The efficacy of insecticide treatments can wane over time as insects either develop resistance or the active ingredient is degraded in the environment. Sublethal insecticide exposures can change vector behaviour in ways that affect vectorial capacity. To determine whether Culicoides feeding behaviour is altered by sublethal exposure to commonly used agricultural insecticides, we exposed female C. sonorensis Wirth and Jones to permethrin and coumaphos at lethal concentrations (LC) ranging from LC₁₀ to LC₃₀. We also exposed midges to fluralaner at 100 mg/mL. Midges were offered a blood meal at 6, 12, 18 and 24 h post-exposure, and blood-feeding success was measured. We identified a significant inhibition of engorgement by permethrin up to 12 h post-exposure as well as by fluralaner up to 6 h post-exposure. Engorgement after coumaphos exposure was paradoxically higher in the LC₃₀ group after 18 and 24 h post-exposure, but decreased at the same timepoints for the LC₂₀ group. The different modes of action of each of these insecticides may account for their differing effects on Culicoides feeding.

Vector-borne diseases pose significant global threats to both human and animal health, and their impacts are expected to intensify with ongoing climate change. Understanding the ecological and environmental drivers of these diseases is essential for developing effective surveillance and control strategies. Central to this is knowledge of the distributions of vectors and hosts, and how these may shift in response to environmental changes. In this study, we present a generalisable framework for predicting the current and future distributions of vectors and wildlife hosts using correlative modelling approaches. We integrate these predictions with data on livestock and human populations to inform the potential risk of West Nile virus (WNV) establishment and exposure in the United Kingdom. Currently absent from the United Kingdom, WNV is an orthoflavivirus maintained in a natural transmission cycle between mosquitoes and birds. Spillover into incidental hosts such as humans and horses can result in febrile illness, with severe cases leading to encephalitis and death. Our findings identify regions at elevated risk of WNV establishment where competent avian hosts and mosquito vectors are likely to co-occur and where infected vectors may interact with spillover hosts. We also explore how these risk patterns may evolve by 2100 under different environmental scenarios. Across all scenarios, risk is projected to increase in the south-east of the United Kingdom and decline in northern regions. This work demonstrates how modelling current and future vector and host distributions can inform risk assessments for emerging vector-borne diseases. Such insights are critical for guiding policy decisions and enhancing preparedness for disease incursions in a changing environment.

Flesh flies (Sarcophagidae), along with blow flies, are among the first colonizers of vertebrate cadavers, including human corpses. Their early colonization and rapid development frequently result in the collection of flesh fly larvae as evidence during crime scene investigations or autopsies. Despite their regular occurrence and confirmed forensic importance, the species-level identification of sarcophagid larvae remains challenging. To address this, the morphology of the first-instar larva of three common and widespread European species with confirmed forensic relevance—Sarcophaga africa, S. caerulescens, S. melanura—was revised. Material was analysed using both light microscopy and scanning electron microscopy (SEM). Taxonomically important characters were identified in the pseudocephalon, the facial mask, mouthhooks and basal sclerite of the cephaloskeleton, and the distribution and shape of spines and papillae of the anal plate. The results are compared with previous descriptions, and an identification key is presented for the first-instar larvae of forensically relevant flesh fly species of central and northern Europe.

Ecological niche models (ENMs) and species distribution models (SDMs) are essential tools for investigating the ecological requirements and geographic distributions of species at multiple spatial and temporal scales. While these modelling techniques have been employed across various taxonomic groups to explore ecology, evolution and biogeography, their application to ticks and tick-borne pathogens (TBPs) has yielded valuable—though not yet conclusive—perspectives for understanding epidemiology and pathogen transmission risk. Advances in research on these topics necessitate a review to determine whether there is consistency in the conceptual and methodological implementation of these approaches, as well as to identify needs for improvement and adaptation to more informative alternatives. Here, we aim to review the state of the art in the use of these concepts and tools in the study of tick species and TBPs worldwide to provide a clear understanding of their theoretical and methodological foundations, study topics, involved species, variables, geographic resolutions, applications of model outputs and thematic evolution. We conducted a formal literature review of 158 publications in the period from 1997 to May 2024, along with bibliometric and scientometric analyses. Results indicate that the main topic of study resides in the prediction of current and future potential geographic distribution, and most of the work has been carried out only for nine genera of ticks, with major focus on species belonging to the family Ixodidae and those affecting human health. Borrelia burgdorferi Johnson et al. (Spirochaetales: Borreliaceae) is the most explored pathogen. Studies have mostly used bioclimatic variables, but some studies also incorporate topographic variables from local to global scales, with resolutions ranging from 30 m to 80 km. Although ENM and SDM in ticks and TBPs have been routinely used, very few have been validated in the field, and their projections are not used in epidemiological monitoring. Over 60% of the studies do not report sufficient methodological information for replication. We also detected imprecise usage of the terms ENM and SDM, which are often used interchangeably. This lack of conceptual clarity impedes the adequate treatment of both ecological niches and geographic distributions, hindering advancement in this research field worldwide. We recommend including species of the family Argasidae in future studies to analyse their ecological requirements and potential distributions. These species have been poorly studied despite being vectors of pathogens causing diseases with medical and veterinary importance (e.g., relapsing fever and spirochetosis). Lastly, we identify key areas for improvement—from biogeographical knowledge gaps to the use of modern sampling methods, algorithms and hypotheses—that would enhance the application of these concepts and modelling techniques.

Aedes aegypti Linnaeus 1762 (Diptera: Culicidae) is the primary vector of several pathogens of public health significance. Insecticide-based preventative measures are a key component of vector-borne disease control programmes. However, widespread insecticide resistance threatens the effectiveness of current control strategies. Sarolaner, an isoxazoline insecticide, offers a novel mode of action and is primarily used for controlling ticks, fleas and mites in companion animals. This study evaluates the insecticidal efficacy of sarolaner against both laboratory-susceptible and resistant strains of Ae. aegypti through various exposure routes. In topical assays, sarolaner outperformed permethrin by >8-fold and >21-fold greater efficacy against resistant strains at 24 and 72 h, respectively. Conversely, it underperformed in susceptible strains by over 8-fold and 2-fold at the same time points. In larval assays, sarolaner exhibited >300-fold greater toxicity than spinosad at 24 and 48 h for both susceptible and resistant strains. Blood-feeding assays showed sarolaner was more toxic than ivermectin by over 17-fold and 10-fold in susceptible and resistant strains, respectively, up to 120 h. While sarolaner was less toxic than dinotefuran in resistant strains through sugar feeding, it was over 3-fold more toxic in susceptible strains. Notably, no cross-resistance was detected with dinotefuran or ivermectin through oral, sugar or blood-feeding applications, though slight cross-resistance was observed with permethrin and spinosad. This study highlights sarolaner's potential as an effective adulticide and larvicide against Ae. aegypti, supporting its further evaluation as a candidate for new chemical formulations.

As a tropical country, Colombia hosts a wide range of arthropods that can act as vectors of disease-causing pathogens, particularly those carrying hemopathogens. Ticks play a crucial role in the transmission of zoonotic pathogens, impacting both human and veterinary health. The pathogen load of ticks from wildlife is of particular concern, as it can contribute to the spillover of infectious agents to domestic animals and humans, highlighting the need for surveillance and control strategies to mitigate emerging tick-borne diseases. Therefore, this study aimed to determine the presence of microorganisms in ticks collected from wildlife in Antioquia (Colombia) through bioinformatic analysis. A prospective, cross-sectional, random, non-probabilistic, convenience-based study involving tick collection from animals in three different zones of Antioquia was conducted. Initially, vertebrate species were morphologically characterized via taxonomic keys and identification guides for amphibians, reptiles, birds, and mammals. Ticks were manually collected from these animals and preserved in absolute ethanol for later taxonomic identification. Genomic DNA was then extracted, and the resulting reads were processed through bioinformatic analysis, achieving taxonomic classification within DNA libraries of gram-positive bacteria, gram-negative bacteria, and parasites. Additionally, descriptive statistics were calculated for all variables of interest at the animal level (e.g., genus, species, sex, and age group, when applicable) and study zone. A total of 570 ticks, predominantly Amblyomma spp., were obtained from 46 host animals. Ticks from lizards presented the highest bacterial richness and diversity (based on 16S gDNA), whereas ticks from amphibians presented the lowest. Proteobacteria dominated most samples, as shown by taxonomic composition at the phylum, family, and genus levels. Ticks collected from mammals displayed lower diversity and richness than those collected from reptiles. For parasitic communities (18S gDNA), dominant eukaryotes were identified in ticks from mammals, excluding host-related taxa. Overall, lizard-associated ticks presented the most complex microbial diversity, whereas amphibian ticks were less diverse, highlighting the significant variation in microbial and parasitic communities across host species. This study highlights the microbial diversity of ticks from wild hosts in Colombia, focusing on the dominance of Francisella, Rickettsia, Aspergillus, and Penicillium. These findings underscore the need for further research on their ecological roles, transmission dynamics, and potential health risks, aiming to inform strategies to mitigate tick-borne diseases.