Medical and Veterinary Entomology最新文献

The aim of this study was to analyse the prevalence and distribution of Bartonella species in companion animals, wildlife and their associated fleas in different landscapes of the Atlantic Forest ecoregion of Argentina, and to analyse the phylogenetic relationships between the Bartonella species identified in this study in addition to those found in other regions available in GenBank. A total of 257 mammals, including rodents, opossums, dogs and cats, were examined to detect the presence of Bartonella in both fleas and host tissues. The study revealed the presence of Bartonella in rodent fleas (47.7%), opossum fleas (7.8%), rodent spleens (6.5%) and cat blood (10%). Analysis of 15 gltA gene fragments revealed the existence of at least three different genotypes and eight haplotypes. Genetic analysis has established a close association between Bartonella species from mammals and fleas in both the Atlantic Forest of Brazil and the Costanera Sur Reserve in Argentina. Bartonella henselae (Regnery et al.) Brenner et al. (Hyphomicrobiales: Bartonellaceae) was identified in three rodent species: Rattus rattus (L.; Muridae), Akodon montensis Thomas (Cricetidae) and Calomys tener Winge (Cricetidae). This marks the first report of B. henselae in R. rattus in Argentina, as well as the initial documentation of its association with A. montensis and C. tener. Additionally, Bartonella clarridgeiae Lawson and Collins (Hyphomicrobiales: Bartonellaceae) was identified in feline blood and in fleas from dogs and cats. These findings are particularly relevant in the context of areas undergoing deforestation, where interactions between wild and domestic hosts increase the risk of zoonotic disease transmission. A One Health approach is crucial to understand transmission dynamics and to address the challenges posed by fleas as infection amplifiers and spillover phenomena. These present significant challenges for public health and biodiversity conservation.

Parasite relationships are influenced by host size, behaviour, population density and location and can affect the ecological dynamics of their hosts. Urban environments provide new contexts for host–parasite interactions, often leading to changes in infection dynamics when compared with the natural environment. This study focuses on the relationship between five genera of haemoparasites (Anaplasma Theiler, Ehrlichia Moshkovski, Hepatozoon Miller, haemotropic Mycoplasma Nowak and Neorickettsia Philip) found in the South American coati Nasua nasua Linnaeus (Carnivora: Procyonidae), a carnivore highly adaptable to urban areas. Here, we used network analysis to verify the interaction between N. nasua and haemoparasites. We also used a General Linear Model to investigate the influence of biotic and abiotic variables and haemoparasite infections on the functional roles of N. nasua individuals, considering weight, age, sex and tick infestation (number of immature ticks collected). The network revealed low modularity, and none of the biotic variables, immature stages of ticks and location of sampling had any influence on the functional role of N. nasua. The most important haemoparasite in the network was haemotropic Mycoplasma, identified as a key non-hub connector, probably spreading efficiently through frequent agonistic social interactions from N. nasua. These findings underscore the complex interplay between host behaviour, environmental factors and parasite ecology in urban environments, offering insights into managing urban wildlife diseases.

The spread of the West Nile (WNV) and Usutu (USUV) flaviviruses in Europe in recent decades highlights the urgent need to understand the transmission networks of these pathogens as a basis for effective decision-making. These viruses are part of a complex disease cycle that involves birds as principal hosts and humans and horses as dead-end hosts. Our study aims to uncover the intricate relationships between the main mosquito vector of these viruses, Culex pipiens L. (Diptera: Culicidae) and its feeding preferences based on the forage ratio among several host species, primarily birds in a land-use gradient. We estimated the bird host potential to act as a host for flavivirus, the reservoir capacity index, based on forage ratios and potential host competence based on molecular prevalence. We sampled mosquitoes and, at the same time, conducted bird censuses in the Camargue region in southern France, where co-circulation of these viruses has been reported. Several localities were sampled along a land-use gradient in peri-urban, agricultural and natural areas from May to November 2021. We identified 55 vertebrate species in 110 engorged Cx. pipiens by PCR amplification and sequencing of mitochondrial 12S and 16S Ribosomal DNA genes. Culex pipiens feeds primarily on 51 bird species and secondarily on two mammals, one amphibian and one reptile. Based on forage ratios, we found a preference of Cx. pipiens in the Camargue for the order Passeriformes and, more specifically, for Columba livia domestica L. (Columbiformes: Columbidae) in agricultural areas, and for Passer domesticus/montanus L. (Passeriformes: Passeridae), in agricultural and peri-urban areas. The natural habitats had significantly higher forage ratio values than agricultural and peri-urban areas. We suggest that certain key species, such as Passer sp., Columba livia and Turdus sp., might be potentially considered locally relevant hosts for transmission in this area, as they are important for mosquito feeding and also potentially important hosts for flavivirus amplification. These data will be beneficial in understanding host–vector interactions and the relationships between bird communities, mosquito feeding preferences and emerging mosquito-borne diseases.

We studied geographic patterns of functional and phylogenetic niche breadth of 194 flea species. Niche breadth was measured as the functional and phylogenetic diversity and uniqueness of the assemblages of small mammal hosts exploited by these fleas.We asked (a) whether the relationships between niche breadth and geographic range size conform to the ‘niche breadth hypothesis’, predicting positive correlations, and (b) whether variation of niche breadth along the latitudinal position of geographic range conforms to the ‘niche breadth-latitude hypothesis’, predicting narrower niche breadth at lower latitudes. We found that the functional and phylogenetic diversity, but not the functional and phylogenetic uniqueness, of the host assemblages demonstrated patterns conforming to the prediction of the ‘niche breadth hypothesis’. Host assemblages exploited by broadly distributed fleas tended to be functionally and phylogenetically more diverse than those of fleas with a restricted geographic distribution, but the functional and phylogenetic uniqueness of hosts decreased in more broadly distributed fleas. The phylogenetic diversity of hosts exploited by a flea did not vary with the latitudinal position of the flea's geographic range. In contrast, the functional diversity and both the functional and phylogenetic uniqueness of hosts decreased from south to north, thus contradicting the predictions of ‘the niche breadth-latitude hypothesis’. Comparing these and earlier results on the geographic patterns of flea niche breadth, we conclude (a) that compositional, functional and phylogenetic diversity could be similarly driven by some factors and differently by other factors and (b) that these diversity facets are not always good surrogates for each other.

Climate change is associated with an increase in adverse weather events such as heatwaves, drought, hurricanes and typhoons, floods and wildfires. These extreme weather events can disrupt public health infrastructure and can be detrimental to hygiene and sanitation practices, leading to knock-on effects on populations of vectors associated with disease transmission. Both the frequency and intensity of climate-related adverse weather events are predicted to increase, likely resulting in changes to vector dynamics and vector–human interactions, leading to an increased risk of disease transmission. Yet, a gap exists in our knowledge of the impact of these events on hygiene and associated pest-borne diseases. A growing body of research connects two groups of pests (domestic flies and cockroaches) that are linked with poor hygiene and sanitary conditions to mechanical disease transmission. We present a review of these specific vectors' population biology and behaviour, links with hygiene and sanitation and how pest populations and public health could be affected by adverse weather events. There is evidence that increased temperatures, extreme rainfall and flooding events are most likely to be associated with increased fly and cockroach populations and changes in the behaviour or activity of these insects, which could exacerbate the risks of disease transmission. Warmer temperatures accelerate their rates of reproduction, while heavy rainfall and flooding disrupt their habitats, driving them indoors. Other factors like habitat destruction, breakdown in healthcare system infrastructure, population displacement and altered pesticide use following an extreme weather event are predicted to influence insect populations and provide opportunities for increased human –pest contact. We highlight research gaps and provide recommendations for the improvement of current domestic and professional pest control products and strategies that might be employed to mitigate the impacts of adverse weather events on hygiene-related pests in a changing world.

Aedes aegypti L. and Aedes albopictus Skuse mosquitoes (Diptera: Culicidae), the principal vectors of many human arboviral diseases, lay eggs and undergo preimaginal development in fresh water. They have recently been shown to also develop in brackish water in coastal areas. Previous findings showed that Ae. aegypti larvae developing in brackish water possessed thicker cuticles and greater larvicide resistance than larvae developing in fresh water. The present study compared cuticle ultrastructure, resistance to adulticides, and the activities of adulticide detoxifying enzymes in female mosquitoes emerging from fresh and brackish water-developing Ae. aegypti preimaginal stages. The results showed that brackish water-derived females possessed significantly thicker tarsal and abdominal cuticles compared to fresh water-derived females. Brackish water-derived Ae. aegypti females were also significantly more resistant to three different types of pyrethroids and malathion compared to fresh water-derived females. Corresponding reversal of cuticle changes and adulticide resistance when preimaginal salinity was reversed showed that preimaginal salinity determined both procuticle structure and adulticide resistance in brackish water-derived females. Compared with fresh water-derived Ae. aegypti females, brackish water-derived females had similar activities of the adulticide-detoxifying enzyme families of esterases and glutathione S-transferases and a modest increase in the activity of monooxygenases, all of which were lower than the threshold values attributed to resistance in field populations of Ae. aegypti. Reduced permeability of the thicker and remodelled cuticles in brackish water-derived Ae. aegypti females to adulticides is proposed to be mainly responsible for their greater resistance to different types of adulticides. Greater salinity tolerance of preimaginal stages, adult cuticle changes and higher larvicide and adulticide resistance are inherited properties of brackish water-developing Ae. aegypti that reverse in a few generations after transfer to fresh water. This is compatible with a role for epigenetic changes in the adaptation of Ae. aegypti to brackish water. Greater resistance of salinity-tolerant Ae. aegypti to adulticides and larvicides poses a hitherto unappreciated problem for controlling arboviral diseases, with attendant implications also for other mosquito-borne diseases.

Blood meal patterns of mosquitoes (Diptera: Culicidae) are strongly influenced by host availability. However, the role of community composition and abundance of vertebrate hosts in determining such patterns is still unclear. Here, we analysed the blood meal sources of field-collected mosquitoes in settings with a permanent overabundance of a specific vertebrate species. Mosquitoes were collected using a battery-powered handheld aspirator every 2 months between November 2021 and April 2022 in temperate Argentina. Blood-engorged mosquitoes were collected at 11 sites corresponding to five types of settings: two cattle fields, one rabbit breeding farm, three chicken farms, two dog boarding facilities, and three geriatric hospitals, characterised by the permanent overabundance of cows, rabbits, chickens, dogs, and humans, respectively. Blood meal analysis was performed via polymerase chain reaction (PCR) and sequencing. A principal component analysis (PCA) was performed in which variables were pairs comprising an engorged mosquito species and the host species it fed on. A total of 242 blood meals from Aedes (3 species), Culex (4), Isostomyia (1) and Psorophora (1) were identified. Among these, five mammals and 12 avian species were identified as hosts. Overall, 79% of the blood meals were taken from the overabundant host, ranging from 67% to 99% in all settings except for geriatric hospitals (7%). The proportion of feeds taken on the overabundant host was lowest for Culex quinquefasciatus Say (0.67, N = 119), Cx. pipiens molestus Forskal (0.5, N = 18) and the hybrid between the two (0.5, N = 2), and highest for Aedes aegypti Linnaeus (1, N = 2), Ae. albifasciatus Macquart (1, N = 3), Ae. crinifer Theobald (1, N = 46), Cx. eduardoi Casal & García (0.9, N = 10), Isostomyia paranensis Brèthes (1, N = 20) and Psorophora ferox Humboldt (1, N = 21). By fixing host abundance in preselected settings, we propose a field design that overcomes the difficulties of estimating host community composition. This approach aids in achieving a clearer understanding of mosquito feeding patterns and their implications for arbovirus disease transmission.

Many ectoparasite species serve as vectors for bacteria that are significant to both public and animal health, with wild, domestic and synanthropic mammals acting as reservoirs. However, limited information exists on the circulation and incidence of these vectors in Argentina. We examined the diversity, prevalence and abundance of ectoparasites, along with the presence of Rickettsia spp., of Didelphis albiventris Lund (Didelphimorphia, Didelphidae) within a rural landscape of the Pampas region, Argentina. We also analysed variations in ectoparasite populations concerning seasonality, livestock farm type and farmers' management practices. Seven species of hematophagous ectoparasites were collected, including mites (Mesostigmata, Laelapidae: Laelaps echidninus Berlese); ticks (Ixodida, Ixodidae: Ixodes loricatus Neumann); fleas (Siphonaptera, Rhopalopsyllidae: Polygenis platensis Jordan and Rothschild and Polygenis rimatus Jordan); Stephanocircidae: Craneopsylla minerva wolffhuegeli (Rothschild, Pulicidae: Ctenocephalides felis Bouché); and lice (Phthiraptera, Polyplacidae: Polyplax spinulosa Burmeister). Additionally, two bacteria were detected: Rickettsia felis Bouyer et al. (Rickettsiales, Rickettsiaceae) and Rickettsia sp. (Rickettsiales, Rickettsiaceae) were closely related to Rickettsia bellii Philip et al. (Rickettsiales, Rickettsiaceae). Fleas were the most prevalent and abundant group, with C. felis showing the highest values of mean abundance and prevalence. Parasitological comparisons between dairy farms and feedlots revealed similar results, with comparable densities of D. albiventris in both farm types. Ectoparasite abundance varied seasonally, peaking during the colder season. Regression analysis indicated higher ectoparasite infestation levels on farms with more dogs. The detection of pathogenic bacteria, coupled with the high prevalence and abundance of vectors, such as C. felis, suggests a significant epidemiological risk in the region. The commensal behaviour of D. albiventris facilitates it to thrive in areas modified by anthropogenic activity, positioning this species as a potential nexus between wild and domestic epidemiological cycles of parasites and emerging pathogens. Therefore, our findings suggest that D. albiventris plays a key role in the transmission and maintenance of ectoparasites and ectoparasite-borne bacteria within these ecosystems.

Changes in climate may cause changes in the ranges, phenology and interactions of insects with other species and lead parasites to switch host species. A study of louse (flat) flies in the United Kingdom, Republic of Ireland and Isle of Man, in which licensed bird ringers acting as citizen scientists collected ectoparasites that left birds during ringing, showed recent range shifts of several species. The Common or Bird Louse Fly Ornithomya avicularia (Linnaeus, 1758), a vector of Haemoproteus sp. and trypanosomes, has undergone a major northwards range expansion of over 300 km in the United Kingdom (UK) since the 1960s. The Finch Louse Fly Ornithomya fringillina (Curtis, 1836) has also expanded its range over 300 km northwards and 400 km westwards into the Island of Ireland, and the Swallow Louse Fly Ornithomya biloba (Dufour, 1827) is now established in Wales and Southern England. The Grouse Louse Fly Ornithomya chloropus (Bergroth, 1901) has undergone a range contraction at lower altitudes and on the southern edge of its range. Other species of louse fly were detected: Crataerina pallida (Latreille, 1812), Stenepteryx hirundinis (Linnaeus, 1758), Pseudolynchia garzettae (Rondani, 1879) and Icosta minor (Bigot, 1858). Some generalist species have shifted their phenology, whereas the more specialist nest parasites of migrant birds have not, as the arrival and breeding dates of their hosts have not changed. The range changes of the generalist species of these ectoparasites may have implications for bird health, especially if they switch to new host species as their ranges shift.