搜索结果：Journal of vector ecology : journal of the Society for Vector Ecology

Brazil is endemic for both visceral (VL) and cutaneous (CL) clinical forms of leishmaniasis, poverty-associated diseases with worldwide distribution. Leishmania parasites are the etiological agents of leishmaniases, which are transmitted to humans through the bites of infected phlebotomine sand flies. From 2018 to 2023, 15 cases of VL and 129 cases of CL were reported in Téofilo Otoni, an important economic center in the Brazilian state of Minas Gerais. Owing to the lack of data on the entomological fauna, the present study aimed to clarify this main aspect of leishmaniasis. From May, 2021 to April, 2023, entomological captures were performed monthly in ten neighborhoods in Teófilo Otoni. The influence of bioclimatic variables on insect populations was evaluated, and natural infection by Leishmania spp. was investigated using molecular methods. A total of 306 specimens of 12 species of phlebotomine sand fly were collected. The majority (91.6%) were proven or putative vectors of leishmaniasis agents. The population of insects tended to increase during the cooler and drier months. Although Leishmania infection was not detected in any of the samples, the presence of vectors provides conditions for the maintenance and expansion of the transmission cycle of leishmaniasis in Teófilo Otoni.

In 2021, Japanese encephalitis virus (JEV) reverse transcription quantitative RT-qPCR testing of mosquitoes was used for the first time in the Northern Territory (NT) in an attempt to determine the presence of circulating JEV and identify probable vector mosquito species. All test results for 2021 and 2022 returned negative for JEV. Testing resumed in January, 2023, with mosquitoes also tested for Murray Valley encephalitis virus (MVEV) following an outbreak resulting in eight confirmed human cases. Mosquito pools tested positive by RT-qPCR for both viruses on several occasions, confirming the suitability of this method for flavivirus surveillance. Culex annulirostris (Skuse) and Cx. gelidus (Theobald) tested RT-qPCR positive for both viruses in 2023, incriminating them as JEV and MVEV vectors in the NT. Aedes normanensis (Taylor) also tested positive for JEV and MVEV, identifying this species as a probable vector species for both viruses in the NT. While Cx. annulirostris is known to be the principal MVEV vector in the NT, the fact that all three vector mosquito species potentially play a part in the JEV transmission cycle is of major public health concern. While Cx. tritaeniorhynchus (Giles) did not test positive to JEV in 2023, this species is the principal JEV vector in SE Asia and could potentially play a role in JEV transmission in the NT. Genotyping of viruses from the NT mosquitoes confirmed the continued circulation of genotype IV JEV and showed that both genotypes 1A and 2 of MVEV were co-circulating in the NT in 2023.

There are many invasive alien insect species, several of these species can affect human health by causing disease. These include vectors of vector-borne diseases, such as the triatomines that transmit Chagas disease. Triatoma longipennis Usinger (Hemiptera: Reduviidae) is one of the most epidemiologically important vector species of Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae) in Mexico. This study reports the third collection of T. longipennis from the state of Hidalgo, Mexico, where the prevalence of T. cruzi infection in humans has historically exceeded 3.38%. This study evaluates several biological parameters of T. longipennis related to the egg-to-adult development time, number of blood meals to molt, and mortality for each instar, of two populations of the invasive species T. longipennis, recently detected in Hidalgo, as well as fecundity and fertility of females at the end of the cycle. Similar results were observed in the two populations for parameters studied, such as median egg-to-adult development time (162, 174 days), number of blood meals at each nymphal instar (7, 8 meals), total mortality (56%, 61%), fecundity (2.8 eggs/female/day) and fertility (83.3, 84.2%). These observed parameters suggest that both populations of the invasive T. longipennis detected in Hidalgo could be important transmitters of T. cruzi and could replace key triatomine species within their new distribution area.

Lutzia vorax Theobald (Diptera: Culicidae) is a ferocious predator of small container habitats in the forests and rural areas of the eastern Palearctic and Oriental regions. Owing to its consumption of various invertebrates, including mosquito larvae, it is considered a potential biological control agent of vector species. However, studies on the general biology of Lt. vorax are scarce; thus, our understanding of its role in natural habitats is limited. To elucidate its ecological role with regard to its interaction with vector species populations, we conducted field monitoring surveys in two different deciduous forests in South Korea, using tire traps for larvae in 2023. Community samples of mosquito larvae were collected every three weeks (July to September, 2023) from each trap, which replicated the natural container environment in forest areas. Then, community structures were compared based on the presence or absence of Lt. vorax. Communities with Lt. vorax larvae exhibited distinct structures characterized by lower species richness, diversity, and vector species density. Furthermore, non-metric multidimensional scaling results showed that the group structure differed depending on the presence of Lt. vorax larvae. Gut content analysis of the predaceous larvae supported the evidence of top-down regulation of Lt. vorax with considerable predation rates on other mosquito larvae in each habitat: 63.92 ± 30.72% in Site A and 72.85 ± 18.03% in Site B (mean ± SD). Thus, we suggest that Lt. vorax serves as both a significant natural enemy and key predator species in container habitats in the forested areas of Korea.

Culicoides midges are vectors of bluetongue virus (BTV), an arbovirus affecting wild and domestic ruminants. Bluetongue distribution generally overlaps with vector range, so understanding the vector's ecology is necessary for predicting BTV risk. Culicoides require moist substrate for development, and C. sonorensis, the primary recognized vector in the western United States, is classically associated with livestock wastewater ponds. However, it is well-known that BTV can be found outside of livestock areas, with transmission occurring in natural settings. To better classify development habitat, we conducted a broad biweekly survey of moist and wet habitats from June to September of 2022 in northern Colorado at ten sites, including large livestock operations, non-commercial domestic operations, and natural spaces. Samples were maintained in the insectary for 11 weeks and monitored for emergence of adult midges. Standing water substrates displayed higher presence and abundance of midges than running or transient habitats, though all microhabitats showed emergence. Additionally, livestock sites did not produce more midges than other site types, and in fact more midges were observed in natural spaces per sample and overall. Livestock spaces did, however, show significantly higher proportions of C. sonorensis midges, which are thought to be the most competent vectors of BTV in this region, as opposed to other Culicoides species. These results suggest that development sites in natural areas may play an important role in maintaining vector populations in the western U.S. outside of previously implicated livestock operations, and that differences in larval habitat lead to differences in vector species composition.

Land cover is recognized as an important determinant of mosquito community assemblages and pathogen transmission, but few studies have investigated the role of land cover in populations of La Crosse virus (LACV) vectors. La Crosse virus is a zoonotic disease primarily maintained by native Aedes triseriatus, with accessory transmission by invasive vectors Ae. albopictus and Ae. japonicus. The objective of this study was to investigate the association between land cover composition and the egg abundances of LACV vectors in a city with endemic LACV transmission. Oviposition cups were deployed at sites ranging from recreational forests to urban areas. Mixed-effects regression models were used to test the relationships between land cover composition and species abundances. Sites characterized by large percentages of impervious and built surfaces were dominated by Ae. albopictus, but Ae. triseriatus was the most abundant species in forested areas. Aedes japonicus was rare at all sites, but its presence was associated with higher percentages of forested land. These results indicate that forested areas may allow Ae. triseriatus to maintain large populations near urban areas that are dominated by Ae. albopictus. Further research should explore the potential for these land cover-dependent population dynamics to influence LACV transmission cycles.

We investigated the abundance and distribution of Aedes aegypti and Aedes albopictus mosquitoes in urban parks in the eastern zone of the city of São Paulo, where the highest number of autochthonous dengue cases during the major 2015-2016 epidemic was reported. The association of climatic and environmental factors with the spatiotemporal distribution of species in relation to vegetation cover and human proximity was examined. Twelve geo-referenced ovitraps were randomly installed in each park, covering areas with varying degrees of vegetation and human activity from September, 2018 to February, 2020, during three weeks each season. A total of 57,604 Aedes aegypti or Aedes albopictus eggs were collected, identifying 10,228 Ae. aegypti and 23,764 Ae. albopictus larvae. Seasonal variations showed distinct patterns with higher mosquito abundances during warmer and rainier seasons. The association between abundance and climatic factors was more evident at the level of the aedini assemblies than at the level of the local populations. Aedes aegypti was predominantly found in peripheral and transitional areas with higher human activity during rainy and warmer seasons. In contrast, Ae. albopictus thrived in inner park areas with greater vegetation cover and lower human activity during drier and milder seasons. The abundance of Ae. aegypti and Ae. albopictus was influenced by climatic factors and park-specific microhabitats. These findings underscore the importance of targeted vector control strategies in urban park settings during seasons favorable for mosquito reproduction. Understanding the interaction between ecological factors and these mosquitoes in urban environments is critical for effective public health interventions.

Spatial and temporal differences in the relative abundance of arthropod vectors are important factors that influence the risk of disease for mammalian hosts. Seasonal changes in the diversity and abundance of fleas (Siphonaptera) in Richardson's ground squirrel (Urocitellus richardsonii) burrows were studied at two sites in central Saskatchewan. A total of 225 fleas (151 at an urban site and 74 at a rural site) were collected. Flea prevalence differed among seasons at the urban site but not at the rural site. Of the nine flea species detected (eight at the urban site and six at the rural site), Oropsylla rupestris, O. bruneri, O. labis, O. tuberculata, and Aetheca wagneri are vectors of Yersinia pestis, the causative agent of plague. The presence and abundance of some fleas differed between sites and seasons. Neopsylla inopina and O. rupestris were the most abundant species at the urban site during the spring and summer, respectively, while O. bruneri was the most abundant species at the rural site. Our findings may have implications for the management of the black-tailed prairie dogs (Cynomys ludovicianus) in southwestern Saskatchewan because they coexist with U. richardsonii, are hosts for Oropsylla, and are at great risk of plague exposure/infection.

In Peru, since the beginning of the 20th century, 18 mosquito species (Diptera: Culicidae) and three forms have been discovered by previous authors: Anopheles acanthotorynus, An. calderoni, An. peruvianus, Chagasia ablusa, Ae. (Howardina) Iquitos form, Aedes epinolus, Haemagogus obscurescens, Hg. (Conopostegus) Peruvian highland form, Hg. (Con.) Peruvian lowland form, Culex archegus, Cx. debilis, Cx. diplophyllum, Cx. escomeli, Cx. raymondii, Onirion aenigma, On. celatum, Sabethes idiogenes, Trichoprosopon hyperlecum, Tr. subsplendens, Wyeomyia baltae, and Wy. paucartamboensis. Of these, seven species were later synonymized under the name of other species, the rest remain as valid species, one of them is placed in Nomen dubium, and the forms continue retained without specific status. With the intention of updating the checklist of mosquito species in Peru, historical and recent species-records were reviewed and mosquito collections were conducted in specific sites of Peru, resulting in the confirmation of the presence of Hg. anastasionis, Hg. capricornii, Psorophora dimidiata, Ps. cilipes, Cx. usquatissimus, Cx. dunni, Mansonia wilsoni, Johnbelkinia leucopus, Limatus pseudomethysticus, Tr. compressum, and Uranotaenia socialis. Additionally, Ae. aurivittatus, Ae. terrens/zavortinki, Cx. acharistus, Cx. dolosus, and Cx. surinamensis are reported for the first time in Peru, while An. apicimacula, An. mediopunctatus, Ae. condolescens, Cx. bihaicolus, and Sa. tarsopus are removed from the Peruvian mosquito fauna. An updated list of 198 nominal species and four forms of mosquitoes from Peru is presented.

Amazonian savannas are among the most noteworthy landscape components of the coastal plain of French Guiana. Although they cover only 0.22% of the territory, they bring together a large part of the animal and plant diversity of this overseas region of France. This article outlines the results of the first study dedicated to mosquitoes (Diptera: Culicidae) of Amazonian savannas. Samplings were conducted in eight independent savannas evenly distributed along a transect of 170 km on the coastal plain of French Guiana. A total of 50 mosquito species were recorded, which is about 20% of the culicid fauna currently known in French Guiana. Among them, Culex (Melanoconion) organaboensis sp. nov. and Cx. (Mel.) zabanicus sp. nov. are newly described based on both morphological features of the male genitalia and a DNA barcode obtained from type specimens. Diagnostic characters to assist their identification are provided and their placement within the infrasubgeneric classification of the subgenus Melanoconion is discussed.

Because the vertical distribution and diversity of blood-sucking flies are poorly known, we determined the diversity, structure, and composition of culicids between vertical vegetation strata. We evaluated the influence of microclimatic variables during different times of the day over a year. We used eight CDC traps baited with CO2 at a height of 1.5 m and 12-15 m. We conducted rank-abundance curves, similarity analysis (ANOSIM and SIMPER), and multivariate clustering with incidence and abundance data. We used GAM models to analyze the influence of strata (understory vs canopy), humidity, and temperature on insect richness and abundance. During the day, the difference between strata was mainly due to higher abundance of Wyeomyia arthrostigma and Wyeomyia ca. adelpha in the understory. During the night, the differences were mainly due to higher abundance of Culex stigmatosoma, Culex salinarius, and Aedes allotecnon in the canopy, and Wyeomyia arthrostigma in the understory. Seasonality played a role in the similarity between the strata. Diversity during the day was positively related to humidity and temperature, and nocturnal diversity increased with temperature but decreased with higher humidity. The effects of environmental factors on the spatiotemporal distribution of fly species are essential for epidemiological surveillance.

Chagas disease is one of the most important vector-borne diseases in Latin America. Triatoma picturata (Usinger), distributed in western Mexico, is one of the most important vectors of Trypanosoma cruzi Chagas. Knowing the type and materials used for building homes could lead to improved methods for controlling triatomines by focusing efforts on controlling every species of triatomine in its specific microhabitat. Houses in three studied localities of western Mexico that harbored T. picturata were characterized, as well as two entomological indices. Infestation Index values varied from 10.8% to 51.9% in the three localities, whereas Natural Infection Index values varied from 18.1% to 35.2%. Characteristics of houses invaded by T. picturata also varied. In Juan Gil Preciado, with the highest Entomological Index values, most houses were built of adobe walls with a roof of clay tiles and a dirt floor, and included the presence of domestic animals. Our data indicate that the potential risk of infection with T. cruzi differs markedly for inhabitants of the three studied localities, which demonstrates the importance of studying local populations of triatomines. Our study should contribute to decision-making regarding triatomine control efforts by providing profiles of houses that are more susceptible to triatomine invasion.

The CDC light trap with incandescent light is the most commonly used method for conducting sand fly surveillance. However, new trap models that use LED lights might provide a more cost-effective alternative. This study compared the efficacy of a modified commercial Katchy light trap with two CDC light trap models in capturing sand flies in the Amazonian rainforest of Peru. Using a 3 x 3 randomized Latin square design, the light traps were compared based on phlebotomine sand fly species total abundance, species richness, sex-specific collections, and efficiency in capturing potential vector species. A total of 1,184 sand flies were collected, representing nine genera and 25 species, including three species that had not been previously reported in the Cusco department. Significant differences in sand fly collections based on trap type were found, with the modified Katchy light trap capturing significantly higher total abundance and species richness compared to CDC light traps. This pattern held for both female and male sand flies, with the modified Katchy trap also collecting more potential vector species in terms of both abundance and species richness, although differences in potential vector species richness were only significant compared to the incandescent CDC light trap. These results suggest that the modified Katchy trap is a viable, cost-effective alternative for sand fly surveillance, offering potential improvements in leishmaniasis vector monitoring.

Ticks are vectors of many zoonotic pathogens of clinical relevance, including Anaplasma and Rickettsia species. Since few data about these tick-borne pathogens are available in the Canary Islands, the aim of the present study was to screen their presence in questing and feeding ticks on the island of Tenerife. A total of 81 ticks was removed from six hedgehogs, and eight ticks were collected from the grass. PCR assays for tick species identification based on the LSU rRNA gene, and detection of Anaplasma spp. and Rickettsia spp. by targeting the 16s rRNA and gltA gene, respectively, were carried out. Rhipicephalus sanguineus and Haemaphysalis formosensis tick species were identified, with Rickettsia hoogstraalii detected in H. formosensis. In addition, Rickettsia helvetica and one unidentified Rickettsia species were detected. The overall prevalence of Rickettsia in ticks was 12.2%, and none harbored Anaplasma sp. This work constitutes the first identification in the Canary Islands of pathogenic R. helvetica and the species of unknown pathogenicity R. hoogstraalii in questing ticks. The clinical relevance of the pathogens identified highlights the need for studies with increased sample size and locations, including potential hosts, as well as warning the population about the relevance of ticks as vectors.

Dermacentor ticks are widespread in eastern Washington and are known vectors of bacterial pathogens and harborers of endosymbionts belonging to the genera Francisella and Rickettsia. Some Dermacentor species can become infected with Ehrlichia chaffeensis Anderson et al. (Rickettsiales: Ehrlichiaceae); it remains unclear if any are competent vectors for this bacterial pathogen. This study reports the abundance of Dermacentor species and prevalence of select tick-borne bacterial pathogens collected from two conservation areas popular among hikers in Spokane County, Washington. In total, DNA from 599 adult ticks was analyzed using PCR; 87.8% (526/599) were identified as Dermacentor andersoni Stiles and 12.2% (73/599) as D. similis Lado, Glon and Klompen (Ixodida: Ixodidae). Ticks were also screened for the presence of bacterial DNA using genus- or species-specific primers targeting Rickettsia spp., Francisella spp., and E. chaffeensis. Rickettsia endosymbionts, R. peacockii Niebylski et al. or R. rhipicephali (Burgdorfer et al.) Weiss and Moulder (Rickettsiales: Rickettsiaceae), were found in 4.0% (21/526) of D. andersoni. Francisella-like endosymbionts were detected in 65.9% (395/599) of all ticks. No species known to be pathogenic belonging to either Rickettsia or Francisella were detected. However, E. chaffeensis was detected in 15.3% (12/73) of D. similis, which to our knowledge is the first report of ticks harboring this species of bacteria in Washington state. These findings contribute to understanding the microbial ecology of ticks in the Inland Northwest.

Lyme disease is the most prevalent vector-borne disease in the U.S., and acaricidal feeds administered to white-tailed deer (Odocoileus virginianus) have potential to disrupt blood feeding by the blacklegged tick, Ixodes scapularis. Two studies were conducted with the aim of determining an ideal formulation to deliver oral acaricides to white-tailed deer and finding the lowest fipronil dose level to effectively control I. scapularis. During formulation screening, various commercial attractants (baits) were presented to deer in large paddocks under semi-field conditions and motion-sensitive cameras were used to monitor consumption by deer and non-target species. During dose range-finding, deer were housed individually and presented a fipronil feed at one of five dose levels for 48 h (two deer untreated). At 24 h post-exposure, the deer were anesthetized, blood was drawn, and deer were manually infested with 20 I. scapularis mating pairs in feeding capsules. Tick mortality was monitored up to nine days post-attachment. Results of formulation screening indicated that loose/granular formulations were substantially more palatable to deer, relative to block formulations, and would be more effective under field conditions. Dose range-finding concluded fipronil feeds with doses of 25 ppm and higher would eliminate 100% of I. scapularis parasitizing deer. Additionally, 10 ppm fipronil feed controlled a considerable proportion of ticks, and results suggested 100% ticks could be eliminated if fipronil sulfone was present in plasma at ≥25.1 ppb. These results were paramount in developing a low dose fipronil deer feed for tick control and should provide valuable insights prior to execution of future field trials.

The stridulation in the subfamily Triatominae has been identified as a means of communication between species, produced by the friction of the proboscis on the prosternal stridulatory groove. Despite its biological significance, this phenomenon remains understudied, with the signal's production seemingly contingent upon the morphology of the stridulatory groove. In this study, we examined the morphology of stridulatory grooves in females and males of five species and two subspecies of Mexican triatomines using morphometric and scanning electron microscopical analysis. Our findings reveal that all analyzed species exhibit triangular-shaped stridulatory grooves with parallel ridges covering the entire groove, bordered on each side, and covered with setae. Surprisingly, we observed noticeable differences in the number of ridges and inter-ridge distance between the species Triatoma lecticularia and Triatoma rubida (p < 0.001 and p < 0.009, respectively), indicating sexual dimorphism in this aspect, a phenomenon not previously reported in the morphology of this structure. Our findings shed light on the intricate morphology of the stridulatory groove in Mexican triatomines, suggesting potential implications for their behavior and intra-specific communication.

Exposure to ticks (Acari: Ixodidae) puts humans and their companion animals at risk of tick bites and potential pathogen transmission. Bites often occur when humans encounter ticks outdoors, but there may also be a risk in the home given the propensity of ticks to hitchhike on clothes and pets. We assessed survival of two tick species widely distributed across the southeastern United States, Amblyomma maculatum Koch and A. americanum Linnaeus, on different types of flooring commonly found in residential homes. We placed ticks individually onto one of five different types of flooring (tile, wood, vinyl, short pile carpet, and long pile carpet; n = 180 total, 36 ticks per species per floor type). Ticks were contained in plastic cups fixed in place on each floor type to reduce movement and/or escape and promote tick contact with the flooring. Survival was assessed as a function of the interaction between species and floor type. We found that A. maculatum ticks survived for significantly longer periods of time than A. americanum (median survival/mean survival) on vinyl (22.5/25.4 vs. 11.5/10.4 d), wood (18.5/16.1 vs. 11.0/12.2 d), tile (21.0/20.4 vs. 6.5/7.33 d) and short pile carpet (20.0/20.8 vs. 10.5/10.8 d), but A. americanum lived longer overall on long pile carpet (13.0/10.4 vs. 13.0/14.9 d). Our findings help clarify expected tick survival following entry into the home, and how floor type can mediate in-home tick exposure. Furthermore, this work emphasizes the necessity of performing tick checks, wearing protective clothing, and applying appropriate acaricides to people and pets to prevent tick transportation into the home.

Triatominae are associated with various Brazilian habitats, including bird nests, animal burrows, and peridomestic structures. Despite extensive studies on triatomines in domiciliary environments in Cear&#xe1;, Brazil, there has been limited research on their presence in the wild. This study focuses on the municipality of Morrinhos in Cear&#xe1;, which is characterized by a Caatinga biome and riparian forests along the Acara&#xfa; River. During the study, a total of 185 nests of Pseudoseisura cristata were analyzed in rural locations and triatomines were collected in 26 nests from 12 different locations. A total of 117 triatomines was collected, belonging to three species: Psammolestes tertius, Rhodnius nasutus, and Triatoma pseudomaculata. Rhodnius nasutus was the only species found in a nest inhabited by Didelphis albiventris. Nests of P. cristata serve as shelters for various animals, providing an ideal environment for triatomines to establish colonies due to their proximity to food sources and their generalist feeding habits. The incorporation of anthropogenic materials by birds in nest construction can indirectly affect the presence of other animals that may serve as food sources for triatomines. Understanding the interactions between triatomines, birds, and their habitats is essential for assessing the risks associated with triatomine infestation in wild ecosystems.