Journal of Vector Ecology最新文献

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.

Dermacentor reticulatus is a widely distributed tick species in Europe, whose rapid range expansion and importance as a vector of multiple pathogens have increased scientific interest in its genetic diversity and population structure. The Baltic States region, which has been experiencing D. reticulatus tick migration into northern areas over the last two decades, with its unique ecological and climatic conditions, could offer valuable insights into tick distribution patterns and their genetic structure in northern European ranges. This study aimed to investigate the genetic variation of D. reticulatus across its European range, including new data from the Baltic States. Genetic variability of 83 D. reticulatus tick samples from 42 locations across the Baltic states, central, western, and southeastern Europe was assessed using mitochondrial (12S rRNA, 16S rRNA) and nuclear (ITS2) markers. The study revealed low genetic variability in D. reticulatus populations across Europe, characterized by a dominant haplotype present in the Baltic states as well as central and western Europe. Unique haplotypes discovered in the Baltic region may be associated with environmental factors and the recent range expansion of the species. The presence of unique haplotypes and genetic variability among northern D. reticulatus populations suggests ongoing local adaptation driven by environmental pressures, including regional climate and landscape heterogeneity in newly colonized habitats.

Tick-borne pathogens pose an ongoing threat to human health in the southeastern United States, where tick and host abundances are high. In North Carolina, several medically important tick species are present, but in the Piedmont region, Amblyomma americanum is particularly abundant and associated with multiple human pathogens, including Rickettsia amblyommatis, a hypothesized human pathogen. In this study, we build on recent tick surveillance efforts across several North Carolina counties by screening A. americanum for Ehrlichia ewingii, Ehrlichia chaffeensis, and R. amblyommatis while also analyzing tick abundance, pathogen prevalence, and county-level human disease case data from the North Carolina Department of Health to assess potential correlations. Our results reveal variation in pathogen prevalence across counties, with Chatham County consistently emerging as a high-risk area due to high tick abundance and elevated infection rates. However, we did not observe a strong correlation between tick abundance or pathogen prevalence and reported human disease cases at the county level. These findings highlight counties of elevated risk in a region experiencing an increasing burden of tick-borne disease and contribute to our understanding of ongoing public health trends.

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.

The subtropical coastal plain of Deep South Texas provides a wildlife corridor for hosts of disease-transmitting ixodid species, including the southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini). Wind tides and storm surges push hypersaline Lower Laguna Madre water inland on occasion, creating substantial areas of saline soil dominated by sea ox-eye daisy, Borrichia frutescens (L.) DC, and inhabited by numerous mud flat fiddler crabs, Uca rapax (Smith). Ixodid populations, especially larvae, in the saline areas are mostly negligible because of saltwater toxicity to eggs, desiccation, and predators. Soil salinity, U. rapax populations, and ant foraging activity were determined for areas dominated by B. frutescens, areas with intermediate stands, and areas without the plant. Borrichia frutescens density and U. rapax populations were moderately correlated with soil salinity, but predatory ant foraging was not correlated with soil salinity, B. frutescens density, and U. rapax abundance. Borrichia frutescens stand density, however, was strongly correlated with numbers of U. rapax holes, hence, the plant is an indicator of negligible ixodid activity. GIS mapping of high-Borrichia habitats might be useful for refining surveillance of ixodid populations, particularly one-host ixodids, such as R. (B.) microplus.

Many farmers house livestock in open pens or sheds that offer no physical protection against biting flies, with protection relying heavily on the use of residual or on-animal insecticides. Insecticidal barriers can offer an alternative or additional option to managing pestiferous biting flies near livestock but they need to be evaluated in the field. We assessed the efficacy of a deltamethrin-incorporated net to reduce contact of Culicoides and mosquitoes with livestock. On cervid farms, reduction of biting-midges in light traps was assessed for traps surrounded by deltamethrin-treated nets, untreated nets, or no-net controls. Significantly fewer Culicoides were collected in pens surrounded by untreated nets compared to no-net, and further significant reductions were achieved with deltamethrin-treated nets. Similar results were observed on a subsistence poultry and swine farm. Total Culicoides and mosquito abundance and abundance of blood-fed females was significantly reduced in light-trap collections after surrounding livestock units with a deltamethrin-treated net. These results suggest the use of insecticidal nets at a 2 m height can reduce contact between livestock and some biting flies in open areas or sheds.

In Peru, since the beginning of the 20^th 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.

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.

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.