Journal of Vector Ecology最新文献

The genus Bartonella contains facultative Gram-negative intracellular bacteria from the family Bartonellaceae that can cause diseases in humans and animals. Various Bartonella species have been detected in rodents' ectoparasites, such as fleas, ticks, mites, and lice. However, the role of laelapid mites (Mesostigmata: Laelapidae) as carriers of Bartonella spp. needs to be confirmed. We aimed to investigate the presence of Bartonella spp. in laelapid mites collected from small rodents in Lithuania using real-time PCR targeting the transfer-messenger RNA/tmRNA (ssrA) gene and to characterize Bartonella strains using nested PCR and sequence analysis of the 16S-23S rRNA intergenic transcribed spacer region (ITS). A total of 271 laelapid mites of five species (Laelaps agilis, Haemogamasus nidi, Eulaelaps stabularis, Myonyssus gigas, and Hyperlaelaps microti) were collected from five rodent species (Apodemus flavicollis, Apodemus agrarius, Clethrionomys glareolus, Micromys minutus, and Microtus oeconomus) during 2015-2016. Bartonella DNA was detected in three mite species L. agilis, M. gigas, and Hg. nidi with an overall prevalence of 11.4%. Sequence analysis of the 16S-23S rRNA ITS region revealed the presence of Bartonella taylorii in L. agilis, Hg. nidi, and M. gigas, and Bartonella grahamii in L. agilis. Our results suggest that laelapid mites are involved in the maintenance of rodent-associated Bartonella spp. in nature. To the best of the authors' knowledge, this is the first study to demonstrate the presence of Bartonella spp. DNA in laelapid mites from small rodents.

A statewide survey of the tick fauna found on deer, using harvested deer heads as the sample unit, was conducted during the Alabama hunting seasons of 2019-2020 and 2020-2021. Four species of ticks: Ixodes scapularis (n= 936, % of catch 69.1%), Amblyomma americanum (315, 23.2%), Dermacentor albipictus (97, 7.1%), and Amblyomma maculatum (6, 0.4%) were taken from 151 deer heads harvested from 21 deer processing centers (n = 4-17 heads/processor). A total of 87.7% (prevalence) of deer heads had one or more ticks. We used two standard numerical descriptors of tick numbers, abundance, and relative abundance. No significant stepwise regressions (p > 0.05) were found between tick abundance (all ticks, I. scapularis, A. americanum) and the predictor variables of latitude, deer density, season, and year. In addition, the correlation between the abundance of I. scapularis and A. americanum was not significant (p > 0.5). In contrast, the relative abundance of both I. scapularis and A. americanum showed a significant (P < 0.05) relationship with latitude, with the relative abundance of I. scapularis increasing on deer with increased latitude and A. americanum showing the opposite pattern.

Woody plant encroachment into grasslands is occurring worldwide, affecting ecosystems in ways that likely influence mosquito-borne disease transmission. In the U.S. Great Plains, encroachment by eastern redcedar (Juniperus virginiana) (ERC) may be expanding conducive habitat for mosquitoes and their hosts, but few studies have evaluated associations between ERC encroachment and West Nile virus (WNV). To test the hypotheses that mosquito abundance and WNV-infected mosquitoes increase with increasing ERC cover, we collected mosquitoes in 32 sites in Oklahoma reflecting various ERC encroachment stages. We found support for our first hypothesis, as mean abundance of Aedes albopictus increased significantly with ERC cover. However, Psorophora columbiae and Anopheles quadrimaculatus abundance decreased with increasing ERC. There was no significant association with ERC for other mosquito species. We could not test our second hypothesis due to low WNV prevalence, but the only detected WNV-infected pool of mosquitoes (Cx. tarsalis) was collected in ERC. Our results suggest ERC encroachment increases abundance of at least one medically important mosquito species, but further research is needed to clarify how encroachment affects ecology of the entire WNV disease system through changes to vector and host communities, vector-host interactions, and thus disease transmission and prevalence. Understanding relationships between woody plant encroachment and the nidus of infection for mosquito-borne diseases will be crucial for targeting public health efforts, including land management activities that limit and/or eradicate woody plant encroachment, particularly in areas with high levels of disease risk.

Mosquitoes affect human health and well-being globally through their roles as disease-causing pathogen vectors. Utilizing genetic techniques, we conducted a large-scale dietary study of three bat species common to the southeastern U.S.A., Lasiurus seminolus (Seminole bat), Nycticeius humeralis (evening bat), and Myotis austroriparius (southeastern myotis). Through next-generation sequencing of a 180 bp portion of cytochrome oxidase subunit I (COI) of mitochondrial DNA from 180 bat guano samples, we documented consumption of 17 species of mosquitoes by bats, including six endemic arbovirus vectors. Culex quinquefasciatus, Culex coronator, Culiseta melanura, Culex salinarius, Culex erraticus, and Coquillettidia perturbans were consumed by 51.3%, 43.7%, 27.2%, 22.8%, 18.0%, and 12.7% of bats sampled, respectively. Consumption of two of these mosquito species was explained by spatial variables reflecting the prevalence of mosquito larval habitat, five were explained by bat traits (bat mass, bat species), and two were explained by these factors plus temporal variables (maximum daily temperature, time since sunset, date), making it challenging to offer specific guidance on how best to promote bats as a means of reducing arbovirus vector species. Our results show that common bat species of the southeastern U.S.A. consume endemic, but not exotic, arbovirus mosquito vectors. Future studies are needed to understand the impact of bat consumption on mosquito numbers and public health.

Toxorhynchites mosquitoes have been studied as potential biological mosquito control agents because they consume other mosquito larvae. As a top predator, Toxorhynchites species are also considered keystone predators in phytotelmata. However, limited information is available regarding Toxorhynchites christophi, which is found in northeast Asia. The present study investigated whether Tx. christophi could reduce mosquito populations and increase species diversity by functioning as a mosquito control agent and keystone predator, respectively. During the study, aquatic insects were collected every three weeks (May-October, 2018) from tire habitats, which resemble treehole ecosystems, at the Korean National Arboretum in the central region of the Korean Peninsula. The samples were separated into the surface- and the substrate-groups based on their behavior, and the communities were compared based on the density of Tx. christophi. As a result, the communities with a higher density of the predators showed a higher diversity and evenness, and the communities also had a lower mosquito ratio, dominance, and density of the surface-group. The results of both non-metric multi-dimensional scaling and one-way analysis of similarities also indicated that the communities were affected by the density of Tx. christophi larvae. Similarity percentage analysis results revealed the effects of this predator on the communities could mainly be attributed to reductions in the densities of the three dominant mosquito species (Aedes koreicus, Ae. flavopictus, and Tripteroides bambusa). Thus, Tx. christophi may be valuable as both a biological mosquito control agent and keystone species of treehole ecosystems by reducing dominant mosquito species and improving species diversity.

Successful surveillance and control of mosquito arbovirus vectors requires effective and sensitive trapping methods for adult insects. The Biogents Sentinel (BGS) trap is widely used for mosquito trapping but has low capture efficiency for both female and male Aedes aegypti under semi-field conditions. Efficiency refers to the proportion of mosquitoes that are trapped of those encountering the trap. We verified the efficiency of the BGS under field conditions in suburban Riverside, California, U.S.A., following our previous work determining the efficiency under semi-field conditions in Cairns, Northern Australia. The efficiency of the BGS with CO₂ and a human skin odor mimic (BG-Lure) for both Ae. aegypti sexes in the field was 9%. This closely aligns with the results of our previous study, the efficiency for females being 5% and males being 9%. In the present study microclimatic conditions were monitored and capture occurred during periods of significantly lower mean temperature. There were no discernible changes in wind directionality or strength in the 60 s leading up to mosquito capture by the BGS. Our results support our previous findings that capture efficiency of the BGS for Ae. aegypti is low.

Everglades virus (EVEV), an enzootic subtype of Venezuelan equine encephalitis virus, along with its endemic mosquito vector, Culex cedecei, is known only from South Florida. The taxonomy of Cx. cedecei is complex and was once synonymous with Culex opisthopus and Culex taeniopus. We modeled potential distribution of Cx. cedecei in Florida and the Caribbean using an ecological niche model and compared this distribution to the recorded distribution of EVEV in Florida as well as historical records of Cx. opisthopus/Cx. taeniopus. We used recent collections and occurrence data from scientific publications and temperature/precipitation variables and vegetation greenness values to calibrate models. We found mean annual temperature contributed the greatest to model performance. Everglades virus in humans and wildlife corresponded with areas predicted suitable for Cx. cedecei in Florida but not with incidence of antibodies reported in dogs. Most records of Cx. opisthopus/Cx. taeniopus in the Caribbean did not correspond to areas predicted suitable for Cx. cedecei, which may be due to mean annual temperature values in the Caribbean exceeding values within the calibration region, imposing model constraints. Results indicated that this model may adequately predict the distributions of Cx. cedecei within Florida but cannot predict areas suitable in the Caribbean.

In many areas, the main sources of mosquito vectors are not natural habitats but small artificial water bodies that are provided unintentionally by humans. Such container habitats have been linked to outbreaks of dengue fever and other arboviral diseases. However, in many parts of the world the possible risks associated with container habitats have not been assessed. Here, we focused on a human population expansion area in northern Tanzania with a high incidence of dengue and other cases of high fever. We explored the importance of anthropogenic container habitats for mosquito production in the Lake Manyara Basin. We also assessed how biotic and physicochemical habitat characteristics limit mosquito abundance in containers. Results showed that Aedes aegypti (Linnaeus), vector of dengue and other arboviruses, and Culex quinquefasciatus (Say), vector of filarial worms, were the dominant mosquitoes ovipositing in large numbers in different containers. Old tires were the dominant and most productive container habitat for mosquitoes in the region. However, there were strong differences among villages, illustrating that the mosquito burden associated with container habitats varies locally. We concluded that in this region, removal of artificial container habitats could be a simple strategy to reduce the mosquito-mediated disease burden within the local population.