Journal of Vector Ecology最新文献

The study assessed the distribution of Malaysian Ae. albopictus adults associated with Wolbachia detection in low-rise residential areas using a modified sticky ovitrap (MSO). The relationship between Ae. albopictus and climatological parameters were also determined. Fifty-two weeks of surveillance using 273 MSOs were conducted in four installation areas of eleven sampling sites. Specimens were subjected to PCR using wsp-specific primers for Wolbachia detection. The relationship between climatological parameters and Ae. albopictus captured were analyzed using Spearman rank correlation coefficient test. The majority of Ae. albopictus were captured in residential houses (87%), followed by playgrounds or parks (11.5%), guardhouses (1%), and community halls (0.5%). Most of the specimens (92%) were superinfected with wAlbA and wAlbB strains. A positive correlation with no significant association was found for rainfall (r = 0.015, P = 0.072), relative humidity (r = 0.005, P = 0.526), minimum temperature (r = 0.005, P = 0.516), and mean temperature (r = 0.003, P = 0.689). MSO effectively captured a high number of Ae. albopictus that was determined to be the predominant mosquito species found in low-rise residential areas. The adult collection is not only influenced by climatological parameters but also by other factors, including environmental conditions and general sanitation status.

Seasonality of fleas (Siphonaptera) may be due to species competition, prompting the idea that flea species partition temperature, along with correlated variables such as moisture (thermal-niche partitioning hypothesis). I compared the fleas of five rodent-flea communities described from the literature for thermal-niche optima by fitting non-linear LRF (Lobry-Rosso-Flandrois) curves to examine whether flea species in a community show distinct, partitioned thermal niches. LRF curves estimate physiological parameters of temperature minimum, optimum, maximum, and maximum abundance, and facilitate comparison between species by summarizing seasonal data. Flea-communities were on Nearctic Southern flying squirrel (Glaucomys volans volans), Richardson's ground-squirrel (Urocitellus richardsonii), North American deer-mouse (Peromyscus maniculatus), and Palearctic Midday jird (Meriones meridianus), and Wagner's gerbil (Dipodillus dasyurus). Flea communities appeared to show seasonality consistent with thermal-niche partitioning. Several flea families and genera had characteristic thermal niches: Ceratophyllidae had broad tolerance to extreme temperature, Leptopsyllidae (one species in this study) to cold, and Pulicidae to hot. In contrast, at the local, species level, climatic speciation could be significant in flea diversification. Non-competition hypotheses (environmental filtering, neutrality) require testing, too. Thermal-niche partitioning may increase flea species richness on hosts and could occur in other insect and plant communities. Implications for biodiversity conservation and disease ecology under global warming are wide-ranging.

The movement of Ixodes pacificus and Dermacentor occidentalis adult ticks down a hill slope under natural conditions was investigated using the mark-release-recapture (MRR) method. We evaluated the movement of host-seeking adult ticks down a hill slope to determine if ticks travel downhill from an uphill area to trail margins below. During the tick seasons in 2016-2018, the ticks were collected by flagging, marked with paint, released at a predetermined location, and recaptured by weekly flagging. Of the 188 female and 114 male I. pacificus marked and released 30 m above the trail in 2016, 11 (5.8%) females and one (0.9%) male were recaptured at the trail. In 2017, of the 71 female and 52 male I. pacificus, none were recaptured. In 2018, nine (3.6%) female and one (0.4%) male I. pacificus were recaptured of the 247 female and 287 males marked and released. Fifteen (18.5%) female and six (7.3%) male D. occidentalis were recaptured of the 81 females and 82 males marked and released in 2017. The trail deterred further movement with only 0.6% of I. pacificus and 8.3% of D. occidentalis recaptured on the opposite side of the trail. This study demonstrated that some I. pacificus and D. occidentalis adults found along the uphill side of trails may have originated from an area 30 m from the trail margin, some travelling at a rate of 1.6-1.9 m/day under natural conditions in chaparral.

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.