Aedes Vexans Research Articles

Host-Feeding Patterns of Mosquito Species in Aras Valley, Turkey

Identifying hosts of blood-feeding mosquito species is important to elucidate the role of vector species in disease transmission cycles. Herein, the aim was to identify the vertebrate hosts of mosquito species using the polymerase chain reaction-based reverse line blotting method. The mosquito species were Anopheles maculipennis sensu lato Meigen, 1818; Aedes caspius Pallas, 1771; Aedes vexans Meigen, 1830; Culex theileri Theobald, 1903; Anopheles hyrcanus Pallas 1771; Culex pipiens sensu lato Linnaeus, 1758; and Culiseta annulata Schrank, 1776, which were collected from the Aras Valley between July-August 2012 and June-September 2013. The analysis of mosquito blood-meal samples revealed several mammalian and avian host species. And also varying degrees of opportunistic mosquito feeding behavior in both birds and mammals were noted. These mosquito species fed on eight mammal species, i.e., humans, cows, sheep, horses, dogs, cats, goats, and porcupines, as well as avian species. Studies on the host-feeding patterns of blood-feeding vector arthropods may provide information about the vector potential of these species. However, the host-feeding patterns of the vector species are only one part of the vector capacity. To detect the exact potential of vector species, further studies are needed on vector competence for different pathogens.

The Efficiency of Biogents Sentinel 2.0 Trapping and Human-Landing Catching Methods to Calculate Human Biting Rates.

To calculate human biting rates for various mosquito species, we performed simultaneous collections for 15 wk at 6 ecologically variable sites in Hungary. Of the dominant species, the relative abundance of Aedes vexans, Ae. sticticus, and Coquillettidia richiardii showed a significant positive correlation between CO2 + Biogents lure and human landing catch (HLC). The relative abundance of Culex pipiens was significantly lower in the HLC samples than in the CO2 + BG lure samples. Of the invasive species, Aedes korecius was found more frequently in HLC, while Ae. japonicus was more common in CO2 + BG lure samples. Estimated human biting rates, determined with the 2 collection methods, showed no significant differences at high mosquito density (100-120 bites/h/person), but there was considerable variation at low mosquito biting rates. Therefore, correcting the CO2 + BG lure trapping data to include only species biting humans provides estimates approaching the values of the HLC. Our study confirmed that while HLC is the gold standard method for determining the human biting rate, provided appropriate data adjustments are made, trapping methods performing automated data collection can provide similar data while reducing the exposure of the data collector.

Surveillance of Tahyna Orthobunyavirus in Urban Areas in Croatia-The "One Health" Approach.

Background: Tahyna orthobunyavirus (TAHV) is a neglected mosquito-borne bunyavirus. Although the virus is widespread in continental Europe, TAHV infections are rarely reported. We analyzed the prevalence of TAHV in humans and different animal species as well as mosquitoes collected in urban areas of Zagreb and its surroundings in the period from 2020 to 2022. Methods: The study included 32 patients with neuroinvasive disease (NID), 218 asymptomatic individuals, 98 horses, 94 pet animals (dogs and cats), and 4456 Aedes vexans mosquitoes. Cerebrospinal fluid (CSF) and urine samples of patients with NID were tested for the TAHV RNA using a real-time reverse transcription-polymerase chain reaction (RT-qPCR). Human and animal serum samples were tested for TAHV-neutralizing (NT) antibodies using a virus-neutralization test (VNT). Mosquito pools were tested for TAHV RNA using an RT-qPCR. Results: TAHV NT antibodies were detected in 3/9.4% of patients with NID, 8/3.7% of asymptomatic individuals, 29/29.6% of horses, and 11/11.7% of pet animals. There was no difference in the seroprevalence according to age, sex, and area of residence in asymptomatic individuals. In addition, TAHV seropositivity did not differ according to age and sex in pet animals. None of the tested mosquito pools was TAHV RNA-positive. Conclusions: The presented results highlight the importance of interdisciplinary surveillance (“One Health”) of this neglected viral zoonosis.

First description of the mitogenome and phylogeny:Aedes vexansand Ochlerotatus caspius of the Tribe Aedini (Diptera: Culicidae)

Culicidae, the mosquito family, includes more than 3600 species subdivided into the subfamilies Anophelinae and Culicinae. One-third of mosquitoes belong to the Aedini tribe, which is subordinate to the subfamily Culicinae, which comprises common vectors of viral zoonoses. The tribe of Aedini is extremely diverse in morphology and geographical distribution and has high ecological and medical significance. However, knowledge about the systematics of the Aedini tribe is still limited owing to its large population and the similar morphological characteristics of its species. This study provides the first description of the complete mitochondrial (mt) genome sequence of Aedes vexans and Ochlerotatus caspius belonging to the Aedini tribe. The mt genomes of A. vexans and O. caspius are circular molecules that are 15,861bp and 15,954bp in size, with AT contents of 78.54% and 79.36%, respectively. Both the circular mt genomes comprise 37 functional subunits, including 13 protein-coding genes (PCGs), two ribosomal RNA genes, 22 transfer RNA genes (tRNAs), and a control region (also known as the AT-rich region). The most common start codons are ATT/ATG, apart from cox1 (TCG) and nad5 (GTG), while TAA is the termination codon for all PCGs. All tRNAs have a typical clover leaf structure, except tRNA Ser1. Phylogenetic analysis of the concatenated, aligned amino acid sequences of the 13 PCGs showed that A. vexans gathered with Aedes sp. in a sister taxon, and O. caspius gathered with Ochlerotatus sp. in a sister taxon. The findings from the present study support the concept of monophyly of all groups, ratify the current taxonomic classification, and provide vital molecular marker resources for further studies of the taxonomy, population genetics, and systematics of the Aedini tribe.

Rift Valley fever, Mauritania, 2020: Lessons from a one health approach

A new outbreak of Rift Valley fever (RVF) occurred in Mauritania from September to November 2020, involving 78 reported human cases and 186 reported animal cases. Eleven out of the 13 regions of the country were affected by the epidemic, with the highest number of both human and animal cases in Tagant, Assaba and Brakna regions. The most affected animal species in this outbreak was camels, followed by small ruminants. Among the 10 mosquito species caught, 7 species, Culex poicilipes, Cx. quinquefasciatus, Cx. antennatus, Cx. univitattus, Aedes vexans, Mansonia africana and Ma. uniformis, are known to be involved in the transmission of RVF virus. Phylogenetic analyses based on the partial NSs gene revealed close proximity between the human/animal Mauritania 2020 viral strains and the Mauritania 2015/Niger 2016 strains, suggesting re-emergence of the RVF virus in the country since the last reported outbreak in 2015.

Larval biotopes of mosquitoes (Diptera: Culicidae) on the Berezinsky Biosphere Reserve (Belarus)

The purpose of the research is to study of larval biotopes of the family Culicidae Meigen, 1818 on the territory of the Berezinsky Biosphere Reserve.Materials and methods. Mosquito larvae collected on the Berezinsky Biosphere Reserve in 2016–2020. A total of 7772 mosquito larvae were collected in the course of 1467 counts. Mosquito larvae were collected in four types of natural reservoirs: permanent open (I); permanent shaded (II); temporary open (III) and temporary shaded (IV). The larvae were collected by dip net. The specimens were identifed using standard keys; in certain cases, the taxonomic collection of the Zoological Institute of the Russian Academy of Sciences (St. Petersburg) was used.Results and discussion.We found larvae of 22 mosquito species on the Berezinsky Biosphere Reserve. The genus Aedes Meigen, 1818 is the most abundant – 16 species (72,7%). The genus Anopheles Meigen, 1818 is represented by 2 species (9,2%), the genus Culiseta Felt, 1904 – 3 species (13,6%) and the genus Culex Linnaeus, 1758 – 1 species (4,5%). The largest number of species (18) is recorded in permanent and temporary open-type reservoirs, 17 – in temporary shaded reservoirs and the smallest number – 6 in permanent shaded reservoirs. Three species, Aedes vexans (Meigen, 1830), Ae. cantans (Meigen, 1818), and Ae. sticticus (Meigen, 1838) were found at all types of water bodies. The main larval breeding habitats are reservoirs of temporary origin with varying degrees of shading (88,0%). There are the highest abundance and mean average density of larvae. Thus, in temporary open water bodies, the abundance is 52,4% (with an average density of 197,0±45,7 sp./m2), and in temporary shaded water bodies, the abundance is 35,5% (with an average density of 287,2±162,1 sp./m2). For permanent reservoirs with varying degrees of shading, a low abundance and an average density of larvae are noted. Thus, in permanent open water bodies, the abundance is 9,6% (with an average density of 27,0±7,7 sp./m2), and in permanent shaded water bodies, the abundance is 2,5% (with an average density of 19,4±6,0 sp./m2). In permanent open water bodies, the greatest species diversity is noted, which is confrmed by the values of the indices (Нʹ = 3,06; D Mg = 2,57 and DSm = 0,16).

DNA Barcoding of Potential Mosquito Disease Vectors (Diptera, Culicidae) in Jazan Region, Saudi Arabia.

The conventional morphological characterization of mosquito species remains heavily used for species identification in Jazan, Saudi Arabia. It requires substantial expertise and time, as well as having difficulty in confirming identity of morphologically similar species. Therefore, to establish a reliable and accurate identification system that can be applied to understanding spatial distribution of local mosquito species from the Jazan region, DNA barcoding was explored as an integrated tool for mosquito species identification. In this study, 44 adult mosquito specimens were analyzed, which contain 16 species belong to three genera of potential mosquito disease vectors (Aedes, Anopheles, and Culex). The specimens were collected from the Jazan region located in southwest Saudi Arabia. These included old and preserved mosquito voucher specimens. In addition, we assessed the genetic distance based on the generated mitochondrial partial COI DNA barcodes to detect cryptic diversity across these taxa. Nine mosquito species belonging to three genera were successfully barcoded and submitted to GenBank, namely: Aedes aegypti, Aedes caspius, Aedes vexans, Aedes vittatus, Anopheles arabiensis, Culex pipiens, Culex quinquefasciatus, Culex sitiens, and Culex tritaeniorhynchus. Of these nine species, Aedes vexans, Aedes vittatus, Culex sitiens, and Culex tritaeniorhynchus were registered in GenBank for the first time from Saudi Arabia. The DNA barcodes generated a 100% match to known barcodes of these mosquito species, that also matched with the morphological identification. Ae. vexans was found to be either a case of cryptic species (subspecies) or a new species from the region. However, more research has to be conducted to prove the latter. This study directly contributes to the development of a molecular reference library of mosquito species from the Jazan region and Saudi Arabia. The library is essential for confirmation of species in support of existing mosquito surveillance and control programmes.

Density and Distribution of the Mosquitoes Population Inhabiting Jeonbuk Region

Following the increase of vector-borne infectious diseases due to climate change and international exchange, the study collected mosquitoes using BL and BG twice a month for nine months, from March to November 2019, at cattle sheds, habitats for migratory birds, and city centers, after which they were classified, identified, and checked for the presence of flavivirus by using real time RT-PCR in order to classify and identify the species of disease vector mosquitoes in the Jeonbuk, estimate their population, and investigate their regional distribution and the presence of viral pathogen infection. A total of 8,234 mosquitoes were collected, which were categorized as seven genera and twelve species. In terms of environment types, the highest number of mosquitoes – 3,884 (Trap Index 215.8) – were collected at the Wanju cattle shed. In terms of mosquito populations, Anopheles spp. was the dominant species with 2,538 mosquitoes (30.9%) collected. As the dominant species, Anopheles spp. mosquitoes were first collected in April, and the greatest numbers were collected in the order of July, August, and June, with numbers gradually decreasing starting in August. In terms of the mosquito species collected in each environment, Anopheles spp. mosquitoes were collected in cattle sheds, Aedes vexans mosquitoes were collected in habitats for migratory birds, and Culex pipiens pallens mosquitoes were collected in city centers, revealing a difference in the species of mosquitoes collected depending on the environmental characteristics. The collected mosquitoes were tested for flavivirus using real time RT-PCR, but all tests turned out negative. The results of the collection confirmed the habitation of mosquitoes related to vector-borne diseases, predicting further results if an abnormal climate further progresses. The study is also expected to be used as comprehensive pest control standards for future mosquitoes.

Global potential distribution of three underappreciated arboviruses vectors (Aedes japonicus, Aedes vexans and Aedes vittatus) under current and future climate conditions.

Arboviruses (arthropod-borne viruses) are expanding their geographic range, posing significant health threats to millions of people worldwide. This expansion is associated with efficient and suitable vector availability. Apart from the well-known Aedes aegypti and Ae. albopictus, other Aedes species may potentially promote the geographic spread of arboviruses because these viruses have similar vector requirements. Aedes japonicus, Ae. vexans and Ae. vittatus are a growing concern, given their potential and known vector competence for several arboviruses including dengue, chikungunya, and Zika viruses. In the present study, we developed detailed maps of their global potential distributions under both current and future (2050) climate conditions, using an ecological niche modeling approach (Maxent). Under present-day conditions, Ae. japonicus and Ae. vexans have suitable areas in the northeastern United States, across Europe and in southeastern China, whereas the tropical regions of South America, Africa and Asia are more suitable for Ae. vittatus. Future scenarios anticipated range changes for the three species, with each expected to expand into new areas that are currently not suitable. By 2050, Ae. japonicus will have a broader potential distribution across much of Europe, the United States, western Russia and central Asia. Aedes vexans may be able to expand its range, especially in Libya, Egypt and southern Australia. For Ae. vittatus, future projections indicated areas at risk in sub-Saharan Africa and the Middle East. As such, these species deserve as much attention as Ae. aegypti and Ae. albopictus when processing arboviruses risk assessments and our findings may help to better understand the potential distribution of each species.

Identification, surveillance and management of Aedes vexans in a flooded river valley in Nottinghamshire, United Kingdom

Aedes vexans is known to occur in large populations in riverine floodplains in much of Europe, where it can cause a significant biting nuisance and is often subject to large scale control strategies. Until recently it had only been reported in very small numbers in the United Kingdom. After receiving reports of nuisance biting near the river Idle, Nottinghamshire (East Midlands, England), mosquito surveillance was conducted over three years (2018-2020) using Mosquito Magnet adult traps. Ae. vexans was found in all years, in very high numbers, particularly in 2020, reaching a peak of almost 5,000 female mosquitoes per trap night, the highest reported density of trapped adult mosquitoes in the UK. Larval control was conducted in all years, and adult control in one year, however local peculiarities of flood and water management presents challenges and necessitates a multi-faceted approach. Strategies for further expansion of the control operation by developing strategies for water management, coupled with larval surveys to define the extent and seasonality of larval habitats, and application methods of Bacillus thuringiensis israelensis products are discussed.

Mosquito abundance in relation to extremely high temperatures in urban and rural areas of Incheon Metropolitan City, South Korea from 2015 to 2020: an observational study

BackgroundDespite concerns regarding increasingly frequent and intense heat waves due to global warming, there is still a lack of information on the effects of extremely high temperatures on the adult abundance of mosquito species that are known to transmit vector-borne diseases. This study aimed to evaluate the effects of extremely high temperatures on the abundance of mosquitoes by analyzing time series data for temperature and mosquito abundance in Incheon Metropolitan City (IMC), Republic of Korea, for the period from 2015 to 2020.MethodsA generalized linear model with Poisson distribution and overdispersion was used to model the nonlinear association between temperature and mosquito count for the whole study area and for its constituent urban and rural regions. The association parameters were pooled using multivariate meta-regression. The temperature–mosquito abundance curve was estimated from the pooled estimates, and the ambient temperature at which mosquito populations reached maximum abundance (TMA) was estimated using a Monte Carlo simulation method. To quantify the effect of extremely high temperatures on mosquito abundance, we estimated the mosquito abundance ratio (AR) at the 99th temperature percentile (AR99th) against the TMA.ResultsCulex pipiens was the most common mosquito species (51.7%) in the urban region of the IMC, while mosquitoes of the genus Aedes (Ochlerotatus) were the most common in the rural region (47.8%). Mosquito abundance reached a maximum at 23.5 °C for Cx. pipiens and 26.4 °C for Aedes vexans. Exposure to extremely high temperatures reduced the abundance of Cx. pipiens mosquitoes {AR99th 0.34 [95% confidence interval (CI) 0.21–0.54]} to a greater extent than that of Anopheles spp. [AR99th 0.64 (95% CI 0.40–1.03)]. When stratified by region, Ae. vexans and Ochlerotatus koreicus mosquitoes showed higher TMA and a smaller reduction in abundance at extreme heat in urban Incheon than in Ganghwa, suggesting that urban mosquitoes can thrive at extremely high temperatures as they adapt to urban thermal environments.ConclusionsWe confirmed that the temperature-related abundance of the adult mosquitoes was species and location specific. Tailoring measures for mosquito prevention and control according to mosquito species and anticipated extreme temperature conditions would help to improve the effectiveness of mosquito-borne disease control programs.Graphical abstract

Susceptibility and barriers to infection of Colorado mosquitoes with Rift Valley fever virus.

Rift Valley fever virus (RVFV) causes morbidity and mortality in humans and domestic ungulates in sub-Saharan Africa, Egypt, and the Arabian Peninsula. Mosquito vectors transmit RVFV between vertebrates by bite, and also vertically to produce infectious progeny. Arrival of RVFV into the United States by infected mosquitoes or humans could result in significant impacts on food security, human health, and wildlife health. Elucidation of the vectors involved in the post-introduction RVFV ecology is paramount to rapid implementation of vector control. We performed vector competence experiments in which field-collected mosquitoes were orally exposed to an epidemic strain of RVFV via infectious blood meals. We targeted floodwater Aedes species known to feed on cattle, and/or deer species (Aedes melanimon Dyar, Aedes increpitus Dyar, Aedes vexans [Meigen]). Two permanent-water-breeding species were targeted as well: Culiseta inornata (Williston) of unknown competence considering United States populations, and Culex tarsalis Coquillett as a control species for which transmission efficiency is known. We tested the potential for midgut infection, midgut escape (dissemination), ovarian infection (vertical transmission), and transmission by bite (infectious saliva). Tissues were assayed by plaque assay and RT-qPCR, to quantify infectious virus and confirm virus identity. Tissue infection data were analyzed using a within-host model under a Bayesian framework to determine the probabilities of infection outcomes (midgut-limited infection, disseminated infection, etc.) while estimating barriers to infection between tissues. Permanent-water-breeding mosquitoes (Cx. tarsalis and Cs. inornata) exhibited more efficient horizontal transmission, as well as potential for vertical transmission, which is contrary to the current assumptions of RVFV ecology. Barrier estimates trended higher for Aedes spp., suggesting systemic factors in the differences between these species and Cx. tarsalis and Cs. inornata. These data indicate higher potential for vertical transmission than previously appreciated, and support the consensus of RVFV transmission including a broad range of potential vectors.

National Monitoring of Mosquito Populations and Molecular Analysis of Flavivirus in the Republic of Korea in 2020.

The Korea Disease Control and Prevention Agency has established centers at 16 locations to screen vector populations and pathogens. The aims of this study were to determine the relative spatiotemporal distributions of mosquitoes that are flavivirus vectors, and to correlate them with instances of flaviviral disease in the Republic of Korea (ROK). We collected 67,203 mosquitoes in traps at 36 collection sites in 30 urban regions and migratory bird habitats in 2020. The trap index was 36.6, and the predominant mosquito species were the Culex pipiens complex, Armigeres subalbatus, Aedes albopictus, Aedes vexans, and Culex tritaeniorhynchus. The mosquitoes were pooled into 4953 pools to monitor flavivirus infection. We determined that the minimum infection rate of flavivirus was 0.01%. Japanese encephalitis virus (JEV) was detected in only seven pools of Culex orientalis from Sangju, and we isolated JVE from two pools. All detected JEV was found to be genotype V by phylogenetic analysis. To the best of our knowledge, this is the first study to isolate genotype V JVE from Culex orientalis in the ROK. Subsequent geographical and ecological studies on mosquitoes will help improve our understanding of the relative risk of flavivirus infection. Future studies should analyze mosquito species distribution and improve flavivirus monitoring and long-term surveillance.

Mosquito fauna in Extremadura (western Spain): Updated catalog with new records, distribution maps, and medical relevance.

An important element of vector control and surveillance of mosquito-borne diseases is updated information on vector species distribution. The aim of this study was to collect available information about mosquito species reported in Extremadura between 1920 and 2020 and create a catalog that would combine both published data and our recent field identifications. An exhaustive list is hereby presented, including species status and detailed distribution maps at a municipal level as well as their importance for public health. A total of 33 species, classified into five genera: Anopheles (five species), Aedes (14), Culex (nine), Culiseta (four), and Orthopodomyia (one) has been recorded, including 31 autochthonous, one invasive, Aedes (Stegomyia) albopictus, and one disappeared since 1953, Aedes (Stegomyia) aegypti. For the first time in Extremadura, we report the presence of important vectors such as Aedes (Aedimorphus) vexans vexans and Culex (Culex) perexiguus, and the new record of six species in the province of Badajoz, namely: Aedes (Dahliana) echinus, Aedes (Fredwardsius) vittatus, Aedes (Ochlerotatus) berlandi, Aedes (Ochlerotatus) pulcritarsis, Culex (Culex) mimeticus, and Culiseta (Culiseta) subochrea. Nineteen of these species are potential vectors of medical and veterinary relevance.

On the suitability of Aedes vexans to Wolbachia‐based control strategies

AbstractAedes vexans (Meigen) (Diptera: Culicidae) is a common mosquito species with worldwide distribution and it is a potential vector of various pathogens such as West Nile, Rift Valley, and Zika viruses, and Dirofilaria nematodes. Also due to its abundance, Ae. vexans could be a key species in determining new outbreaks of these important pathogens outside their present geographical range. Herein, we report on studies carried out in the laboratory to ascertain the suitability of the species for control strategies based on the exploitation of the endosymbiotic bacterium Wolbachia, known to induce reproductive incompatibility and/or virus resistance in the hosts. Aedes vexans showed low propensity to mate in narrow places, low male survival, and reduced hatchability of the eggs collected on artificial devices. Embryonic and adult transinfection with various Wolbachia strains were attempted. Whereas the first approach was barely tolerated by Ae. vexans eggs, transinfected progeny was obtained by adult microinjection using wAlbA and wAlbB Wolbachia but both strains were not efficiently transmitted vertically, leading to the loss of the infection by three generations. The present study highlights the low suitability of Ae. vexans to the infection by this bacterium and to the mass‐rearing conditions generally required for Wolbachia‐based control strategies.

Diversity and community structure of mosquitoes (Diptera: Culicidae) in suburban, field, and forest habitats in Montréal, Québec, Canada

AbstractUnderstanding the medical and economic impacts of mosquitoes (Diptera: Culicidae) begins with knowing their natural history and distribution, including their association with habitat types, particularly those in which human activity is high. The effects of habitat on shaping the community structure of mosquitoes were studied across periurban habitats on the island of Montréal, Québec, Canada in 2014 and 2015. Mosquitoes were collected from 20 fixed sampling locations in suburban backyards, fields, and forests, using CO2-baited light-emitting diode encephalitis vector survey traps. A total of 184 607 mosquitoes were collected, representing eight genera and 35 species. Suburban, field, and forest sites had different communities of mosquitoes, but differences were not apparent among sites within similar habitat types in nonmetric multidimensional scaling ordinations and permutational multivariate analysis of variance. In both years, the greatest abundance of mosquitoes was collected from field habitat, and the highest species richness, from forests. Suburban sites consistently generated the lowest abundance and diversity. Nearly 75% of the total individuals collected were from three species:Aedes vexans(Meigen), 39%;Coquillettidia perturbans(Walker), 18%; andAedes canadensis(Theobald), 16%. This research shows that diverse communities of mosquitoes can be found in forests, fields, and backyards, yet the communities between forests differ from more open habitats. Our community analysis reveals that medically important species (e.g.,Culexsp.) are more commonly encountered in suburban backyards, yet overall mosquito nuisance potential is greater in forest and field habitats. This information highlights important patterns of mosquito abundance and species occurrence, vital for the development of management programmes.

Seasonal surveillance of mosquitoes in three different habitats in Gyeongbuk Province, Republic of Korea, 2017–2019

AbstractMosquitoes were collected biweekly from March to November for 3 years (2017–2019) in three different habitats, including a migratory bird refuge, cowshed, and an urban area. Among a total of 22,783 female mosquitoes comprising six genera and 13 species collected for 3 years, Aedes vexans nipponii (56.08%) was the dominant species, followed by Culex pipiens complex (14.26%), Anopheles spp. (11.57%), Culex orientalis (6.90%), Aedes albopictus (4.66%), Armigeres subalbatus (4.06%), and Culex tritaeniorhynchus (1.41%); the remaining six species comprised only 1.1% of all mosquito species collected. In the three habitats, 70.42% of mosquitoes were collected in the migratory bird refuge, whereas 10.68% and 18.90% were investigated in the cowshed and urban areas, respectively. The dominant species were Ae. vexans nipponii in the migratory bird refuge, Anopheles spp. in the cowshed, and Cx. pipiens complex in the urban area. The seasonal distribution of mosquitoes showed that most were obtained between May and September, with bimodal peaks in the third week of June and third week of August. Meteorological analysis revealed a high correlation between temperature and mosquito abundance. In the flavivirus detection analysis, no virus‐transmitting infectious diseases were amplified by PCR, but the Chaoyang virus was found in Ae. vexans nipponii. Considering that global warming is a major risk factor for the spread of vector‐borne diseases and that mosquito has been a fatal vector of infectious disease, our study of surveillance and analysis of seasonal/environmental mosquito population dynamics are essential for public health.

Population dynamics of mosquitoes (Diptera: Culicidae) and their disease-harboring rates in Gyeonggi province, South Korea

• Population dynamics of mosquitoes were monitored from 2017 to 2019 in South Korea. • Population peak was observed in August and September from survey sites conducted. • Dominant mosquito species were varied between suburban residential and rural area. • From the pools tested, three pools were positive for Japanese encephalitis virus. Population dynamics and species composition of mosquitoes were monitored in a suburban residential area and rural areas, including a migratory bird refuge area and a cattle farm area, from 2017 to 2019. Mosquitoes were collected every two weeks using one BG sentinel trap and two black-light traps in a suburban residential area and a migratory bird refuge area, and one black-light trap in a cattle farm area from March to November. From the surveillance, a total of 13,267, 9,697 and 6,688 mosquitoes were collected in 2017, 2018, and 2019, respectively. The peak of the mosquito population was observed in August and September in both the suburban residential area and rural areas. In general, Culex pipiens pallens was the dominant species in the suburban residential area, whereas Aedes vexans nipponii and Anopheles spp. were the most dominant in the rural areas. Collected mosquitoes were pooled into groups for each collection site and species to investigate flavivirus harboring. Three pools were positive for Japanese encephalitis virus type V, one pool was positive for Chaoyang virus, and six pools were positive for Culex flavi virus from the 731 pools tested. When total numbers of collected mosquitoes were further analyzed by linear regression analysis for their interaction with ambient temperature and relative humidity, the number of mosquitoes were significantly affected by the ambient temperature. In contrast, relative humidity was significantly affecting the total number of mosquitoes only for the migratory bird refuge area.

EVALUATION OF MULTIPLE TRAP TYPES FOR THE CAPTURE OF VECTOR MOSQUITOES OF EASTERN EQUINE ENCEPHALITIS VIRUS IN SAINT JOHNS COUNTY, FLORIDA

Eastern equine encephalitis virus (EEEV) is a highly dangerous alphavirus vectored by multiple mosquito species in the United states. Vector surveillance and control is used to prevent the spread of EEEV, so highly efficient and attractive traps are needed to accurately assess mosquito abundance. Mosquitoes can be captured in various physiological states (host-seeking, gravid, resting, etc.), depending on what trap type is used. this study analyzed 6 trap types to determine which captured the most EEEV vectors in saint Johns county. the trap types analyzed were the biogents sentinel trap, centers for Disease control (cDc) Light trap, the sentinel Mosquito Arbovirus capture Kit, Mosquito Magnet X trap, cDc resting trap, and gravid traps. For the gravid traps, two different infusions were tested: hay infusion and cattail infusion. Aedes atlanticus Dyar and Knab was the most abundant EEEV vector captured in this study. Other EEEV vectors collected were Aedes vexans (Meigen), Culex erraticus (Dyar and Knab), and Culex nigripalpus theobald. bG traps caught the highest abundance of EEEV vectors (1520 ± 743) compared to all the other trap types analyzed. Despite capturing multiple EEEV vectors during the testing period at the chosen site, Culiseta melanura (coquillett) and Coquillettidia perturbans (Walker) were never captured.

It’s risky to wander in September: Modelling the epidemic potential of Rift Valley fever in a Sahelian setting

Estimating the epidemic potential of vector-borne diseases, along with the relative contribution of underlying mechanisms, is crucial for animal and human health worldwide. In West African Sahel, several outbreaks of Rift Valley fever (RVF) have occurred over the last decades, but uncertainty remains about the conditions necessary to trigger these outbreaks. We use the basic reproduction number (R0) as a measure of RVF epidemic potential in northern Senegal, and map its value in two distinct ecosystems, namely the Ferlo and the Senegal River delta and valley. We consider three consecutive rainy seasons (July-November 2014, 2015 and 2016) and account for several vector and animal species. We parametrize our model with estimates of Aedes vexans arabiensis, Culex poicilipes, Culex tritaeniorhynchus, cattle, sheep and goat abundances. The impact of RVF virus introduction is assessed every week over northern Senegal. We highlight September as the period of highest epidemic potential in northern Senegal, resulting from distinct dynamics in the two study areas. Spatially, in the seasonal environment of the Ferlo, we observe that high-risk locations vary between years. We show that decreased vector densities do not greatly reduce R0 and that cattle immunity has a greater impact on reducing transmission than small ruminant immunity. The host preferences of vectors and the temperature-dependent time interval between their blood meals are crucial parameters needing further biological investigations.