Isolation and Characterization of Mosquito-Associated Spiroplasma cantharicola from Aedes japonicus Collected in Hokkaido, Japan

Species of the genus Spiroplasma are common within arthropods and plants worldwide. Mosquito-associated Spiroplasma spp. have been reported to show pathogenicity toward mosquitoes, which serve as vectors of several infectious diseases that have detrimental effects on public health. Although Spiroplasma spp. are expected to have potential use as biological vector-control tools, characteristics such as their distribution, host species, and cytopathogenic effects (CPEs) are not well understood. In this study, we isolated a Spiroplasma sp. from a female Aedes japonicus collected in Hokkaido, northern Japan. Phylogenetic analysis based on the 16S rRNA gene sequence indicated our isolate was closely related to S. cantharicola. We screened 103 mosquito pools consisting of 3 genera and 9 species, but only detected S. cantharicola in the first isolation. In an in vitro assay, our isolate grew well at 28 °C, but no propagation was observed at 37 °C. Furthermore, the isolate showed strong CPE on a mosquito-derived cultured cell line (C6/36), and its propagation slightly increased when co-cultured with C6/36 cells. To our knowledge, this is the third report of the isolation of S. cantharicola from mosquitoes and the first case in Asia. Our findings provide epidemiological data on S. cantharicola distribution in the region.

A New Record of Uranotaenia sapphirina and Aedes japonicus in Lee and Ogle Counties, Illinois

ABSTRACT Mosquito surveillance was conducted in Nachusa Grasslands Preserve located in north central Illinois in May through October during 2018 and 2019. In the Lee and Ogle counties, Illinois, boundaries of the preserve, 3 Uranotaenia sapphirina and 3 Aedes japonicus were collected and documented over the 2 field seasons in wetland and stream habitats. While Ur. sapphirina has been reported in nearby states, this is the first record in Lee County and on the preserve. Aedes japonicus has previously been recorded in Lee County; however, this is the first observance of this species within Ogle County and on the preserve.

An unwanted companion reaches the country: the first record of the alien mosquito Aedes japonicus japonicus (Theobald, 1901) in Slovakia

Background Invasive mosquitoes of the genus Aedes are quickly spreading around the world. The presence of these alien species is concerning for both their impact on the native biodiversity and their high vector competence. The surveillance of Aedes invasive mosquito (AIM) species is one of the most important steps in vector-borne disease control and prevention. Methods In 2020, the monitoring of AIM species was conducted in five areas (Bratislava, Zvolen, Banská Bystrica, Prešov, Košice) of Slovakia. The sites were located at points of entry (border crossings with Austria and Hungary) and in the urban and rural zones of cities and their surroundings. Ovitraps were used at the majority of sites as a standard method of monitoring. The collected specimens were identified morphologically, with subsequent molecular identification by conventional PCR (cox1) and Sanger sequencing. The phylogenetic relatedness of the obtained sequences was inferred by the maximum likelihood (ML) method. The nucleotide heterogeneity of the Slovak sequences was analysed by the index of disparity. Results A bush mosquito, Aedes japonicus japonicus, was found and confirmed by molecular methods in three geographically distant areas of Slovakia—Bratislava, Zvolen and Prešov. The presence of AIM species is also likely in Košice; however, the material was not subjected to molecular identification. The nucleotide sequences of some Slovak strains confirm their significant heterogeneity. They were placed in several clusters on the ML phylogenetic tree. Moreover, Ae. j. japonicus was discovered in regions of Slovakia that are not close to a point of entry, where the mosquitoes could find favourable habitats in dendrothelms in city parks or forests. Conclusion Despite being a first record of the Ae. j. japonicus in Slovakia, our study indicates that the established populations already exist across the country, underlining the urgent need for intensified surveillance of AIM species as well as mosquito-borne pathogens. Graphical Abstract

At the tip of an iceberg: citizen science and active surveillance collaborating to broaden the known distribution of Aedes japonicus in Spain

Background Active surveillance aimed at the early detection of invasive mosquito species is usually focused on seaports and airports as points of entry, and along road networks as dispersion paths. In a number of cases, however, the first detections of colonizing populations are made by citizens, either because the species has already moved beyond the implemented active surveillance sites or because there is no surveillance in place. This was the case of the first detection in 2018 of the Asian bush mosquito, Aedes japonicus, in Asturias (northern Spain) by the citizen science platform Mosquito Alert. Methods The collaboration between Mosquito Alert, the Ministry of Health, local authorities and academic researchers resulted in a multi-source surveillance combining active field sampling with broader temporal and spatial citizen-sourced data, resulting in a more flexible and efficient surveillance strategy. Results Between 2018 and 2020, the joint efforts of administrative bodies, academic teams and citizen-sourced data led to the discovery of this species in northern regions of Spain such as Cantabria and the Basque Country. This raised the estimated area of occurrence of Ae. japonicus from < 900 km2 in 2018 to > 7000 km2 in 2020. Conclusions This population cluster is geographically isolated from any other population in Europe, which raises questions about its origin, path of introduction and dispersal means, while also highlighting the need to enhance surveillance systems by closely combining crowd-sourced surveillance with public health and mosquito control agencies’ efforts, from local to continental scales. This multi-actor approach for surveillance (either passive and active) shows high potential efficiency in the surveillance of other invasive mosquito species, and specifically the major vector Aedes aegypti which is already present in some parts of Europe. Graphical abstract

The larval environment strongly influences the bacterial communities of Aedes triseriatus and Aedes japonicus (Diptera: Culicidae)

Mosquito bacterial communities are essential in mosquito biology, and knowing the factors shaping these bacterial communities is critical to their application in mosquito-borne disease control. This study investigated how the larval environment influences the bacterial communities of larval stages of two container-dwelling mosquito species, Aedes triseriatus, and Aedes japonicus. Larval and water samples were collected from tree holes and used tires at two study sites, and their bacteria characterized through MiSeq sequencing of the 16S rRNA gene. Bacterial richness was highest in Ae. japonicus, intermediate in Ae. triseriatus, and lowest in water samples. Dysgonomonas was the dominant bacterial taxa in Ae. triseriatus larvae; the unclassified Comamonadaceae was dominant in water samples from waste tires, while Mycobacterium and Carnobacterium, dominated Ae. japonicus. The two mosquito species harbored distinct bacterial communities that were different from those of the water samples. The bacterial communities also clustered by habitat type (used tires vs. tree holes) and study site. These findings demonstrate that host species, and the larval sampling environment are important determinants of a significant component of bacterial community composition and diversity in mosquito larvae and that the mosquito body may select for microbes that are generally rare in the larval environment.

Asian Bush Mosquito, Asian Rock Pool Mosquito Aedes japonicus japonicus (Theobald, 1901) (Insecta: Diptera: Culicidae)

Contents: Introduction - Synonymy - Distribution - Life Cycle - Medical Importance - Surveillance and Management - Selected References Also published on the Featured Creatures website at http://entnemdept.ufl.edu/creatures/AQUATIC/aedes_japonicus.html

Population genetic structure of the Asian bush mosquito, Aedes japonicus (Diptera, Culicidae), in Belgium suggests multiple introductions

Background Aedes japonicus japonicus has expanded beyond its native range and has established in multiple European countries, including Belgium. In addition to the population located at Natoye, Belgium, locally established since 2002, specimens were recently collected along the Belgian border. The first objective of this study was therefore to investigate the origin of these new introductions, which were assumed to be related to the expansion of the nearby population in western Germany. Also, an intensive elimination campaign was undertaken at Natoye between 2012 and 2015, after which the species was declared to be eradicated. This species was re-detected in 2017, and thus the second objective was to investigate if these specimens resulted from a new introduction event and/or from a few undetected specimens that escaped the elimination campaign. Methods Population genetic variation at nad4 and seven microsatellite loci was surveyed in 224 and 68 specimens collected in Belgium and Germany, respectively. German samples were included as reference to investigate putative introduction source(s). At Natoye, 52 and 135 specimens were collected before and after the elimination campaign, respectively, to investigate temporal changes in the genetic composition and diversity. Results At Natoye, the genotypic microsatellite make-up showed a clear difference before and after the elimination campaign. Also, the population after 2017 displayed an increased allelic richness and number of private alleles, indicative of new introduction(s). However, the Natoye population present before the elimination programme is believed to have survived at low density. At the Belgian border, clustering results suggest a relation with the western German population. Whether the introduction(s) occur via passive human-mediated ground transport or, alternatively, by natural spread cannot be determined yet from the dataset. Conclusion Further introductions within Belgium are expected to occur in the near future, especially along the eastern Belgian border, which is at the front of the invasion of Ae. japonicus towards the west. Our results also point to the complexity of controlling invasive species, since 4 years of intense control measures were found to be not completely successful at eliminating this exotic at Natoye.

UPDATED COUNTY MOSQUITO SPECIES RECORDS FOR NORTHWEST FLORIDA

This report updates the mosquito species composition for Santa Rosa, Okaloosa, Walton, Holmes, Washington, Jackson, Calhoun, Liberty, Gadsden, Leon, Wakulla, Jefferson, Madison, and Taylor Counties, through collections made in a centralized surveillance program operated from 2002-2020 in northwest Florida. 91 county species records were documented. The most notable discoveries included finding Mansonia titillans (Walker) in eleven of the fourteen surveyed counties, Psorophora horrida (Dyar and Knab) in nine, Anopheles perplexens Ludlow in eight and Culex erraticus (Dyar and Knab) and Uranotaenia lowii Theobald in seven. Psorophora mathesoni Belkin and Heinemann and Aedes japonicus japonicus (Theobald) were found in six new counties. Culex pilosus (Dyar and Knab) was found solely in Calhoun and Liberty Cos., while Culex peccator Dyar and Knab and Culex tarsalis Coquillett were recovered in Calhoun Co. and Santa Rosa Co., respectively. Mansonia titillans, Cx. erraticus, Cx. tarsalis and Ae. j. japonicus are known arbovirus vectors, thus increasing the disease risk in this region.