Container-breeding Species Research Articles

Landscape and Anthropogenic Factors Associated with Adult Aedes aegypti and Aedes albopictus in Small Cities in the Southern Great Plains.

Simple SummaryMosquito-borne diseases are a growing human health concern in the United States. While recent studies have updated the distribution of Aedes aegypti in southern Great Plains, little is known about what factors can be used to predict where important mosquito species thrive in the region. The aim of the study assessed different factors associated with encountering adult container-breeding mosquitoes in small cities in southern Oklahoma. Collections using two types of traps were carried out over a ten week period from June to August 2017 along two geographical transects, each consisting of three cities, equally distant from the Red River/Texas border. After five rounds of collection, 6628 female mosquitoes were collected from 242 commercial or residential sites in six cities. Of the mosquitoes collected, 80% consisted of container-breeding species. Regionally, Ae. aegypti was most likely to be collected in cities closest to the Texas border while Aedes albopictus was spread throughout the region. In general, Ae. aegypti and Ae. albopictus were more associated with residential sites or sites featuring no or low vegetation. The study highlighted important factors involved in the distribution of Ae. aegypti and Ae. albopictus in small cities in the southern Great Plains.As mosquito-borne diseases are a growing human health concern in the United States, the distribution and potential arbovirus risk from container-breeding Aedes mosquitoes is understudied in the southern Great Plains. The aim of the study was to assess landscape and anthropogenic factors associated with encountering adult container-breeding mosquitoes in small cities in southern Oklahoma. Collections were carried out over a 10 week period from June to August 2017 along two geographical transects, each consisting of three cities, equally distant from the Red River/Texas border. Mosquitoes were collected weekly using two trap types along with data for 13 landscape, vegetation, and anthropogenic variables. After five rounds of collection, 6628 female mosquitoes were collected over 2110 trap-nights involving 242 commercial or residential sites in six cities. Of the mosquitoes collected, 80% consisted of container-breeding species: Aedes albopictus (72%), Culex pipiens complex (16%) and Aedes aegypti (8%). Regionally, Aedes aegypti was more likely present in cities closest to the Texas border while Ae. albopictus was spread throughout the region. In general, Ae. aegypti and Ae. albopictus were significantly more present in sites featuring no or low vegetation and residential sites. Variables associated with Ae. albopictus presence and abundance varied between cities and highlighted the urban nature of the species. The study highlighted the distribution of Ae. aegypti geographically and within the urban context, indicated potential habitat preferences of container-breeding mosquito species in small towns, and demonstrated the usefulness of Gravid Aedes traps (GAT) traps for monitoring Aedes populations in urban habitats in small cities.

How Does eDNA Compare to Traditional Trapping? Detecting Mosquito Communities in South-African Freshwater Ponds

Improved biomonitoring of mosquitoes requires an in-depth understanding on occurrences of both vector and non-vector species, in larval, and adult stages. Accurate descriptions of the ecological context in which mosquitoes thrive remain limited, particularly for larval stages. The aim of this study was to develop a mixed-amplicon eDNA approach to assess (i) whether mosquito larval communities of stagnant fresh-water bodies can be detected using a Culicidae-specific primer and (ii) how these results compare to traditional trapping of adult mosquitoes. Results from 32 ponds inside and outside Kruger National Park, South Africa show that our primer detected mosquito eDNA. However, it yielded only a subset of the species found using adult trapping methods. Particularly the less frequent and container-breeding species were not found. Our approach provides the first steps toward an eDNA-based method to assess the entire community of larval-stage mosquitoes. It may thereby overcome current taxonomic hurdles presented by morphological identification of larvae. As such, it holds great promise for biomonitoring and ecological studies of mosquitoes.

Mosquito (Diptera: Culicidae) communities of metropolitan Perth, Western Australia, and implications for managing pest and public health risks

AbstractMosquito population data in the Perth Metropolitan area are limited. This research aimed to determine mosquito species abundance and composition within three local government areas of inner metropolitan Perth. A secondary aim was to determine whether mosquito species abundance and composition in the study area were related to proximity of known saltmarsh mosquito breeding sites along two major tidal estuary systems. Eleven mosquito species were collected, of which four were found in high abundance: Aedes vigilax, Culex quinquefasciatus, Culex annulirostris and Aedes notoscriptus. The majority of mosquitoes were collected within 1 km of the tidal estuary systems, suggesting that productive mosquito breeding habitat is likely to be located along the fringe of the estuaries. The implication for mosquito management is that saltmarsh mosquitoes are not the only type of mosquito species in the study area. Broadening surveillance and management methods to include freshwater and container breeding species will reduce nuisance concerns for the public and is also likely to reduce incidence of disease in the area.

Oviposition preference and offspring performance in container breeding mosquitoes: evaluating the effects of organic compounds and laboratory colonisation.

The preference-performance hypothesis predicts that organisms lacking parental care should oviposit in habitats that optimize offspring performance. We investigated preference-performance relationships for the Asian tiger mosquito (Aedes albopictus Skuse) and the southern house mosquito (Culex quinquefasciatus Say) (Diptera:Culicidae), two medically important container-breeding species, in response to an organic chemical blend mimicking decaying plant matter. Additionally, we evaluated the effects of long-term laboratory colonization of Cx. quinquefasciatus by using wild and laboratory strains.Oviposition bioassays were conducted by releasing gravid mosquitoes into field enclosures with automobile tires containing low and high concentrations of the chemical blend, and water controls. The offspring were then reared in water collected from the tires in which they were deposited.Aedes albopictus and wild Cx. quinquefasciatus laid more eggs in the chemical blend than water controls but did not differentiate between the low and high concentrations. Conversely, laboratory Cx. quinquefasciatus only preferred the high concentration to the low concentration. No statistical associations between oviposition preference and larval survival were found, as the chemical blend did not affect survivorship of either species.The oviposition preference for the chemical blend over water controls suggests that both species oviposit in the best available resource environment, but further studies are needed before conclusions regarding preference-performance relationships can be drawn.We found that long-term laboratory colonization affects oviposition behavior in Cx. quinquefasciatus, suggesting that behavioral studies on laboratory strains are not always applicable to wild populations.

Ascension Island: a survey to assess the presence of Zika virus vectors

Background and aimFollowing concerns regarding the spread of Zika virus, Joint Services Health Unit (Cyprus) were tasked to carry out a mosquito survey on the Ascension Island, South Atlantic. This...

First Record ofStegomyia albopictain Turkey Determined By Active Ovitrap Surveillance and DNA Barcoding

Despite its confirmed establishment in neighboring Greece and Bulgaria, the presence of the Oriental invasive species Stegomyia albopicta (Skuse) (=Aedes albopictus) has never been confirmed in Turkey. Active surveillance for this container-breeding species was carried out using oviposition traps at 15 discrete sites in the towns of Ipsala (n=8 sites), Kesan (n=5) (Edirne District), and Malkara (n=2) (Tekirdag District) in the Thrace region of northwestern Turkey, from May 23 through November 10, 2011. Eggs collected were reared to the fourth larval instar and adult stages where possible to facilitate integrated morphological and molecular species identification. DNA barcodes (658 bp of the mitochondrial cytochrome c oxidase I [COI] gene) were compared with all four potentially invasive Stegomyia species: St. aegypti, St. albopicta, St. cretina, and St. japonica. Sequences generated for samples collected in Thrace Region were herein confirmed as St. albopicta, the first record of this vector species in Turkey. Eggs of St. albopicta were detected in two discrete localities: (1) In the grounds of a restaurant in Kesan (in week 36), and (2) in the customs area of the Turkish-Greek border at Ipsala (in weeks 32 and 38). Multiple detection of St. albopicta eggs indicates the possible establishment of the species in northwestern Turkey. Finding this important disease vector has implications for public health and requires the implementation of active vector monitoring programs and targeted vector suppression strategies to limit the spread of this invasive vector species in Turkey.

Unusual Life History Traits of Aedes (Stegomyia) Mosquitoes (Diptera: Culicidae) Inhabiting Nepenthes Pitchers

Abstract Unusual life history traits of Aedes (Stegomyia) dybasi Bohart of Palau and Aedes (S.) maehleri Bohart of Yap, Micronesia, were observed in the laboratory. These species are unique in the subgenus Stegomyia in that they use pitchers of a carnivorous plant, Nepenthes mirabilis Druce, as larval habitats. Traits of Ae. dybasi were compared with two sympatric, container-breeding species, Aedes (S.) palauensis Bohart, a probable ancestor of Ae. dybasi, and Aedes (S.) hensilli Farner. Life history traits of Ae. dybasi differ distinctly from those of Ae. palauensis and Ae. hensilli in egg and adult stages as well as in the larva. The female is autogenous and lays a few but extremely large eggs that can neither resist desiccation nor postpone hatch. The latter two species take blood and produce many smaller eggs with desiccation resistance as usual in Stegomyia. Developmental time of eggs was shorter in Ae. dybasi, whereas that for larvae and pupae was longer. Ae. maehleri differs from other Stegomyia species in its early copulation, where males copulate with newly emerging females on the water surface. Females neither are autogenous nor take blood from human hands. Nepenthes pitchers that provide mosquito larvae with a unique environment could contribute to studying either converging or diverging patterns in mosquito evolution under phylogenic potential and constraints after acquisition of a new larval habitat.

Leaf-Associated Bacterial and Fungal Taxa Shifts in Response to Larvae of the Tree Hole Mosquito, Ochlerotatus triseriatus

Larvae of the eastern tree hole mosquito, Ochlerotatus triseriatus (Say), and related container-breeding species are known to feed upon substrate-associated microorganisms. Although the importance of these microbial resources to larval growth has been established, almost nothing is known about the taxonomic composition and dynamics of these critical microbial food sources. We examined bacterial and fungal community compositional changes on oak leaves tethered in natural tree hole habitats of O. triseriatus. We eliminated larvae experimentally in a subset of the tree holes and examined 16S rDNA gene sequences for bacteria and ergosterol concentrations and 18S rRNA gene sequences for fungi collected from leaf material subsamples. Leaf ergosterol content varied significantly with time, but not treatment. Principal component analysis (PCA) was used to compare microbial taxonomic patterns found in leaves incubated with or without larvae present, and we found that larval presence affected both bacterial and fungal groups, either from loosely attached or strongly adherent categories. Bacterial communities generally grouped more tightly when larvae were present, and class level taxa proportions changed when larvae were present, suggesting selection by larval feeding or activities for particular taxa such as members of the Bacteroidetes, Alphaproteobacteria, and Betaproteobacteria classes. Fungal taxa composite scores also separated along PC axes related to the presence of larvae and indicated larval feeding effects on several higher taxonomic groups, including Saccharomycetes, Dothideomycetes, and Chytridiomycota. These results support the hypothesis that larval mosquito feeding and activities altered microbial communities associated with substrate surfaces, potentially leading to decreased food value of the resource and affecting decomposition of particulate matter in the system.

Spatial Statistical Analysis of Adult Mosquito (Diptera: Culicidae) Counts: An Example Using Light Trap Data, in Redland Shire, Southeastern Queensland, Australia

Many mosquito control agencies use carbon dioxide-baited traps as surveillance tools for adult vector populations. However, decisions regarding the number and location of trap sites and the frequency of collections are often based on logistical issues, and not on the bionomics or spatial distribution of the target species. Therefore, with the aim of providing practical information for adult mosquito surveillance programs, we used an array of 81 carbon dioxide- and octenol-baited lights traps to obtain weekly samples of adult mosquitoes in Redland Shire in southeastern Queensland, Australia. The spatial patterns of four different mosquito species were examined, and positive spatial autocorrelation in trap counts was evident for Ochlerotatus vigilax (Skuse), Coquillettidia linealis (Skuse), and Culex annulirostris Skuse, but not for the container species Ochlerotatus notoscriptus (Skuse). Of the three species that exhibited spatially correlated trap counts, the autocorrelation was greatest in Oc. vigilax at a lag distance of 0-1.5 km, with Moran's I values of 0.30-0.64. Moran's I indices were also positive and statistically significant (P < 0.05) at lag distances of 1.5-3.0 and 3.0-4.5 km on each of the 15 sampling occasions. However, at 3.0-4.5 km the Moran's I values were low, which indicated only weak spatial autocorrelation in trap counts. Universal kriging was used to estimate the numbers of each species at unsampled locations throughout the study area, and leave-one-out cross validation analyses indicated that this was a robust method for Cq. linealis and Oc. vigilax. In contrast, trap counts for the container-breeding species Oc. notoscriptus were randomly distributed and the interpolated counts were not reliable. Comparisons of weekly contour maps of adult mosquito counts indicated a consistent spatial pattern for Oc. vigilax and Cq. linealis. Particular geographic areas had consistently high or low numbers of vectors, and these patterns were stable from year to year. Definition of geographic areas with consistently high or low numbers of vectors may allow control activities to be focused in areas with the greatest risk of arbovirus transmission.

HIGHER MOSQUITO-BORNE DISEASE RISK IN ANTHROPOGENICALLY MODIFIED ENVIRONMENTS IN THE KAPITI COAST REGION, NEW ZEALAND.

The recent worldwide spread of disease-vector mosquitoes is a serious threat to public health. The ‘emergence’ and ‘re-emergence’ of some major arboviral diseases (eg. Dengue Fever virus and Ross River virus) in recent decades have been linked to the flow-on effects of anthropogenic environmental change on the physical structure and biodiversity of mosquito larval habitats. Although New Zealand has so far remained free from arboviral human diseases an eventual outbreak is very probable in the long term. Four exotic disease vector species have already become well established in New Zealand. Escalating international travel and commerce may introduce more exotic disease vectors as well as disease-infected people, which both exotic and native species may ingest from. To predict how anthropogenic environmental change alters the risk of exposure to disease-vector mosquitoes we need an intimate knowledge of the ecology and biology of species currently in New Zealand. The overarching aim of this paper is to compare the effects of different land uses on the productivity of container breeding species in the Kapiti Coast region, New Zealand. In 2002–03, disease-vector mosquito productivity was examined in artificial containers and other resident water bodies in three land use types, farmland, suburban area and native bush, at three sites in the Kapiti Coast region. Additionally, nutrient and shade levels were experimentally manipulated in mosquito container habitats placed in native bush to approximate the effects of deforestation and agriculture on larval populations. In the field survey, suburban and farmland sites had lower resident biodiversity and substantially higher numbers of disease-vector mosquitoes than native bush sites. Disease-vector mosquitoes also colonised experimental containers in an open, non-forested environment with medium to high nutrient additions more quickly and in greater numbers than in containers under a forest canopy with low or ultra high nutrient levels. These results suggest that modified environments have increased mosquito-borne disease risk from invading species, and that ecosystem integrity in the form of aquatic macro-invertebrate biodiversity may play a fundamental role in protecting against arboviral introduction and spread.

Parasitism of mosquitoes (Diptera: Culicidae) by larval mites (Acari: Parasitengona) in Adelaide, South Australia

Larval mites (Acari) from the cohort Parasitengona were collected from adult female mosquitoes captured in Adelaide, South Australia, from 1997 to 2000. Larvae from three families were identified: Arrenuridae, Hydryphantidae and Erythraeidae. Arrenurid larvae were associated with mosquitoes that use ground pools for larval habitat, while hydryphantids were associated with tree-hole and container-breeding species. Only a single erythraeid record was made. The overall prevalence of parasitism was very low (0.27% of 19 280 mosquitoes) and ranged from 0 to 5.6% for the 16 mosquito species collected. New mite–host records are presented.

Potential North American vectors of West Nile virus.

The outbreak of disease in the New York area in 1999 due to West Nile (WN) virus was the first evidence of the occurrence of this virus in the Americas. To determine potential vectors, more than 15 mosquito species (including Culex pipiens, Cx. nigripalpus, Cx. quinquefasciatus, Cx. salinarius, Aedes albopictus, Ae. vexans, Ochlerotatus japonicus, Oc. sollicitans, Oc. taeniorhynchus, and Oc. triseriatus) from the eastern United States were evaluated for their ability to serve as vectors for the virus isolated from birds collected during the 1999 outbreak in New York. Mosquitoes were allowed to feed on one- to four-day old chickens that had been inoculated with WN virus 1-3 days previously. The mosquitoes were incubated for 12-15 days at 26 degrees C and then allowed to refeed on susceptible chickens and assayed to determine transmission and infection rates. Several container-breeding species (e.g., Ae. albopictus, Oc. atropalpus, and Oc. japonicus) were highly efficient laboratory vectors of WN virus. The Culex species were intermediate in their susceptibility. However, if a disseminated infection developed, all species were able to transmit WN virus by bite. Factors such as population density, feeding preference, longevity, and season of activity also need to be considered in determining the role these species could play in the transmission of WN virus.