Mosquito distribution in a saltmarsh: determinants of eggs in a variable environment

Two saltmarsh mosquitoes dominate the transmission of Ross River virus (RRV, Togoviridae: Alphavirus), one of Australia's most prominent mosquito‐borne diseases. Ecologically, saltmarshes vary in their structure, including habitat types, hydrological regimes, and diversity of aquatic fauna, all of which drive mosquito oviposition behavior. Understanding the distribution of vector mosquitoes within saltmarshes can inform early warning systems, surveillance, and management of vector populations. The aim of this study was to identify the distribution of Ae. camptorhynchus, a known vector for RRV, across a saltmarsh and investigate the influence that other invertebrate assemblage might have on Ae. camptorhynchus egg dispersal. We demonstrate that vegetation is a strong indicator for Ae. camptorhynchus egg distribution, and this was not correlated with elevation or other invertebrates located at this saltmarsh. Also, habitats within this marsh are less frequently inundated, resulting in dryer conditions. We conclude that this information can be applied in vector surveillance and monitoring of temperate saltmarsh environments and also provides a baseline for future investigations into understanding mosquito vector habitat requirements.     

Detection of and monitoring for Aedes albopictus (Diptera: Culicidae) in suburban and sylvatic habitats in north central Florida using four sampling techniques

A sampling study using a BG-Sentinel trap baited with CO(2), a gravid trap baited with an oak-pine infusion, a human subject, and a vegetative aspirator was conducted to compare their reliability at detecting Aedes albopictus Skuse in suburban and sylvatic habitats. We collected 73,849 mosquitoes, representing 29 species from 11 genera over a 20-wk period. The BG-Sentinel trap accounted for over 85% of all Ae. albopictus captured and was significantly more effective at detecting the presence of Ae. albopictus compared with the other three techniques. Landing counts provided the fewest mosquito species (n = 10), yet provided a quick and effective weekly assessment of the major biting species and were the most effective method for sampling Ae. albopictus within a 10-min period. Fewer Ae. albopictus were sampled from sylvatic habitats compared with suburban ones. Sampling criteria advantageous for surveying Ae. albopictus and other mosquito species are discussed.     

The distribution of mosquitoes (Diptera,Culicidae) in the Republic of Azerbaijan

The mosquito fauna in the territory of the Republic of Azerbaijan comprises 24 species from 7 genera. The dominant species are Anopheles sacharovi, Culex pipiens, Aedes caspius, and Ae. geniculatus in the forest area, and Coquillettidia richiardii in the lowlands, where there are swamps overgrown with reeds.     

Mosquitoes (Diptera,Culicidae) of the Morava River floodplain,Slovakia

Research on the Morava River floodplain mosquito fauna was carried out from April to October in 2009 and 2010. Altogether, 5864 adults were collected and identified from 12 selected sites. The presence of 28 mosquito species belonging to 6 genera were confirmed in the study area. The floodplain of the Morava River is known for its frequent inundation every year. The floods are quite irregular and often followed by the mass production of mosquitoes. The most abundant species were Aedes vexans (41.4%), Ae. cinereus (7.5%), Ae. rossicus (16.7%), Ochlerotatus sticticus (20.5%), and Culex pipiens (3.1%). Ae. vexans and Oc. sticticus are typical outbreak species for the Morava River floodplain. The years 2009 and 2010 differed in the number of floods, which influenced the mosquito faunal composition and abundance during the year.     

Seasonal profiles of Aedes aegypti (Diptera: Culicidae) larval habitats in an urban area of Costa Rica with a history of mosquito control

Dengue is the most important arboviral disease worldwide and the principal vector-borne disease in Costa Rica. Control of Aedes aegypti populations through source reduction is still considered the most effective way of prevention and control, although it has proven ineffective or unsustainable in many areas with a history of mosquito control. In this study, seasonal profiles and productivity of Aedes aegypti were analyzed in the city of Puntarenas, Costa Rica, where vector control has been practiced for more than ten years. Households contained more than 80% of larval habitats identified, although presence of habitats was more likely in other locations like lots and streets. In the wet season, habitats in the "other" category, like appliances, small manholes, and miscellaneous containers, were the most frequent habitats observed as well as the most common and productive habitats for Ae. aegypti. In the dry season, domestic animal drinking containers were very common, although concrete washtubs contained 79% of Ae. aegypti pupae collected. Individually, non-disposable habitats were as likely or more likely to contain mosquito larvae, and large containers were more likely to harbor mosquito larvae than the small ones only in the dry season. Considering various variables in the logistic regressions, predictors for Ae. aegypti in a habitat were habitat type (p < 0.001), setting (p = 0.043), and disposability (p = 0.022) in the wet season and habitat capacity in the dry season (p = 0.025). Overall, traditional Ae. aegypti larval indices and pupal indices in Puntarenas were high enough to allow viral transmission during the wet season. In spite of continued vector control, it has not been possible to reduce vector densities below threshold levels in Puntarenas, and the habitat profiles show that non-household locations, as well as non-disposable containers, should be targeted in addition to the standard control activities.     

On the spider population of the area adjacent to Teletskoe Lake (Northeast Altai)

Investigations have been carried out in the area adjacent to Teletskoe Lake in the Altai Nature Reserve. Checklists of species for the studied habitats and their comparative analysis are given. Previous data on the fauna of spiders in the Altai Nature Reserve have been supplemented by 39 species. Three species have been recorded for the first time in the fauna of the Altai Mountains. The complexes of dominant species have been revealed. Peculiarities of the seasonal dynamics of the population for order as a whole and for separate herpetobiont spiders groups have been considered.     

Assessment of Aedes albopictus (Skuse) (Diptera: Culicidae) clutch size in wild and laboratory populations

Aedes albopictus (Skuse) is an invasive mosquito species found across the southern U.S. with range expansion into many northern states. Intra‐ and interspecific larval competition have been evaluated for Ae. albopictus with respect to subsequent adult size, immature and adult survivability, and its capacity to vector pathogens as an adult. However, limited data are available on egg production as related to larval rearing conditions. Because Ae. albopictus is a container‐inhabiting mosquito that oviposits in resource‐limited habitats, it is found under variable density‐dependent conditions. Therefore, we examined the impact of specific rearing conditions on Ae. albopictus clutch size and adult body size; comparing the egg production values and wing lengths from known developmental densities to those from field‐collected populations. Field populations varied significantly among collection sites in mean clutch size (23 to 46). These clutch sizes were comparable to the mean clutch sizes of females reared at the larval densities of nine (20 eggs) and three (53 eggs) larvae per 3 ml of water in the laboratory. Field populations experienced density‐dependent effects impacting adult mosquito size. Mosquitoes from the four sample sites had mean wing lengths of 1.99, 2.47, 2.51, and 2.54 mm, which were less than the mean wing length of mosquitoes reared at larval densities of three larvae per 3 ml of water (2.57 mm).     

Conservation of Heathland Ground Beetles (Coleoptera,Carabidae): The Value of Lowland Coniferous Plantations

The value of conifer-dominated plantation forestry for heathland carabids is examined, in Breckland, eastern England. Historically dominated by heathland habitats supporting scarce species of restricted distribution within the UK, approximately 47% of Breckland was afforested in the early 20th century. The carabid fauna of this forest, previously little known, was sampled by intensive pitfall trapping, and results compared to samples from heathland and arable. The results affirm that Breckland supports many range-restricted carabid beetles, including scarce species restricted to lowland heathland or sandy habitats. Approximately half of the heathland-associated species, and also half of the Nationally Scarce carabid species recorded in Breckland, were found within the forest landscape. Carabid species composition differed between closed-canopy forest, heathland and arable, while open forest habitats (clear-felled stands, young restocked stands, and track margins) contained a diverse fauna with elements from all habitats. The proportion of heathland-associated species was significantly greater in open forest habitats than in closed-canopy forest and was similar to that of heathland assemblages. Wing morphology did not differ between heathland species solely recorded from heathland and those also recorded in the forest. Nationally Scarce species from the forest had a wider UK distribution than those recorded only from heathland. Our study shows that, within conifer forest planted in lowland heathland areas, open habitats provided by trackway networks and clear-felling management can have significant value for the conservation of open-ground carabids, including species of conservation importance.     

Temporal Patterns of Abundance of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) and Mitochondrial DNA Analysis of Ae. albopictus in the Central African Republic

The invasive Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) was first reported in central Africa in 2000, in Cameroon, with the indigenous mosquito species Ae. aegypti (Diptera: Culicidae). Today, this invasive species is present in almost all countries of the region, including the Central African Republic (CAR), where it was first recorded in 2009. As invasive species of mosquitoes can affect the distribution of native species, resulting in new patterns of vectors and concomitant risk for disease, we undertook a comparative study early and late in the wet season in the capital and the main cities of CAR to document infestation and the ecological preferences of the two species. In addition, we determined the probable geographical origin of invasive populations of Ae. albopictus with two mitochondrial DNA genes, COI and ND5. Analysis revealed that Ae. aegypti was more abundant earlier in the wet season and Ae. albopictus in the late wet season. Used tyres were the most heavily colonized productive larval habitats for both species in both seasons. The invasive species Ae. albopictus predominated over the resident species at all sites in which the two species were sympatric. Mitochondrial DNA analysis revealed broad low genetic diversity, confirming recent introduction of Ae. albopictus in CAR. Phylogeographical analysis based on COI polymorphism indicated that the Ae. albopictus haplotype in the CAR population segregated into two lineages, suggesting multiple sources of Ae. albopictus. These data may have important implications for vector control strategies in central Africa.     

Successional mosquito dynamics in surrogate treehole and ground‐container habitats in the northeastern United States: Where does Aedes albopictus fit in?

This study assessed the risk of larval displacement of the eastern treehole mosquito, Aedes triseriatus, and the northern house mosquito, Culex pipiens, by Aedes albopictus, the Asian tiger mosquito, during the establishment and successional stages of novel larval mosquito treehole and ground‐container habitats in the state of New Jersey, U.S.A. Culex pipiens and Culex restuans were the first mosquito species to colonize ground‐container habitats and were the dominant larval species throughout the study period, whereas Ae. albopictus was late to colonize ground habitats and accounted for less than 15% of weekly larval collections once established. Ae. albopictus had a much stronger community presence within treehole ovitraps; however, Ae. albopictus never reached the average larval densities of the expected primary colonizer, Ae. triseriatus. Throughout the study period, the weekly abundances of Ae. triseriatus and Ae. albopictus were positively correlated and there were no significant differences between the abundances of each species. The larval dominance of Ae. triseriatus appears to be enhanced by the presence of Toxorhynchites rutilus septentrionalis, a large predatory mosquito species. When Tx. rut. septentrionalis was present, mature larvae (3^rd–4^th instar) of Ae. albopictus were also present in only 16.7% of collections, whereas mature larvae of Ae. triseriatus were collected concurrently with Tx. rut. septentrionalis in 53.8% of collections. These data suggest that Ae. triseriatus is at a greater risk of displacement by Ae. albopictus than are Cx. pipiens and Cx. restuans.     

Prevalence of Aedes camptorhynchus (Thomson) (Diptera: Culicidae) and Other Mosquitoes in the Eastern Coast of Victoria

Adult mosquito populations were monitored using dry-ice baited EVS light traps at weekly intervals for four seasons (1991–95) in Avon, Bairnsdale, Rosedale and Hastings, and for three seasons (1991–94) in Tambo, in the eastern coast of Victoria. Among the 20 species of adult mosquitoes recorded, Aedes camptorhynchus (Thomson) was dominant (74–99%). Higher Ae camptorhynchus adult populations were recorded in the 1992–93 and 1993–94 seasons, than in 1991–92 and 1994–95 seasons. Rosedale shire recorded higher Ae camptorhynchus adult populations than the Avon, Bairnsdale, Hastings and Tambo shires. In all shires, two peaks of Ae camptorhynchus activity reaching high (100–1,000 adults/trap) to very high (> 1,000 adults/trap) levels were recorded, with the first peak in the middle of December (summer) and the second peak in the middle of April (autumn). the Ae camptorhynchus activity in the coastal region increased with an increase in the minimum temperature.     

Occurrence of Toxorhynchites guadeloupensis (Dyar Knab) in oviposition trap of Aedes aegypti (L.) (Diptera: Culicidae)

Toxorhynchites guadeloupensis (Dyar Knab), a poorly known mosquito species, was observed preying upon Aedes aegypti (L.) larvae, in an oviposition trap placed for routine dengue entomological surveillance, during 2003-2004 in the urban area of Boa Vista, Roraima, Brazil. This is the first report for Tx. guadeloupensis using Ae. aegypti oviposition traps as breeding places. This finding may have important consequences in the epidemiology and local dengue control since Ae. aegypti density is a basic variable in dengue prediction. Whether predation of Ae aegypti by Tx. guadeloupensis in the Amazon is of significance, is a question to be examined. Also, larval predation may be a cause for underestimation of the actual Ae aegypti numbers. Together these hypotheses need to be better investigated as they are directly related to dengue epidemiology, to the success of any outbreak prediction and surveillance program.     

State‐wide survey of Aedes aegypti and Aedes albopictus (Diptera: Culicidae) in Florida

Aedes aegypti and Aedes albopictus are invasive mosquito species with geographic ranges that have oscillated within Florida since their presence was first documented. Local transmission of dengue, chikungunya, and Zika viruses serves as evidence of the public health importance of these two species. It is important to have detailed knowledge of their distribution to aid in mosquito control efforts and understand the risk of arbovirus transmission to humans. Through a partnership involving the University of Florida Institute of Food and Agricultural Sciences Cooperative Extension Service and the Florida Medical Entomology Laboratory; the Florida Department of Health; and mosquito control agencies throughout Florida, a container mosquito surveillance program involving all life stages was launched in the summer of 2016 to detect the presence of Ae. aegypti and Ae. albopictus. Results from this survey were mapped to provide a picture of the current known distribution of Ae. aegypti and Ae. albopictus in Florida. Aedes aegypti and/or Ae. albopictus were detected in the 56 counties that were part of the survey. Only Aedes albopictus was detected in 26 counties, primarily in the panhandle region of Florida. The results of this work underscore the importance of maintaining container mosquito surveillance in a state where chikungunya, dengue, and Zika viruses are present and where there is continued risk for exotic arbovirus introductions.     

Mosquitoes of Rarotonga,Cook Islands: A survey of breeding sites

Abstract

Two surveys of Rarotonga, Cook Islands (21°20^'S, 160°16^'W) were made to determine the mosquito fauna of the island, and to identify the habitats required for breeding by searching for larvae. The first survey was made during the “dry season” in May 2001, the second during the “wet season” in February 2002. The mosquito fauna comprised four species Culex (Culex) quinquefasciatus Say, Culex (Culex) annulirostris Skuse, Aedes (Stego‐myia) aegypti (Linnaeus) and Aedes (Stegomyia) polynesiensis Marks. Larvae of the Culex species were most often found in larger natural and artificial water bodies. The Aedes species bred in both natural and artificial containers of all sizes. Ae. polynesiensis was the most widespread species, using natural holes in all regions as well as artificial containers in the urban areas. Most larvae of Ae. aegypti were located in small artificial containers. The two Aedes species are the vectors of dengue fever on the island. Mosquito control during outbreaks should specifically target the artificial containers preferred by Aedes sp. for breeding habitats.     

Host range of the parasite Strelkovimermis spiculatus (Nematoda: Mermithidae) in Argentina mosquitoes

Strelkovimermis spiculatus ( Poinar and Camino 1986 ) is a nematode parasite of mosquitoes isolated from the Neotropical region. We investigated the host range of this parasite in mosquito populations for a better understanding of the dynamics of temporary breeding sites. Five grassy‐pool habitats filled by rainwater were sampled from the summer 2007 through the fall 2008. Eight mosquito species were collected: Anopheles albitarsis, Culex chidesteri, Culex dolosus, Culex maxi, Aedes albifasciatus, Psorophora ciliata, Psorophora cyanescens, and Psorophora albigenu. Six of these species were parasitized: Cx. chidesteri, Cx. dolosus, Cx. maxi, Ae. albifasciatus, Ps. ciliata, and Ps. cyanescens. The occurrence of this mermithid in natural mosquito populations was increased from the end of winter to the end of the spring. Prevalence ranged from 11% to 100%. High levels of infections were registered only in Ae. albifasciatus larvae, the most abundant mosquito species (95%), followed by Cx. dolosus (2.7%). Strelkovimermis spiculatus completed its development in all infected mosquito larvae. The presence of S. spiculatus in six natural mosquito populations increases the number of susceptible species to 24.     

Drosophilidae (Diptera) of Australia's Northern Territory: ecology and biogeography

Abstract   The drosophilid fauna is well documented in eastern Australia but is poorly known in other parts of the continent. This paper summarises what is known of this fauna in the Northern Territory (NT), and includes results from banana trapping in the humid and arid zones. The 42 recorded species include species that breed in fruit, fungi and/or flowers, and a larval predator of scale insects. Drosophilids occur in all three major climate zones (humid, semiarid and arid) but predominate in the humid zone. Banana-attracted species in the humid zone (wet-dry tropics) were common in all sampled habitats: urban, rainforest and open woodland. They included predominantly urban and/or rainforest species. Of the species collected in open woodland, some are likely to be breeding there, whereas others may have been intercepted during movement across the area. The semiarid fauna is a depauperate version of that found in the humid region. Only three species have been recorded in the arid region: an endemic arid specialist, and two cosmopolitan species ( D. simulans and D. melanogaster ) in urban Alice Springs. Overall, the NT drosophilid fauna represents a depauperate version of that found in eastern Australia, probably because of climatic factors and natural barriers to range expansion. There is little evidence of regional endemism, with probably only one (and at most three) species endemic to the NT, and no evidence of independent, natural dispersion from nearby Indonesia.     

Epizootiological studies of Amblyospora albifasciati (Microsporidiida: Amblyosporidae) in natural populations of Aedes albifasciatus (Diptera: Culicidae) and Mesocyclops annulatus (Copepoda: Cyclopidae) in a transient floodwater habitat

The epizootiology of the microsporidium Amblyospora albifasciati was studied in natural populations of its definitive host, a multivoltine, neotropical, floodwater mosquito, Aedes albifasciatus, and its intermediate copepod host, Mesocyclops annulatus, in an ephemeral floodwater habitat during a 12-month period. A. albifasciati was enzootic in mosquitoes. Vertically (transovarially) transmitted meiospore infections occurred regularly and were detected in five of eight larval broods but the prevalence of infection was always low, ranging from 0.5 to 6.9% with an overall average of 0.7%. Horizontal transmission of A. albifasciati infection from copepods to mosquitoes was nominal and limited. It was detected at levels of 6.4 to 20% in larval Ae. albifasciatus populations on two occasions, the month of August and late September through early October. The low levels of horizontal transmission of infection to mosquito larvae appeared to be the principal limiting factor that prevented the proliferation of A. albifasciati in Ae. albifasciatus populations. Copepod populations were abundant from May through September and weekly prevalence rates of A. albifasciati averaged over 50% (range = 5.8 to 100%). The moderately high infection rates in M. annulatus copepods were inconsistent with the low prevalence of meiospore infection in Ae. albifasciatus mosquito larvae. Results suggest that either meiospores of A. albifasciati produced in the mosquito host are highly infectious to copepods or they are long-lived and remain viable within the pool as long as some standing water is present. Observations further indicate that A. albifasciati has a significant detrimental impact on M. annulatus copepod populations but minimal impact on larval populations of Ae. albifasciatus at this site.     

Phylogeography of the medically important mosquito Aedes (Ochlerotatus) vigilax (Diptera: Culicidae) in Australasia

Aim Within Australia the Carpentaria Barrier has been identified as an important biogeographical barrier. Here we test this long‐standing hypothesis using a medically important mosquito, Aedes (Ochlerotatus) vigilax. Location We obtained samples of Ae. vigilax from throughout its Australian distribution and from New Caledonia. Methods We constructed a distributional database from 602,417 specimens and obtained sequence data from 66 female specimens from 16 localities. The distributional database of Ae. vigilax comprised historical data from 13 organizations and was used to develop our molecular sampling strategy. Genetic structure within Ae. vigilax was examined via haplotype networks, F_ST values, analysis of molecular variance and neutrality test statistics based on one mitochondrial (cytochrome c oxidase subunit I, COI) and two nuclear (alpha amalyse and zinc finger) loci. The historical demography of Ae. vigilax was investigated using extended Bayesian skyline plot (EBSP) methods, with past migration rates estimated using migrate . Results We identified three distinct lineages within Ae. vigilax; however, two of the three lineages show a large distributional overlap across the Carpentaria Barrier. The mitochondrial locus suggested a pattern of significant genetic differentiation, with high F_ST values, significant genetic differentiation within the COI locus, and significantly more variation between the lineages than within. A higher number of migrants per generation were estimated for the overlapping lineages and both the neutrality test statistics and EBSP suggested the occurrence of post‐population expansion in these lineages. Main conclusions Significant deviation from genetic neutrality, in combination with estimates of migration and the demographic history of Ae. vigilax lineages, suggests that the incongruence of the Ae. vigilax phylogeny with the hypothesized Carpentaria Barrier could be attributed to the separation of eastern and western populations of Ae. vigilax around 770 ka and subsequent secondary contact within the last 100 kyr. Sea‐level and precipitation fluctuations within the Carpentaria area during the late Quaternary could have facilitated the current biogeographical patterns of Ae. vigilax. Mosquitoes represent one of the most medically important insect groups; however, understanding the factors that influence past and present distributions of mosquitoes is critical in the face of a range of emerging arboviruses.