Invasive Asian Tiger Mosquito Research Articles

The interplay between vector microbial community and pathogen transmission on the invasive Asian tiger mosquito, Aedes albopictus: current knowledge and future directions.

The invasive Asian tiger mosquito Aedes albopictus is nowadays broadly distributed with established populations in all continents except Antarctica. In the invaded areas, this species represents an important nuisance for humans and, more relevant, it is involved in the local transmission of pathogens relevant under a public health perspective. Aedes albopictus is a competent vector of parasites such as Dirofilaria and viruses including dengue virus, Zika virus, and chikungunya virus, among others. The mosquito microbiota has been identified as one of the major drivers of vector competence, acting upon relevant vector functions as development or immunity. Here, we review the available literature on the interaction between Ae. albopictus microbiota and pathogen transmission and identify the knowledge gaps on the topic. Most studies are strictly focused on the interplay between pathogens and Wolbachia endosymbiont while studies screening whole microbiota are still scarce but increasing in recent years, supported on Next-generation sequencing tools. Most experimental trials use lab-reared mosquitoes or cell lines, exploring the molecular mechanisms of the microbiota-pathogen interaction. Yet, correlational studies on wild populations are underrepresented. Consequently, we still lack sufficient evidence to reveal whether the microbiota of introduced populations of Ae. albopictus differ from those of native populations, or how microbiota is shaped by different environmental and anthropic factors, but especially, how these changes affect the ability of Ae. albopictus to transmit pathogens and favor the occurrence of outbreaks in the colonized areas. Finally, we propose future research directions on this research topic.

A SENSOR NETWORK BASED ON IOT AND ISTSOS TO ANALYSE THE CATCH BASIN ENVIRONMENT IN THE CONTEXT OF THE AE. ALBOPICTUS EXPANSION IN SWITZERLAND

Abstract. The continuous expansion of invasive Asian tiger mosquito, Aedes albopictus, combined to its ability to transmit arboviruses (e.g. dengue, chikungunya) is raising major public health concern in Europe. In Switzerland, the mosquito is firmly established in most urban areas of the Canton of Ticino, south of the Alps, and there is a real risk that it will colonize also urban areas north of the Alps in the next years. The spatial distribution and colonization of new areas by Ae. albopictus depends on several environmental parameters, such as winter and summer temperatures, and precipitation patterns. A key factor for Ae. albopictus to establish at higher latitudes is the capability to develop cold-tolerant overwintering diapausing eggs under specific environmental conditions. Weather-driven abundance models are used to map the areas of potential distribution and to predict temporal dynamics of Ae. albopictus and the transmission potential of arboviruses. This contribution presents the designed system that integrates low-cost and on-line IoT sensors to monitor temperature, humidity and light with istSOS an OGC Sensor Observation Service server implementation with a user friendly interface and rich feature collection to easily manage this sensor network and distribute data in a standard way (www.istsos.org).

Asian tiger mosquito far from home: Assessing the impact of invasive mosquitoes on the French Mediterranean littoral

• Invasive Asian tiger mosquito both cause nuisance and can transmit serious diseases. • We value these disservices with two stated preferences methods. • The most frequent attitude places the risk of contracting mosquito-borne diseases first. • We identify 3 groups: averse to disease risk, averse to the nuisance, and indifferent. • The main explanatory factors are insecticides and repellents expenditure, housing place and income.

Do Invasive Mosquito and Bird Species Alter Avian Malaria Parasite Transmission?

Alien mosquito and vertebrate host species may create novel epidemiological scenarios for the transmission of pathogens naturally circulating in the invaded area. The exotic Monk parakeet (Myiopsitta monachus) has established populations in Europe and is currently considered an invasive pest. Due to their high abundance in urban areas, Monk parakeets could be involved in the transmission of pathogens, potentially affecting wildlife and livestock. To test this hypothesis, we determined the prevalence and diversity of three vector-borne parasites, namely Plasmodium, Haemoproteus and Leucocytozoon, in Monk parakeets from Barcelona. Many areas of southern Europe shelter high densities of the invasive Asian tiger mosquito Aedes albopictus, which in addition to native mosquito species could affect the transmission of mosquito-borne parasites, such as avian Plasmodium. Thus, we also sampled mosquitoes in the area to trace their blood-feeding hosts and determine the presence of Plasmodium parasites. Monk parakeets were neither infected by Plasmodium nor by Haemoproteus parasites, and only five individuals (3.13%; n = 160) were infected by Leucocytozoon. Monk parakeets were bitten by Culiseta longiareolata and represented 9.5% of Culex pipiens blood meals. The invasive Ae. albopictus showed a clear anthropophilic feeding pattern, with humans dominating its diet. Three Plasmodium lineages were detected in pools of Cx pipiens. These results suggest that Plasmodium circulating in the area cannot develop in the invasive Monk parakeet, in spite of the relatively high fraction of native mosquito vectors feeding on this species in its invaded distribution range.

Bioclimatic modeling of the European distribution of the invasive Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse, 1895), with special reference to Ukraine

Bioclimatic modeling of the European distribution of the invasive Asian tiger mosquito, Aedes (Stegomyia) albopictus (Skuse, 1895), with special reference to Ukraine

The invasive Asian tiger mosquito Aedes albopictus in Romania: towards a country-wide colonization?

Currently, five invasive Aedes mosquito species are of concern in Europe according to the European Centre for Disease Prevention and Control: Aedes aegypti, Ae. albopictus, Ae. atropalpus, Ae. japonicus, and Ae. koreicus. Among these, only Ae. albopictus was reported to occur in Romania, in Bucharest. The aim of this study was to update the knowledge on the distribution of this invasive mosquito species in Romania, by investigating new potential locations. Monitoring of Ae. albopictus was carried out between May 2017 and October 2018. Three types of traps (CDC-Gravid Traps, CDC miniature Light Traps, ovitraps) were placed in 53 localities in 13 counties at sites suitable for container-breeding mosquitoes. Collected adult mosquitoes were counted and identified according to morphological criteria. Larvae were found present in domestic containers and rain catch basins. Aedes albopictus adults and eggs were collected in 10 localities in eight counties across Romania. Our study confirms nine new localities and seven counties where Ae. albopictus became established in Romania, highlighting the need for surveillance to further assess the species' distribution and abundance, as well as the pathogen transmission risk related to that vector species.

A novel metric reveals biotic resistance potential and informs predictions of invasion success

Invasive species continue to proliferate and detrimentally impact ecosystems on a global scale. Whilst impacts are well-documented for many invaders, we lack tools to predict biotic resistance and invasion success. Biotic resistance from communities may be a particularly important determinant of the success of invaders. The present study develops traditional ecological concepts to better understand and quantify biotic resistance. We quantified predation towards the highly invasive Asian tiger mosquito Aedes albopictus and a representative native mosquito Culex pipiens by three native and widespread cyclopoid copepods, using functional response and prey switching experiments. All copepods demonstrated higher magnitude type II functional responses towards the invasive prey over the analogous native prey, aligned with higher attack and maximum feeding rates. All predators exhibited significant, frequency-independent prey preferences for the invader. With these results, we developed a novel metric for biotic resistance which integrates predator numerical response proxies, revealing differential biotic resistance potential among predators. Our results are consistent with field patterns of biotic resistance and invasion success, illustrating the predictive capacity of our methods. We thus propose the further development of traditional ecological concepts, such as functional responses, numerical responses and prey switching, in the evaluation of biotic resistance and invasion success.

Rapid local adaptation to northern winters in the invasive Asian tiger mosquito Aedes albopictus: A moving target

Abstract Rapid adaptation in response to novel environments can facilitate species invasions and range expansions. Understanding how invasive disease vectors rapidly evolve to novel conditions—particularly at the edge of its non‐native range—has important implications for mitigating the prevalence and spread of disease. Here, we evaluate the role of local adaptation in overwintering capability of the Asian tiger mosquito, Aedes albopictus. This species invaded the Southern United States in the 1980s and rapidly spread northward into novel climate compared to its native range. Photoperiodically induced egg diapause is a key trait contributing to the establishment and spread of Ae. albopictus in temperate latitudes, and diapause incidence rapidly developed a cline along a latitudinal gradient in the United States shortly after its initial invasion. However, variation in overwintering survival of diapause‐induced eggs along this gradient is not known, but is critical to the fitness‐related role of diapause evolution in the establishment of Ae. albopictus in its northern US range. Using reciprocal transplants, we detected local adaptation in overwinter survival of diapausing Aedes albopictus eggs. In northern range‐edge winters, eggs produced by range‐edge individuals survived better than those produced by range‐core individuals. Diapause eggs from range‐edge and range‐core locations survived equally well in range‐core winters, and no eggs survived a winter beyond the current northern range limit in the United States. Synthesis and applications. These results demonstrate rapid (~3 decades) local adaptation of egg diapause, a key trait facilitating overwinter survival and range expansion for the invasive Asian tiger mosquito. In light of these results, control efforts could shift from targeting satellite populations to a focus on preventing dispersal into locally adapted, range‐edge locations and to aim removal efforts towards areas surrounding locally adapted populations. Adopting new approaches to target rapidly adapting populations will require large‐scale collaboration among control agencies and research institutions, and should begin in the northern US range to better control Aedes albopictus mosquito populations in the face of rapid adaptation.

Neighbors help neighbors control urban mosquitoes

The worldwide spread of invasive Aedes mosquitoes and arboviral disease, have renewed the pressure for effective and sustainable urban mosquito control. We report on the success of a model we are confident will usher in a new era of urban mosquito control. The key innovation is the mobilization of neighbors guided by scientific advisors, an approach we termed Citizen Action through Science (Citizen AcTS). This approach was tested in a NE US town of approximately 1,000 residential yards infested with the invasive Asian tiger mosquito, Aedes albopictus, a major nuisance arboviral vector. We report a highly significant reduction in biting pressure that was maintained over time, and establish the thresholds needed for success. The Citizen AcTS model rejects the top-down approach consistently associated with intervention failures. Instead, it works through respectful exchanges among scientists and residents that lead to trust and individual ‘buy-in’ and transferring program ownership to the community.

The Asian tiger mosquito Aedes albopictus (Diptera: Culicidae) in Central Germany: Surveillance in its northernmost distribution area

The invasive Asian tiger mosquito Aedes albopictus has recently been observed in southern Germany for the first time to reproduce and even overwinter north of the Alps. After the accidental capture of adult specimens in Jena, German federal state of Thuringia, in mid-2015, regular inspections brought forth developmental stages until autumn 2015, indicating local reproduction. Surveillance activities implemented in 2016 showed larvae already in early May, suggesting overwintering, and throughout the season until late October, although population densities remained low. Further sporadic specimens found in 2017 argue for establishment. Jena is located in Central Germany, north of all known distribution areas of Ae. albopictus, with the area of the municipality affected by the tiger mosquito characterised by a relatively mild climate. To check the suitability of the local climate for Ae. albopictus, winter temperatures, measured in a cemetery of Jena where larvae had regularly been found in 2015 and 2016, were analysed and compared with two sites of establishment in southern Germany. The conditions were similar at all three locations, suggesting that the Jena population might also be able to survive in the long term. While the municipality authorities have been informed and education of the Jena citizens to avoid producing potential breeding places has started, insecticidal control has not yet been implemented.

Investigation of temperature conditions in Swiss urban and suburban microhabitats for the overwintering suitability of diapausing Aedes albopictus eggs

BackgroundIn Switzerland, the invasive Asian tiger mosquito, Aedes albopictus, is firmly established in the Canton of Ticino, south of the Alps. According to a large-scale distribution model developed in 2013, suitable climatic conditions for the establishment of Ae. albopictus north of the Alps are found in Basel and Geneva while Zurich appears to be characterized by winters currently being too cold for survival of diapausing eggs. However, the spatial resolution of large-scale distribution models might not be sufficient to detect particular climatic conditions existing in urban settings, such as the presence of microclimatic temperatures, which may positively influence the probability of diapausing eggs to overwinter. In order to investigate this, microclimatic monitoring of potential diapausing sites (i.e. catch basins) and external controls was performed in January 2017 in Ticino and within the cities of Basel, Geneva and Zurich.ResultsMean January temperatures in catch basins of Basel, Geneva and Zurich were always higher than the -1 °C temperature threshold previously set for survival probability of diapausing eggs, while mean January temperatures were below -1 °C in several catch basins south of the Alps, where Ae. albopictus eggs currently overwinter. The catch basin absolute January daily minimum temperatures both south and north of the Alps were in general higher than the external control temperatures. Absolute January daily minimum temperatures in catch basins in Basel, Geneva and Zurich were always above -10 °C, indicating that diapausing Ae. albopictus eggs could potentially survive winter nights in urban areas north of the Alps.ConclusionsThe findings confirmed previous conclusions that urban catch basins can provide favourable conditions for overwintering of diapausing eggs compared to more cold-exposed sites. The results confirmed the presence of suitable winter conditions for the establishment of Ae. albopictus in the cities of Basel and Geneva. In addition, the microclimate-scale analysis added new information compared to the previous large-scale prevision model by showing that also the city of Zurich could provide winter conditions suitable for the establishment of Ae. albopictus. This illustrates the importance of the resolution of climate data in using models to predict Ae. albopictus distribution.

High-throughput sequencing of transposable element insertions suggests adaptive evolution of the invasive Asian tiger mosquito towards temperate environments.

Invasive species represent unique opportunities to evaluate the role of local adaptation during colonization of new environments. Among these species, the Asian tiger mosquito, Aedes albopictus, is a threatening vector of several human viral diseases, including dengue and chikungunya, and raises concerns about the Zika fever. Its broad presence in both temperate and tropical environments has been considered the reflection of great "ecological plasticity." However, no study has been conducted to assess the role of adaptive evolution in the ecological success of Ae.albopictus at the molecular level. In the present study, we performed a genomic scan to search for potential signatures of selection leading to local adaptation in one-hundred-forty field-collected mosquitoes from native populations of Vietnam and temperate invasive populations of Europe. High-throughput genotyping of transposable element insertions led to the discovery of more than 120,000 polymorphic loci, which, in their great majority, revealed a virtual absence of structure between the biogeographic areas. Nevertheless, 92 outlier loci showed a high level of differentiation between temperate and tropical populations. The majority of these loci segregate at high insertion frequencies among European populations, indicating that this pattern could have been caused by recent adaptive evolution events in temperate areas. An analysis of the overlapping and neighbouring genes highlighted several candidates, including diapause, lipid and juvenile hormone pathways.

Epidemiology of La Crosse Virus Emergence, Appalachia Region, United States.

La Crosse encephalitis is a viral disease that has emerged in new locations across the Appalachian region of the United States. Conventional wisdom suggests that ongoing emergence of La Crosse virus (LACV) could stem from the invasive Asian tiger (Aedes albopictus) mosquito. Efforts to prove this, however, are complicated by the numerous transmission routes and species interactions involved in LACV dynamics. To analyze LACV transmission by Asian tiger mosquitoes, we constructed epidemiologic models. These models accurately predict empirical infection rates. They do not, however, support the hypothesis that Asian tiger mosquitoes are responsible for the recent emergence of LACV at new foci. Consequently, we conclude that other factors, including different invasive mosquitoes, changes in climate variables, or changes in wildlife densities, should be considered as alternative explanations for recent increases in La Crosse encephalitis.

First report of Aedes (Stegomyia) albopictus (Diptera: Culicidae) in Oran, West of Algeria

The increasing globalisation of trades, human movements and environmental changes facilitate the introduction and the establishment of the invasive Asian tiger mosquito Aedes albopictus outside its native geographical area. Alerted by the complaints about mosquito biting which occurred daytime for the inhabitants of the seaside town Ain Turk (West of Algeria), an entomological survey was conducted in December 2015 to determine the origin of this nuisance. Among the collected mosquitoes, specimens of Ae. albopictus (2 males, 3 females and 3 pupae) were collected. This is the first observation of that invasive mosquito in the west of Algeria which confirms its presence and establishment in Mediterranean Africa.

Seasonal Synchronization of Diapause Phases in Aedes albopictus (Diptera: Culicidae).

In temperate areas, population dynamics of the invasive Asian tiger mosquito Aedes albopictus are strongly affected by winter. The work we present here analyzes the adaptive synchronization of the diapause process in the wintry generation of A. albopictus, where the egg stage is exposed to adverse winter conditions. The seasonal pattern of egg laying activity of a French Mediterranean population of the Asian tiger mosquito was monitored weekly for 2 years with ovitraps. The field diapause incidence and the critical photoperiod (CPP, i.e. the maternal day length inducing diapause in 50% of the eggs), were determined by hatching experiments on the collected eggs. The period of diapause termination was estimated by a field survey of the first hatchings for both years. The CPP is equal to 13.5 hours of light and occurs in the field on the 25th of August. Thus, it is on September 11th, 17 days after the CPP, that 50% of the eggs are in a prediapause stage in the field. The egg diapause rate increases rapidly during September, whereas the mean number of eggs laid decreases sharply after mid-September. Surprisingly, after having reached a peak of 95% at the end of September, from mid-October the diapause incidence declined and stayed below 50%. Indeed, both years the diapause initiates before the rapid decrease of the environmental temperature. This leaves a sufficient period of time to the complete development of one generation of A. albopictus with effective induction of diapause in the laid eggs. The very first larvae hatched were sampled both years in the first half of March. With 20 to 26 weeks in the egg stage and about 7 weeks in the larval stages, the first annual generation spends a long time in immature stages. On a practical point of view, this long development time represents a wide window for eggs and larvae control in early spring.

French invasive Asian tiger mosquito populations harbor reduced bacterial microbiota and genetic diversity compared to Vietnamese autochthonous relatives.

The Asian tiger mosquito Aedes albopictus is one of the most significant pathogen vectors of the twenty-first century. Originating from Asia, it has invaded a wide range of eco-climatic regions worldwide. The insect-associated microbiota is now recognized to play a significant role in host biology. While genetic diversity bottlenecks are known to result from biological invasions, the resulting shifts in host-associated microbiota diversity has not been thoroughly investigated. To address this subject, we compared four autochthonous Ae. albopictus populations in Vietnam, the native area of Ae. albopictus, and three populations recently introduced to Metropolitan France, with the aim of documenting whether these populations display differences in host genotype and bacterial microbiota. Population-level genetic diversity (microsatellite markers and COI haplotype) and bacterial diversity (16S rDNA metabarcoding) were compared between field-caught mosquitoes. Bacterial microbiota from the whole insect bodies were largely dominated by Wolbachia pipientis. Targeted analysis of the gut microbiota revealed a greater bacterial diversity in which a fraction was common between French and Vietnamese populations. The genus Dysgonomonas was the most prevalent and abundant across all studied populations. Overall genetic diversities of both hosts and bacterial microbiota were significantly reduced in recently established populations of France compared to the autochthonous populations of Vietnam. These results open up many important avenues of investigation in order to link the process of geographical invasion to shifts in commensal and symbiotic microbiome communities, as such shifts may have dramatic impacts on the biology and/or vector competence of invading hematophagous insects.

Avian malaria parasites in the last supper: identifying encounters between parasites and the invasive Asian mosquito tiger and native mosquito species in Italy.

BackgroundThe invasive Asian tiger mosquito Aedes albopictus has dramatically expanded its distribution range, being catalogued as one of the world’s 100 worst invasive alien species. As vectors of pathogens, Ae. albopictus may create novel epidemiological scenarios in the invaded areas.MethodsHere, the frequency of encounters of Ae. albopictus with the avian malaria parasite Plasmodium and the related Haemoproteus was studied in an area with established populations in northeastern Italy and compared with those from four native mosquito species, Anopheles maculipennis s.l., Culex hortensis, Culex pipiens, and Ochlerotatus caspius. The abdomens of mosquitoes with a recent blood meal were used to identify both the blood meal source and the parasites harboured.ResultsAedes albopictus had a clear antropophilic behaviour while An. maculipennis and Oc. caspius fed mainly on non-human mammals. Birds were the most common hosts of Cx. pipiens and reptiles of Cx. hortensis. Parasites were isolated from three mosquito species, with Cx. pipiens (30%) showing the highest parasite prevalence followed by Cx. hortensis (9%) and Ae. albopictus (5%).ConclusionsThese results are the first identifying the avian malaria parasites harboured by mosquitoes in Italy and represent the first evidence supporting that, although Ae. albopictus could be involved in the transmission of avian malaria parasites, the risk of avian malaria parasite spread by this invasive mosquito in Europe would be minimal.

Size Matters: Purple Pitcher Plant (Sarracenia purpurea) Pitcher Size Influences the Presence of Aedes albopictus Larvae

A vector of multiple arboviruses, the invasive Asian tiger mosquito Aedes albopictus was recently found to develop inside the pitchers of the purple pitcher plant Sarracenia purpurea in a forested environment. In this study larvae and pupae of Ae. albopictus were found in S. purpurea pitchers in a peridomestic habitat in central North Carolina. Evidence of direct oviposition on the inner sides of the pitchers was obtained by dissecting pitchers and examining the insides for eggs, which were then raised to adults. To determine if pitcher size and origin (same or different plant) affected the presence of immature Ae. albopictus, these variables were measured and compared against the presence/absence of larvae and/or pupae through a logistic regression analysis. Statistical evidence showed pitchers with larger openings were much more likely to contain larvae and/or pupae, and pitchers from the same plant were not significantly more often colonized than pitchers on other plants. These data, in combination with the presence of dead adult females in pitchers, suggest the morphology of some pitchers may prevent successful oviposition by gravid females.

Comparison of the vector potential of different mosquito species for the transmission of heartworm, Dirofilaria immitis, in rural and urban areas in and surrounding Stillwater, Oklahoma, U.S.A.

Dirofilaria immitis Leidy (Spirurida: Onchocercidae), or heartworm, is a mosquito-borne nematode that causes a fatal disease in carnivores. Although infection is preventable through prophylactic drugs, compliance and the spectre of resistance suggest vector control is a viable alternative. There were two main objectives in this study: (a) to evaluate the relationships between landscape and social factors and the number and species of heartworm-positive mosquitoes, with a specific focus on the importance of the invasive Asian tiger mosquito, Aedes albopictus (Skuse) (Stegomyia albopicta) (Diptera: Culicidae), and (b) to test the hypothesis that dog heartworm is more prevalent in suburban than in rural areas. To achieve these objectives, mosquitoes were collected from May to November 2010 at 16 rural and 16 urban locations in Payne County, Oklahoma, U.S.A. using three trapping methods that utilized, respectively, resting boxes, carbon dioxide traps and BG Sentinel traps. Urban areas showed greater numbers of Ae. albopictus and a higher overall likelihood of infection with D. immitis. Because many species of mosquito are responsible for heartworm transmission, current prophylactic treatment remains the best method of controlling this parasite.

Evolution of resistance to satyrization through reproductive character displacement in populations of invasive dengue vectors

Recently, the highly invasive Asian tiger mosquito, Aedes albopictus, rapidly displaced resident populations of the yellow fever mosquito, Aedes aegypti in the southeastern United States and in Bermuda. Although multiple mechanisms of competitive displacement have been hypothesized, recent evidence of cross-insemination between these species in nature and the sterilizing effects of male accessory gland products asymmetrically favoring A. albopictus in interspecific matings support a role for satyrization (a form of reproductive interference) to explain the rapid displacements. Because of the drastic reproductive loss of A. aegypti females satyrized by A. albopictus males, we predicted selection for prezygotic isolation in populations of A. aegypti sympatric with A. albopictus. Exposures in cages demonstrated that female A. aegypti from populations in Florida sympatric with A. albopictus for the past 20 y were significantly less likely than nearby allopatric populations to mate with heterospecific males. Cross-inseminations of A. albopictus females by A. aegypti males were significantly less common, supporting the one-way direction of displacements observed in nature. Our results indicate rapid sexual selection leading to reproductive character displacement and the potential for satyr-resistant A. aegypti to recover from competitive displacements. These results have implications for increased risks of dengue transmission where these vector species meet worldwide.