Exotic Mosquito Species Research Articles

A survey targeting exotic Aedes mosquito species in Central Europe, summer 2023, reveals the extensive occurrence of Aedes japonicus in Poland

A survey targeting exotic Aedes mosquito species in Central Europe, summer 2023, reveals the extensive occurrence of Aedes japonicus in Poland

Validating a surveillance program of invasive mosquitoes based on citizen science in Hungary

Abstract Climate change, intensified tourism and trade activity have resulted in several exotic mosquito species invading the temperate zone, with considerable ecological and economic consequences, as well as threats to human health, due to the pathogen‐transmitting role of these organisms. Accordingly, three invasive mosquito species (Aedes albopictus, Ae. japonicus and Ae. koreicus) have been described in the last decade in Hungary, a Central European country. It is crucial to understand how invasive species are introduced and their distribution is expanded at the country‐level, for which intense surveillance programs are needed. We have established a citizen science program, in which we asked the public to submit reports on their observations of invasive mosquitoes. During a 3‐year campaign, we collected and taxonomically validated about 3000 reports that can be arranged along both temporal and spatial scales. We aggregated these observations into 35 km2 quadrats and examined if these can be used for reliable scientific inferences. We first found that the number of validated reports in a quadrat depends on the underlying sampling effort (i.e. number of total reports), but this relationship varies among species and study years. Second, after controlling for study effort, we showed that the prevalence and presence/absence of invasive mosquitoes within quadrats are significantly repeatable among years, but this consistency varies in a species‐specific way. Third, we demonstrated that conclusions about the local presence/absence of focal species based on citizen reports corroborate well the results of direct field sampling with conventional trapping protocols. Synthesis and applications: We suggest that if the reporting intensity is appropriate (i.e. the number of reports reaches a species‐specific threshold), citizen science results can be used to derive biologically meaningful conclusions about the distribution of invasive mosquitoes in a country. Distribution maps of the three invasive species in Hungary can be used to identify ecological predictors that determine such spatial patterns and also to develop a mosquito control program and assess epidemiological risk.

MEMO: Monitoring of exotic mosquitoes in Belgium.

Monitoring of Exotic MOsquitoes in Belgium' is a sampling event dataset published by the Institute of Tropical Medicine (ITM) in Antwerp, Belgium. It forms part of the early detection of exotic mosquito species (EMS) along high-risk introduction routes in Belgium, where data are collected at defined points of entry (PoEs) using a standardised protocol. The MEMO dataset contains mosquito sampling counts performed between 2017 and 2020. MEMO+2020, an extension of the MEMO dataset, contains only Aedes albopictus mosquito trap counts performed in 2020. Here, we present these data published as a standardised Darwin Core archive, which includes, for each sampling event, an eventID, date, location and sampling protocol (in the event core); and an occurrenceID for each occurrence (tube), the number of collected individuals per tube, species status (present/absent), information on the identification and scientific name (in the occurrence extension).

Two fatal autochthonous cases of airport malaria, Belgium, 2020.

We report an outbreak investigation of two fatal cases of autochthonous Plasmodium falciparum malaria that occurred in Belgium in September 2020. Various hypotheses of the potential source of infection were investigated. The most likely route of transmission was through an infectious exotic Anopheles mosquito that was imported via the international airport of Brussels or the military airport Melsbroek and infected the cases who lived at 5 km from the airports. Based on genomic analysis of the parasites collected from the two cases, the most likely origin of the Plasmodium was Gabon or Cameroon. Further, the parasites collected from the two Belgian patients were identical by descent, which supports the assumption that the two infections originated from the bite of the same mosquito, during interrupted feeding. Although airport malaria remains a rare event, it has significant implications, particularly for the patient, as delayed or missed diagnosis of the cause of illness often results in complications and mortality. Therefore, to prevent such severe or fatal outcomes, we suggest a number of public health actions including increased awareness among health practitioners, especially those working in the vicinity of airports, and increased surveillance of exotic mosquito species at airports.

FACTORS AFFECTING THE DEVELOPMENT OF DIROFILARIASIS PATHOGENS IN INTERMEDIATE HOSTS, BLOOD-SUCKING MOSQUITOES (REVIEW)

Dirofilariasis is a transmissible parasitic disease caused by helminths Dirofilaria repens and D. immitis. Vectors of pathogens are blood-sucking mosquitoes (Diptera, Culicidae). Climate change, urbanization, and importation of exotic mosquito species into the territory of Russia lead to the expansion of the Dirofilaria vector range and, consequently, an increase in the incidence of the disease among the population and animals. The purpose of this research was to study the literature data on factors of the dirofilariasis pathogen development in blood-sucking mosquitoes. An important factor in the development of Dirofilaria from the larval stage to the invasive stage is an optimal environmental temperature, the average daily value of which should not be less than 130. This number is referred to as the "Dirofilaria Development Unit (DDU)". The immune response of the insect plays an important role in the helminth development in the intermediate host. Melanin, which is produced by mosquito hemocytes, forms a capsule around the larvae thus preventing their maturation. However, the extent of this response depends on the phenoloxidase enzyme and the age of the mosquito. The symbiotic intracellular Wolbachia bacteria found in Dirofilaria are essential for the helminth development in mosquitoes. But no information has currently been found on interaction between mosquito immunity and these bacteria in the literature; although a correlation has been found between the mosquito infected with the bacteria and the probability of infection transmitted by them.

The first record of the invasive mosquito species Aedes albopictus in Chi\u015fin\u04d1u, Republic of Moldova, 2020

BackgroundIn Europe, Aedes albopictus is an important vector of chikungunya virus and Dirofilaria nematodes and has been involved in local autochthonous circulation of dengue and Zika viruses. Due to the ongoing spread, targeted field surveillance at potential points of entry of invasive Aedes mosquitoes was initiated by the Republic of Moldova in 2020 as part of the transboundary “Invasive Aedes Mosquitoes COST-Action project.”MethodsIn 2020, ovitraps were positioned at each of three locations: the border crossing to Romania in Leuşeni (Hancesti region), Chişinӑu International Airport and Chişinӑu Botanical Garden.ResultsA total of 188 Aedes spp. eggs were collected at the Chişinӑu International Airport between August and September 2020. Twenty-three adults reared in the laboratory were identified morphologically as Ae. albopictus (Skuse, 1895), and 12 selected specimens were confirmed by molecular barcoding of the cytochrome oxidase subunit I gene region. In addition, one adult Ae. albopictus female at the same site was caught with a manual aspirator.ConclusionsThis is the first documented report of Ae. albopictus in the Republic of Moldova. The presence of immature and adult stages indicates the local reproduction of the species in the country. Therefore, it is crucial to extend and strengthen surveillance of the invasive Aedes mosquitoes to prevent Ae. albopictus and other exotic mosquito species from becoming established in the Republic of Moldova.Graphical abstract

First record of the West Nile virus bridge vector Culex modestus Ficalbi (Diptera: Culicidae) in Belgium, validated by DNA barcoding.

A thorough knowledge of the presence and spatio-temporal distribution patterns of vector species are pivotal to assess the risk of mosquito-borne diseases in Europe. In 2018, a Culex larva was collected during routine monitoring activities to intercept exotic Aedes mosquito species in the port of Antwerp (Kallo, Belgium). The larva, collected from a pond in mid-September, was morphologically identified as Culex modestus, and this identification was subsequently confirmed by COI barcoding. It is the first confirmed record of this West Nile virus bridge vector in Belgium. The present study also demonstrates the value of DNA-based identification techniques to validate the presence of potential vector species.

Detection of Exotic Mosquito Species (Diptera: Culicidae) at International Airports in Europe.

In Europe, the air-borne accidental introduction of exotic mosquito species (EMS) has been demonstrated using mosquito surveillance schemes at Schiphol International Airport (Amsterdam, The Netherlands). Based upon these findings and given the increasing volume of air transport movements per year, the establishment of EMS after introduction via aircraft is being considered a potential risk. Here we present the airport surveillance results performed by the Centre for Monitoring of Vectors of the Netherlands, by the Monitoring of Exotic Mosquitoes (MEMO) project in Belgium, and by the Public Health England project on invasive mosquito surveillance. The findings of our study demonstrate the aircraft mediated transport of EMS into Europe from a wide range of possible areas in the world. Results show accidental introductions of Aedes aegypti and Ae. albopictus, as well as exotic Anopheles and Mansonia specimens. The findings of Ae. albopictus at Schiphol airport are the first evidence of accidental introduction of the species using this pathway in Europe. Furthermore, our results stress the importance of the use of molecular tools to validate the morphology-based species identifications. We recommend monitoring of EMS at airports with special attention to locations with a high movement of cargo and passengers.

Habitat suitability modelling to assess the introductions of Aedes albopictus (Diptera: Culicidae) in the Netherlands

BackgroundIn the Netherlands, Aedes albopictus has been found each year since 2010 during routine exotic mosquito species surveillance at companies that import used tires. We developed habitat suitability models to investigate the potential risk of establishment and spread of this invasive species at these locations.MethodsWe used two methodologies: first, a species distribution model based on the maximum entropy modelling approach (MaxEnt) taking into consideration updated occurrence data of the species in Europe, and secondly, a spatial logic conditional model based on the temperature requirements of the species and using land surface temperature data (LST model).ResultsSuitability assessment obtained with the MaxEnt model at European level accurately reflect the current distribution of the species and these results also depict moderately low values in parts of the Netherlands, Belgium, Denmark, the British islands and southern parts of Scandinavia. Winter temperature was the variable that contributed most to the performance of the model (47.3%). The results of the LST model showed that: (i) coastal areas are suitable for overwintering of eggs; (ii) large areas in the northern part of the country have a low suitability for adult survival; and (iii) the entire country is suitable for successful completion of the life-cycle if the species is introduced after the winter months. Results of the LST model revealed that temperatures in 2012 and 2014 did not limit the overwintering of eggs or survival of adults at the locations where the species was found. By contrast, for the years 2010, 2011 and 2013, overwintering of eggs at these locations is considered unlikely.ConclusionsResults using two modelling methodologies show differences in predicted habitat suitability values. Based on the results of both models, the climatic conditions could hamper the successful overwintering of eggs of Ae. albopictus and their survival as adults in many areas of the country. However, during warm years with mild winters, many areas of the Netherlands offer climatic conditions suitable for developing populations. Regular updates of the models, using updated occurrence and climatic data, are recommended to study the areas at risk.

Entomological Studies on the Mosquito Borne Diseases in Iran: An Up-To-Date

Mosquitoes are insects that bit animal hosts to get blood as the nutrient source to develop their eggs. They may transmit a wide range of pathogens such as viruses and parasites to the hosts’ body through their blood meal. It may lead to a number of mosquito-borne diseases. In Iran, there is a major risk for mosquito-borne diseases due to the introducing the exotic mosquito species from the neighboring countries. Recently, in neighboring countries of Iran, epidemics of mosquito-borne viral infections including chikungunya, dengue and West Nile infections in Pakistan, dengue and Rift Valley fever in Saudi Arabia, and West Nile infection in Iraq have been reported. Ae. albopictus has become a significant pest mosquito species in Pakistan and has also been reported from Syria, Lebanon and Turkey. According to the World Health Organization WHO, malaria is in the pre-elimination stage in Iran. In this review, it was attempted to discuss some issue including mosquito bionomics, mosquito-borne diseases in human and surveillance. Mosquito-borne disease in Iran including historically reported diseases, emerging infectious diseases as well as the mosquito fauna of Iran were also reviewed.

Guidance for Evaluating the Safety of Experimental Releases of Mosquitoes, Emphasizing Mark-Release-Recapture Techniques.

Experimental releases of mosquitoes are performed to understand characteristics of populations related to the biology, ability to transmit pathogens, and ultimately their control. In this article, we discuss considerations related to the safety of experimental releases of living mosquitoes, applying principles of good practice in vector biology that protect human health and comfort. We describe specific factors of experimental releases of mosquitoes that we believe are critical to inform institutional biosafety committees and similar review boards to which proposals to conduct mosquito release experiments have been submitted. In this study, “experimental releases” means those that do not significantly increase vector capacity or nuisance biting relative to the unperturbed natural baseline. This document specifically does not address releases of mosquitoes for ongoing control programs or trials of new control methods for which broader assessments of risk are required. It also does not address releases of transgenic or exotic (non-native) mosquito species, both of which require particular regulatory approval. Experimental releases may include females and males and evaluation must consider their effects based on the number released, their genotype and phenotype, the environment into which they are released, and postrelease collection activities. We consider whether increases of disease transmission and nuisance biting might result from proposed experimental releases against the backdrop of natural population size variation. We recommend that experimental releases be conducted in a manner that can be reasonably argued to have insignificant negative effects. Reviewers of proposals for experimental releases should expect applicants to provide such an argument based on evidence from similar studies and their planned activities. This document provides guidance for creating and evaluating such proposals.

First report of the invasive mosquito species Aedes koreicus in the Swiss-Italian border region.

BackgroundIn 2012 and 2013, an entomological survey of Aedes albopictus, the Asian tiger mosquito, was carried out in the border region of southern Switzerland and northern Italy, using ovitraps. In July 2013, besides A. albopictus already known to the region several unusual eggs were recovered.FindingsA total of 548 seemingly different eggs were found within three communities: Chiasso (Switzerland), and Como and Brunate (Italy). Proteomic diagnostics based on matrix-assisted laser desorption/ionization mass-spectrometry (MALDI-TOF MS) and morphological identification of one reared adult revealed the presence of at least 18 A. (Finlaya) koreicus (Edwards, 1917) specimens. A. koreicus is a species native to Southeast Asia and is competent to transmit Japanese encephalitis and potentially other arboviruses, as well as the dog heartworm Dirofilaria immitis. While new to Switzerland, this invasive species has previously been reported from Belgium, north-eastern Italy and European Russia.ConclusionsThis is the first report of the introduction of this exotic mosquito species into Switzerland and Lombardy, Italy, suggesting the range of A. koreicus is expanding in Central Europe. As A. koreicus is competent to vector pathogens its establishment imposes a risk to public and veterinary health. From a technical point of view, the presence of A. koreicus alongside A. albopictus requires careful analysis and reliable diagnostics. As a diagnostic tool the use of the recently developed MALDI-TOF MS approach has proofed to be a very useful approach, particularly since hatching rates of A. koreicus seem to be low, making identification by classic morphology difficult, if not impossible.

Os mosquitos (Diptera, Culicidae) e a sua importância médica em Portugal: desafios para o século XXI.

Mosquitoes are dipterous insects, responsible for the transmission of several pathogenic agents to humans, causing vector-borne diseases, such as malaria, lymphatic and other filariasis, and several arboviral diseases such as yellow fever and dengue. In this revision, Culicidae or mosquitoes are summarily characterized, as well as their bioecology, internal morphology, digestive and egg maturation physiology, and the main methods for their collection and control. The epidemiology of mosquito-borne diseases depends on parameters such as Vectorial efficiency, Vector competence and Vectorial capacity, the concepts of which are presented. Forty one species of mosquitoes have been detected so far in mainland Portugal. Malaria was endemic till 1959, yellow fever outbreaks were registered in the XIX century, and human cases of dirofilarisis and West Nile fever have been detected. In face of the current climate changes in course and the threat of the (re)-introduction of exotic mosquito species, not only new cases of some of these diseases may occur, increasing their risk, but also other mosquito-borne diseases may be introduced constituting challenges for the XXI century, demanding a continued surveillance in a Public Health perspective.

Weak Larval Competition Between the Invasive Mosquito Aedes japonicus japonicus (Diptera: Culicidae) and Three Resident Container-Inhabiting Mosquitoes in the Laboratory

The spread of exotic mosquito species into new environments can introduce shifts in mosquito populations and potentially alter public health risks to mosquito-borne diseases. The successful establishment of exotic species may occur due to their competitive advantage over other cohabitating species. We hypothesized that the recently introduced exotic mosquito Aedes japonicus japonicus (Theobald) would be a more effective competitor than Aedes atropalpus (Coquillett) and Aedes triseriatus (Say), and an equal competitor to Culex pipiens (L.) based on larval abundance data within tire habitats. Impacts of competition were measured using the larval developmental rate and survival of larvae, adult mortality, wing length, and sex ratio. We found that intraspecific competition acted strongest against Ae. japonicus versus the other three resident mosquito species by delaying larval development and increasing adult mortality. Interspecific competition was generally weak and significant main effects were only detected for species and density. Overall, our results show that larval competition between Ae. japonicus and the three resident species was weak when present, indicating that other ecological or behavioral factors may be influencing the invasion success for Ae. japonicus in North America.

Two invasive mosquito species, Aedes albopictus and Aedes japonicus japonicus, trapped in south-west Germany, July to August 2011

Adult females of two invasive species, Aedes albopictus and Aedes japonicus japonicus, were collected for the first time in July and August 2011 in Germany. Previously, only immature stages of these species had been found in the country. Repeated detection of these species reveals the Upper Rhine Valley in south-west Germany to be a particularly sensitive region for the introduction and establishment of exotic mosquito species that needs careful observation.

First report in italy of the exotic mosquito species Aedes (Finlaya) koreicus, a potential vector of arboviruses and filariae

BackgroundIn the Veneto region (north-eastern Italy) an entomological surveillance system has been implemented since the introduction of the Asian tiger mosquito (Aedes albopictus) in 1991. During the routine monitoring activity in a tiger mosquito-free area, an unexpected mosquito was noticed, which clearly did not belong to the recorded Italian fauna.FindingsAt the end of May 2011, twelve larvae and pupae were collected in a small village in Belluno province (Veneto region) from a single manhole. Ten adults reared in the laboratory were morphologically and genetically identified as Aedes (Finlaya) koreicus (Edwards, 1917), a species native to Southeast Asia. The subsequent investigations carried out in the following months in the same village provided evidence that this species had become established locally. Entomological and epidemiological investigations are currently ongoing in the surrounding area, to verify the eventual extension of the species outside the village and to trace back the route of entry into Italy.ConclusionsThis is the first report in Italy of the introduction of the exotic mosquito Ae. koreicus. This species has been shown experimentally to be competent in the transmission of the Japanese encephalitis virus and of the dog heartworm Dirofilaria immitis and is considered a potential vector of other arboviruses. Thus, the establishment of this species may increase the current risk or pose new potential threats, for human and animal health. This finding considerably complicates the entomological monitoring of the Asian tiger mosquito Ae. albopictus in Italy and stresses the importance of implementing the entomological surveillance for the early detection of and the rapid response against invasive mosquito species.

Are exotic invaders less susceptible to native predators? A test using native and exotic mosquito species in New Zealand

AbstractA major hypothesis in invasion ecology is that native predators have less impact on exotic relative to native prey species. Here, we tested this hypothesis by examining the New Zealand native predator Anisops wakefieldi consuming native (Culex pervigilans) and exotic (Aedes notoscriptus) mosquito larvae. Anisops wakefieldi exhibited a decelerating type II functional response for both prey species, but at high prey densities consumed more of the exotic mosquito Ae. notoscriptus. A significantly higher attack rate was observed for the native predator feeding on exotic species. In the presence of both prey species, the predator showed preferences towards Ae. notoscriptus and demonstrated switching behavior towards this exotic species. The preference of the native predator towards the exotic mosquito appeared related to behavioral differences between the two prey species. We tested the behavioral response of both mosquito species in four conditions; (1) control (without predators), (2) free‐roaming predators, (3) caged predators, and (4) kairomones only. Resting activities at the water surface and wall positions were the most frequently behaviors exhibited by Cx. pervigilans in the presence of predator. In contrast, the exotic species Ae. notoscriptus demonstrated significantly higher levels of “thrashing” behaviors, apparently making itself more obvious to the predators. The behaviors showed by Cx. pervigilans fulfilled the “threat sensitivity hypothesis”. No evidence here supported the idea that exotic mosquito species are less prone to the influence of native predators and the “escape from natural enemies” hypothesis seems not apply in our study. In fact, we observed that this invader was more susceptible to the predator.

Introduction and Establishment of the Exotic Mosquito SpeciesAedes japonicus japonicus(Diptera: Culicidae) in Belgium

The establishment of the potential vector species Aedes (Finlaya) japonicusjaponicus (Theobald) (Diptera: Culicidae) in southern Belgium is reported. The species was most likely introduced through the international trade in used tires. It was first collected in 2002 on the premises of a second-hand tire company and was sampled using different sampling methods in the two consecutive years (2003-2004). It was only in 2007 and 2008, during a national mosquito survey (MODIRISK), that its presence as adults and larvae at the above-mentioned site and at another tire company in the area was confirmed based on morphological and molecular identification. This discovery is the first record for Belgium of an exotic mosquito species that established successfully and raises the question on the need for monitoring and control. Considering the accompanying species found during the surveys, we also report here the first observation of Culex (Maillotia) hortensis hortensis (Ficalbi) in Belgium.

Association Between Habitat Size, Brushtail Possum Density, and the Mosquito Fauna of Native Forests in the Auckland Region, New Zealand

Human activities have been causing dramatic and unprecedented changes to the Earth's ecosystems, and are a primary factor associated with biological invasions. Disturbed and fragmented habitats allow some vector mosquitoes to thrive. The New Zealand landscape has been extensively modified since the arrival of humans, and there is accumulating evidence that the distribution of mosquitoes is being altered as a result of anthropogenic environmental changes. This study aimed to assess whether forest habitat size affected the community composition of mosquitoes, and whether the density of the introduced brushtail possum would benefit exotic mosquito species that feed primarily on mammal hosts. Extensive sampling of the mosquito community was carried out using dry ice-baited light traps, oviposition traps, and larval surveys. The results provided the first experimental evidence in New Zealand that changes in forest habitat size affect the indigenous and introduced mosquito fauna differently. The proportion of native species making up the mosquito community appears to be steadily reduced as native forest habitats become smaller. In contrast, the opposite pattern appears to occur for the introduced vector Aedes notoscriptus. Although there was a trend indicating that possums may have a negative impact on a native species (Culex pervigilans), the impact of these animals on the mosquito fauna remains unclear. The evidence suggests that the conservation of large pristine forest ecosystems in New Zealand could have human health implications.

Laboratory Colonization of Aedes japonicus japonicus

We describe methodology used for the laboratory colonization of Aedes japonicus japonicus, an exotic mosquito species native to eastern Asia and first collected in New Jersey as larvae in 1999. We created a free mating colony in 2000 that readily bloodfed on restrained bobwhite quail (Colinus virginianus). A larval diet of finely ground Purina Lab Diet dissolved in dechlorinated water has proven acceptable. This is the first report of Ae. j. japonicus colonization from mosquitoes collected in the United States.