Capelli et al. Parasites & Vectors 2011, 4:188
http://www.parasitesandvectors.com/content/4/1/188
SHORT REPORT
Open Access
First report in italy of the exotic mosquito species
Aedes (Finlaya) koreicus, a potential vector of
arboviruses and filariae
Gioia Capelli1*, Andrea Drago2, Simone Martini2, Fabrizio Montarsi1, Mauro Soppelsa3, Nicola Delai3,
Silvia Ravagnan1, Luca Mazzon4, Francis Schaffner5, Alexander Mathis5, Marco Di Luca6, Roberto Romi6 and
Francesca Russo7
Abstract
Background: In 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.
Findings: At 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.
Conclusions: This 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.
Keywords: Aedes koreicus, Italy, exotic mosquito, invasive species, entomological monitoring
Background
After the introduction and establishment of the Asian
tiger mosquito (Aedes albopictus) in north-eastern Italy
in 1991 [1], an entomological surveillance, promoted by
the Public Health Service of the Veneto region, was
started. The entomological monitoring primarily relies
on the use of ovitraps in the areas where the tiger mosquito is endemic, while in non-colonized areas,
collection of larvae/pupae and adult trapping are carried
out. In addition, information and education is provided
targeting municipalities and Local Health Units as well
as residents [2]. During the routine surveillance activity
in a tiger mosquito-free area, an unexpected mosquito
was noticed which clearly did not belong to the
recorded Italian fauna.
Mosquito findings and identification
* Correspondence: gcapelli@izsvenezie.it
1
Istituto Zooprofilattico Sperimentale delle Venezie, Laboratory of
Parasitology, Viale dell’Università 10, Legnaro, 35020, Italy
Full list of author information is available at the end of the article
At the end of May 2011, twelve larvae and pupae were
collected in a small village in Belluno province, located
at 447 m.a.s.l. (Lat 46° 8’30.27"N; Long 12° 4’19.33"E)
© 2011 Capelli et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Capelli et al. Parasites & Vectors 2011, 4:188
http://www.parasitesandvectors.com/content/4/1/188
(Figure 1). The larvae and pupae were collected from a
single manhole.
The immature stages collected were reared in the
laboratory and the ten adults obtained were morphologically identified, using taxonomic keys [3-6], as Aedes (Finlaya) koreicus (Edwards, 1917). Further investigations were
carried out based on previously described morphological
variations [5, Versteirt et al., pers. comm ], which had
been observed on specimens from Belgium. In particular,
the presence of a basal pale band on hind tarsomere V, led
us to attribute the Italian specimens to the morphological
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form reported from Jeju-do, an island located in the Korea
Strait, south of the peninsula. Due to this unexpected finding and considering that Ae. koreicus is closely related to
Ae. japonicus, a biomolecular confirmation was considered
appropriate. Three PCR assays were performed in different
laboratories. DNA was amplified at three mitochondrial
loci, two at the nicotinamide adenine dinucleotide dehydrogenase subunit 4 (ND4) gene and one at the cytochrome oxidase subunit II (COII) gene. The PCR
protocols followed the methods of Cameron et al. [7],
Uribe Soto et al. [8] and Simon et al. [9], respectively.
Figure 1 Map showing the locality of the first Aedes koreicus finding in north-eastern Italy.
Capelli et al. Parasites & Vectors 2011, 4:188
http://www.parasitesandvectors.com/content/4/1/188
Amplicons were then sequenced and compared with
GenBank entries. Thus, identities ranging from 99.6% to
99.7% with sequences attributed to Ae. koreicus (GenBank accession numbers: GU229897.1, GU229925,
GU229926 and GU229927) were observed, confirming
the morphological identification. At the mitochondrial
loci, the intra-specific range of nucleotide differences is
reported to be 0.2% and the inter-specific percent difference (among Ae. koreicus and the subspecies in the Ae.
japonicus complex) ranges from 4.4% to 9.2% [7].
After the biomolecular confirmation, the village was
checked again for the presence of the mosquito on July
17th. All the possible breeding sites, mainly public and
private small water containers, were examined. Four
additional sites were found positive for larvae of Ae. koreicus, namely two manholes, one bucket in a private garden and two flower pots at the cemetery, all included in
a range of one km2. In particular the private garden was
heavily infested, with thousands of larvae in the bucket
of clean water. Approximately 300 larvae were collected,
partly mounted on a slide and partly let to moult into
adults. All the larvae and 40 adults were confirmed as
Ae. koreicus. No other mosquito species were found to
share the same breeding sites.
These new findings indicated that the species was
already established in the village, although with a very
limited spatial distribution. The territory of the municipality extends from 305 to 2.149 m.a.s.l. and is characterised by a temperate climate, with cold and often
snowy winters and mild warm summers.
Discussion and conclusions
Ae. koreicus is an Asian species native to Korea, Japan,
China and eastern Russia. Not much information is
available on the biology and activity of this species. It is
reported to feed on humans and domestic animals, and
it seems to be well adapted to the urban environment
[5]. Larvae develop in all types of artificial containers
close to houses, and even in pools on rocks in the hills
or in tree holes. The adults seem to bite humans both
during the day and at night. Like other species of the
genus Aedes, Ae. koreicus overwinters in the egg stage,
hatching in the spring when the snow melts [3,4]. As
compared to the Asian tiger mosquito, Ae. koreicus
seems to be more tolerant to a cold climate, making this
species capable of surviving and becoming established in
the hilly and pre-alpine areas of Italy.
Indeed, this species has previously been identified in
Belgium in 2008, where it successfully established [10].
These are also the first findings of Ae. koreicus outside
its native range, demonstrating its ability to establish
and colonize new areas in a temperate climate, as previously suggested by Cameron et al. [7] who commented: “It is perhaps surprising, or just a matter of chance,
Page 3 of 5
that the most recent introduction to the United States
was Ae. j. japonicus and not Ae. koreicus “ and “there is
the distinct possibility that Ae. koreicus will also begin
spreading across the world”.
It is currently difficult to speculate about the time of
arrival of the mosquito in this part of Italy. Certainly,
the species was not present or went unnoticed in the
2009-2010 summer surveillance at this location, where
only a few adult specimens of Ae. geniculatus were
identified.
Entomological and epidemiological surveys at the village and the surrounding area are ongoing in order to
understand whether the species is already established
outside the village and to attempt to trace back the
possible route of entry. Morphological analysis led to
the assumption that Jeju-do was the possible origin of
the introduced population, and then international
trade with this Korean province might be the cause for
this introduction. Alternatively, connection with export
companies from the area where Ae. koreicus is established in Belgium could be considered as a possible
route of entry. Investigations on invasive mosquito
species introduced into the USA and Europe (i.e. Ae.
albopictus and Ae. japonicus) suggest that used tires
and plant cuttings were the major vehicles [11]. Discarded tires are a common breeding habitat for many
mosquito species, as shown for the USA by Yee [12],
who documented 32 such mosquito species in his
review of the literature over the last 50 years. Recently,
Scholte et al. [13], during routine mosquito surveillance inspections at companies that import used tires
in The Netherlands, reported the detection of three
invasive species within a few months: the yellow fever
mosquito (Ae. aegypti), the Asian tiger mosquito (Ae.
albopictus), and the American rock-pool mosquito (Ae.
atropalpus), demonstrating how frequently an exotic
mosquito may be introduced.
In Italy in the past 20 years, invasive mosquito species
were detected three times, namely Ae. albopictus in
1990 and 1991 [14,1], now endemic all over the country,
Ae. atropalpus in 1996 [15], detected in Treviso province and promptly eradicated, and currently Ae. koreicus. The first two introductions were due to infested
used tires from USA [15,16]. Interestingly, all these
introductions occurred in different provinces of the
same area of north-eastern Italy (Veneto Region). It is
not clear whether this is due to the intense local active
surveillance of the tiger mosquito or to the trade of
goods, possibly infested. Indeed, north-eastern Italy is
regarded as one of the most developed industrial and
commercial area of the country.
The possible establishment of Ae. koreicus in regions
where the tiger mosquito is endemic would complicate
the current entomological surveillance system of Ae.
Capelli et al. Parasites & Vectors 2011, 4:188
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Page 4 of 5
Acknowledgements
Authors would like to thank Matteo Mazzucato (IZSVe) for map drawing.
Author details
Istituto Zooprofilattico Sperimentale delle Venezie, Laboratory of
Parasitology, Viale dell’Università 10, Legnaro, 35020, Italy. 2Entostudio, Via
Buffa 9, Brugine, 35020, Italy. 3Local Health Unit (ULSS 2), Department of
Prevention, Via Borgo Ruga 30, Feltre, 32032, Italy. 4University of Padua,
Department of Environmental Agronomy and Crop Science, Viale
dell’Università 16, Legnaro, 35020, Italy. 5University of Zurich, Institute of
Parasitology, Winterthurerstr. 266a, Zurich, 8057, Switzerland. 6Department of
Infectious, Parasitic and Immuno-mediated Diseases, Vector-Borne Diseases
and International Health Unit, Istituto Superiore di Sanità, Viale Regina Elena
299, Rome, 00161, Italy. 7Veneto Region, Direzione Prevenzione, Servizio
Promozione e Sviluppo Igiene e Sanita’ Pubblica, Dorsoduro 3493, Venice,
30123, Italy.
1
Figure 2 Particular of the mesonotum of Aedes koreicus (left)
compared to Ae. albopictus (right).
albopictus, which is mainly based on the use of inexpensive ovitraps. The detection of the typical black Aedes
eggs in ovitraps, easy recognizable by non-expert personnel, was sufficient to determine the infestation status
of a location with regard to the tiger mosquito. Unfortunately, tiger mosquito eggs are indistinguishable by simple observation under a binocular microscope from the
eggs of other Aedes spp., including those of Ae. koreicus.
Hence, the species identification at a routine basis in
areas where Ae. albopictus and Ae. koreicus may share
the same breeding sites, will require to rear the eggs in
the laboratory or to include into the surveillance system
the more laborious systematic collection of larvae and
adults, which require an equipped laboratory and well
trained personnel for identification (Figure 2).
Ae. koreicus is considered a potential vector of arboviruses [7], albeit the published evidence for its vector
status is very scant. Many authors [3-5] argue that the
species has been probably misidentified as Ae. japonicus
in the past, thus confounding the vector competence of
these two mosquitoes. Ae. koreicus has been, however,
reported to be involved in the transmission of the Japanese encephalitis virus (JEV) [17], exotic to Europe, and
of the dog heartworm Dirofilaria immitis [4].
Dog heartworm is currently endemic in the lowlands
of north-eastern Italy [18], but it’s seldom reported in
hilly areas, like the one where Ae. koreicus was detected.
Thus, its establishment may increase the current risk or
pose new potential threats, for human and animal
health. Certainly, vector competence studies are strongly
required to better define the role of this mosquito species in the transmission of JEV and D. immitis and of
other arboviruses, such as West Nile and USUTU
viruses, both endemic in Veneto region [19].
This finding, once again, stresses the importance to
implement the entomological surveillance for early
detection of invasive species, which is imperative to prevent new establishments and to have a chance to
promptly eradicate them.
Authors’ contributions
GC wrote the paper; FM, AD, SM, ND and MS where involved in the mosquito
collection and laboratory rearing; FS, RR, FM and MDL morphologically
identified the specimens; SR, LM and AM genetically identified the specimens;
FR provided part of the funding; all the Authors, and especially RR, FS and AM,
revised the MS and contributed with comments and suggestions. All authors
read and approved the final version of the manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 7 September 2011 Accepted: 28 September 2011
Published: 28 September 2011
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doi:10.1186/1756-3305-4-188
Cite this article as: Capelli et al.: First report in italy of the exotic
mosquito species Aedes (Finlaya) koreicus, a potential vector of
arboviruses and filariae. Parasites & Vectors 2011 4:188.
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