impaginato piccolo - Società Italiana di Parassitologia (SoIPa)

Parassitologia 50: 103-104, 2008
Blood-feeding preferences of Aedes albopictus (Diptera:
Culicidae) in urban and rural settings within the Province of
Rome, Italy.
L. Valerio 1, F. Marini 1, G. Bongiorno 2, L. Facchinelli 1, M. Pombi 1, B. Caputo 1,
M. Maroli 2, A. della Torre 1
1 Parasitology Unit, Department of Public Health Sciences, University of Rome “Sapienza”, Italy; 2 Section of Vector-Borne
Diseases and International Health, MIPI Department, Istituto Superiore di Sanità, Rome, Italy.
Introduction
One of the most important parameters in vectorborne
pathogen (e.g. arbovirus) transmission is the
blood-feeding behaviour. In fact, this parameter can
influence vector potential depending on the vertebrate
host groups with which the mosquito interacts.
Obviously, the likelihood of pathogen transmission by
a vector species greatly increases if reservoir and
amplification hosts are the primary targets of the vector’s
feeding activity. Consequently, knowledge of the
frequency of human-mosquito contact is essential for
understanding the role of each vector species in disease
transmission to humans. Although Aedes
albopictus is thought to be a generalist feeder 1, with a
predilection to feed on mammals 2, it is not yet clear
how frequently it feeds on humans and how its feeding
pattern is influenced by the abundance and availability
of alternative hosts.
Aim
Abstract. We here report the results of field trials carried out in Rome with the aim to obtain data on the feeding
behaviour of Aedes albopictus, in relation to different availability and abundance of putative hosts.
Human Blood Index values were found higher than 75% in urban areas, where humans represented the
most abundant hosts, and lower than 60% in rural areas, where host alternative to humans were frequent.
The overall results confirm the generalist feeding-behaviour shown by this species in its original range of
distribution and highlighting its high potential as vector of human pathogens in urban areas of Italy.
Keywords: mosquitoes, human-blood index, host-feeding patterns, arbovirus.
During 2006 and 2007 Ae. albopictus reproductive
seasons (May-October), we carried out field trials in
urban and rural sites within the Province of Rome, with
the aim to obtain data on its host-feeding patterns, in
relation to different availability and abundance of putative
hosts. In fact, so far, no studies on feeding prefer-
Correspondence: Alessandra della Torre
Department of Public Health Sciences, Parasitology Unit,
"Sapienza" - University of Rome, P.le Aldo Moro, 5,
00185, Rome, Italy
Tel +39 06 4969 4268; Fax +39 06 4991 4653
e-mail: ale.dellatorre@uniroma1.it
ences of Ae. albopictus have been conducted in recently
colonised temperate regions of Europe, despite the
great relevance of this parameter.
Methods
The study was carried out in 4 sites, two of which (Site
1: “La Sapienza” University and Site 2: “Verano
Cemetery”) were located in urban settings close to the
town’s centre, while the other two (Site 3: a horsebreeding
farm/riding school in “Acilia” and Site 4: a
cattle-breeding farm in “Palestrina”) were located in
rural settings in the town’s outskirts. Mosquitoes were
collected weekly using the sticky-trap (ST) developed
by Facchinelli and colleagues 3. The mosquitoes collected
were observed under a dissecting microscope, morphologically
subdivided by species, gender and physiological
stage. All blood-fed females were classified on
the basis of the amount and colour of the blood in the
abdomen and stored individually at -20°C. Blood meal
origin was determined by direct ELISA on nitro-cellulose
membrane according to Bongiorno et al 4. Eight
peroxidase-labelled anti-animal IgG antibodies (Sigma)
were tested, namely anti-human, anti-dog, anti-cat,
anti-bird, anti-rabbit, anti-bovine, anti-rat, anti-horse.
Results and conclusions
Cumulative collections from urban and rural areas
yielded 518 Ae. albopictus blood-fed females, of which
303 (58.4%) produced results at the direct dot-ELISA:
the relatively high frequency of unidentified bloodmeals
is to be attributed to a limited amount and/or
bad conservation of the blood in the specimens collected
on the ST. The Human Blood Index (i.e. the propor-