download report - Istituto Pasteur

P a r t i c i p a n t s :
Maria Angela Di Deco, researcher; Beniamino Caputo,
Emiliano Mancini, Marco Pombi, Federica Santolamazza,
post-doc fellows; Maria Calzetta, Erika Rossi, graduate students.
C o l l a b o r a t i o n s :
Center for Global Health and Infectious Diseases, Department of
Biological Sciences, University of Notre Dame, IN, USA (Prof. Nora J.
Besansky); Centro de Malária e outras Doenças Tropicais, Instituto
de Higiene e Medicina Tropical, Lisbon, Portugal (Dr. João Pinto);
Department of Ecology and Evolutionary Biology, Yale University,
New Haven CT, USA (Prof. Jeffrey Powell, Prof. Adalgisa
Caccone); Département de Biologie Animale, Faculté des Sciences et
Techniques, Université de Dakar, Sénégal (Dr. Lassana Konate);
Department of Biochemistry, Virginia Polytechnic Institute and State
University, Blacksburg VA, USA (Prof. Zhijian Tu); Dipartimento di
Biologia Animale e Genetica, Università di Firenze (Dr. Francesca
Dani, Prof. Stefano Turillazzi); Institut de Recherche pour le
Développement (France: Prof. Didier Fontenille; Burkina Faso: Dr.
Frédéric Simard; Cameroun: Dr. Carlo Costantini); Malaria
Research and Training Center, University of Bamako, Mali (Dr. Sékou
Traoré); Medical Research Council Laboratories, Fajara, Banjul, The
Gambia (Prof. David Conway, Dr. Davis Nwakanma); Medical
Entomology Unit, Pasteur Institute, Dakar, Sénégal (Dr. Ibrahima
Dia); Ministry of Health, National Program of Malaria Control,
Luanda, Angola (Dr. Filomeno Fortes); Natural Resources Institute,
University of Greenwich, Chatham, UK (Dr. Gabriella Gibson, Dr.
Steve J. Torr); Vector Group, Liverpool School of Tropical Medicine,
Liverpool, UK (Dr. Martin J. Donnelly).
Report of Activity
The following bionomical, genetic and molecular
studies on Anopheles gambiae populations have been
carried out.
Geographical distribution of species and
molecular forms of the A. gambiae complex
The geographical distribution of species and molecular
forms of the A. gambiae complex has been
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Biology of malaria and other vector-borne diseases - AREA 7
Bionomical, genetical and molecular characterization of
populations of the Anopheles gambiae complex of sibling species
(Diptera: Culicidae), malaria vector in sub-Saharan Africa
Principal investigators: Alessandra della Torre - Vincenzo Petrarca
Professors of Parasitology
Dipartimento di Scienze di Sanità Pubblica; Dipartimento di Genetica
e Biologia Molecolare
Tel: (+39) 06 49694268; 06 49914932; Fax: (+39 ) 06 49914653
ale.dellatorre@uniroma1.it; vincenzo.petrarca@uniroma1.it
analysed, particularly in 2 geographical areas at the
extremes of A. gambiae s.s range in West/Central
Africa, where pertinent literature data were scarce
and dated. i) 1,336 specimens were sampled across
Angola from 2001 to 2005: M-form predominated in
localities of the tropical dry and semi-desertic belts,
where unexpectedly no A. arabiensis was found, while
the S-form predominated in comparatively more
humid and less anthropized sites; A. melas was found
in northern coastal sites. ii) Over 4,000 specimens
were collected and identified in dry season 2005 and
rainy season 2006 along the Gambia river in The
Gambia and in Senegal; M-form was mainly found in
sympatry with A. melas and S-form in the western
part of the transect, and with A. arabiensis in the central
part; S-form was found to prevail in rural
Sudano-Guinean savanna areas of Eastern Senegal,
in sympatry with A. arabiensis; A. melas and A. arabiensis
relative frequencies were generally lower in the
rainy season samples, while no large seasonal fluctuations
were observed for M and S-forms; in areas
where both M and S were recorded, an unusual high
frequency (1%-7%) of MxS hybrids was observed.
Chromosomal characterization of species and
molecular forms of the A. gambiae complex
Half-gravid female samples from Angola and
Senegambia were scored for inversion polymorphisms.
In Angola, A. gambiae M and S forms were
characterized by a low degree of polymorphism,
based solely on inversion 2La, a pattern usually associated
with populations from forested and humid
savanna areas. In Senegambia, the populations were
characterized by: i) 2Rb, 2Rd and 2La polymorphisms
in both forms in the coastal area; ii) higher
frequencies of 2Rb and 2La inverted arrangements
in M-form from flooded and rice field areas in the
central part of the transect, where S-form was not
found; iii) presence of S-form populations in eastern
sites characterised by higher genetic complexity due
to additional inversions on chromosome-2R.