Email updates

Keep up to date with the latest news and content from Parasites & Vectors and BioMed Central.

Open Access Research

Larval ecology of mosquitoes in sylvatic arbovirus foci in southeastern Senegal

Diawo Diallo1*, Cheikh T Diagne1, Kathryn A Hanley2, Amadou A Sall3, Michaela Buenemann4, Yamar Ba1, Ibrahima Dia1, Scott C Weaver5 and Mawlouth Diallo1

Author Affiliations

1 Unité d’entomologie médicale, Institut Pasteur de Dakar, Dakar, Sénégal

2 Department of Biology, New Mexico State University, Las Cruces, New Mexico, United States of America

3 Unité des arbovirus et virus des fièvres hémorragiques, Institut Pasteur de Dakar, Dakar, Sénégal

4 Department of Geography, New Mexico State University, Las Cruces, New Mexico, United States of America

5 Institute for Human Infections and Immunity, Center for Biodefense and Emerging Infectious Diseases, and Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America

For all author emails, please log on.

Parasites & Vectors 2012, 5:286  doi:10.1186/1756-3305-5-286

Published: 7 December 2012

Abstract

Background

Although adult mosquito vectors of sylvatic arbovirus [yellow fever (YFV), dengue-2 (DENV-2) and chikungunya (CHIKV)] have been studied for the past 40 years in southeastern Senegal, data are still lacking on the ecology of larval mosquitoes in this area. In this study, we investigated the larval habitats of mosquitoes and characterized their seasonal and spatial dynamics in arbovirus foci.

Methods

We searched for wet microhabitats, classified in 9 categories, in five land cover classes (agriculture, forest, savannah, barren and village) from June, 2010 to January, 2011. Mosquito immatures were sampled monthly in up to 30 microhabitats of each category per land cover and bred until adult stage for determination.

Results

No wet microhabitats were found in the agricultural sites; in the remaining land covers immature stages of 35 mosquito species in 7 genera were sampled from 9 microhabitats (tree holes, fresh fruit husks, decaying fruit husks, puddles, bamboo holes, discarded containers, tires, rock holes and storage containers). The most abundant species was Aedes aegypti formosus, representing 30.2% of the collections, followed by 12 species, representing each more than 1% of the total, among them the arbovirus vectors Ae. vittatus (7.9%), Ae. luteocephalus (5.7%), Ae. taylori (5.0%), and Ae. furcifer (1.3%). Aedes aegypti, Cx. nebulosus, Cx. perfuscus, Cx. tritaeniorhynchus, Er. chrysogster and Ae. vittatus were the only common species collected from all land covers. Aedes furcifer and Ae. taylori were collected in fresh fruit husks and tree holes. Species richness and dominance varied significantly in land covers and microhabitats. Positive associations were found mainly between Ae. furcifer, Ae. taylori and Ae. luteocephalus. A high proportion of potential enzootic vectors that are not anthropophilic were found in the larval mosquito fauna.

Conclusions

In southeastern Senegal, Ae. furcifer and Ae. taylori larvae showed a more limited distribution among both land cover and microhabitat types than the other common species. Uniquely among vector species, Ae. aegypti formosus larvae occurred at the highest frequency in villages. Finally, a high proportion of the potential non-anthropophilic vectors were represented in the larval mosquito fauna, suggesting the existence of unidentified sylvatic arbovirus cycles in southeastern Senegal.

Keywords:
Mosquito larvae; Sylvatic arbovirus vectors; Microhabitats; Land covers; Species association, Aedes furcifer,Aedes taylori; Aedes aegypti formosus; Southeastern Senegal