Population dynamics of Anopheles gambiae s.l. in Bobo-Dioulasso city: bionomics, infection rate and susceptibility to insecticides

A - Papers appearing in refereed journals

Dabire, R. K., Namountougou, M., Sawadogo, S. P., Yaro, L. B., Toe, H. K., Ouari, A., Gouagna, L-C., Simard, F., Chandre, F., Baldet, T., Bass, C. and Diabate, A. 2012. Population dynamics of Anopheles gambiae s.l. in Bobo-Dioulasso city: bionomics, infection rate and susceptibility to insecticides. Parasites & Vectors. 5, p. 127.

AuthorsDabire, R. K., Namountougou, M., Sawadogo, S. P., Yaro, L. B., Toe, H. K., Ouari, A., Gouagna, L-C., Simard, F., Chandre, F., Baldet, T., Bass, C. and Diabate, A.
Abstract

Background
Historical studies have indicated that An. gambiae s.s. is the predominant malaria vector species in Bobo-Dioulasso the second biggest city of Burkina Faso (West Africa). However, over the last decade, An. arabiensis appears to be replacing An. gambiae s.s. as the most prevalent malaria vector in this urban setting. To investigate this species transition in more detail the present study aims to provide an update on the malaria vector composition in Bobo-Dioulasso, and also the Plasmodium infection rates and susceptibility to insecticides of the local An. gambiae s.l. population.

Methods
An entomological survey was carried out from May to December 2008 in Dioulassoba and Kodeni (central and peripheral districts respectively), which are representative of the main ecological features of the city. Sampling consisted of the collection of larval stages from water bodies, and adults by monthly indoor residual spraying (IRS) using aerosol insecticides. Insecticide susceptibility tests were performed using the WHO filter paper protocol on adults emerged from larvae. PCR was used to determine vector species and to identify resistance mechanisms (kdr and ace-1R). The Plasmodium infection rate was estimated by ELISA performed on female mosquitoes collected indoors by IRS.

Results
An. arabiensis was found to be the major malaria vector in Bobo-Dioulasso, comprising 50 to 100% of the vector population. The sporozoite infection rate for An. arabiensis was higher than An. gambiae s.s. at both Dioulassoba and Kodeni. An. gambiae s.l. was resistant to DDT and cross-resistant to pyrethroids at the two sites with higher levels of resistance observed in An. gambiae s.s. than An. arabiensis. Resistance to 0.1% bendiocarb was observed in the An. gambiae s.s. S form but not the M form or in An. arabiensis. The L1014F kdr mutation was detected in the two molecular forms of An. gambiae s.s. at varying frequencies (0.45 to 0.92), but was not detected in An. arabiensis, suggesting that other mechanisms are involved in DDT resistance in this species. The ace-1R mutation was only detected in the S molecular form and was observed at the two sites at similar frequency (0.3).

Conclusions
Over the last ten years, An. arabiensis has become the major malaria vector in Bobo-Dioulasso city where it was formerly present only at low frequency. However, the ecological determinant that enhances the settlement of this species into urban and peri-urban areas of Bobo-Dioulasso remains to be clarified. The impact of the changing An. gambiae s.l. population in this region for vector control including resistance management strategies is discussed.

Year of Publication2012
JournalParasites & Vectors
Journal citation5, p. 127
Digital Object Identifier (DOI)doi:10.1186/1756-3305-5-127
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeDelivering Sustainable Systems (SS) [ISPG]
BBSRC Institute Career Path Fellowship: A genomic approach to understanding insecticide resistance in crop pests
Publisher's version
Output statusPublished
Publication dates
Online21 Jun 2012
Publication process dates
Accepted30 May 2012
Copyright licenseCC BY
PublisherBiomed Central Ltd
ISSN1756-3305

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