Dynamics of multiple insecticide resistance in the malaria vector Anopheles gambiae in a rice growing area in South-Western Burkina Faso - art. no. 188 Dabiré, K. R. Diabaté, A. /Djogbénou, Luc Ouari, A. N'Guessan, R. Ouédraogo, J. B. /Hougard, Jean-Marc /Chandre, Fabrice Baldet, T. Background: Insecticide resistance of the main malaria vector, Anopheles gambiae, has been reported in south-western Burkina Faso, West Africa. Cross-resistance to DDT and pyrethroids was conferred by alterations at site of action in the sodium channel, the Leu-Phe kdr mutation; resistance to organophosphates and carbamates resulted from a single point mutation in the oxyanion hole of the acetylcholinesterase enzyme designed as ace-1(R). Methods: An entomological survey was carried out during the rainy season of 2005 at Vallee du Kou, a rice growing area in south-western Burkina Faso. At the Vallee du Kou, both insecticide resistance mechanisms have been previously described in the M and S molecular forms of An. gambiae. This survey aimed i) to update the temporal dynamics and the circumsporozoite infection rate of the two molecular forms M and S of An. gambiae ii) to update the frequency of the Leu-Phe kdr mutation within these forms and finally iii) to investigate the occurrence of the ace-1(R) mutation. Mosquitoes collected by indoor residual collection and by human landing catches were counted and morphologically identified. Species and molecular forms of An. gambiae, ace-1(R) and Leu-Phe kdr mutations were determined using PCR techniques. The presence of the circumsporozoite protein of Plasmodium falciparum was determined using ELISA. Results: Anopheles gambiae populations were dominated by the M form. However the S form occurred in relative important proportion towards the end of the rainy season with a maximum peak in October at 51%. Sporozoite rates were similar in both forms. The frequency of the LeuPhe kdr mutation in the S form reached a fixation level while it is still spreading in the M form. Furthermore, the ace-1(R) mutation prevailed predominately in the S form and has just started spreading in the M form. The two mutations occurred concomitantly both in M and S populations. Conclusion: These results showed that the Vallee du Kou, a rice growing area formerly occupied mainly by M susceptible populations, is progressively colonized by S resistant populations living in sympatry with the former. As a result, the distribution pattern of insecticide resistance mutations shows the occurrence of both resistance mechanisms concomitantly in the same populations. The impact of multiple resistance mechanisms in M and S populations of An. gambiae on vector control measures against malaria transmission, such as insecticide-treated nets (ITNs) and indoor residual spraying (IRS), in this area is discussed. 2008 text https://www.documentation.ird.fr/hor/fdi:010044067 fdi:010044067 Dabiré K. R., Diabaté A., Djogbénou Luc, Ouari A., N'Guessan R., Ouédraogo J. B., Hougard Jean-Marc, Chandre Fabrice, Baldet T.. Dynamics of multiple insecticide resistance in the malaria vector Anopheles gambiae in a rice growing area in South-Western Burkina Faso - art. no. 188. 2008, 7, EN