Assortative mating in mixed swarms of the mosquito Anopheles gambiae s.s. M and S molecular forms, in Burkina Faso, West Africa

Authors

  • K. R. DABIRE,

    Corresponding author
    • Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, West Africa
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  • S. SAWADODGO,

    1. Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, West Africa
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  • A. DIABATE,

    1. Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, West Africa
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  • K. H. TOE,

    1. Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, West Africa
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  • P. KENGNE,

    1. Institut de Recherche pour le Développement (IRD), Université de Montpellier 1-Université de Montpellier 2, MIVEGEC (Maladies Infectieuses et Vecteurs:Ecologie, Genetique, Evolution et Contrôle), Montpellier, France
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  • A. OUARI,

    1. Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso, West Africa
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  • C. COSTANTINI,

    1. Institut de Recherche pour le Développement (IRD), Université de Montpellier 1-Université de Montpellier 2, MIVEGEC (Maladies Infectieuses et Vecteurs:Ecologie, Genetique, Evolution et Contrôle), Montpellier, France
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  • C. GOUAGNA,

    1. Institut de Recherche pour le Développement (IRD), Université de Montpellier 1-Université de Montpellier 2, MIVEGEC (Maladies Infectieuses et Vecteurs:Ecologie, Genetique, Evolution et Contrôle), Montpellier, France
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  • F. SIMARD,

    1. Institut de Recherche pour le Développement (IRD), Université de Montpellier 1-Université de Montpellier 2, MIVEGEC (Maladies Infectieuses et Vecteurs:Ecologie, Genetique, Evolution et Contrôle), Montpellier, France
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  • T. BALDET,

    1. Centre de Coopération Internationale en Recherche Agronomique pour le Développement/IRD/Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
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  • T. LEHMANN,

    1. Laboratory of Malaria and Vector Research/NIAID/NIH, Rockville, WA, U.S.A.
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  • G. GIBSON

    1. Department of Agriculture, Health and Environment, Natural Resources Institute, University of Greenwich at Medway, Chatham, U.K.
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Dr Kounbobr Roch Dabiré, IRSS/Centre Muraz, BP 390, Bobo-Dioulasso, West Africa. Tel.: +226 70 73 90 69; Fax: +226 20 97 04 57; E-mail: dabire_roch@hotmail.com

Abstract

The molecular form composition of Anopheles gambiae Giles s.s. (Diptera: Culicidae) mating swarms and the associated mating pairs (copulae) were investigated during two rainy seasons (July to October, 2005 and July to November, 2006) in the villages of Soumousso and Vallée du Kou (VK7). Although the habitats of these villages differ markedly, sympatric populations of M and S molecular forms of An. gambiae s.s. occur in both places periodically. The main aim was to assess the degree to which these molecular forms mate assortatively. In Soumousso, a wooded savannah habitat, the majority of swarm samples consisted of only S-form males (21/28), although a few M-form males were found in mixed M- and S-form swarms. In VK7, a rice growing area, the majority of swarm samples consisted of only M-form males (38/62), until October and November 2006, when there were nearly as many mixed-form as single-form swarms. Overall, ∼60% of M- and S-form swarms were temporally or spatially segregated; the two forms were effectively prevented from encountering each other. Of the remaining 40% of swarms, however, only about half were single-form and the rest were mixed-form. Of the 33 copulae collected from mixed-form swarms, only four were mixed-form pairs, significantly fewer than expected by random pairing between forms (χ2 = 10.34, d.f. = 2, P < 0.01). Finally, all specimens of inseminated females were of the same form as the sperm contained within their spermatheca (n = 91), even for the four mixed-form copulae. These findings indicate that assortative mating occurs within mixed-form swarms, mediated most probably by close-range mate recognition cues.

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