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Potential impacts of climate change on stable flies, investigated along an altitudinal gradient

Authors

  • J. GILLES,

    Corresponding author
    1. 1 Department of Comparative Tropical Medicine and Parasitology, Institut für Vergleichende Tropenmedizin und Parasitologie, Munich, Germany, 2Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique (CNRS), Montpellier, France and 3Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Elevage et Médecine Vétérinaire Tropicale, Montpellier, France
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  • 1,2,3 J.-F. DAVID,

    1. 1 Department of Comparative Tropical Medicine and Parasitology, Institut für Vergleichende Tropenmedizin und Parasitologie, Munich, Germany, 2Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique (CNRS), Montpellier, France and 3Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Elevage et Médecine Vétérinaire Tropicale, Montpellier, France
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  • 2 G. DUVALLET,

    1. 1 Department of Comparative Tropical Medicine and Parasitology, Institut für Vergleichende Tropenmedizin und Parasitologie, Munich, Germany, 2Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique (CNRS), Montpellier, France and 3Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Elevage et Médecine Vétérinaire Tropicale, Montpellier, France
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  • and 2 E. TILLARD 3

    1. 1 Department of Comparative Tropical Medicine and Parasitology, Institut für Vergleichende Tropenmedizin und Parasitologie, Munich, Germany, 2Centre d’Ecologie Fonctionnelle et Evolutive, Centre National de la Recherche Scientifique (CNRS), Montpellier, France and 3Centre de Coopération Internationale en Recherche Agronomique pour le Développement (CIRAD), Elevage et Médecine Vétérinaire Tropicale, Montpellier, France
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Dr J. Gilles, University of Kentucky, Department of Entomology, S.225 Agriculture Science Center North, Lexington 40546–0091, KY. Tel: (859) 2572513; fax: (859) 323 1120; e-mail: jeremie.gilles@gmail.com

Abstract

Abstract Adult populations of stable flies were sampled along an altitudinal transect in Reunion Island to determine whether higher temperatures were associated with: (a) higher numbers of flies; (b) a longer season of infestation, and/or (c) different responses to warming in the cosmopolitan Stomoxys calcitrans (L) and the tropical Stomoxys niger niger Macquart (Diptera: Muscidae). Flies of both species were trapped at seven farms situated at four altitudes (100−1600 m a.s.l.) over a 90-week period. For both species, there were no relationships between the maximum or mean fly abundance and altitude. Only minimum abundance in winter was significantly higher at lower altitudes. Maximum and mean abundances differed significantly between nearby farms under similar climatic conditions. Seasonal fluctuations in fly abundance changed along the gradient. At lower altitudes, population growth started earlier after the winter but abundance declined earlier in summer, which resulted in a shift of the season of infestation. Seasonal fluctuations of both species were strongly related to climate variables at high altitude, mainly temperature. However, climate variables explained a decreasing proportion of the variations in abundance at lower altitudes. Stomoxys calcitrans was the most abundant species overall, but the proportion of S. n. niger increased significantly at lower altitudes and this species became predominant at 100 m a.s.l. It is concluded that stable fly infestations are unlikely to worsen in response to global warming. Maximum abundance is limited by local factors, possibly larval resources, which suggests that adequate husbandry practices could override the impact of climate change. Because S. n. niger tends to be the predominant pest at elevated temperatures, it is recommended that this species should not be introduced in areas where climate is changing.

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