Wolbachia increases susceptibility to Plasmodium infection in a natural system.
Current views about the impact of Wolbachia on Plasmodium infections are almost entirely based on data regarding artificially transfected mosquitoes. This work has shown that Wolbachia reduces the intensity of Plasmodium infections in mosquitoes, raising the exciting possibility of using Wolbachia to control or limit the spread of malaria. Whether natural Wolbachia infections have the same parasite-inhibiting properties is not yet clear. Wolbachia-mosquito combinations with a long evolutionary history are, however, key for understanding what may happen with Wolbachia-transfected mosquitoes after several generations of coevolution. We investigate this issue using an entirely natural mosquito-Wolbachia-Plasmodium combination. In contrast to most previous studies, which have been centred on the quantification of the midgut stages of Plasmodium, we obtain a measurement of parasitaemia that relates directly to transmission by following infections to the salivary gland stages. We show that Wolbachia increases the susceptibility of Culex pipiens mosquitoes to Plasmodium relictum, significantly increasing the prevalence of salivary gland stage infections. This effect is independent of the density of Wolbachia in the mosquito. These results suggest that naturally Wolbachia-infected mosquitoes may, in fact, be better vectors of malaria than Wolbachia-free ones.
Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle, CNRS (UMR CNRS-UM1-UM2 5290, IRD 224), Centre de Recherche IRD, 911 Avenue Agropolis, Montpellier 34394, France, Institut des Sciences de l'Evolution, CNRS (UMR 5554), Université de Montpellier II, , Montpellier 34095, France, Centre d'Ecologie Fonctionnelle et Evolutive, CNRS (UMR 5175), 1919 Route de Mende, Montpellier 34293, France.
F
F
Zélé
A
A
Nicot
A
A
Berthomieu
M
M
Weill
O
O
Duron
A
A
Rivero
D000818:Animals; D003465:Culex / Q000382:microbiology / Q000469:parasitology*; D060467:Disease Resistance; D006790:Host-Parasite Interactions; D010961:Plasmodium / Q000472:pathogenicity / Q000502:physiology*; D020577:Wolbachia / Q000502:physiology*
infection intensity; infection prevalence; oocysts; sporozoites; symbiont-mediated protection; vectorial competence