Résumé
The costs of parasitism to a host's reproductive success (RS) often increase with time since infection. For hosts experiencing this type of infection, it is predicted that they will maximize their RS by bringing forward their schedule of reproduction. This is because the costs associated with such a response can be discounted against a reduced future RS due to parasitism. The microsporidian Vavraia culicis is a natural parasite of mosquitoes and one whose costs increase over time as its spores accumulate and damage host tissues. As larvae, male and female Culex pipiens mosquitoes behaved differently towards infection with V. culicis. Infected females pupated earlier than uninfected females and tended to emerge as smaller adults, indicating a cost to their fecundity. However, the age and size at maturity of infected male mosquitoes was no different from uninfected males. The results of this study support theoretical predictions and highlight the potential roles that host gender and density-dependent interactions may have in determining the response of host life-history traits to parasitism.