Enhanced Iteroparity Is a Correlated Response to Direct Selection on Blood Feeding in a Mosquito

Herein, we determine life-history consequences of selection on blood feeding in a polymorphic population of the pitcher-plant mosquito, Wyeomyia smithii Coq. (Diptera: Culicidae). All populations of W. smithii produce an initial batch of eggs without ever taking a blood meal (biting); southern populations require a blood meal for the second and subsequent batches of eggs, but are polymorphic for propensity to bite. To determine correlated life-history responses to direct selection on blood feeding, we compared fecundity, adult longevity, and reproductive allocation between a line selected specifically for increased blood feeding and its unselected, control line maintained in parallel for 11 generations. Previous studies have focused on the fitness benefits of blood feeding in terms of overall fecundity. Herein, we evaluate a novel fitness benefit of blood feeding that reduces the risk of reproductive failure by spreading that risk across multiple reproductive events in a population confronted with an unpredictably variable larval environment. We propose that "spreading the risk" reinforces selection on blood feeding in other arthropods in which the separation of fecundity from reproductive allocation in time or space has previously been neglected. Importantly, heritable variation for "spreading the risk" should enhance vectorial capacity and make more difficult vector control through larval source reduction.