Résumé
Accumulating evidence indicates that species interactions such as
competition and predation can indirectly alter interactions with other
community members, including parasites. For example, presence of predators
can induce behavioral defenses in the prey, resulting in a change in
susceptibility to parasites. Such predator-induced phenotypic changes may
be especially pervasive in prey with discrete larval and adult stages for
which exposure to predators during larval development can have strong
carry-over effects on adult phenotypes. To our knowledge, no study to date
has examined possible carry-over effects of predator exposure on pathogen
transmission. We addressed this question using a natural food web
consisting of the human malaria parasite Plasmodium falciparum, the
mosquito vector Anopheles coluzzii, and a backswimmer, an aquatic predator
of mosquito larvae. Although predator exposure did not significantly alter
mosquito susceptibility to P. falciparum, it incurred strong fitness costs
on other key mosquito life history traits including larval development,
adult size, fecundity and longevity. Using an epidemiological model we
show that larval predator exposure should overall significantly decrease
malaria transmission. These results highlight the importance of taking
into account the effect of environmental stressors on disease ecology and
epidemiology.