Résumé
The ecological context in which mosquitoes and malaria parasites interact
has received little attention, compared to the genetic and molecular
aspects of malaria transmission. Plant nectar and fruits are important for
the nutritional ecology of malaria vectors, but how the natural diversity
of plant-derived sugar sources affects mosquito competence for malaria
parasites is unclear. To test this, we infected Anopheles coluzzi, an
important African malaria vector, with sympatric field isolates of
Plasmodium falciparum, using direct membrane feeding assays. Through a
series of experiments, we then examined the effects of sugar meals from
Thevetia neriifolia and Barleria lupilina cuttings that included flowers,
and fruit from Lannea microcarpa and Mangifera indica on parasite and
mosquito traits that are key for determining the intensity of malaria
transmission. We found that the source of plant sugar meal differentially
affected infection prevalence and intensity, the development duration of
the parasites, as well as the survival and fecundity of the vector. These
effects are likely the result of complex interactions between toxic
secondary metabolites and the nutritional quality of the plant sugar
source, as well as of host resource availability and parasite growth.
Using an epidemiological model, we show that plant sugar source can be a
significant driver of malaria transmission dynamics, with some plant
species exhibiting either transmission-reducing or -enhancing activities.