Do microbes mediate rhythmic malaria parasite–mosquito vector interactions?

Daily rhythms in the blood-feeding activity of insect vectors determine the time of day that parasites transmit between hosts and vectors. Within the vector, parasites are exposed to myriad physiological rhythms, including in immunity and nutrition, which affect transmission success. Recently discovered rhythmicity in gut microbes, coupled with the knowledge that microbes mediate malaria transmission by modulating vector immunity and metabolism, and via direct interactions with parasites, suggest that microbes have an underappreciated influence on rhythms in parasite-vector interactions. We integrate chronobiology with evolutionary ecology to propose that microbes mediate rhythmicity in mosquito susceptibility and malaria parasite development. Understanding how the time of day transmission occurs influences the spread of malaria transmission is urgently needed, given that rhythmic activities of mosquito microbiota are likely affected by changes in mosquito biting rhythms.