Time-of-day of blood feeding: effects on mosquito life history and malaria transmission

Biological rhythms allow organisms to compartmentalise and coordinate aspects of their life with the predictable daily rhythms of their environment. There is increasing recognition that understanding the biological rhythms of mosquitoes that transmit parasites is important for global health. For example, perturbations in blood foraging rhythms as a consequence of vector control measures may undermine disease control. To address this, we explore the impacts of altered timing of blood feeding on mosquito life history traits and malaria transmission. We carried out three experiments in which Anopheles stephensi mosquitoes were fed in the morning or evening on blood that had different qualities, including: chemical or Plasmodium chabaudi infection induced anaemia, Plasmodium berghei infection but no anaemia, or originating from hosts at different times of day. We then compared mosquito fitness proxies relating to survival and reproduction, and malaria transmission proxies where relevant, using mixed-effects models and survival analysis. Mosquito lifespan is not influenced by the time of day they received a blood meal but several reproductive metrics are affected, in some experiments. Overall, receiving a blood meal in the morning makes mosquitoes more likely to lay eggs. Furthermore, in the experiment with the largest sample size, morning fed mosquitoes laid sooner and have a larger clutch size. In keeping with previous work, P. berghei infection reduces mosquito lifespan and the likelihood of laying eggs, but time of day of blood feeding does not impact upon these metrics nor on parasite transmission. The time of day of blood feeding does not appear to have major consequences for mosquito fitness or transmission of asynchronous malaria species. If our results from a lab colony of mosquitoes living in benign conditions hold for wild mosquitoes, it suggests that mosquitoes have sufficient flexibility in their physiology to cope with changes in biting time induced by evading insecticide treated bed nets. Future work should consider the impact of multiple feeding cycles and the abiotic stresses imposed by the need to forage for blood when hosts are not protected by bed nets.

O'Donnell, Aidan J; Rund, Sam SC; Reece, Sarah E. (2019). Time-of-day of blood feeding: effects on mosquito life history and malaria transmission, [dataset]. University of Edinburgh. School of Biological Sciences. https://doi.org/10.7488/ds/2485