Vector control: agents of selection on malaria parasites?

Insect vectors are responsible for spreading many infectious diseases, yet interactions between pathogens/parasites and insect vectors remain poorly understood. Filling this knowledge gap matters because vectors are evolving in response to the deployment of vector control tools (VCTs). Yet, whilst the evolutionary responses of vectors to VCTs are being carefully monitored, the knock-on consequences for parasite evolution have been overlooked. By examining how mosquito responses to VCTs impact upon malaria parasite ecology, we derive a framework for predicting parasite responses. Understanding how VCTs affect the selection pressures imposed on parasites could help to mitigate against parasite evolution that leads to unfavourable epidemiological outcomes. Furthermore, anticipating parasite evolution will inform monitoring strategies for VCT programmes as well as uncovering novel VCT strategies. Vector control tools (VCTs) affect diverse aspects of mosquito biology and are a driver of vector evolution. VCTs change parasite ecology by exposing parasites to insecticides and to vectors with altered genotypes and phenotypes (e.g., lifespan, behaviour, immunity, metabolism, microbiome). Parasite activities are affected by the ways that VCTs alter parasite–vector interactions, and this can drive parasite evolution. Parasite responses to VCTs are likely to include plastic and evolutionary changes to transmission traits expressed during infections in hosts/vectors. Parasite responses could undermine gains made towards malaria elimination and may have knock-on consequences for parasite–host interactions. Knowledge of parasite responses to the selection pressures imposed by VCTs could offer new approaches to reduce disease transmission that are robust to parasite evolution. [ABSTRACT FROM AUTHOR]