Table 1.

The critical components of malaria transmission that can either be determined directly or indirectly by parasites and how they affect our understanding of transmission

Component of vectorial capacity	Effect of increase in component on disease transmission (everything else being equal)	Interactions or trade‐offs to consider	Key questions to address	Applications and outlook
Mosquito competence (V)	↑	Virulence transmission trade‐off could result in mosquitoes with higher competence having reduced survival	Does mosquito competence correlates with a, n and/or p? Is competence predicted by G p × G H × E? Do environmentally driven changes in competence illustrate adaptive or nonadaptive phenotypic plasticity on the part of the parasite or the vector?	Understanding the genetic basis of competence can identify targets for genetic modification‐based control strategies
Vector biting rate and host preference (a)	↑	Biting rate increases mortality risk and could reduce vector survival. Changing host preference could increase survival by reducing exposure to insecticides	How does parasite impact vector biting rate? Can malaria parasites manipulate the vertebrate host choice of their vectors? Is malaria manipulation of vector biting rate a general phenomenon among the different mosquito–parasite combinations? Is there any parasite genetic variation for manipulation? Does the intensity of manipulation vary with environmental conditions (e.g., seasonally with mosquito densities)? Does a correlate with n and/or p?	Identifying parasite–mosquito associations that exhibit altered feeding behavior during infection will help improve transmission predictions by more accurately estimating biting rates and could also provide the opportunity to selectively target infected mosquitoes for control
The extrinsic incubation period (n)	↓	Faster developing parasites might inflict higher fitness costs on mosquitoes and reduce their ability to transmit	How does EIP length respond to within‐vector and environmental conditions? Can EIP be predicted by vector or parasite genotype? What affects EIP length besides temperature?	Shorter EIPs could evolve in response to interventions if there is a genetic basis for EIP length and sufficient selection pressure. For example, insecticides that reduce vector lifespan may favor faster parasite development
Mosquito longevity (p)	↑	Longer‐lived mosquitoes may have reduced biting rates	Do parasite traits, such as EIP or virulence, covary with mosquito lifespan? How does malaria infection impact vector lifespan? How does vector lifespan affect selection on parasites with different traits?	Mosquito longevity is the most sensitive parameter in vectorial capacity, and understanding how this trait covaries with other vector and parasite traits related to transmission is crucial for better characterizing transmission in the field