Vector-borne diseases cause significant financial and human loss, with
billions of dollars spent on control. Arthropod vectors experience a
complex suite of environmental factors that affect fitness, population
growth, and species interactions across multiple spatial and temporal
scales. Temperature and water availability are two of the most important
abiotic variables influencing their distributions and abundances. While
extensive research on temperature exists, the influence of humidity on
vector and pathogen parameters affecting disease dynamics are less
understood. Humidity is often underemphasized, and when considered, is
often treated as independent of temperature even though desiccation
likely contributes to declines in trait performance at warmer
temperatures. This Perspectives explores how humidity shapes the thermal
performance of mosquito-borne pathogen transmission. We summarize what
is known about its effects and propose a conceptual model for how
temperature and humidity interact to shape the range of temperatures
across which mosquitoes persist and achieve high transmission potential.
We discuss how failing to account for these interactions hinders efforts
to forecast transmission dynamics and respond to epidemics of
mosquito-borne infections. We outline future research areas that will
ground the effects of humidity on the thermal biology of pathogen
transmission in a theoretical and empirical framework to improve spatial
and temporal prediction of vector-borne pathogen transmission.