When does temperature limit bee flight? Identifying the missing pieces of the puzzle

Bees are the most important insect pollinators, and nearly all
bee-mediated pollination depends on flight. In this review, we identify
five key gaps that limit our ability to predict how abiotic factors shape
bee flight performance and ecology. First, while clade strongly influences
endothermy and flight temperature limits, we still know little about how
phylogeny, body size, and ecological traits shape thermal biology across
the full diversity of bee species - most data come from temperate,
northern hemisphere  Apinae. Second, because the mechanisms of
thermal balance during flight have only been studied in a handful of
species, and these vary, we clearly lack a predictive understanding of
when bees will be physiologically stressed by temperature during flight.
Third, although some studies suggest desiccation may limit flight more
than overheating, the links between thermal balance and water regulation
remain poorly understood. Fourth, we know very little about bees’ capacity
to respond to thermal variation through acclimation, developmental
plasticity, or evolutionary adaptation. Finally, we need advances in
biophysical modeling to better simulate heat and water exchange in bees,
including the role of cuticular structures and internal heat transfer
among body regions. Filling these gaps is essential for building
predictive, mechanistic models of how climate change will affect bee
physiology and the pollination services bees provide.