Tropical insects approach a thermal ceiling, signaling limited buffering against warming
A global study measured CTmax and CTmin for about 2,300 tropical insects across Afrotropical and Neotropical elevational gradients, finding that thermal limits do not track environmental temperatures and instead approach a tropical lowland ceiling. High-elevation species show plasticity to rising heat, while lowland species have limited plastic responses; heat tolerance also varies markedly among insect orders and aligns with protein stability via protein melting temperatures. Heat-shock tests indicate CTmax can increase at high elevations but may decrease tolerance in warm lowlands. Using field data and climate projections, the authors predict that up to ~52% of future surface temperatures and ~38% of future air temperatures in Amazonian lowlands could cause heat mortality for half the studied community, suggesting tropical insects have a limited capacity to buffer future warming.