Data: Impact of thermal stress during pupal development in a key pollinator

The increasing frequency and intensity of extreme thermal events like
heatwaves, driven by climate change, threaten global biodiversity and
entire ecosystems. Despite alarming projections of population declines for
key pollinators like bumblebees, little is known about the direct impact
of varying elevated temperatures during their pupal development. To gain a
better understanding of the dose-response to thermal stress, we
experimentally exposed Bombus terrestris L. (Hymenoptera: Apidae) pupae in
vitro to varying thermal stress lengths (3-7 days) and intensities
(36-38°C). This mechanistic approach allowed us to uniquely isolate the
direct physiological effects of temperature on pupal development from
complex colony dynamics and assess individual emergence success,
developmental duration, body size, relative lipid content, and wing
geometric morphometrics. At the critical threshold of 38°C, pupal
emergence was drastically reduced (2-5 fold) and wing deformities
increased (4-7 fold). Even excluding wing deformities, we found thermal
stress-induced effects on emerged worker wing shape and directional
asymmetry. Hence, our findings suggest that increased extreme thermal
stress negatively impacts bumblebee pupal development. Given the relative
heat tolerance of B. terrestris, we expect even greater vulnerability in
more cold-adapted bumblebee species.