Original paper
The impact of experimental warming on bumblebees: Higher temperatures induce behavioral changes in Bombus terrestris queens
Kim, Han Soo; Yoon, Hyung Joo; Kim, Bo Yeon; Lee, Kyeong Yong; Trewick, Steven A.; Lee, Kwang Sik; Jin, Byung Rae
Entomologia Generalis Volume 45 Number 2 (2025), p. 517 - 525
published: May 22, 2025
published online: Apr 25, 2025
manuscript accepted: Mar 5, 2025
final revised version received: Feb 5, 2025
manuscript revision requested: Jan 22, 2025
manuscript received: Aug 30, 2024
DOI: 10.1127/entomologia/2025/2984
Open Access (paper may be downloaded free of charge)
Abstract
Bumblebees (Bombus terrestris) are important pollinators in most temperate and boreal ecosystems, but these regions are increasingly affected by heatwaves that are a symptom of anthropogenic climate change. Bumblebee queens may be particularly vulnerable to elevated temperatures during their solitary period following overwintering. Using an experimental system with numerous replicates, we investigated the oviposition behavior of overwintered spring queens, the resulting colony characteristics, and the mating behavior of newly emerged fall queens at three different temperatures: optimal (27 °C; C27), moderately high (32 °C; C32), and high (35 °C; C35). Spring queens exposed to higher temperatures exhibited unusual behavior, with spring queens in the C35 group more frequently digging up and destroying egg cells, ultimately leading to colony failure. Compared to C27, spring queens in the C32 treatment displayed more frequent oviposition, a higher colony formation rate, a higher number of offspring per colony, a shorter colony development period, and lower body sizes in their adult offspring. These results indicate that elevated temperatures lead to behavioral changes in spring queens and affect the characteristics of resulting colonies. Fall queens exhibited mating avoidance behavior at higher temperatures, resulting in a lower mating rate. Our results demonstrate that bumblebee queens respond to thermal conditions that can lead to colony failure when thermal limits are exceeded. In nature, behavioral changes induced in bumblebee queens exposed to persistent heatwaves during the solitary period may be seriously deleterious to bumblebee populations in many regions.
Keywords
Bumblebee • elevated temperature • oviposition behavior • mating behavior • pollinator • climate change