Global effects of extreme temperatures on wild bumblebees

Abstract

Climate plays a key role in shaping population trends and determining the geographic distribution of species because of limits in species' thermal tolerance. An evaluation of species tolerance to temperature change can therefore help predict their potential spatial shifts and population trends triggered by ongoing global warming. We assessed inter-and intraspecific variations in heat resistance in relation to body mass, local mean temperatures, and evolutionary relationships in 39 bumblebee species, a major group of pollinators in temperate and cold ecosystems, across 3 continents, 6 biomes, and 20 regions (2386 male specimens). Based on experimental bioassays, we measured the time before heat stupor of bumblebee males at a heatwave temperature of 40°C. Interspecific variability was significant, in contrast to interpopulational variability, which was consistent with heat resistance being a species-specific trait. Moreover, cold-adapted species are much more sensitive to heat stress than temperate and Mediterranean species. Relative to their sensitivity to extreme temperatures, our results help explain recent population declines and range shifts in bumblebees following climate change.

Effects of Heat Stress on Mating Behavior and Colony Development in Bombus terrestris (Hymenoptera: Apidae)

“…For several years, many studies have explored effects of microbiota, diet, temperature, and pesticide exposure on bumblebee's health in lab conditions (Gill and Raine, 2014;Vanderplanck et al, 2019;Barraud et al, 2020;Rothman et al, 2020;Maebe et al, 2021a;Oyen et al, 2021). However, most of these studies used commercially available bumblebee species (i.e., Bombus impatiens in North America and B. terrestris in Europe, and Bombus hypocrita in Asia) which are known to be tolerant and resistant to environmental changes (Oyen and Dillon, 2018;Maebe et al, 2021b;Martinet et al, 2021a). Limiting studies to reared species may bias our overall view of the adaptive response of bumblebees to decline factors as these species are selected throughout this rearing process.…”

“…We used the buff-tailed bumblebee (B. terrestris) as a model species even though it is considered a resistant species (Martinet et al, 2021a) because it is easy to manage and available all year. Colonies were bought at Biobest NV (Westerlo, Belgium).…”

“…As a model species, we used Bombus terrestris, a Euro-Mediterranean species domesticated for crop pollination (Rasmont et al, 2008). This species is highly tolerant to environmental changes and is expanding globally (Inari et al, 2005;Torretta et al, 2006;Rasmont et al, 2015;Martinet et al, 2021a). It has previously been shown that for this heat-tolerant species, no effect of heat exposure was observed on sperm viability, sperm DNA integrity and composition of the attractive secretions of males (Martinet et al, 2021b).…”

Bumblebee resilience to climate change, through plastic and adaptive responses

“…Additionally, range expansion in B . haematurus seems to indicate an ability to track suitable climate conditions (Biella et al, 2020) but is also likely associated with a high tolerance for temperature extremes (Martinet, Dellicour et al, 2021).…”

A workflow to design new directed domestication programs to move forward current and future insect production

“…Insect farming can face these changes thanks to species intrinsic features such as large climatic tolerance or generalist diet. In the context of global changes, the ability to cope with environmental changes is thus a valuable information that should be considered early in the process, during the assessment of candidate species domestication potential (see examples of species-specific responses to climate change or abiotic parameters between closely related species in ( Oyen et al, 2016 ; Martinet et al, 2020 ).…”