Are Bumblebees Relevant Models for Understanding Wild Bee Decline?

Abstract

The unsustainable use of ecosystems by human societies has put global biodiversity in peril. Bees are, in this context, a popular example of a highly diversified group of pollinators whose collapse is a major concern given the invaluable ecosystem services they provide. Amongst them, bumblebees (Bombus) have increasingly drawn the attention of scientists due to their dramatic population declines globally. This regression has converted them into popular conservation entities, making them the second most studied group of bees worldwide. However, in addition to have become relevant models in the fields of ecology, evolution and biogeography, bumblebees have also been used as models for studying wild bee decline and conservation worldwide. Integrating evidence from the comparative ecology and resilience of bumblebees and wild bees, I discuss the relevance of using Bombus as radars for wild bee decline worldwide. Responses of bumblebees to environmental changes are generally not comparable with those of wild bees because of their relatively long activity period, their inherent sensitivity to high temperatures, their relatively generalist diet breadth and many aspects arising from their eusocial behavior. Moreover, important differences in the available historical data between bumblebees and other bees make comparisons of conservation status even more arduous. Overall, these results reinforce the need for conservation actions that consider a higher level of understanding of ecological diversity in wild bees, highlight the need for an updated and more extensive sampling of these organisms, and emphasize that more caution is required when extrapolating trends from model species.

Seasonality of pollinators in montane habitats: Cool‐blooded bees for early‐blooming plants

“…Recent reviews and empirical research on the impact of climate change on insect pollinators have often acknowledged the importance of thermal biology as a determinant of bee responses to climate warming, but most inferences have been based on studies of large‐sized, strongly endothermic species, particularly bumble bees in the genus Bombus (Ghisbain et al, 2021; Marshall et al, 2018; Oyen et al, 2016; Ploquin et al, 2013; Rasmont et al, 2015; Scaven & Rafferty, 2013). In the same vein, concerns on wild bee declines have been almost invariably based on data from just two, extremely endothermic genera ( Apis , Bombus ) which collectively account for a tiny fraction of all species of bees (~1.5%) and whose biological and ecological attributes are far from representative of wild bees in most respects (Ghisbain, 2021; Wood et al, 2020). Results of this study suggest that medium‐ and large‐sized weakly endothermic bees with low upper thermal limits and weak thermoregulatory ability (~50–100 mg body mass) can be more adversely affected by increasing ambient temperatures than the large, strongly endothermic species with high thermoregulatory ability most frequently investigated (>100 mg).…”

Seasonality of pollinators in Mediterranean montane habitats: cool-blooded bees for early-blooming plants

“…Recent reviews and empirical research on the impact of climate change on insect pollinators have often acknowledged the importance of thermal biology as a determinant of bee responses to climate warming, but most inferences have been based on studies of large-sized endothermic species, particularly bumble bees in the genus Bombus (Scaven and Rafferty 2013, Ploquin et al 2013, Rasmont et al 2015, Oyen et al 2016, Marshall et al 2020, Ghisbain et al 2021). In the same vein, concerns on wild bee declines have been almost invariably based on data from just two endothermic genera ( Apis , Bombus ) which collectively account for a tiny fraction of all species of bees (~1.5%) and whose biological and ecological attributes are far from representative of wild bees in most respects (Wood et al 2020, Ghisbain 2021). Results of this study suggest that medium- and large-sized ectothermic bees with low upper thermal limits and weak thermoregulatory ability can be more adversely affected by increasing ambient temperatures than the large endothermic species with high thermoregulatory ability most frequently investigated.…”

Book review: The Bumblebees of the Himalaya – An Identification Guide, by Paul H. Williams

“…Bumblebees are the most studied wild bees worldwide (Cameron and Sadd 2020;Ghisbain 2021). Their big body size, colorful appearance, natural abundance and diversity in areas visited by naturalists of the northern hemisphere have made them relatively well represented in museum collections compared to other bees (Wood et al 2019(Wood et al , 2021.…”