Global Trends in Bumble Bee Health

Area of Science:

• Ecology
• Conservation Biology
• Entomology

Background:

• Bumble bees (Bombus) are crucial pollinators in natural ecosystems and agriculture.
• Global bumble bee populations face significant declines in distribution and abundance.
• There is a growing scientific interest in understanding the drivers of bumble bee population decline.

Purpose of the Study:

• To summarize the threat status of wild bumble bee species across biogeographic regions.
• To synthesize recent research on the potential causes of bumble bee population declines.
• To identify regions lacking sufficient bumble bee assessment data.

Main Methods:

• Review and synthesis of data on bumble bee threat status.
• Analysis of data-rich studies on bumble bee population declines.
• Distinguishing between correlational and causal evidence for decline factors.

Main Results:

• Evidence indicates habitat loss, climate change, pathogen transmission, invasive species, and pesticides negatively impact bumble bees.
• These factors can act individually or in combination, with effects varying by species and location.
• Significant gaps exist in assessment data for many biogeographic regions.

Conclusions:

• Multiple interacting factors threaten wild bumble bee populations.
• Further experimental research, beyond commercially relevant species, is essential to determine causal relationships.
• Urgent conservation strategies are needed to address the decline of these vital pollinators.