Spatial ecology of a range-expanding bumble bee pollinator

Area of Science:

• Ecology
• Evolutionary Biology
• Conservation Biology

Background:

• Molecular methods have advanced understanding of bumble bee (Bombus spp.) spatial ecology, crucial for their conservation.
• The Tree Bumble Bee (Bombus hypnorum) has rapidly expanded its range across the UK since 2001.
• The spatial ecology of Bombus hypnorum remains largely uninvestigated.

Purpose of the Study:

• To investigate the spatial ecology of Bombus hypnorum.
• To determine if specific spatial ecology features are associated with its rapid range expansion.
• To establish critical spatial ecological parameters and mating system of this bumble bee.

Main Methods:

• Used 14 microsatellite markers to analyze a UK Bombus hypnorum population.
• Estimated worker foraging distance, nest density, lineage survival, and isolation by distance.
• Genotyped stored sperm from queens to confirm polyandry.

Main Results:

• Mean worker foraging distance was 103.6 m, lower than most bumble bee populations.
• Nest density was high (2.56 and 0.72 colonies ha⁻¹ in 2014 and 2015).
• Between-year lineage survival rate was 0.07; no fine-scale isolation by distance was detected.
• Confirmed polyandry with a mean minimum mating frequency of 1.7 males per queen.

Conclusions:

• Short worker foraging distances and high nest densities are associated with Bombus hypnorum's rapid range expansion.
• Findings provide critical spatial ecological data for this unusual bumble bee.
• Understanding these factors aids in conserving essential pollination services.