Risk-averse parenting: bumble bees prioritize metal avoidance over sugar intake to safeguard offspring

Area of Science:

• Ecology
• Environmental Toxicology
• Behavioral Ecology

Background:

• Metal pollution is a significant threat to wildlife, impacting essential pollinators like bees.
• While metal toxicity in bees is known, their ability to detect and avoid contaminated food sources, and how social factors influence this, requires further investigation.

Purpose of the Study:

• To investigate whether buff-tailed bumble bee workers avoid metal-contaminated food sources.
• To determine if social context, specifically brood care, affects this avoidance behavior.
• To explore the interplay between metal contamination, food energy content, and bee foraging decisions.

Main Methods:

• Buff-tailed bumble bee workers were presented with choices between sucrose solutions laced with copper or cadmium and uncontaminated alternatives.
• An energetic trade-off was created by varying sucrose concentrations (50% vs. 20%).
• The influence of brood care was assessed by comparing worker choices with and without the presence of larvae.

Main Results:

• Workers consistently avoided metal-contaminated solutions when both options were equally concentrated (50% sucrose).
• When the uncontaminated option had lower sugar content (20% sucrose), workers chose the metal-laced solution, but only when not tending to brood.
• In the presence of brood, workers prioritized the metal-free, albeit lower-sugar, solution, indicating adaptive provisioning.

Conclusions:

• Bumble bee workers actively avoid metal-contaminated food sources.
• Foraging behavior in bumble bees is context-dependent, influenced by both food quality and the presence of brood.
• These findings highlight the complex adaptive strategies bees employ to balance nutritional needs with environmental risks, particularly in the context of parental care.