Patterns of pollen and nectar foraging specialization by bumblebees over multiple timescales using RFID

Area of Science:

• Behavioral Ecology
• Insect Social Behavior

Background:

• Social insects achieve ecological success through division of labor.
• Lifetime task specialization is well-studied, but shorter-term specialization is less understood.
• Bumblebees forage for pollen and nectar, with workers often mixing these tasks.

Purpose of the Study:

• To investigate if bumblebees exhibit task specialization on a daily timescale.
• To identify factors influencing short-term and long-term foraging specialization.
• To determine if specialists engage in more foraging bouts than generalists.

Main Methods:

• Utilized radio frequency identification (RFID) to track individual bumblebee foragers.
• Recorded antennal morphology and body size of all foragers.
• Correlated morphological traits and size with complete foraging histories.

Main Results:

• A small fraction of bumblebees were lifetime specialists.
• >50% of foragers demonstrated daily specialization in collecting either pollen or nectar.
• Neither daily nor lifetime specialists were superior foragers (size or bout number).
• Larger bees with more antennal olfactory sensilla made more foraging bouts but showed no increased specialization.

Conclusions:

• Bumblebees exhibit significant daily task specialization, alongside lifetime specialization.
• Foraging specialization patterns are complex and not solely driven by size or olfactory sensilla.
• Understanding short-term specialization is crucial for comprehending bumblebee colony efficiency.