Kin-selected conflict in the bumble-bee Bombus terrestris (Hymenoptera: Apidae)

Area of Science:

• Evolutionary Biology
• Behavioral Ecology
• Social Insects

Background:

• Kin selection theory predicts reproductive conflict between queens and workers in social Hymenoptera over male parentage due to differing relatedness.
• While some reproductive aspects of Bombus terrestris align with kin selection, others present inconsistencies.
• Previous studies highlight queen-worker conflict mechanisms and characteristic bimodal sex ratios in this species.

Purpose of the Study:

• To propose a novel hypothesis explaining the timing of reproductive events and parentage conflict in Bombus terrestris colonies.
• To reconcile previously unexplained reproductive patterns with kin selection theory.
• To provide ultimate explanations for observed queen-worker conflict dynamics.

Main Methods:

• The study presents a theoretical hypothesis based on existing knowledge of Bombus terrestris reproductive biology.
• It proposes specific worker-triggered events (detecting male brood or queen signals) that influence egg-laying timing.
• The hypothesis is evaluated against known reproductive patterns and experimental results.

Main Results:

• Workers delay egg-laying until their kin-selected interests are met, signaled by queen-produced male brood or queen-to-larvae signals.
• This delay mechanism explains the timing of reproductive events in colonies with early vs. late queen egg-laying.
• The hypothesis accounts for the characteristic bimodal (split) sex ratios observed in Bombus terrestris.

Conclusions:

• Kin selection theory can provide a robust explanation for the complex reproductive patterns in Bombus terrestris.
• The proposed hypothesis offers a unified framework for understanding worker reproductive timing and queen-worker conflict.
• Further research can test the specific cues and mechanisms proposed in this novel hypothesis.