Queen Longevity and Fecundity Affect Conflict with Workers over Resource Inheritance in a Social Insect

Area of Science:

• Evolutionary biology
• Behavioral ecology
• Social insect behavior

Background:

• Resource inheritance is a key driver of conflict in animal societies.
• Models predict conflict zones where workers and queens compete over reproduction and nest inheritance.
• Previous research has not systematically tested these models within a single system.

Purpose of the Study:

• To develop and experimentally test an inclusive fitness model for annual eusocial Hymenoptera, specifically focusing on conflict over nest inheritance.
• To investigate the conditions under which workers are selected to enforce nest inheritance before the queen cedes control.
• To provide empirical support for kin-selected conflict theory in the context of resource inheritance.

Main Methods:

• Developed an inclusive fitness model for annual eusocial Hymenoptera.
• Conducted experiments on the bumblebee (Bombus terrestris) colonies.
• Manipulated queen presence and queen fecundity (egg removal) to observe worker behavior and reproduction.

Main Results:

• Queen tenure negatively correlated with worker male production, indicating workers gain direct fitness by usurping queens.
• Queen fecundity decreased significantly over the colony cycle, reducing workers' indirect fitness benefits from queen maintenance.
• Simulated loss of queen fecundity increased worker-to-queen aggression, with aggressive workers more likely to lay eggs.

Conclusions:

• Experimental results uphold key assumptions and predictions of the inclusive fitness model.
• Findings provide novel empirical support for kin-selected conflict over resource inheritance in bumblebees.
• Worker behavior, including aggression and egg-laying, is influenced by perceived queen fecundity and potential for direct reproduction.