Evolution of worker sterility in honey-bees ( Apis mellifera) : how anarchistic workers evade policing by laying eggs that have low removal rates

Abstract

In anarchistic honey-bee colonies, many workers’ sons are reared despite the presence of the queen. Worker-laid eggs are normally eaten by other workers in queenright colonies. Workers are thought to discriminate between queen-laid and worker-laid eggs by the presence or absence of a queen-produced egg-marking pheromone. This study compared the survival of three classes of eggs (worker-laid eggs from anarchistic colonies, worker-laid eggs from non-anarchistic queenless colonies, and queen-laid eggs) in both queenright normal colonies and queenright anarchistic colonies, in order to test the hypothesis that anarchistic workers evade policing by laying more acceptable eggs. As expected, few worker-laid eggs from non-anarchistic colonies survived more than 2 h. In contrast, worker-laid eggs from anarchistic colonies had much greater acceptability, which in some trials equalled the acceptability of queen-laid eggs. Anarchistic colonies were generally less discriminatory than normal queenright colonies towards worker-laid eggs, whether these originated from anarchistic colonies or normal queenless colonies. This indicates that the egg-removal aspect of the anarchistic syndrome involves both worker laying of eggs with greater acceptability and reduced discriminatory behaviour of policing workers.