Egg marking pheromones of anarchistic worker honeybees (Apis mellifera)

In honeybees, worker policing via egg eating enforces functionalworker sterility in colonies with a queen and brood. It is thoughtthat queens mark their eggs with a chemical signal, indicatingthat their eggs are queen-laid. Worker-laid eggs lack this signaland are, therefore, eaten by policing workers. Anarchistic workerhoneybees have been hypothesized to circumvent worker policingby mimicking the queen egg-marking signal. We investigated thisphenomenon by relating chemical profiles of workers and theireggs to egg acceptability. We found that the ability of someworkers (anarchistic workers in queenright colonies and deviantworkers from a queenless colony) to lay more acceptable eggsis due to them producing significant amounts of queen-like estersfrom their Dufour's gland. These esters appear to be transferredto eggs during laying and increase egg survival. However, theseesters cannot be the normal queen egg-marking signal, as theyare generally absent from queen-laid eggs and only increasethe short-term persistence of worker-laid eggs, because only7–30% of anarchistic worker-laid eggs persisted to hatchingversus 91–92% of queen-laid eggs. All workers can producesome esters, but only workers that greatly increase their esterproduction lay more acceptable eggs. The production of estersappears to be a flexible response, as anarchistic workers rearedin queenless colonies did not increase their ester production,while some deviant workers in queenless colonies did increasetheir ester production.