Regulation of worker reproduction in the honey bee (Apis mellifera L.)

Reproductive division of labour is a defining characteristic of eusocial insects. In honey bees, there is normally a single, highly fecund queen, responsible for producing all the brood in the colony. Workers are functionally sterile, developing their latent ovaries only upon queen loss. Workers cannot mate, and are only capable of laying unfertilised, male eggs. I investigated the effects of various chemical, genetic, and nutritional factors on the ovary development of honey bee workers. I demonstrate that queen mandibular pheromone inhibits worker ovary development in caged queenless workers to the same degree as queen extracts. Four newly identified queen pheromone components did not inhibit ovary development alone, nor did they increase the efficacy of the other components. Anarchistic bees are a line developed by recurrent selection in which workers commonly reproduce in queenright colonies. There was no difference between the ovary development of anarchistic or wild type workers in colonies headed by anarchistic or wild type queens, therefore queen type is not responsible for the phenomenon. Anarchistic workers perceive queen pheromones, and anarchistic queens produce an attractive blend, as I found no differences in the retinue response of either worker type to either queen type. There also was no difference in response to queen pheromones at a high dose. At lower doses, however, wild type workers were more inhibited by queen pheromones than were anarchistic workers. Both adult and larval diet influenced adult ovary development, but workers fed high quality diets as adults had higher levels of ovary development than those fed low quality diets as adults regardless of larval diet quality. Nutrition is likely responsible for the seasonal variation observed in ovary development. Disruptive selection resulted in lines of bees with high or low levels of ovary development. High ovary development colonies collected far more pollen than their low line counterparts. Cross-fostering workers from the high line into the low line and vice versa demonstrated that there is an effect of both genotype and rearing environment. These results demonstrate the complex interactions between nutrition, pheromones, genetics, and environment that determine worker reproductive potential.