Nutritional factors affecting the egg sex ratio adjustment by a honeybee queen

To determine whether and how honeybee (Apis mellifera L.) queens control the proportion of male reproductives, experiments were done with colonies under two nutritional conditions at two seasons. During the reproductive season the proportion of male eggs laid by queens under insufficiently-food-supplied conditions was lower than that under sufficiently-food-supplied conditions. The smaller proportion of male egg production could not be accounted for by cannibalization of male eggs by workers. The workers' allocation to male cell construction did not differ between sufficiently- and insufficiently-food-supplied conditions. During the non-reproductive season, however, queens showed much reduced or nearly no production of male eggs, even if the colonies were sufficiently supplied with food. These results suggest that the honeybee queen adjusts the egg sex ratio by referring to both the nutritional resources and their own intrinsic seasonal factors.