Different ranks, different strategies and constraints: analysis of anatomical and physiological traits supports work castration and social coercion in a paper wasp

摘要

Reproductive dominance may underlie several different mechanisms in various social insect species, from offspring destruction to the manipulation of workers in order to reduce their fertility. Alternatively, some individuals may renounce direct reproduction if this behaviour leads to a high indirect fitness payoff. In this paper, we re-analyse a large data set from a previous study and we found that the generalized renunciation of egg-laying by subordinate foundresses of Polistes dominulus does not follow a general rule. Low-ranked subordinate females and solitary dominant ones have reduced ovaries probably as a result of external task performance. Conversely, beta females from multiple colonies do not have dramatically reduced ovaries, probably as a result of less external work. The renunciation of egg-laying also shown by these females is probably due to the high efficiency of queen policing. Challenging for direct reproduction by beta females would generally result in an increased supply of food for alpha females and a further energetic cost for beta ones, which probably wait for the dominant females to weaken or disappear.