An almost defining feature of the social hymenoptera (wasps, bees, and ants) is the absence of male workers; typically, females perform all of the tasks associated with care of the nest and larvae. Theoretical explanations centered on the genetic asymmetry of males and females (the males being haploid and the females diploid) have been discussed for decades, though experimental studies of this question have been few.
Sen and Gadagkar investigated whether males of the Indian wasp Ropalidia marginata would feed larvae, by manipulating the presence of females and the amount of food nearby. When food supplements were available and when females were missing, males were able to provision larvae at a frequency similar to that observed for females. It appears that under normal circumstances, males do not have enough access to food or are prevented from feeding larvae by females. Thus, the capacity to feed larvae is common to both sexes, and the mechanism preventing males from doing so may be behavioral rather than genetic or developmental. -- AMS
Anim. Behav. 71, 345 (2006).
