Selection for reproductive workers in the Cape honeybee population, Apis mellifera capensis, leads to social parasitism in bee colonies from the savanna

摘要

Colonies of Apis mellifera scutellata in the northern half of South Africa suffer from social parasitism by an A. m. capensis pseudo-clone. Inside scutellata colonies, these capensis workers increase their numbers by reproducing thelytokously. Infected colonies dwindle because normal worker tasks are neglected and eventually they die. We show that larvae of the pseudo-clone get more food in scutellata colonies than scutellata larvae do. Normal capensis larvae also get more food in scutellata coloniesbut not as much as larvae of the pseudo-clone. Earlier we found that more food results in more queen-like bees. Moreover, pseudo-clones are on average more queen-like than normal capensis bees when both are raised in a scutellata colony. This confirms the link between food and queen-like bees, because pseudo-clone larvae get most food of all. We present a new theory, postulating that capensis workers are selected to contribute to the next generation of queens by laying in queen cups prior to swarming.Such reproductive bees probably manage to get more food as larvae. At the same time nurse bees are selected to adjust the amount of food given, to maintain clear caste differences between workers and queens for optimizing colony performance. Therefore, selection for reproductive workers inside the capensis population may have changed the communication between nurse bees and larvae on allocation of food. This changed communication results in capensis pseudo-clones being overfed in scutellata colonies.