Tiny but socially valuable: eggs as sources of communication in the social wasp Mischocyttarus cerberus

Chemical compounds play a major role in the recognition processes in social insects, and one class of compounds namely hydrocarbons cover the adult body, but also the surface of their eggs. The ability to discriminate between friends from foes minimizes the exploitation of resources. We investigated for the first time whether females of Mischocyttarus cerberus, which is often attacked by other wasp species, can discriminate their own eggs over the eggs of foes. By using a non-destructive technique, we experimentally collected eggs from post-worker emergent nests, and we offered their eggs to other nests to test the policing behavior in M. cerberus. Overall, our results show that the females of M. cerberus can discriminate eggs according to their origin, and most of the removed eggs were policed within the first hour of the experiment, revealing that females have accurate discrimination skills. The discrimination skill allows females to detect eggs. We discuss that chemical cues present over the surface of eggs may be important for them to be accepted or removed, and these cues may be important to avoid parasitism. In this case, eggs represent alternative tools of communication, once they carry chemical compounds linked to their nest. Additionally, dominant females (= queens) are the most likely individuals to remove the eggs. Altogether, our results reinforce that the nestmate recognition ability is not restricted to recognizing adult relatives, but it is also extended to recognizing brood in Mischocyttarus societies.Significance statementNestmate recognition is responsible to maintain social integrity in social insect colonies, as individuals can recognize friends from foes. We investigated whether nestmate recognition works on brood recognition in the primitively eusocial wasp Mischocyttarus cerberus. The nest of this species is deprived of an envelope and often can be attacked by parasitoids or other wasp species. By transplanting eggs from one colony to another using paper cells, we studied whether females would destroy introduced eggs more often. As a result, we found that M. cerberus females are capable to recognize introduced and their own eggs and remove introduced eggs more often. Hydrocarbons covering the egg surface are the likely chemical cues that allow such recognition to occur. These results suggest that nestmate recognition is not limited to perceiving adult nestmates, but also brood in this wasp species.

Automated summary

Chemical compounds, particularly hydrocarbons, play a crucial role in the recognition processes of social insects. In this study, we investigated the ability of females in the wasp species Mischocyttarus cerberus to discriminate between their own eggs and those of other species. By experimentally collecting eggs and offering them to different nests, we found that M. cerberus females can accurately discriminate eggs according to their origin. This discrimination skill is likely important for avoiding parasitism and maintaining the social integrity of the colony.