Recognition of conspecific immunological status in a neotropical paper wasp

Host immune activation is common under a pathogen invasion. This
physiological response can promote changes in body surface compounds, thus
providing chemical cues related to health that might be useful to
conspecifics. By recognizing the current immunological status of social
partners, individuals can modulate their behavior to minimize the risk of
infection. Tegument wounding, an immune elicitor, is a required step for
many parasites to become established in a host. By using the neotropical
eusocial paper wasp Mischocyttarus metathoracicus as a model organism, we
first performed a lure presentation experiment in the field to test if
wasps discriminate conspecific immunological status (experimentally
manipulated by wounding) during on-nest social interactions. Then, we
performed gas chromatography-mass spectrometry analyses to test if
immunostimulation by wounding alters the wasps’ cuticular hydrocarbon
profile. We found that wasps reduce the duration of aggressive physical
contact when interacting with wounded lures, despite displaying a similar
frequency of inspective and aggressive behaviors toward both the wounded
and the control lures. Besides, we found a subtle increase in a single
cuticular hydrocarbon in the wounded wasps. Thus, wasps recognize
conspecific immunological status, likely by chemical cues, and modulate
their behavior in order to defend the colony against intruders while
minimizing the personal risk of infection.