Facial markings in the social cuckoo wasp Polistes sulcifer: no support for the visual deception and the assessment hypothesis.

Insect social parasites have to conquer a host colony by overcoming its defensive barriers. In additionto increased fighting abilities, many social parasites evolved sophisticated sensory deception mecha-nisms to elude host colonies defenses by exploiting host communication channels. Recently, it has beenshown that the conspicuous facial markings of a paper wasp social parasite, Polistes sulcifer, decrease theaggressiveness of host foundresses. Two main hypotheses stand as explanations of this phenomenon:visual sensory deception (i.e. the black patterning reduces host aggression by exploiting the host visualcommunication system) and visual quality assessment (i.e. facial markings reduce aggressiveness as theysignal the increased fighting ability of parasites). Through behavioral assays and morphological measure-ments we tested three predictions resulting from these hypotheses and found no support either for thevisual sensory deception or for the quality assessment to explain the reduction in host aggressivenesstowards the parasite. Our results suggest that other discrimination processes may explain the observedphenomenon.