Zusammenfassung
A recent study showed that a wingless parasitoid, Gelis agilis, exhibits a suite of ant-like traits that repels attack from wolf
spiders. When agitated, G. agilis secreted 6-methyl-5-hepten-2-one (sulcatone), which a small number of ant species
produce as an alarm/panic pheromone. Here, we tested four Gelis parasitoid species, occurring in the same food chain
and microhabitats, for the presence of sulcatone and conducted two-species choice bioassays with wolf spiders to determine
their degree of susceptibility to attack. All four Gelis species, including both winged and wingless species, produced
sulcatone, whereas a closely related species, Acrolyta nens, and the more distantly related Cotesia glomerata, did not. In
two-choice bioassays, spiders overwhelmingly rejected the wingless Gelis species, preferring A. nens and C. glomerata.
However, spiders exhibited no preference for either A. nens or G. areator, both of which are winged. Wingless gelines
exhibited several ant-like traits, perhaps accounting for the reluctance of spiders to attack them. On the other hand, despite
producing sulcatone, the winged G. areator more closely resembles other winged cryptines like A. nens, making it harder
for spiders to distinguish between these two species. C. glomerata was also preferred by spiders over A. nens, suggesting
that other non-sulcatone producing cryptines nevertheless possess traits that make them less attractive as prey.
Phylogenetic reconstruction of the Cryptinae reveals that G. hortensis and G. proximus are ‘sister’species, with G. agilis,
and G.areator in particular evolving along more distant trajectories. We discuss the possibility that wingless Gelis species
have evolved a suite of ant-like traits as a form, of mimicry to repel predators on the ground.
