Evidence for sex pheromones and inbreeding avoidance in select North American yellowjacket species

Abstract

Abstract Little is known about the roles of sex pheromones in mate‐finding behavior of social wasps ( V espidae). Working with the aerial yellowjacket, D olichovespula arenaria ( F abricius), baldfaced hornet, D olichovespula maculata (L.), western yellowjacket, V espula pensylvanica ( S aussure), southern yellowjacket, V espula squamosa ( D rury), and V espula alascensis P ackard, we tested the hypotheses (1) that gynes produce an airborne sex pheromone attractive to males, and (2) that males are more strongly attracted to non‐sibling gynes based on olfactory cues. A field experiment provided the first definitive evidence that D . arenaria gynes attract males. Surprisingly, we did not find such evidence in similar field experiments for sexual attractiveness of gynes of V . squamosa , V . pensylvanica , V . alascensis , or D . maculata . In Y‐tube olfactometer experiments with three of these species ( D . arenaria , D . maculata , V . pensylvanica ), only D . maculata gynes attracted males, provided they were non‐siblings, implying an olfactory‐based mechanism of nestmate recognition and inbreeding avoidance. Lack of sex attraction responses for V . pensylvanica , V . alascensis , and V . squamosa in this study does not rule out pheromone‐mediated sexual communication. Instead, it highlights the possibility that pheromonal signaling may be dependent on the presence of appropriate contextual cues.