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

Abstract

Little is known about the roles of sex pheromones in mate‐finding behavior of social wasps (Vespidae). Working with the aerial yellowjacket, Dolichovespula arenaria (Fabricius), baldfaced hornet, Dolichovespula maculata (L.), western yellowjacket, Vespula pensylvanica (Saussure), southern yellowjacket, Vespula squamosa (Drury), and Vespula alascensisPackard, 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.

Drone aggregation behavior in the social wasp Vespula germanica (Hymenoptera: Vespidae): Effect of kinship and density

“…Our results also indicate that kin recognition in V. germanica is based on chemical cues, since experimental subjects had no access to visual information from drones in the olfactometer chambers. The recognition of castes or relatives through cuticular lipids has been reported previously in insects 27,31 . Such recognition is based on chemical cues composed of a combination of colony-specific hydrocarbons present on both insect cuticles and nest surfaces 32,33 .…”

“…Previous studies describing the mating behavior of social wasps have focused mainly on females, and suggest that mating occurs outside nests, mediated by a sexual pheromone produced by females, with mating occurring with one to several drones at random 8,[25][26][27] . Additionally, field observations report loose aggregations of up to several hundreds of males around trees and shrubs 28,29 .…”

Maculatic Acids—Sex Attractant Pheromone Components of Bald‐Faced Hornets

“…Gynes-at close range-attract non-sibling males with ah eretofore unknown sex attractant pheromone. [12] Indeed, to date,n ot as ingle sex attractant pheromone of yellowjackets has been identified. [13][14][15][16] Here,w ed escribe the isolation, structural elucidation, syntheses,a nd behavioural testing of the first sex attractant pheromone components in yellowjackets.…”

“…[12] We ran laboratory instead of field experiments because caged gynes as at rap bait did not exhibit long-range attractiveness to males in af ield setting. [12] Fore ach experimental replicate (see the Supporting Information for details), we placed ap iece of filter paper near the opening of as ide arm and treated it by random assignment either with ab lend of synthetic candidate pheromone components dissolved in CH 2 Cl 2 or the equivalent volume of CH 2 Cl 2 .Wethen released asingle male into the stem of the olfactometer and scored him as ar esponder if he approached the treatment or control stimulus to within at least 3cm. To proceed most efficiently, we opted to test first those maculatic acids (A and C) that elicited the strongest responses from male antennae ( Figure 1, ii, iii).…”

“…Despite mounting evidence that gynes of yellowjackets (Vespula spp.and Dolichovespula spp.) produce sex attractant pheromones, [12] to date none had been identified. [13][14][15][16] However,w orking on ae usocial taxon related to yellowjackets, Wene tal.…”