Queen Sex Pheromone of the Slave-making Ant, Polyergus breviceps

Abstract

Workers of the slave-making ant, Polyergus breviceps, raid nests of Formica ants and return with Formica pupae that mature into worker ants in the slave-makers' colony. These Formica workers then tend the Polyergus brood, workers, and reproductives. During raids in the mating season, winged virgin Polyergus queens accompany the workers in the raiding columns. During the raid, the virgin queens release a pheromone that attracts males that quickly mate with the queens. We report the identification, synthesis, and bioassay of the sex attractant pheromone of the queens as an approximately 1:6 ratio of (R)-3-ethyl-4-methylpentan-1-ol and methyl 6-methylsalicylate. The ants produce exclusively the (R)-enantiomer of the alcohol, and the (S)-enantiomer has no biological activity, neither inhibiting nor increasing attraction to blends of methyl 6-methylsalicylate with the (R)-enantiomer.

Chemical communication in mating behaviour of the slave-making ant Polyergus rufescens (Hymenoptera, Formicidae): 3-ethyl-4-methylpentanol as a critical component of the queen sex pheromone

“…In this species, virgin queens attract males with sex pheromones, and the mandibular gland has been shown to be the source of these signals . Similar results have been demonstrated for the American species P. breviceps (Topoff and Greenberg, 1988), and the role of methyl 6-methylsalicylate as a component of the female sex pheromone has been demonstrated in both species (Greenberg et al, 2004(Greenberg et al, , 2007Castracani et al, 2005). In particular, P. breviceps males are strongly attracted by a highly synergistic, 7 : 1 blend of methyl 6-methylsalicylate with 3-ethyl-4-methylpentanol (Greenberg et al, 2004).…”

“…Four of these (nonanal, tetradecanoic acid, hexadecanoic acid, and oleic acid) were common lipid components and seemed unlikely to be involved in chemical communication. Five of the remaining chemicals were deemed to be possible components of the P. rufescens sex pheromone, and among them 3-ethyl-4-methylpentanol seemed to be the most probable because it was the most abundant of the five, and its biological role had been demonstrated in the congeneric American species P. breviceps (Greenberg et al, 2004(Greenberg et al, , 2007. Thus, comparisons between binary blends of methyl 6-methylsalicylate/3-ethyl-4-methylpentanol and the full reconstructed blend were tested in a series of field bioassays.…”

“…In particular, P. breviceps males are strongly attracted by a highly synergistic, 7 : 1 blend of methyl 6-methylsalicylate with 3-ethyl-4-methylpentanol (Greenberg et al, 2004). More recent studies showed that P. breviceps queens produce exclusively the (R)-enantiomer of the alcohol, and only this enantiomer was attractive to male ants; the (S)-enantiomer neither increased nor antagonized responses to blends containing the (R)-enantiomer (Greenberg et al, 2007).…”

“…The two enantiomers were synthesized as previously described (Greenberg et al, 2007). Seven treatments (replicated 11 times) were tested: salicylate:alcohol 9 : 0.5(R), 9 : 0.5(S), 9 : 0.4(R) : 0.1(S), 50 : 0.5(R), 50 : 0.5(S), 50 : 0.4(R) : 0.1(S), and solvent control (a blend of hexane and dichloromethane).…”

Seed odor mediates an obligate ant–plant mutualism in Amazonian rainforests

“…Also outstanding for its unusual pattern of occurrence in nature, this compound has never been reported from plants other than AG seeds. It is, however, a common metabolite of fungi and insects, particularly as a semiochemical of ants (21)(22)(23)(24). It is a trail pheromone in two myrmicine species, elicits alarm or stinging behavior in two ponerine species, and is a component of queen sex pheromone in the formicine Polyergus rufescens.…”