title: Volatile emission by contest losers revealed by real-time chemical analysis.
abstract: Animal interactions often involve chemical exchange but simultaneous evaluation of chemistry and behaviour has been problematical. Here we report findings from a novel method, atmospheric pressure chemical ionization-mass spectrometry (APCI-MS) coupled with manipulation of molecular-mass achieved by rearing organisms on deuterium-enhanced nutrients. This allows real-time monitoring of the occurrence and quantity of volatile chemicals released by each of two interacting individuals, in tandem with behavioural observations. We apply these methods to female-female contests in the parasitoid wasp Goniozus legneri. We show that this species emits the spiroacetal 2-methyl-1,7-dioxaspiro[5.5]undecane. Chemical release is most common in more behaviourally aggressive contests, which occur when prior resource owners successfully resist take-over by similar-sized intruder females. Volatiles released during contests are always emitted by the loser. Aggression in contests is reduced after spiroacetal release. We suggest that the spiroacetal functions as a weapon of rearguard action. We anticipate that APCI-MS, which is rapid, non-intrusive and relatively inexpensive to operate, will be widely applied in studies linking chemistry and behaviour.
authors.affiliation: School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leicestershire LE12 5RD, UK.
authors.forename: Marlène
authors.initials: M
authors.lastname: Goubault
authors.forename: Tim P
authors.initials: TP
authors.lastname: Batchelor
authors.forename: Robert S T
authors.initials: RS
authors.lastname: Linforth
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Taylor
authors.forename: Ian C W
authors.initials: IC
authors.lastname: Hardy
mesh_terms: D000374:Aggression; D000818:Animals; D001522:Behavior, Animal; D003163:Competitive Behavior; D003903:Deuterium / Q000032:analysis; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D013997:Time Factors; D014863:Wasps / Q000378:metabolism / Q000502:physiology*
chemical_list: D003903:Deuterium