title: Volatile compounds in the larval frass ofDendroctonus valens andDendroctonus micans (Coleoptera: Scolytidae) in relation to oviposition by the predator,Rhizophagus grandis (Coleoptera: Rhizophagidae).
abstract: During a laboratory study evaluatingRhizophagus grandis (a specific native predator of the Eurasian bark beetle,Dendroctonus micans), as a potential biocontrol agent against the North American bark beetle,Dendroctonus valens, it was found that feeding larvae and laboratory-produced frass of the potential prey elicited very high oviposition responses in the predator. Comparative chemical analysis of this laboratory-produced larval frass revealed that one major volatile compound, (-)-fenchone, is associated with the larvae of bothDendroctonus species.D. micans also generated pinocamphone while oxygenated monoterpenes in the frass ofD. valens were camphor,cis-4-thujanol, fenchol, terpinen-4-ol, myrtenal, pinocarvone, borneol, verbenone, piperitone, campholenaldehyde,trans-myrtanol,cis-myrtanol,p-cymen-8-ol and 5-oxo-camphor. This range of prey-produced compounds with a possible biological effect onR. grandis was narrowed down subsequent to comparative analysis of field-collected larval frass. (-)-Fenchone, pinocamphone, camphor, terpinen-4-ol, borneol, fenchol, and verbenone were found to be common to both prey species. A mixture of these seven components was tested in a bioassay, where it elicited as much oviposition as did larval frass ofD. micans. The oviposition stimulants forR. grandis are thus clearly among the mixture's constituents.
authors.affiliation: Laboratoire de Biologie animale et cellulaire CP 160, Université Libre de Bruxelles, 50 av. F.D. Roosevelt, B-1050, Bruxelles, Belgium.
authors.forename: J C
authors.initials: JC
authors.lastname: Grégoire
authors.forename: M
authors.initials: M
authors.lastname: Baisier
authors.forename: A
authors.initials: A
authors.lastname: Drumont
authors.forename: D L
authors.initials: DL
authors.lastname: Dahlsten
authors.forename: H
authors.initials: H
authors.lastname: Meyer
authors.forename: W
authors.initials: W
authors.lastname: Francke