title: Identification of a widespread monomolecular odor differentially attractive to several Delia radicum ground-dwelling predators in the field.
abstract: Dimethyl disulfide (DMDS) was identified as a major volatile constituent of Brassica napus roots heavily infested by Delia radicum, the cabbage root fly. Attractiveness of this widespread compound was tested in the field in a naturally complex odorous environment. By using an original setup especially designed for ground dwelling beetles, different concentrations of the pure molecule as well as attractiveness of the natural blend emitted by the rotten part of infested roots were tested simultaneously. The use of general linear model (GLM) statistics permitted us to finely discriminate the responses among the different treatments. The main predators of D. radicum (i.e., two staphylinids Aleochara bilineata and Aleochara bipustulata and carabid beetles of the genus Bembidion) were significantly attracted by DMDS, but responded in different ways to the natural blend and to the different concentrations tested. The dose-response curves were similar for the two staphylinids. However, whereas A. bilineata was more attracted by the natural volatile blend than by its preferred DMDS concentration, A. bipustulata was attracted as much by the natural blend as by its preferred DMDS concentration. Carabid beetles exhibited a different response. They were not attracted by the natural blend, but responded to a wider range of DMDS concentrations that included low concentrations that did not attract the staphylinid beetles. These results are discussed according to the potential resources searched by each taxon studied and their specificity for the resources. The possible use of DMDS for enhancing biological control of D. radicum is mentioned.
authors.affiliation: Laboratoire d'Ecobiologie des Insectes Parasitoïdes, EA3193, Université de Rennes 1, Rennes, France. antoninferry@hotmail.fr
authors.forename: Antonin
authors.initials: A
authors.lastname: Ferry
authors.forename: Sebastien
authors.initials: S
authors.lastname: Dugravot
authors.forename: Thomas
authors.initials: T
authors.lastname: Delattre
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Christides
authors.forename: Jacques
authors.initials: J
authors.lastname: Auger
authors.forename: Anne-Geneviève
authors.initials: AG
authors.lastname: Bagnères
authors.forename: Denis
authors.initials: D
authors.lastname: Poinsot
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Cortesero
mesh_terms: D000818:Animals; D029688:Brassica napus / Q000378:metabolism*; D001517:Coleoptera / Q000502:physiology*; D004175:Diptera / Q000502:physiology*; D005260:Female; D008297:Male; D009812:Odorants; D011235:Predatory Behavior / Q000502:physiology*; D012744:Sex Ratio; D013440:Sulfides / Q000378:metabolism / Q000494:pharmacology*; D013997:Time Factors
chemical_list: D013440:Sulfides; C004784:dimethyl sulfide