title: Ecdysteroid receptor docking suggests that dibenzoylhydrazine-based insecticides are devoid of any deleterious effect on the parasitic wasp Psyttalia concolor (Hym. Braconidae).
abstract: BACKGROUND
  The moulting accelerating compounds (MACs) or ecdysteroid agonists represent a selective group of insecticides acting upon binding to the ecdysteroid receptor (EcR) and leading to lethal premature moulting in larval stages and aborted reproduction in adults. Psyttalia concolor Szèpl. is a useful parasitic wasp attacking important tephritid pests such as the medfly and olive fruit fly.
  
  
  RESULTS
  Contact and oral exposure in the laboratory of female parasitic wasps to the dibenzoylhydrazine-based methoxyfenozide, tebufenozide and RH-5849 did not provoke negative effects. No mortality and no reduction in beneficial capacity were observed. The ligand-binding domain (LBD) of the EcR of P. concolor was sequenced, and a homology protein model was constructed which confirmed a cavity structure with 12 α-helices, harbouring the natural insect moulting hormone 20-hydroxyecdysone. However, a steric clash occurred for the MAC insecticides owing to a restricted extent of the ligand-binding cavity of the PcLBD-EcR, while they did dock well in that of susceptible insects.
  
  
  CONCLUSIONS
  The insect toxicity assays demonstrated that MACs are selective for P. concolor. The modelling/docking experiments are indications that these insecticides do not bind with the LBD-EcR of P. concolor and support the theory that they show no biological effects in the parasitic wasp. These data may help in explaining the compatible use of MACs together with parasitic wasps in IPM programmes.
authors.affiliation: Unidad de Protección de Cultivos, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain.
authors.forename: Paloma
authors.initials: P
authors.lastname: Bengochea
authors.forename: Olivier
authors.initials: O
authors.lastname: Christiaens
authors.forename: Fermín
authors.initials: F
authors.lastname: Amor
authors.forename: Elisa
authors.initials: E
authors.lastname: Viñuela
authors.forename: Pierre
authors.initials: P
authors.lastname: Rougé
authors.forename: Pilar
authors.initials: P
authors.lastname: Medina
authors.forename: Guy
authors.initials: G
authors.lastname: Smagghe
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D026461:Ecdysteroids / Q000819:agonists; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006834:Hydrazines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D019476:Insect Proteins / Q000737:chemistry* / Q000378:metabolism*; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018978:Molting / Q000187:drug effects; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011987:Receptors, Steroid / Q000737:chemistry* / Q000378:metabolism*; D014863:Wasps / Q000378:metabolism* / Q000502:physiology
chemical_list: D026461:Ecdysteroids; D006834:Hydrazines; D019476:Insect Proteins; D007306:Insecticides; D008024:Ligands; D011987:Receptors, Steroid; C414807:dibenzohydrazine; C034808:ecdysteroid receptor