Selectivity of diacylhydrazine insecticides to the predatory bug Orius laevigatus: in vivo and modelling/docking experiments

Authors

  • Fermín Amor,

    1. Unidad de Protección de Cultivos, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Olivier Christiaens,

    1. Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
    Search for more papers by this author
    • These authors contributed equally to this work.

  • Paloma Bengochea,

    1. Unidad de Protección de Cultivos, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
    Search for more papers by this author
  • Pilar Medina,

    1. Unidad de Protección de Cultivos, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
    Search for more papers by this author
  • Pierre Rougé,

    1. UMR UPS-IRD 152 Pharma Dev, Université Paul Sabatier, Faculté de Pharmacie, Toulouse, France
    Search for more papers by this author
  • Elisa Viñuela,

    1. Unidad de Protección de Cultivos, Escuela Técnica Superior de Ingenieros Agrónomos, Universidad Politécnica de Madrid, Madrid, Spain
    Search for more papers by this author
  • Guy Smagghe

    Corresponding author
    1. Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
    • Laboratory of Agrozoology, Department of Crop Protection, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
    Search for more papers by this author

Abstract

BACKGROUND: Knowledge of pesticide selectivity to natural enemies is necessary for a successful implementation of biological and chemical control methods in integrated pest management (IPM) programmes. Diacylhydrazine (DAH)-based ecdysone agonists, also known as moulting-accelerating compounds (MACs), are considered to be a selective group of insecticides, and their compatibility with predatory Heteroptera, which are used as biological control agents, is known. However, their molecular mode of action has not been explored in beneficial insects such as Orius laevigatus (Fieber) (Hemiptera: Anthocoridae).

RESULTS: In this project, in vivo toxicity assays demonstrated that the DAH-based RH-5849, tebufenozide and methoxyfenozide have no toxic effect against O. laevigatus. The ligand-binding domain (LBD) of the ecdysone receptor (EcR) of O. laevigatus was sequenced, and a homology protein model was constructed that confirmed a cavity structure with 12 α-helices, harbouring the natural insect moulting hormone 20-hydroxyecdysone. However, docking studies showed that a steric clash occurred for the DAH-based insecticides owing to a restricted extent of the ligand-binding cavity of the EcR of O. laevigatus.

CONCLUSIONS: The insect toxicity assays demonstrated that MACs are selective for O. laevigatus. The modelling/docking experiments are indications that these pesticides do not bind with the LBD-EcR of O. laevigatus and support the supposition that they show no biological effects in the predatory bug. These data help in explaining the compatible use of MACs together with predatory bugs in IPM programmes. Copyright © 2012 Society of Chemical Industry

Ancillary