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Identifier 000397349
Title Adaptation of arthropod pests in plant allelochemicals and pesticides, with emphasis on the role of detoxification
Alternative Title Μελέτη προσαρμογής των αρθροπόδων στις τοξίνες των φυτών (plant allelochemicals) και τα εντομοκτόνα, με έμφαση στον ρόλο των μηχανισμών αποτοξικοποίησης
Author Παυλίδη, Νένα
Thesis advisor Βόντας, Ιωάννης
Καλαντίδης, Κρίτων
Reviewer Λάμπρου, Νικόλαος
Μπουριώτης, Βασίλειος
Van Leeuwen, Thomas
Siden-Kiamos, Inga
Τσαγκαράκου, Αναστασία
Abstract Arthropod pests seriously threaten food security and human health, as they attack agricultural crops and transmit various diseases. Their control has been largely based on chemical insecticides. However the intense use of insecticides has led in the development of resistance, mainly achieved by target site resistance mutations and detoxification, enzymes, such as the Cytochrome P450s, the Glutathione S-transferases GSTs and the Carboxylesterases (CCEs). The same detoxification enzymes also participate in the adaptation of arthropod pests to their hosts, as they also metabolize – inactivate phytotoxins. In this thesis, I used transgenic approaches, bioassays, transcriptomics and biochemical/ functional techniques to investigate detoxification mechanisms of major arthropod pests, such as the Aedes aegypti, the Bactrocera oleae and the Tetranychus urticae, against xenobiotics. First, the A. aegypti cytochrome P450 CYP9J28 was successfully expressed in Drosophila melanogaster and shown to confer significant levels of resistance in vivo, providing solid evidence for its role in pyrethroid resistance and showing that ectopic expression in D. melanogaster may be a robust approach for validation of candidate resistance genes. Second, a large transcriptomic dataset of B. oleae was generated and more than 130 putative detoxification genes were identified and phylogenetically classified. The transcriptome was used for the construction of a microarray tool, which was used, in its pilot application, to study detoxification and adaptation mechanisms of the olive fly against insecticides and olive flesh/phytotoxins, respectively. The pyrethroid resistance study indicated the association of two cytochrome P450 genes with the phenotype. Several detoxification and digestive genes were found over-expressed upon development in olives (green versus black versus artificial diet), providing a useful starting point for further investigation. In the last chapter, my study dealt and focused on T. urticae GSTs that had been associated with insecticide resistance by microarray studies. Four GSTs were functionally expressed and characterized. TuGSTd14 was found to interact with abamectin, supporting earlier work that GSTs are may play a role in abamectin resistance. Strong evidence were provided that TuGSTd05 catalyzes the conjugation of glutathione (GSH) to cyflumetofen in vitro and the possible site of attack as well as key amino acids possibly implicated in the interaction were identified. This study represents the first functional convincing report for the implication of an acari GST in resistance.
Language English
Subject Adaptation
Issue date 2015-11-26
Collection   Faculty/Department--Faculty of Sciences and Engineering--Department of Biology--Doctoral theses
  Type of Work--Doctoral theses
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