title: Organophosphate Resistance and its Main Mechanism in Populations of Codling Moth (Lepidoptera: Tortricidae) from Central Chile.
abstract: The codling moth, Cydia pomonella (L.), is the key pest of apple production worldwide. Insecticide resistance has been reported in all producing countries, based on five different mechanisms. Codling moth in Chile has resistance to azinphos-methyl and tebufenozide in post-diapausing larvae. However, there are no studies about the susceptibility of these populations to insecticides from other chemical groups. Therefore, the efficacy of azinphos-methyl, chlorpyrifos-ethyl, esfenvalerate, methoxyfenozide, tebufenozide, and thiacloprid on neonate and post-diapausing larvae from six field populations was investigated, and identified resistance mechanisms in this species were evaluated. Neonate larvae were susceptible to all insecticides studied, but post-diapausing larvae from four populations were resistant to chlorpyrifos, one of them was also resistant to azinphos-methyl, and another one was resistant to tebufenozide. The acetylcholinesterase insensitivity mutation was not detected, and the sodium channel knockdown resistance mutation was present in a low frequency in one population. Detoxifying enzymatic activity of glutathione S-transferases, esterases, and cytochrome P-450 monooxygenases in adults differed among populations, but chlorpyrifos resistance was associated only with a decreased esterase activity as shown by a significant negative correlation between chlorpyrifos mortality and esterase activity.
authors.affiliation: Instituto de Producción y Sanidad Vegetal, Facultad de Ciencias Agrarias, Universidad Austral de Chile, Casilla 567, Valdivia, Chile.
authors.forename: Maritza
authors.initials: M
authors.lastname: Reyes
authors.affiliation: Departamento de Producción Agrícola, Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747, Talca, Chile. Millennium Nucleus in Molecular Ecology and Evolutionary Applications of Agroecosystems, Casilla 747, Talca, Chile.
authors.forename: Wilson
authors.initials: W
authors.lastname: Barros-Parada
authors.affiliation: Millennium Nucleus in Molecular Ecology and Evolutionary Applications of Agroecosystems, Casilla 747, Talca, Chile. Instituto de Ciencias Biológicas, Universidad de Talca, Casilla 747, Talca, Chile.
authors.forename: Claudio C
authors.initials: CC
authors.lastname: Ramírez
authors.affiliation: Departamento de Producción Agrícola, Facultad de Ciencias Agrarias, Universidad de Talca, Casilla 747, Talca, Chile. Millennium Nucleus in Molecular Ecology and Evolutionary Applications of Agroecosystems, Casilla 747, Talca, Chile. efuentes@utalca.cl.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Fuentes-Contreras
mesh_terms: D000818:Animals; D005260:Female; D007305:Insecticide Resistance / Q000502:physiology*; D008297:Male; D009036:Moths / Q000201:enzymology* / Q000235:genetics; D010755:Organophosphates
chemical_list: D010755:Organophosphates
keywords: azinphos-methyl; chlorpyrifos; esterase; resistance; tebufenozide