Charles Grant1, Rob Jacobson2, Aris Ilias3, Madeleine Berger4, Emmanouil Vasakis5, Pablo Bielza6, Christoph T Zimmer1, Martin S Williamson4, Richard H Ffrench-Constant1, John Vontas3,7, Emmanouil Roditakis5, Chris Bass1. 1. College of Life and Environmental Sciences, Biosciences, University of Exeter, Penryn Campus, Penryn, UK. 2. RJC Ltd, Bramham, UK. 3. Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Crete, Greece. 4. Department of Biointeractions and Crop Protection, Rothamsted Research, Harpenden, UK. 5. Hellenic Agricultural Organisation - 'Demeter', Institute of Olive Tree, Subtropical Crops and Viticulture, Heraklion, Greece. 6. Departamento de Producción Vegetal, Universidad Politécnica de Cartagena, Cartagena, Spain. 7. Department of Crop Science, Agricultural University of Athens, Athens, Greece.
Abstract
BACKGROUND: The tomato leafminer, Tuta absoluta, is an economically important pest of tomatoes in Europe, Africa, Asia and South America. In the UK this species is controlled using an integrated pest management (IPM) programme which incorporates the insecticides spinosad and chlorantraniliprole. In response to UK grower concerns of loss of efficacy of these compounds at certain sites, insecticide bioassays were performed on five populations collected from four commercial glasshouses and potential mechanisms of resistance investigated. RESULTS: We observed high levels of resistance to spinosad in four of the strains, and in two of these tolerance to chlorantraniliprole. Selection of one of these strains with chlorantraniliprole rapidly resulted in a line exhibiting potent resistance to this compound. Sequencing of messenger RNA encoding the nicotinic acetylcholine receptor (nAChR) α6 subunit, target of spinosad, revealed Taα6 transcripts in the spinosad-resistant strains that lack exon 4 and encode a highly truncated protein, or contain a triplet deletion in the predicted first transmembrane domain resulting in the loss of a highly conserved amino acid. Sequencing of the ryanodine receptor gene, encoding the target of diamide insecticides, of the chlorantraniliprole-selected line revealed an amino acid substitution (G4903V) that has been previously linked to diamide resistance in populations of T. absoluta in the Mediterranean and South America. CONCLUSION: Taken together our results reveal emerging resistance in UK populations of T. absoluta to two of the most important insecticides used as part of IPM, with significant implications for the control of this species in the UK.
BACKGROUND: The tomato leafminer, Tuta absoluta, is an economically important pest of tomatoes in Europe, Africa, Asia and South America. In the UK this species is controlled using an integrated pest management (IPM) programme which incorporates the insecticides spinosad and chlorantraniliprole. In response to UK grower concerns of loss of efficacy of these compounds at certain sites, insecticide bioassays were performed on five populations collected from four commercial glasshouses and potential mechanisms of resistance investigated. RESULTS: We observed high levels of resistance to spinosad in four of the strains, and in two of these tolerance to chlorantraniliprole. Selection of one of these strains with chlorantraniliprole rapidly resulted in a line exhibiting potent resistance to this compound. Sequencing of messenger RNA encoding the nicotinic acetylcholine receptor (nAChR) α6 subunit, target of spinosad, revealed Taα6 transcripts in the spinosad-resistant strains that lack exon 4 and encode a highly truncated protein, or contain a triplet deletion in the predicted first transmembrane domain resulting in the loss of a highly conserved amino acid. Sequencing of the ryanodine receptor gene, encoding the target of diamide insecticides, of the chlorantraniliprole-selected line revealed an amino acid substitution (G4903V) that has been previously linked to diamide resistance in populations of T. absoluta in the Mediterranean and South America. CONCLUSION: Taken together our results reveal emerging resistance in UK populations of T. absoluta to two of the most important insecticides used as part of IPM, with significant implications for the control of this species in the UK.
Authors: Juliana Dantas; Isabela O Motta; Leonardo A Vidal; Eliza F M B Nascimento; João Bilio; Júlia M Pupe; Adriano Veiga; Carlos Carvalho; Rogerio B Lopes; Thales L Rocha; Luciano P Silva; José R Pujol-Luz; Érika V S Albuquerque Journal: Insects Date: 2021-12-17 Impact factor: 2.769