Mutation (G275E) of the nicotinic acetylcholine receptor alpha 6 subunit is associated with high levels of resistance to spinosyns in Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)

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Silva, W. M., Berger, M., Bass, C., Williamson, M. S., Moura, D. M. N., Ribeiro, L. M. S. and Siqueira, H. A. A. 2016. Mutation (G275E) of the nicotinic acetylcholine receptor alpha 6 subunit is associated with high levels of resistance to spinosyns in Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). Pesticide Biochemistry and Physiology. 131 (July), pp. 1-8. https://doi.org/10.1016/j.pestbp.2016.02.006

AuthorsSilva, W. M., Berger, M., Bass, C., Williamson, M. S., Moura, D. M. N., Ribeiro, L. M. S. and Siqueira, H. A. A.
Abstract

The tomato leafminer, Tuta absoluta, now a major pest of tomato crops worldwide, is primarily controlled using chemical insecticides. Recently, high levels of resistance to the insecticide spinosad have been described in T. absoluta populations in Brazil. Selection of a resistant field-collected strain led to very high levels of resistance to spinosad and cross-resistance to spinetoram, but not to other insecticides that target the nicotinic acetylcholine receptor (nAChR). In this study the mechanisms underlying resistance to spinosad were investigated using toxicological, biochemical and molecular approaches. Inhibition of metabolic enzymes using synergists and biochemical assessment of detoxification enzyme activity provided little evidence of metabolic resistance in the selected strain. Cloning and sequencing of the nAChR α6 subunit from T. absoluta, the spinosad target-site, from susceptible and spinosad-resistant strains were done to investigate the role of a target-site mechanism in resistance. A single nucleotide change was identified in exon 9 of the α6 subunit of the resistant strain, resulting in the replacement of the glycine (G) residue at position 275 observed in susceptible T. absoluta strains with a glutamic acid (E). A high-throughput DNA-based diagnostic assay was developed and used to assess the prevalence of the G275E mutation in 17 field populations collected from different geographical regions of Brazil. The resistant allele was found at low frequency, and in the heterozygous form, in seven of these populations but at much higher frequency and in the homozygous form in a population collected in the Iraquara municipality. The frequency of the mutation was significantly correlated with the mortality of these populations in discriminating dose bioassays. In summary our results provide evidence that the G275E mutation is an important mechanism of resistance to spinosyns in T. absoluta, and may be used as a marker for resistance monitoring in field populations.

Year of Publication2016
JournalPesticide Biochemistry and Physiology
Journal citation131 (July), pp. 1-8
Digital Object Identifier (DOI)https://doi.org/10.1016/j.pestbp.2016.02.006
Open accessPublished as green open access
FunderBiotechnology and Biological Sciences Research Council
Marie Sklodowska-Curie Actions
European Union
Funder project or codeSustainability
A genomic approach to understanding insecticide resistance in crop pests
Understanding pesticide resistance and developing sustainable crop protection strategies
Publisher's version
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Safeguarded
Accepted author manuscript
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CC BY
File Access Level
Open
Output statusPublished
Publication dates
Online22 Feb 2016
Publication process dates
Accepted17 Feb 2016
PublisherElsevier
ISSN0048-3575

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