Frequency of Cry1F resistance alleles in Spodoptera frugiperda (Lepidoptera: Noctuidae) in Brazil

BACKGROUND The frequency of resistance alleles is a major factor influencing the rate of resistance evolution. Here, we adapted the F2 screen procedure for Spodoptera frugiperda (J. E. Smith) with a discriminating concentration assay, and extended associated statistical methods to estimate the frequ...

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Published in:Pest management science 2016-12, Vol.72 (12), p.2295-2302
Main Authors: Farias, Juliano R, Andow, David A, Horikoshi, Renato J, Bernardi, Daniel, Ribeiro, Rebeca da S, Nascimento, Antonio RB do, Santos, Antonio C dos, Omoto, Celso
Format: Article
Language:English
Subjects:
Animals
Bacillus thuringiensis
Bacterial Proteins - genetics
Brazil
Bt maize
Corn
Endotoxins - genetics
fall armyworm
Gene Frequency
Hemolysin Proteins - genetics
Insecticide Resistance - genetics
Insecticides
Lepidoptera
Noctuidae
Pest control
Plants, Genetically Modified - genetics
resistance management
Spodoptera - genetics
Spodoptera frugiperda
TC1507 maize
Zea mays
Zea mays - genetics
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Summary:BACKGROUND The frequency of resistance alleles is a major factor influencing the rate of resistance evolution. Here, we adapted the F2 screen procedure for Spodoptera frugiperda (J. E. Smith) with a discriminating concentration assay, and extended associated statistical methods to estimate the frequency of resistance to Cry1F protein in S. frugiperda in Brazil when resistance was not rare. RESULTS We show that F2 screen is efficient even when the resistance frequency is 0.250. It was possible to screen 517 isoparental lines from 12 populations sampled in five states of Brazil during the first half of 2012. Western Bahia had the highest allele frequency of Cry1F resistance, 0.192, with a 95% confidence interval (CI) between 0.163 and 0.220. All other states had a similar and lower frequency varying from 0.042 in Paraná to 0.080 in Mato Grosso do Sul. CONCLUSION The high frequency in western Bahia may be related to year‐round availability of maize, the high population density of S. frugiperda, the lack of refuges and the high adoption rate of Cry1F maize. Cry1F resistance alleles were not rare and occurred at frequencies that have already compromised the useful life of TC1507 maize in western Bahia. © 2016 Society of Chemical Industry
ISSN:1526-498X
1526-4998
DOI:10.1002/ps.4274