TY - JOUR
T1 - Frequency of Cry1F resistance alleles in Spodoptera frugiperda (Lepidoptera
T2 - Noctuidae) in Brazil
AU - Farias, Juliano R.
AU - Andow, David A.
AU - Horikoshi, Renato J.
AU - Bernardi, Daniel
AU - Ribeiro, Rebeca da S
AU - Nascimento, Antonio Rb do
AU - Santos, Antonio C dos
AU - Omoto, Celso
PY - 2016/12/1
Y1 - 2016/12/1
N2 - 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.
AB - 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.
KW - Bacillus thuringiensis
KW - Bt maize
KW - TC1507 maize
KW - fall armyworm
KW - resistance management
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U2 - 10.1002/ps.4274
DO - 10.1002/ps.4274
M3 - Article
C2 - 26990201
AN - SCOPUS:84963627131
SN - 1526-498X
VL - 72
SP - 2295
EP - 2302
JO - Pest management science
JF - Pest management science
IS - 12
ER -
