Journal of Economic Entomology (2017) 110, 1770-1778

O.F. Santos-Amaya, C.S. Tavares, J.V.C. Rodrigues, T.C. Souza, N. Rodrigues-Silva, R.N.C. Guedes, A.P. Alves and E.J.G. Pereira (2017)
Magnitude and allele frequency of Cry1F resistance in field populations of the fall armyworm (Lepidoptera: Noctuidae) in Brazil
Journal of Economic Entomology 110 (4), 1770-1778
Abstract: Bacillus thuringiensis (Bt) corn producing the Cry1F protein was the first highly efficacious Bt corn deployed against the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) in Brazil, but reduced efficacy of this technology against the fall armyworm has been reported in some regions of the country. Here, we surveyed Cry1F resistance allele frequency and susceptibility of eight S. frugiperda populations collected in 2013 from non-Bt fields in different regions of Brazil. In F₁ screen experiments, the overall frequency of the Cry1F resistance alleles in Brazilian populations was estimated at 0.24, with 95% credibility interval between 0.18 and 0.25. In concentration–response bioassays, five of the eight populations surveyed exhibited significant resistance levels, which were over 32 times higher than that of the standard susceptible laboratory strain. The estimates of Cry1F resistance allele frequency were positively correlated with those of median effective or lethal concentrations (i.e., EC₅₀ or LC₅₀). These results show that the allelic frequency and the magnitude of Cry1F resistance are high in field populations of S. frugiperda in Brazil, indicating a challenging situation for resistance management.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Eliseu José G. Pereira, Raul Narciso C. Guedes

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Spodoptera frugiperda		Brazil (south)
Bacillus thuringiensis Cry1F-toxin (entomopathogen)	Spodoptera frugiperda	Maize/corn (Zea mays)