Pest Management Science (2017) 73, 35-43

Oscar F. Santos-Amaya, Clébson S. Tavares, João Victor C. Rodrigues, Silverio O. Campos, Raul Narciso C. Guedes, Analiza P. Alves and Eliseu José G. Pereira (2017)
Fitness costs and stability of Cry1Fa resistance in Brazilian populations of Spodoptera frugiperda
Pest Management Science 73 (1), 35-43
Abstract:
BACKGROUND
The presence of fitness costs of resistance to Bacillus thuringiensis (Bt) insecticidal proteins in insect populations may delay or even reverse the local selection of insect resistance to Bt transgenic crops, and deserves rigorous investigation. Here we assessed the fitness costs associated with Cry1Fa resistance in two strains of fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), derived from field collections in different Brazilian regions and further selected in the laboratory for high levels of resistance to Cry1Fa using leaves of TC1507 corn.
RESULTS
Fitness components were compared using paired resistant and susceptible strains with similar genetic backgrounds and F₁ generations from reciprocal crosses, all of them reared on non-transgenic corn leaves. No apparent life history costs in the larval stage were observed in the Bt-resistant strains. Moreover, the resistance remained stable for seven generations in the absence of selection, with no decrease in the proportion of resistant individuals. Larval respiration rates were also similar between resistant and susceptible homozygotes, and heterozygotes displayed respiration rates and demographic performance equal or superior to those of susceptible homozygotes.
CONCLUSION
In combination, these results indicate the lack of strong fitness costs associated with resistance to Cry1Fa in the fall armyworm strains studied. These findings suggest that Cry1Fa resistance in S. frugiperda populations is unlikely to be counterselected in Cry1Fa-free environments.
(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

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Pest and/or beneficial records:

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