Journal of Economic Entomology (2014) 107, 781-790

Oderlei Bernardi, Douglas Amado, Renan S. Sousa, Fabiana Segatti, Julio Fatoretto, Anthony D. Burd and Celso Omoto (2014)
Baseline susceptibility and monitoring of Brazilian populations of Spodoptera frugiperda (Lepidoptera: Noctuidae) and Diatraea saccharalis (Lepidoptera: Crambidae) to Vip3Aa20 insecticidal protein
Journal of Economic Entomology 107 (2), 781-790
Abstract: The genetically modified maize expressing Vip3Aa20 insecticidal protein from Bacillus thuringiensis Berliner is a biotechnological option for the control of Spodoptera frugiperda (J.E. Smith) and Diatraea saccharalis (F.) in Brazil. To support an Insect Resistance Management program, we conducted studies of baseline susceptibility and monitoring of Brazilian populations of S. frugiperda and D. saccharalis to the Vip3Aa20 insecticidal protein. Neonates were exposed to Vip3Aa20 applied on artificial diet surface. Mortality and growth inhibition were assessed after 7 d. All populations were susceptible to Vip3Aa20. The LC₅₀ ranged from 92.38 to 611.65 ng Vip3Aa20/cm² for 16 populations of S. frugiperda (6.6-fold variation), and between 61.18 and 367.86 ng Vip3Aa20/cm² for 6 populations of D. saccharalis (sixfold variation). The EC₅₀ ranged from 21.76 to 70.09 and 48.65 to 163.60 ng Vip3Aa20/cm² for S. frugiperda and D. saccharalis, respectively. There was a low interpopulation variation in susceptibility to Vip3Aa20, which represents the natural geographic variation in the response, and not the variation caused by previous exposure to selection pressure. For these two pests, the diagnostic concentrations of 2,000 and 3,600 ng of Vip3Aa20/cm² caused high mortality. These diagnostic concentrations will be used in resistance monitoring programs in Brazil.
(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): Celso Omoto, Oderlei Bernardi

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)	Brazil (south)
	Spodoptera frugiperda	Maize/corn (Zea mays)	Brazil (NW)
	Spodoptera frugiperda	Maize/corn (Zea mays)	Brazil (NE)
	Diatraea saccharalis	Maize/corn (Zea mays)	Brazil (south)
	Diatraea saccharalis	Maize/corn (Zea mays)	Brazil (NW)
Bacillus thuringiensis Vip-toxins (entomopathogen)	Spodoptera frugiperda	Maize/corn (Zea mays)
Bacillus thuringiensis Vip-toxins (entomopathogen)	Diatraea saccharalis	Maize/corn (Zea mays)