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Cross-Resistance between Cry1 Proteins in Fall Armyworm (Spodoptera frugiperda) May Affect the Durability of Current Pyramided Bt Maize Hybrids in Brazil.

Bernardi D, Salmeron E, Horikoshi RJ, Bernardi O, Dourado PM, Carvalho RA, Martinelli S, Head GP, Omoto C - PLoS ONE (2015)

Bottom Line: Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found.Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively.Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology and Acarology, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ/USP), Piracicaba, São Paulo, Brazil.

ABSTRACT
Genetically modified plants expressing insecticidal proteins from Bacillus thuringiensis (Bt) offer valuable options for managing insect pests with considerable environmental and economic benefits. Despite the benefits provided by Bt crops, the continuous expression of these insecticidal proteins imposes strong selection for resistance in target pest populations. Bt maize (Zea mays) hybrids have been successful in controlling fall armyworm (Spodoptera frugiperda), the main maize pest in Brazil since 2008; however, field-evolved resistance to the protein Cry1F has recently been reported. Therefore it is important to assess the possibility of cross-resistance between Cry1F and other Cry proteins expressed in Bt maize hybrids. In this study, an F2 screen followed by subsequent selection on MON 89034 maize was used to select an S. frugiperda strain (RR) able to survive on the Bt maize event MON 89034, which expresses the Cry1A.105 and Cry2Ab2 proteins. Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found. The RR strain showed high levels of resistance to Cry1F, which apparently also conferred high levels of cross resistance to Cry1A.105 and Cry1Ab, but had only low-level (10-fold) resistance to Cry2Ab2. Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively. Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil. Nevertheless, the occurrence of Cry1F resistance in S. frugiperda across Brazil, and the cross-resistance to Cry1Ab and Cry1A.105, indicates that current Cry1-based maize hybrids face a challenge in managing S. frugiperda in Brazil and highlights the importance of effective insect resistance management for these technologies.

No MeSH data available.


Related in: MedlinePlus

Distribution of populations of Spodoptera frugiperda used in F2 screen.
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pone.0140130.g004: Distribution of populations of Spodoptera frugiperda used in F2 screen.

Mentions: Permit access to collect material used in our research at various crop sites was granted by Sistema de Autorização e Informação em Biodiversidade (Sisbio) from the Brazilian Ministry of Environment to SGS Gravena (Sisbio License # 10018–1) and PROMIP (Sisbio License # 40380–2). Number of caterpillars collected and respective geographic coordinates of each location are listed in Fig 4 and Table 7.


Cross-Resistance between Cry1 Proteins in Fall Armyworm (Spodoptera frugiperda) May Affect the Durability of Current Pyramided Bt Maize Hybrids in Brazil.

Bernardi D, Salmeron E, Horikoshi RJ, Bernardi O, Dourado PM, Carvalho RA, Martinelli S, Head GP, Omoto C - PLoS ONE (2015)

Distribution of populations of Spodoptera frugiperda used in F2 screen.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608726&req=5

pone.0140130.g004: Distribution of populations of Spodoptera frugiperda used in F2 screen.
Mentions: Permit access to collect material used in our research at various crop sites was granted by Sistema de Autorização e Informação em Biodiversidade (Sisbio) from the Brazilian Ministry of Environment to SGS Gravena (Sisbio License # 10018–1) and PROMIP (Sisbio License # 40380–2). Number of caterpillars collected and respective geographic coordinates of each location are listed in Fig 4 and Table 7.

Bottom Line: Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found.Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively.Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology and Acarology, Escola Superior de Agricultura "Luiz de Queiroz" (ESALQ/USP), Piracicaba, São Paulo, Brazil.

ABSTRACT
Genetically modified plants expressing insecticidal proteins from Bacillus thuringiensis (Bt) offer valuable options for managing insect pests with considerable environmental and economic benefits. Despite the benefits provided by Bt crops, the continuous expression of these insecticidal proteins imposes strong selection for resistance in target pest populations. Bt maize (Zea mays) hybrids have been successful in controlling fall armyworm (Spodoptera frugiperda), the main maize pest in Brazil since 2008; however, field-evolved resistance to the protein Cry1F has recently been reported. Therefore it is important to assess the possibility of cross-resistance between Cry1F and other Cry proteins expressed in Bt maize hybrids. In this study, an F2 screen followed by subsequent selection on MON 89034 maize was used to select an S. frugiperda strain (RR) able to survive on the Bt maize event MON 89034, which expresses the Cry1A.105 and Cry2Ab2 proteins. Field-collected insects from maize expressing the Cry1F protein (event TC1507) represented most of the positive (resistance allele-containing) (iso)families found. The RR strain showed high levels of resistance to Cry1F, which apparently also conferred high levels of cross resistance to Cry1A.105 and Cry1Ab, but had only low-level (10-fold) resistance to Cry2Ab2. Life history studies to investigate fitness costs associated with the resistance in RR strain revealed only small reductions in reproductive rate when compared to susceptible and heterozygous strains, but the RR strain produced 32.2% and 28.4% fewer females from each female relative to the SS and RS (pooled) strains, respectively. Consistent with the lack of significant resistance to Cry2Ab2, MON 89034 maize in combination with appropriate management practices continues to provide effective control of S. frugiperda in Brazil. Nevertheless, the occurrence of Cry1F resistance in S. frugiperda across Brazil, and the cross-resistance to Cry1Ab and Cry1A.105, indicates that current Cry1-based maize hybrids face a challenge in managing S. frugiperda in Brazil and highlights the importance of effective insect resistance management for these technologies.

No MeSH data available.


Related in: MedlinePlus