Evaluating Resistance to Bt Toxin Cry1Ab by F<SUB>2</SUB> Screen in European Populations of Ostrinia nubilalis (Lepidoptera: Crambidae)

Abstract

The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F2 screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the Cry1Ab toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the Cry1Ab toxin. The cost of F2 screen performed in the four countries varied from U.S. dollars 300 to dollars 1300 per line screened. The major difference in cost was mostly due to a severe loss of univoltine lines during the screen in Germany and Slovakia. In none of the screened lines did we detect alleles conferring resistance to Mon810 maize or to the Cry1Ab toxin. The frequency of resistance alleles were < 1.0 x 10(-3), < 1.6 x 10(-3), < 9.2 x 10(-3), and < 2.6 x 10(-2) in France, Germany, Italy, and Slovakia, with 95% probability, respectively. The average detection probability over all lines was approximately 90%. Making the assumption that European corn borer populations in these countries belong to the same genetic entity, the frequency of alleles conferring resistance to the Cry1Ab produced by the Mon810 maize in western and central Europe was 1.0 x 10(-4), with a 95% confidence interval of 0-3.0 x 10(-4).

Frequency of resistance to Vip3Aa20 toxin from Bacillus thuringiensis in Spodoptera frugiperda (Lepidoptera: Noctuidae) populations in Brazil

“…Theoretically, 1/16 of F 2 larvae will be resistant homozygous (RR genotype) in isofemale lines whose parents had the resistance allele . The F 2 screen method was used to estimate the resistance allele frequency to Bt toxins in several pest species, such as Heliothis virescens (F.) (Gould et al, 1997), Pectinophora gossypiella (Saunders) (Tabashnik et al, 2000), Diatraea saccharalis (F.) , Ostrinia nubilalis (Hübner) (Andow et al, , 2000Bourguet et al, 2003;Stodola et al, 2006;Engels et al, 2010;Siegfried et al, 2014), Plutella xylostella (L.) (Zhao et al, 2002), Helicoverpa armigera (Hübner) (Liu et al, 2008;Xu et al, 2009;Mahon et al, 2010Mahon et al, , 2012, Helicoverpa punctigera (Wallengren) (Mahon et al, 2012) and Crysomela tremulae F. (Wenes et al, 2006). The resistance allele frequency in these studies ranged from 0.0009 to 0.0297.…”

Clarifications on EFSA GMO Panel recommendations on the Insect Resistance Management plan for genetically modified maize MON 810

“…The EFSA GMO Panel adopted a scientific opinion on the 2009, 2010, 2012and 2013PMEM reports (EFSA GMO Panel, 2011b, 2012, 2013, 2014, 2015. On the basis of the data provided in these reports, the EFSA GMO Panel did not identify adverse effects on the environment, human and animal health due to maize MON 810 cultivation.…”

“…For its model simulations (EFSA GMO Panel, 2011b, 2013, the EFSA GMO Panel used an initial resistance allele frequency set at the conservative value of 0.006. However, the actual value of the initial resistance allele frequency might be lower in those regions where maize MON810 has been cultivated and this could explain why resistance has not yet been detected in the field (Engels et al, 2010).…”

Emerging issues in Integrated Pest Management Implementation and Adoption in the North Central USA

“…There has been no sign so far of European corn borer populations developing resistance to Bt corn. A possible reason is that alleles conferring resistance appear to be uncommon in natural populations, as indicated by several screening trials (Andow et al 1998(Andow et al , 2000Bourguet et al 2003Bourguet et al , 2005Tabashnik et al 2003;Stodola et al 2006;Siegfried et al 2007;Engels et al 2010). Nevertheless, resistant laboratory strains have been selected (Chaufaux et al 2001;Alves et al 2006;Lopez et al 2010a, b), and monitoring for field resistance continues.…”