Frequency of alleles conferring resistance to Bt maize in French and US corn belt populations of the European corn borer, Ostrinia nubilalis

Abstract

Farmers, industry, governments and environmental groups agree that it would be useful to manage transgenic crops producing insecticidal proteins to delay the evolution of resistance in target pests. The main strategy proposed for delaying resistance to Bacillus thuringiensis ( Bt) toxins in transgenic crops is the high-dose/refuge strategy. This strategy is based on the unverified assumption that resistance alleles are initially rare (<10(-3)). We used an F(2) screen on >1,200 isofemale lines of Ostrinia nubilalis Hübner (Lepidoptera: Crambidae) collected in France and the US corn belt during 1999-2001. In none of the isofemale lines did we detect alleles conferring resistance to Bt maize producing the Cry1Ab toxin. A Bayesian analysis of the data indicates that the frequency of resistance alleles in France was <9.20 x 10(-4) with 95% probability, and a detection probability of >80%. In the northern US corn belt, the frequency of resistance to Bt maize was <4.23 x 10(-4) with 95% probability, and a detection probability of >90%. Only 95 lines have been screened from the southern US corn belt, so these data are still inconclusive. These results suggest that resistance is probably rare enough in France and the northern US corn belt for the high-dose plus refuge strategy to delay resistance to Bt maize.

Applications (EFSA‐GMO‐RX‐MON810) for renewal of authorisation for the continued marketing of (1) existing food and food ingredients produced from genetically modified insect resistant maize MON810; (2) feed consisting of and/or containing maize MON810, including the use of seed for cultivation; and of (3) food and feed additives, and feed materials produced from maize MON810, all under Regulation (EC) No 1829/2003 from Monsanto

“…A recent analysis of these monitoring data indicates that neither in the EU, nor in the US, have populations of resistant European corn borer (Ostrinia nubilalis) or Mediterranean corn borer (Sesamia nonagrioides) been found (Tabashnik et al, 2008a). This confirms previous observations (Andow et al, 2000;Bourguet et al, 2003;Farinós et al, 2004;Eizaguirre et al, 2006;Schuphan, 2006;Stodola et al, 2006;Andreadis et al, 2007;Siegfried et al, 2007). In Spain, for instance, after 6 years of field exposure of Sesamia nonagrioides to Cry1Ab expressing maize, no indications of resistance evolution were found (Farinós et al, 2004;Eizaguirre et al, 2006;Andreadis et al, 2007).…”

“…In Spain, for instance, after 6 years of field exposure of Sesamia nonagrioides to Cry1Ab expressing maize, no indications of resistance evolution were found (Farinós et al, 2004;Eizaguirre et al, 2006;Andreadis et al, 2007). So far, F 2 screenings (Andow and Alstad, 1998) did not detect resistance alleles (dominant or recessive) in corn borer populations (Andow et al, 1998(Andow et al, , 2000Bourguet et al, 2003;Schuphan, 2006;Stodola et al, 2006;Andreadis et al, 2007). Some of these tests were performed on mated females collected from the field across Mediterranean EU countries and their progeny reared under confined conditions.…”

Frequency and fitness cost of resistance to Bacillus thuringiensis in Chrysomela tremulae (Coleoptera: Chrysomelidae)

“…Among these factors, the frequency is certainly one of the most important: the lower the frequency, the more sustainable the strategy. The initial frequency of resistance has been estimated in only a limited number of cases, mostly in lepidopteran pests, due to practical limitations: Helicoverpa armigera (Wu et al, 2002), Heliothis virescens (Gould et al, 1997) and H. zea (Burd et al, 2003) on cotton, Ostrinia nubilalis on maize Bourguet et al, 2003), Scirpophaga incertulas (Bentur et al, 2000) on rice, and Pectinophora gossypiella (Tabashnik et al, 2000) on cotton. These studies yielded contrasting results, with the frequency of Bt resistance alleles ranging from 10 À4 to 10 À1 .…”

Opinion of the Scientific Panel on genetically modified organisms [GMO] related to the notification for the placing on the market of insect resistant genetically modified maize Bt11, for cultivation, feed and industrial processing

“…Up to now, resistant Ostrinia nubilalis or Sesamia nonagrioides have not been found in fields in the US or in Europe (Evans, 2002;Tabashnik et al, 2003;Bourguet et al, 2003;Farinós et al, 2004). Although laboratory tests showed that corn borer populations are capable of developing some degree of tolerance to the Cry1Ab protein (Huang et al, 2002), laboratory selection and F2 screening to generate highly resistant O. nubilalis strains have failed so far (Bourguet, 2004).…”