First detection of a Sesamia nonagrioides resistance allele to Bt maize in Europe

Abstract

The Ebro Valley (Spain) is the only hotspot area in Europe where resistance evolution of target pests to Cry1Ab protein is most likely, owing to the high and regular adoption of Bt maize (>60%). The high-dose/refuge (HDR) strategy was implemented to delay resistance evolution, and to be effective it requires the frequency of resistance alleles to be very low (<0.001). An F2 screen was performed in 2016 to estimate the frequency of resistance alleles in Sesamia nonagrioides from this area and to evaluate if the HDR strategy is still working effectively. Out of the 137 isofemale lines screened on Cry1Ab maize leaf tissue, molted larvae and extensive feeding were observed for two consecutive generations in one line, indicating this line carried a resistance allele. The frequency of resistance alleles in 2016 was 0.0036 (CI 95% 0.0004–0.0100), higher but not statistically different from the value obtained in 2004–2005. Resistance does not seem to be evolving faster than predicted by a S. nonagrioides resistance evolution model, but the frequency of resistance is now triple the value recommended for an effective implementation of the HDR strategy. Owing to this, complementary measures should be considered to further delay resistance evolution in the Ebro Valley.

Annual post‐market environmental monitoring report on the cultivation of genetically modified maize MON 810 in 2016

“…An additional relevant publication (Camargo et al.,) published after the period covered by the literature search performed by the consent holder was identified by EFSA. The findings reported by Camargo et al.…”

“…The value reported by Camargo et al. () was higher than the initial estimation of 2.9 × 10 −3 (95% CI 0 – 8.6 × 10 −3 ), calculated from MCB populations collected in 2004/2005 (Andreadis et al., ) (Table ). However, both estimates are not significantly different because of the low number of lines screened in 2004/2005.…”

“…The findings reported by Camargo et al. () reinforce the need to implement a sensitive monitoring plan, as previously recommended by EFSA.…”

“…near‐isogenic maize variety); (2) using larvae in the control group from the same population as the one tested on Bt ‐maize; (3) confirming the expression of Cry1Ab protein in the Bt ‐maize leaves used (e.g. by using commercial test strips, see Camargo et al., ); (4) duration of the exposure should be the same for the treatment (maize MON 810) and control groups to allow for a proper comparison.…”

“…EFSA identified an additional relevant publication (Camargo et al., ) that was published online on 5 March 2018, after the period covered by the literature search performed by the consent holder.…”