Department of Entomology; Louisiana State University Agricultural Center, Baton Rouge, LA, USA.
GM Crops Food. 2012 Jul-Sep;3(3):245-54. doi: 10.4161/gmcr.20539. Epub 2012 Jul 1.
The sugarcane borer, Diatraea saccharalis (F.), is a major target of transgenic maize expressing Bacillus thuringiensis (Bt) proteins in South America and the mid-Southern region of the United States. During 2007-2009, a total of 986 feral individuals of D. saccharalis were collected from maize fields in six locations of Louisiana and Mississippi and examined for resistance to Cry1Ab maize using F 1/F 2 screens. Major resistance alleles to Cry1Ab maize in the populations sampled from non-Bt maize plants during 2007 and 2008 in Louisiana and 2009 in Mississippi were rare. From a total of 487 individuals collected from three locations in Louisiana in 2007 and 2008, only one individual was identified with major resistance alleles. In addition, no major resistance alleles were detected in 242 individuals collected from three locations in Mississippi in 2009. The frequency of major resistance alleles was estimated to be 0.002 with a 95% CI of 0.00025-0.0057 for the Louisiana populations and < 0.0061, with 95% probability, for the Mississippi populations. The resistance frequency estimated for the Louisiana populations in 2007 and 2008 was not significantly different from those reported previously for populations sampled in 2004-2006. However, among 200 individuals sampled from non-Bt maize plants in 2009 in Louisiana, six individuals were identified to possess major resistance alleles. The estimated major resistance allele frequency for the populations sampled from non-Bt maize plants in 2009 in Louisiana was 0.0176 with a 95% CI of 0.0072 to 0.0328, which was significantly greater than those estimated for the populations collected in 2004-2008. Similarly, the frequency of minor resistance alleles to Cry1Ab maize for the Louisiana populations collected in 2009 was also significantly greater than those estimated for the populations sampled before. In addition, two out of 57 feral individuals collected from Bt maize plants in Louisiana in 2009 were identified to carry major resistance alleles to Cry1Ab maize. Since 2010, transgenic maize expressing pyramided Bt genes has been planted in the US mid-Southern region and by 2011, pyramided Bt maize has replaced Cry1Ab maize as the dominant Bt maize for managing lepidopteran pests including D. saccharalis. The timely switching from single-gene Cry1Ab maize to the pyramided Bt maize should prevent further increases in Cry1Ab resistance allele frequency and thus ensure the continued success of Bt maize for managing D. saccharalis in the region.
甘蔗螟虫（Diatraea saccharalis）是一种主要的目标昆虫，在美国中南部和南美洲，表达苏云金芽孢杆菌（Bt）蛋白的转基因玉米对其具有抗性。2007-2009 年，在路易斯安那州和密西西比州的 6 个地点的玉米田中，共收集了 986 头野生甘蔗螟虫，并用 F1/F2 筛选法检测其对 Cry1Ab 玉米的抗性。在路易斯安那州 2007 年和 2008 年及密西西比州 2009 年从非 Bt 玉米植株上采集的种群中，Cry1Ab 玉米的主要抗性等位基因罕见。在 2007 年和 2008 年从路易斯安那州的 3 个地点共采集了 487 只个体，只有 1 只被鉴定为具有主要抗性等位基因。此外，在 2009 年从密西西比州的 3 个地点采集的 242 只个体中未检测到主要抗性等位基因。路易斯安那州种群的主要抗性等位基因频率估计为 0.002，95%置信区间为 0.00025-0.0057，密西西比州种群的主要抗性等位基因频率估计为 <0.0061，95%概率。2007 年和 2008 年在路易斯安那州采集的种群的抗性频率与 2004-2006 年采集的种群的报告频率没有显著差异。然而，在 2009 年从路易斯安那州的非 Bt 玉米植株上采集的 200 只个体中，有 6 只被鉴定为具有主要抗性等位基因。2009 年从路易斯安那州非 Bt 玉米植株上采集的种群的主要抗性等位基因频率估计为 0.0176，95%置信区间为 0.0072-0.0328，显著高于 2004-2008 年采集的种群。同样，2009 年从路易斯安那州采集的种群对 Cry1Ab 玉米的次要抗性等位基因频率也显著高于之前采集的种群。此外，2009 年在路易斯安那州的 Bt 玉米植株上采集的 57 头野生个体中，有 2 头被鉴定为携带 Cry1Ab 玉米的主要抗性等位基因。自 2010 年以来，在美国中南部地区种植了表达多基因的转基因玉米，到 2011 年，多基因 Bt 玉米已取代 Cry1Ab 玉米，成为防治包括甘蔗螟在内的鳞翅目害虫的主要 Bt 玉米。从单一基因 Cry1Ab 玉米及时切换到多基因 Bt 玉米，应可防止 Cry1Ab 抗性等位基因频率的进一步增加，从而确保 Bt 玉米在该地区继续成功防治甘蔗螟。
