Crespo André Lb, Spencer Terence A, Alves Analiza P, Hellmich Richard L, Blankenship Erin E, Magalhães Leonardo C, Siegfried Blair D
Department of Entomology, University of Nebraska, Lincoln, NE 68583-0816, USA.
Pest Manag Sci. 2009 Oct;65(10):1071-81. doi: 10.1002/ps.1793.
The high dose plus refuge is one of the major components of the resistance management plan mandated for transgenic corn expressing Cry toxins from Bacillus thuringiensis Berliner (Bt) that targets the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae). This strategy was based on assumptions such as functional recessive inheritance, which has not been previously tested for O. nubilalis. The authors used a field-derived resistant strain of O. nubilalis to define the nature of resistance to Cry1Ab toxin by examining the inheritance and on-plant survival of susceptible and resistant insects and their F(1) progeny.
The resistant strain exhibited > 800-fold resistance to Cry1Ab. Resistance was primarily autosomal and controlled by more than one locus or multiple alleles at one locus. The degree of dominance D calculated on the basis of LC(50) values was - 0.45(h' = 0.27), indicating that resistance was incompletely recessive. No survivors were found on vegetative-stage Bt corn, although both resistant larvae and their F(1) progeny were able to survive on reproductive corn 15 days after infestation.
A field derived O. nubilalis strain exhibited high levels of resistance to Cry1Ab and survived on transgenic corn by feeding on tissues with low Cry1Ab expression. The Cry1Ab resistance was primarily autosomal, incompletely recessive and polygenic. Tissue and on-plant survival data indicated that dominance varies depending on plant stage.
高剂量加庇护所策略是针对表达来自苏云金芽孢杆菌（Bt）的Cry毒素的转基因玉米所规定的抗性管理计划的主要组成部分之一，该转基因玉米针对欧洲玉米螟，即欧洲玉米螟（Ostrinia nubilalis (Hübner)，鳞翅目：草螟科）。该策略基于功能隐性遗传等假设，而此前尚未对欧洲玉米螟进行过此类测试。作者使用田间获得的欧洲玉米螟抗性品系，通过检查易感和抗性昆虫及其F(1)代的遗传和植株上的存活率，来确定对Cry1Ab毒素的抗性性质。
抗性品系对Cry1Ab表现出>800倍的抗性。抗性主要是常染色体遗传，由一个以上的基因座或一个基因座上的多个等位基因控制。根据LC(50)值计算的显性度D为-0.45（h' = 0.27），表明抗性是不完全隐性的。在营养期Bt玉米上未发现存活个体，尽管抗性幼虫及其F(1)代在侵染后15天能够在生殖期玉米上存活。
田间获得的欧洲玉米螟品系对Cry1Ab表现出高水平抗性，并通过取食Cry1Ab表达量低的组织在转基因玉米上存活。Cry1Ab抗性主要是常染色体遗传、不完全隐性且为多基因遗传。组织和植株上的存活数据表明显性度因植物阶段而异。
