Gassmann Aaron J
Department of Entomology, Iowa State University, Ames, IA 50011, USA.
Insects. 2021 Feb 5;12(2):136. doi: 10.3390/insects12020136.
The western corn rootworm, LeConte, is among the most serious pests of maize in the United States. Since 2003, transgenic maize that produces insecticidal toxins from the bacterium (Bt) has been used to manage western corn rootworm by killing rootworm larvae, which feed on maize roots. In 2009, the first cases of field-evolved resistance to Bt maize were documented. These cases occurred in Iowa and involved maize that produced Bt toxin Cry3Bb1. Since then, resistance has expanded to include other geographies and additional Bt toxins, with some rootworm populations displaying resistance to all commercially available Bt traits. Factors that contributed to field-evolved resistance likely included non-recessive inheritance of resistance, minimal fitness costs of resistance and limited adult dispersal. Additionally, because maize is the primary agricultural crop on which rootworm larvae can survive, continuous maize cultivation, in particular continuous cultivation of Bt maize, appears to be another key factor facilitating resistance evolution. More diversified management of rootworm larvae, including rotating fields out of maize production and using soil-applied insecticide with non-Bt maize, in addition to planting refuges of non-Bt maize, should help to delay the evolution of resistance to current and future transgenic traits.
西部玉米根萤叶甲（LeConte）是美国玉米最严重的害虫之一。自2003年以来，转基玉米可产生来自苏云金芽孢杆菌（Bt）的杀虫毒素，通过杀死以玉米根为食的根萤叶甲幼虫来防治西部玉米根萤叶甲。2009年，首次记录了田间对Bt玉米产生抗性的案例。这些案例发生在爱荷华州，涉及产生Bt毒素Cry3Bb1的玉米。从那时起，抗性已扩展到其他地区并涉及其他Bt毒素，一些根萤叶甲种群对所有商业可用的Bt性状都表现出抗性。导致田间抗性产生的因素可能包括抗性的非隐性遗传、抗性的最小适合度代价以及成虫扩散有限。此外，由于玉米是根萤叶甲幼虫能够存活的主要农作物，持续种植玉米，特别是持续种植Bt玉米，似乎是促进抗性进化的另一个关键因素。除了种植非Bt玉米避难所外，对根萤叶甲幼虫采取更多样化的管理措施，包括将田地转出玉米生产以及在非Bt玉米上使用土壤杀虫剂，应该有助于延缓对当前和未来转基因性状产生抗性的进化。
