Cry1Ie毒素胁迫下亚洲玉米螟的抗性发展及汰选种群对其他Bt毒素的交互抗性

Selection for Cry1Ie resistance and cross-resistance of the selected strain to other Cry toxins in the Asian corn borer, Ostrinia furnacalis (Lepidoptera: Crambidae)

亚洲玉米螟Ostrinia furnacalis(Guenée)是危害玉米的重要害虫之一,转Bt基因抗虫玉米为其防治提供了新的途径。然而,靶标害虫产生抗性将严重阻碍Bt制剂及转Bt基因抗虫玉米的持续应用。明确害虫对转Bt基因玉米表达的毒素蛋白的抗性演化,对于制定科学有效的抗性治理策略具有重要的理论和实际意义。本实验通过人工饲料汰选法研究了Bt Cry1Ie毒素胁迫下亚洲玉米螟的抗性发展及汰选14代的种群对其他Bt毒素(Cry1Ab,Cry1Ac和Cry1Fa)的交互抗性,并观察了Cry1Ie蛋白胁迫对亚洲玉米螟生物学的影响。结果表明:随着汰选压不断提高,亚洲玉米螟种群对Cry1Ie毒素的敏感性逐渐下降。汰选14代后,种群对Cry1Ie毒素的抗性水平提高了23倍。然而,Cry1Ab,Cry1Ac和Cry1Fa对所获Cry1Ie汰选种群的毒力与对敏感种群的毒力相比没有显著差异,说明Cry1Ie汰选没有引起亚洲玉米螟对Cry1Ab,Cry1Ac和Cry1Fa毒素产生交互抗性。同时,与敏感种群相比,Cry1Ie汰选14代的种群幼虫平均发育历期延长5.7 d,蛹重减轻13.7%,单雌产卵量下降40.0%。本研究结果说明,大面积单一种植转cry1Ie基因抗虫玉米,可能引起亚洲玉米螟产生抗性;亚洲玉米螟Cry1Ie抗性种群对Cry1Ab,Cry1Ac和Cry1Fa没有交互抗性,含有cry1Ie和cry1Ab,cry1Ac或cry1F双/多基因抗虫玉米,可作为靶标害虫抗性治理的重要策略。

The Asian corn borer, Ostriniafurnacalis （Guen6e）, is one of the most important insect pests of maize in China. Transgenic Bacillus thuringiensis （Bt） maize provide an effective mean to control this insect pest. However, evolution of resistance in the target insect will be a great threat to the continued success of Bt toxins used in insecticide formulations or expressed by transgenic maize. It is theoretically and practically important to well characterize resistant strains, which will provide the only way to empirically validate proposed management strategies. A strain of O. furnacalis was selected for resistance to Cry1Ie by exposure to the toxin incorporated into artificial diet in the laboratory. The resistance development and cross-resistance to other Bt toxins such as Cry1Ab, Cry1Ac and Cry1Fa after 14 generations of selection were determined by bioassay. In addition, the changes in biology of O. furnacalis were also observed. The results indicated that the susceptibility of the selected strain to Cry1 Ie toxin declined as the selection pressure increased. The selected strain developed higher than 23-fold resistance to Cry1Ie after 14 generations of selection. However, it was as susceptible to Cry1Ab, Cry1Ac, and Cry1Fa as the unselected control strain. In addition, compared with the unselected strain, the larvae of selected strain required an average 5.7 d longer duration, the pupal weight reduced by 13.7%, and the number of eggs laid per female decreased by 40.0%. These results suggest that the widespread use oftransgenic Cry1 Ie maize could lead to the development of resistance in target pest 0. furnacalis. The lack of cross-resistance between Cry1Ie and Cry1Ab, Cry1 Ac or Cry1 Fa suggests that maize hybrids expressing these two toxins （Cry1Ie and Cry1Ab, Cry1Ac or Cry1F） are likely to be compatible for resistance management of 0. furnacalis.