Synergistic Interactions Between Cry1Ac and Natural Cotton Defenses Limit Survival of Cry1Ac-resistant Helicoverpa Zea (Lepidoptera: Noctuidae) on Bt Cotton
Synergistic Interactions Between Cry1Ac and Natural Cotton Defenses Limit Survival of Cry1Ac-resistant Helicoverpa Zea (Lepidoptera: Noctuidae) on Bt Cotton
复制标题
DOI：
10.1007/s10886-009-9665-x
复制
发表时间：
2009-07-01
影响因子：
2.3
通讯作者：
Moar, William J.
中科院分区：
文献类型：
--
作者：
Anilkumar, Konasale J.;Sivasupramaniam, Sakuntala;Moar, William J.
棉铃虫 Helicoverpa zea (Boddie) 的幼虫对苏云金芽孢杆菌 (Bt) Cry1Ac 表现出一定的耐受性，并且可以在表达 Cry1Ac 的 Bt 棉花上生存，这应该会增加抗性发展的担忧。然而，尚未观察到场演化电阻。在之前的一项研究中，选择了对 Cry1Ac 毒素具有稳定抗性的玉米赤霉种群。在本研究中，我们在实验室生物测定中确定，抗 Cry1Ac 毒素的玉米玉蜀黍种群的幼虫在开花前收集的田间种植的 Bt 棉花方块（=花蕾）上是否表现出比易感玉米玉蜀黍更高的存活率。我们的结果表明，抗 Cry1Ac 毒素的玉米穗轴菌无法在表达 Cry1Ac 的 Bt 棉花上完成幼虫发育，尽管其对 Cry1Ac 毒素的抗性超过 150 倍，并且能够在 Cry1Ac 毒素浓度高于 Bt 棉花方块时存活到化蛹。由于在 Bt 棉花上观察到的抗 Cry1Ac 玉米赤霉病死亡率高于预期，因此我们研究了 Cry1Ac 是否与人工饲料中棉粉中的棉酚和/或其他化合物相互作用。单独使用 Cry1Ac 毒素以及在存在和不存在 Cry1Ac 的情况下使用棉酚和 4% 棉粉进行饮食掺入生物测定。 Cry1Ac 毒素对敏感玉米赤霉的致死率显着高于对抗性玉米赤霉的致死率，但菌株之间对棉酚的敏感性没有差异。然而，Cry1Ac 与棉酚或棉粉的组合对抗性玉米穗轴菌具有协同作用，但对敏感玉米穗轴菌没有协同作用。个体幼虫中的棉酚浓度在昆虫品系之间或单独饲喂棉酚的幼虫与饲喂棉酚加 Cry1Ac 的幼虫之间没有显着差异。这些结果可能有助于解释抗 Cry1Ac 的玉米须虫无法在 Bt 棉花上完成发育，以及该害虫缺乏田间进化的对 Bt 棉花的抗性。
Larvae of the bollworm Helicoverpa zea (Boddie) show some tolerance to Bacillus thuringiensis (Bt) Cry1Ac, and can survive on Cry1Ac-expressing Bt cotton, which should increase resistance development concerns. However, field-evolved resistance has not yet been observed. In a previous study, a population of H. zea was selected for stable resistance to Cry1Ac toxin. In the present study, we determined in laboratory bioassays if larvae of the Cry1Ac toxin-resistant H. zea population show higher survival rates on field-cultivated Bt cotton squares (= flower buds) collected prebloom-bloom than susceptible H. zea. Our results show that Cry1Ac toxin-resistant H. zea cannot complete larval development on Cry1Ac-expressing Bt cotton, despite being more than 150-fold resistant to Cry1Ac toxin and able to survive until pupation on Cry1Ac toxin concentrations greater than present in Bt cotton squares. Since mortality observed for Cry1Ac-resistant H. zea on Bt cotton was higher than expected, we investigated whether Cry1Ac interacts with gossypol and or other compounds offered with cotton powder in artificial diet. Diet incorporation bioassays were conducted with Cry1Ac toxin alone, and with gossypol and 4% cotton powder in the presence and absence of Cry1Ac. Cry1Ac toxin was significantly more lethal to susceptible H. zea than to resistant H. zea, but no difference in susceptibility to gossypol was observed between strains. However, combinations of Cry1Ac with gossypol or cotton powder were synergistic against resistant, but not against susceptible H. zea. Gossypol concentrations in individual larvae showed no significant differences between insect strains, or between larvae fed gossypol alone vs. those fed gossypol plus Cry1Ac. These results may help explain the inability of Cry1Ac-resistant H. zea to complete development on Bt cotton, and the absence of field-evolved resistance to Bt cotton by this pest.