Behavior and development of Tetranychus ludeni Zacher, 1913 (Acari: Tetranychidae) and physiological stress in genetically modified cotton expressing Cry1F and Cry1Ac proteins

Abstract Genetically modified plants are one of the tactics used in integrated pest management - IPM. There is great concern about the impact of these plants on non-target organisms. On the other hand, there is little information in the literature on the effects of transgenics (Bacillus thuringiensis) Bt on populations of phytophagous mites, and the physiological responses that this attack promotes on plants. The objective of this work was to evaluate the biology of the T. ludeni mite in Bt cotton, expressing the Cry1F and Cry1Ac proteins. To evaluate the behavior of food and oviposition preference of the T. ludeni with Bt cotton and isohybrid. Verify if the physiological stress caused by T. ludeni’s attack is differentiated in Bt cotton. The mites were reared in Bt cotton and isohybrid, in a total of 40 replicates in the completely randomized design and the biological cycle was evaluated. The food preference and oviposition analysis were done with 10 replicates, with choice. The physiological stress was evaluated through chlorophyll fluorescence, under greenhouse conditions. The data of the T. ludeni biology were analyzed by Student's t-test, for food and oviposition preference the chi-square test was performed. Regression models were fitted for the fluorescence parameters. The model identity test was used to evaluate the differences between Bt and isohybrid treatments. Cry1F and Cry1Ac proteins have not affected the biology of T. ludeni. The photosynthetic parameters in Bt cotton plants were less influenced by T. ludeni infestation.

摘要 转基因植物（Genetically modified plants）是害虫综合治理（integrated pest management, IPM）所采用的防控策略之一。目前学界对这类植物对非靶标生物的影响存在广泛顾虑。然而，现有文献中关于转苏云金杆菌（Bacillus thuringiensis, Bt）基因作物对植食性螨类种群的影响，以及该类害虫取食胁迫对植物所诱发的生理响应的相关研究仍较为稀缺。本研究的核心目标为：评估表达Cry1F与Cry1Ac蛋白的转Bt棉花上卢氏叶螨（T. ludeni）的生物学特性，比较卢氏叶螨对转Bt棉花与其近等基因系的取食偏好与产卵偏好，验证卢氏叶螨取食引发的生理胁迫在转Bt棉花与非转基因近等基因系棉花间是否存在差异。本研究采用完全随机设计，将卢氏叶螨分别饲养于转Bt棉花与近等基因系棉花上，共设置40次重复以评估其生物学周期；取食偏好与产卵偏好分析设置10次选择重复实验；在温室条件下，通过叶绿素荧光参数评估植物的生理胁迫水平。数据分析方面，卢氏叶螨的生物学数据采用t检验（Student's t-test）进行分析，取食偏好与产卵偏好数据采用卡方检验（chi-square test）进行统计；针对叶绿素荧光参数拟合回归模型，并通过模型同一性检验比较转Bt棉花与近等基因系棉花处理组间的差异。研究结果表明，Cry1F与Cry1Ac蛋白未对卢氏叶螨的生物学特性产生显著影响；转Bt棉花植株的光合参数受卢氏叶螨侵染的影响程度显著低于非转基因近等基因系棉花。