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 转基因植物是害虫综合治理（Integrated Pest Management，IPM）中常用的防控策略之一。当前学界对这类植物对非靶标生物的影响存在广泛担忧，但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，以及该类螨类取食胁迫对植株生理响应的研究信息仍较为匮乏。本研究旨在评价取食表达Cry1F和Cry1Ac蛋白的转Bt棉花的T. ludeni螨的生物学特性，明确该叶螨对转Bt棉花及其近等基因系的取食与产卵偏好性，并验证T. ludeni取食诱导的生理胁迫在转Bt棉花与近等基因系植株间是否存在差异。实验采用完全随机设计，将T. ludeni饲养于转Bt棉花与近等基因系植株上，每组设置40次重复，测定其生物学周期；取食偏好与产卵偏好实验设置10次有选择重复；在温室条件下，通过叶绿素荧光参数评估植株生理胁迫水平。统计分析方面，采用t检验分析T. ludeni的生物学特性数据，针对取食与产卵偏好性数据采用卡方检验，为叶绿素荧光参数拟合回归模型，并通过模型同一性检验评估转Bt棉花与近等基因系处理组间的差异。结果表明，Cry1F与Cry1Ac蛋白未对T. ludeni的生物学特性产生显著影响；转Bt棉花植株的光合参数受T. ludeni侵染的影响程度更低。