Hairy roadblock: Stem trichomes impede herbivore movement in a species and instar-dependent manner

Plants have evolved to deploy a vast set of defense mechanisms against insect herbivores, including physical barriers like leaf trichomes with pre and post ingestive effects. Yet, the role of stem trichomes in plant-herbivore interactions, particularly mobility dynamics, is poorly understood. To test this, we quantified the climbing speed of third and fifth instar soybean looper (SBL, Chrysodeixis includens) and fall armyworm (FAW, Spodoptera frugiperda) in the presence (intact) and absence (shaved off) of soybean (Glycine max) stem trichomes. The results show that SBL was significantly slowed down due to stem trichomes, but FAW was not affected. When compared between instars, fifth instar larvae were twice as fast as the third instar of both herbivores. Interestingly, significantly more fifth instar SBL successfully climbed to the top of the plant, compared to fifth instar FAW. Anecdotal observations also revealed a unique behavior of FAW and SBL larvae where they “girdle” the stems to..., 2. Materials and Methods (a) Plant materials Soybean plants were grown in Milo J. Shult Agricultural Research & Extension Center (SAREC), Arkansas Agricultural Experiment Station, University of Arkansas. Magellan cultivar was used for this study known for its drought tolerance, but no insect resistance has been discovered (See [16] for more details on Magellan). Plants were grown in potting soil (Farmers Co-Op, Van Buren, Arkansas, USA) in standard greenhouse conditions (16:8 light: dark cycle, ~70% relative humidity (RH), and a temperature of 28°C–30°C). (b) Insects Soybean looper and fall armyworm eggs were were obtained from Benzon Research Inc., Pennsylvania, USA and Frontier Agricultural Services, Calexico, CA, USA respectively. See Gautam et al., (2024) for more details regarding SBL and FAW rearing in lab.  Both SBL and FAW were reared in laboratory at University of Arkansas at 25°C, 70% RH until 3rd and 5th instar stage. (c) Shaving the stem trichomes The stem trichomes..., # Hairy roadblock: Stem trichomes impede herbivore movement in a species and instar-dependent manner Dataset DOI: [10.5061/dryad.n02v6wxb4](https://doi.org/10.5061/dryad.n02v6wxb4) ## Description of the data and file structure ### Files and variables #### File: Supplementary_data.xlsx **Description:** The file contains the consolidated data obtained during the experiment. Sheet 1 - Data Sheet 2 - Metadata and definition of variables. ##### Variables * Speed (cm/min): Average speed of the larvae to climb the stem in the given time * Completed: Measure of successful climbing * distance_cm: total distance travelled by the larvae within the given timeframe. (in centimeters). \"0\" distance was assigned for the larvae that did not move from their initial position at all. Hence they correspond to \"not reached\". ## Code/software The data was analyzed using R studio. Data.table package was used to handle the dataset. ANOVA was conducted followed by Tukey HSD for post hoc ...,植物已演化出一系列应对植食性昆虫的防御机制，其中包括兼具摄食前与摄食后效应的物理屏障——叶表皮毛（trichome）。然而，茎表皮毛在植物-植食性昆虫互作中的作用，尤其是对昆虫移动动态的影响，目前仍知之甚少。为验证这一问题，我们量化了3龄和5龄大豆尺蠖（SBL，*Chrysodeixis includens*）与草地贪夜蛾（FAW，*Spodoptera frugiperda*）在保留茎表皮毛（完整植株）与去除茎表皮毛（刮除处理）条件下的攀爬速度。 结果表明，茎表皮毛会显著延缓大豆尺蠖的爬行速度，但对草地贪夜蛾无显著影响。对比不同龄期的幼虫发现，两种植食性昆虫的5龄幼虫爬行速度均为3龄幼虫的2倍。有趣的是，与5龄草地贪夜蛾相比，成功攀爬至植株顶端的5龄大豆尺蠖数量显著更多。此外，我们还观察到两类幼虫对茎秆进行环剥的独特行为…… 2. 材料与方法 (a) 植物材料 本研究所用大豆植株种植于阿肯色大学阿肯色农业试验站Milo J. Shult农业研究与推广中心（SAREC）。本试验采用‘Magellan’大豆品种，该品种以耐旱性见长，但尚未发现抗虫特性，关于‘Magellan’品种的详细信息参见文献[16]。植株种植于美国阿肯色州范布伦市Farmers Co-Op品牌的营养土中，栽培条件为标准温室环境：16小时光照/8小时黑暗周期，相对湿度约70%，温度28℃~30℃。 (b) 供试昆虫 大豆尺蠖与草地贪夜蛾的虫卵分别从美国宾夕法尼亚州的Benzon Research公司以及美国加利福尼亚州卡莱克西科市的Frontier Agricultural Services公司获取。关于实验室饲养大豆尺蠖与草地贪夜蛾的详细方法，参见Gautam等人2024年的研究。两类昆虫均在阿肯色大学实验室中，以25℃、70%相对湿度的条件饲养至3龄和5龄阶段。 (c) 茎表皮毛刮除处理 …… # 表皮毛的阻碍效应：茎表皮毛依物种与龄期阻碍植食性昆虫移动 数据集DOI：[10.5061/dryad.n02v6wxb4](https://doi.org/10.5061/dryad.n02v6wxb4) ## 数据与文件结构说明 ### 文件与变量 #### 文件：Supplementary_data.xlsx（补充数据.xlsx） **描述：** 本文件包含实验中获得的整合实验数据。 Sheet 1 - 数据（"Data"） Sheet 2 - 元数据与变量定义（"Metadata and definition of variables"） ##### 变量说明： * 爬行速度（Speed, cm/min）：指定时长内幼虫攀爬茎秆的平均速度，单位为厘米/分钟 * 攀爬成功情况（"Completed"）：衡量幼虫攀爬成功与否的指标 * 总爬行距离（distance_cm）：指定时长内幼虫的总爬行距离，单位为厘米。对于完全未从初始位置移动的幼虫，赋值为0，对应“未到达植株顶端”。 ## 代码与软件 本数据集采用R Studio进行数据分析，使用data.table包完成数据集的整理与处理。先进行方差分析（ANOVA），随后采用Tukey HSD检验开展事后多重比较……