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 ...,