Elevated nitrogen deposition protects an invasive plant from herbivory through altering leaf volatile-mediated tritrophic interactions
Data files
Sep 28, 2026 version files 104.05 KB
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dataset_for_dryad0427.xlsx
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README.md
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Abstract
Atmospheric nitrogen deposition has risen worldwide and disrupted plant-herbivore interactions. However, the ecological relationships concerning the changes in leaf volatile organic compounds (VOCs) triggered by elevated nitrogen deposition, along with the associated resistance mechanisms against herbivores across multi-trophic levels, remain largely unexplored within the context of plant invasion.
In this study, we explored the impact of elevated nitrogen deposition on the quantity and composition of leaf constitutive and herbivore-induced plant volatiles in the invasive weed Alternanthera philoxeroides and its native congener A. sessilis, as well as the cascading effects on their herbivores and natural enemies.
Field surveys showed that herbivores laid significantly fewer eggs on A. philoxeroides than on A. sessilis in terrestrial habitats experienced high levels of atmospheric nitrogen deposition. Laboratory bioassays revealed that simulated nitrogen deposition increased the emission and altered the composition of both constitutive and herbivore-induced plant volatiles in A. philoxeroides compared to A. sessilis. These changes reduced its attractiveness to specialist and generalist herbivores while enhancing its appeal to predatory beetles.
Methyl salicylate was identified as the key compound driving these changes in insect behaviors, highlighting its critical role in mediating plant-insect interactions in A. philoxeroides under elevated nitrogen deposition.
Elevated nitrogen deposition alters leaf volatile emissions, thereby increasing herbivore repellence and natural-enemy attraction in an invasive plant relative to its native congener.
Description of the Data and File Structure
This workbook contains nine worksheets: (1) plant growth traits and leaf chemical properties, (2) field survey data, (3) blank test for olfactometer, (4) Y-tube olfactometer bioassays, (5) four-arm olfactometer bioassays, (6) oviposition bioassays, (7) CPVs (constitutive plant volatiles), (8) HIPVs (herbivore-induced plant volatiles), and (9) Y-tube olfactometer bioassays with methyl salicylate.
Treatment codes and terminology are defined below:
A.Alternanthera philoxeroides (A. philoxeroides): invasive plant; Alternanthera sessilis (A. sessilis): native plant; Agasicles hygrophila: specialist herbivore; Spodoptera litura: generalist herbivore; Harmonia axyridis: predatory natural enemy; CPVs (constitutive plant volatiles): volatiles emitted constitutively in the absence of herbivory; HIPVs (herbivore-induced plant volatiles): volatiles induced and emitted following herbivore feeding.
CKK — A. philoxeroides grown in control soil
CKL — A. sessilis grown in control soil
NK — A. philoxeroides grown under simulated nitrogen deposition
NL — A. sessilis grown under simulated nitrogen deposition
CK: control treatment without simulated nitrogen deposition
N: simulated nitrogen deposition treatment
plant population: population identity within each plant species
Sheet 1: growth traits and leaf chemicals
Column name: ID: Unique sample identifier composed of the treatment code and the within-treatment sequence number.
Column name: volatile type: Type of volatile collection.
Column name: treatment: Combined code for plant species and nitrogen treatment.
Column name: nitrogen: Nitrogen treatment category.
Column name: species: Plant species.
Column name: population: Plant population.
Column name: leaf dry mass(g): Leaf dry mass (unit: g).
Column name: stem dry mass(g): Stem dry mass (unit: g).
Column name: root dry mass(g): Root dry mass (unit: g).
Column name: total dry mass(g): Total plant dry mass (unit: g).
Column name: number of leaves: Number of leaves (unit: leaves).
Column name: total leaf area (mm2): Total leaf area (unit: mm²).
Column name: leaf nitrogen content%: Leaf nitrogen content (unit: %).
Column name: leaf water content (%): Leaf water content (unit: %).
Column name: leaf chlorophyll content (SPAD): Leaf chlorophyll content, expressed as a SPAD value.
Sheet 2: Field Survey
Column name: species: Plant species surveyed.
Column name: location: Survey location(CX: Chuxiong, JN: Jinan, ZJ: Zhuji, YC: Yichang, HK: Haikou)
Column name: site: Site number within each location.
Column name: quadrat: Quadrat number within each site.
Column name: total amount of atmosphere nitrogen deposition (Kg N Ha-1 yr-1): Total atmospheric nitrogen deposition at the survey location (unit: kg N ha⁻¹ yr⁻¹).
Column name: number of eggs on the leaves: Number of eggs observed on the leaves (unit: eggs).
Column name: consumed leaf area (cm2): Leaf area consumed by herbivores (unit: cm²).
Sheet 3: blank test for olfactometer
Replicates: Replicate number for the Y-tube and four-arm olfactometer assays;
blank: Number of insects choosing a blank arm (unit: individuals);
plant: Number of insects choosing the plant-odor arm (unit: individuals);
No choice: Number of insects making no choice during the assay (unit: individuals).
Column name: Column A: Test-insect section label identifying the species represented by each data block; row 1 denotes Spodoptera litura, and row 15 denotes Agasicles hygrophila.
Column name: Columns B–J: Blank-versus-blank and plant-versus-blank tests conducted with the Y-tube olfactometer.
Column name: Columns L–X: All-blank and plant-versus-blank tests conducted with the four-arm olfactometer.
Sheet 4: Y-Tube Olfactometer Bioassay
Column name: Column A: Test-insect section label identifying the species represented by each data block; row 2 denotes Agasicles hygrophila, row 22 denotes Spodoptera litura, and row 43 denotes Harmonia axyridis.
Column name: Columns B–T: Pairwise comparisons among the four treatments, in the following order: CKK versus CKL, CKL versus NL, CKK versus NK, and NK versus NL. Using the CKK-versus-CKL comparison as an example, Replicates is the replicate number for the Y-tube olfactometer assay; CKK is the number of insects choosing the CKK odor arm (unit: individuals); CKL is the number of insects choosing the CKL odor arm (unit: individuals); and No choice is the number of insects making no choice during the assay (unit: individuals).
Sheet 5: Four-Arm Olfactometer Bioassay
Column name: Column A: Test-insect section label identifying the species represented by each data block; row 2 denotes Agasicles hygrophila, row 80 denotes Spodoptera litura, and row 159 denotes Harmonia axyridis. Numeric entries are replicate numbers for the four-arm olfactometer assay.
Column name: Column B: Odor-arm treatment or no-choice category represented by the row.
Column name: Column C: Original record identifier composed of the treatment category and replicate number.
Column name: Column D: Number of insects choosing the specified odor arm; when Column B is nochoice, this value is the number of insects making no choice (unit: individuals).
Sheet 6: Oviposition Bioassay
Column name: ID: Unique sample identifier composed of the treatment code and the within-treatment sequence number.
Column name: nitrogen treatment: Nitrogen treatment category; CK denotes the control treatment without simulated nitrogen deposition, and N denotes the simulated nitrogen deposition treatment.
Column name: species: Plant species offered in the oviposition-choice assay: A. sessilis or A. philoxeroides.
Column name: plant population: Plant population.
Column name: number of eggs / Agasicles hygrophila: Number of Agasicles hygrophila eggs laid on the corresponding plant material (unit: eggs).
Column name: number of eggs / Spodoptera litura: Number of Spodoptera litura eggs laid on the corresponding plant material (unit: eggs).
Sheet 7: CPVs
Column name: ID: Unique sample identifier composed of the treatment code and the within-treatment sequence number.
Column name: Replicates: Sample replicate identifier composed of the treatment code and a sequence number from 1 to 15.
Column name: Columns C–AT: Measured abundance of each compound in the sample (unit: ng mL⁻¹).
Sheet 8: HIPVs
Column name: ID: Unique sample identifier composed of the treatment code and the within-treatment sequence number.
Column name: Replicates: Sample replicate identifier composed of the treatment code and a sequence number from 1 to 15.
Column name: leaf feeding damage by Spodoptera litura (mm2): Leaf-area loss caused by Spodoptera litura feeding (unit: mm²).
Column name: total emission of HIPV: Sum of the measurements for all listed HIPV compounds in the sample.
Column name: Columns E–AH: Measured abundance of each compound in the sample (unit: ng mL⁻¹).
Sheet 9:Y-Tube For Methyl Salicylate
Column name: test-insect section label / methyl salicylate: The first row of each block identifies the test insect, whereas all other data rows identify the methyl salicylate odor arm. The three test-insect blocks correspond to Agasicles hygrophila, Spodoptera litura, and Harmonia axyridis, respectively.
Column name: number of insects1: Number of insects choosing the methyl salicylate odor arm (unit: individuals).
Column name: number of insects2: Number of insects choosing the control odor arm (unit: individuals).
Column name: control: Identifies the odor arm represented in Column C as the control.
Column name: no choice: Number of insects making no choice within the specified observation period (unit: individuals).