Biomechanical components of the plant-insect herbivore arms race: a model test in leaf-cutter ants
Author(s)
Walthaus, Olivia K
Deegala, Dilanka I
Delattre, Raphael
Labonte, David
Type
Journal Article
Abstract
Insects and plants have been locked in an evolutionary arms race spanning 350 million years. Insects evolved specialized tools to cut into plant tissue, and plants, to counter these attacks, developed diverse defence strategies. Much previous worked has focused on chemical defences. How can plants vary their mechanical properties to deter herbivores, and how can insects respond? We test a simple mechanical model that relates the force required to cut thin, leaf-like tissues to their mechanical properties and the geometry of the cutting tool. To remove the confounding effects of tool shape across size, we use leaf-cutter ant mandibles as a model system. Cutting forces were measured for pristine and worn mandibles that vary by one order of magnitude in size, using a custom-built fibre-optic set-up and homogeneous pseudoleaves as well as a set of plant tissues as model substrates. The results substantially support the model, enabling quantitative predictions. Fracture toughness is identified as a key mechanical defence trait for plants, cutting edge radius as the critical geometric property of the insect mandible and cutting edge wear consequently emerges as a key modulator of cutting forces, elevating it up to fivefold above a physical minimum. Thus, plants may be served by implementing strategies that maximize wear, whereas insects should seek to minimize it.
Date Issued
2025-09-01
Date Acceptance
2025-06-19
Citation
Journal of the Royal Society Interface, 2025, 22 (230)
ISSN
1742-5689
Publisher
The Royal Society
Journal / Book Title
Journal of the Royal Society Interface
Volume
22
Issue
230
Copyright Statement
©2025 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/40925554
Subjects
AGE
ATTA
cutting
CUTTING ANTS
EVOLUTION
fracture
FRACTURE-TOUGHNESS
HYMENOPTERA
INDUCED RESISTANCE
insect herbivory
MANDIBULAR WEAR
MECHANICAL-PROPERTIES
Multidisciplinary Sciences
plant mechanical defences
Science & Technology
Science & Technology - Other Topics
SHARPNESS
Publication Status
Published
Coverage Spatial
England
Article Number
20250091
Date Publish Online
2025-09-10