Plants Anticipating Help: A New Hypothesis in Plant Defence Theory
Michael S Singer1, Tamara M Kancoglu1, Hartmut A Doerwaldt1
1Department of Biology, Wesleyan University, Middletown, Connecticut, USA.
Ecology Letters
|December 31, 2025
Summary
Plants can anticipate help by detecting cues that signal bodyguard protection. This allows them to reduce direct defenses, a strategy termed
Area of Science:
- Plant Ecology
- Chemical Ecology
- Evolutionary Biology
Background:
- Plants can respond to herbivory ('cry for help') and anticipate it using environmental cues.
- The 'anticipating help' hypothesis proposes plants can detect cues for reliable protection from herbivores' enemies (bodyguards).
- This hypothesis suggests plants may downregulate direct defenses when bodyguards offer compensation.
Purpose of the Study:
- To test the assumptions of the 'anticipating help' hypothesis in plant defense.
- To investigate if plants can detect cues for bodyguard protection and adjust their defenses accordingly.
- To explore the role of induced susceptibility in plant-environment interactions.
Main Methods:
- A meta-analysis of sequential herbivory experiments was conducted.
- The study examined cue detection and downregulation of direct resistance in plants.
- Focus was on interactions between sap-feeding herbivores, leaf-chewing herbivores, and ant bodyguards.
Main Results:
- Plants showed induced susceptibility (reduced direct resistance) to leaf-chewing herbivores only after induction by sap-feeding herbivores.
- This induction by sap-feeding herbivores acts as a cue for reliable ant-mediated protection.
- The findings support the idea that plants can anticipate and adjust defenses based on bodyguard availability.
Conclusions:
- The 'anticipating help' hypothesis is supported by evidence of cue detection and defense downregulation.
- This behavior is expected when environmental cues predict reliable bodyguard protection, compensating for reduced direct defenses.
- The hypothesis helps explain phenomena like induced susceptibility and associational resistance, broadening our understanding of indirect plant resistance.
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