# Phytochemical diversity and seasonality are associated with a critical transition in plant–herbivore network structure

## TL;DR

This study shows how seasonal changes and plant chemicals can cause sudden shifts in plant-insect networks, affecting ecosystem stability.

## Contribution

The study identifies a critical transition in plant-herbivore network structure linked to seasonality and phytochemical diversity.

## Key findings

- A critical network structural transition occurs between rainy and dry seasons in tropical forests.
- Seasonal changes and plant phytochemical diversity are associated with this transition.
- The transition increases pathways and potential for cascading effects in the network.

## Abstract

Understanding critical transitions in ecological systems is fundamental for addressing various natural phenomena, from population outbreaks to sudden ecosystem collapses. Ecological interactions are key drivers of these transitions, and theory suggests that the networks formed by these interactions can undergo their own critical transition. By examining interactions between plant individuals and insect species in a tropical forest, we first identified a critical network structural transition between the rainy and dry seasons. Next, we showed that seasonal changes and the phytochemical diversity of plants are associated with this transition. Finally, we quantified the consequences of the critical transition, which significantly increases the number of pathways and the potential for cascading effects among plants and herbivores in the network. Our findings reveal that ecological networks can experience abrupt changes on shorter timescales than previously recognized, with profound implications for cascading effects and the impacts of human‐induced perturbations on the stability of ecological assemblages.