Plant strategies against herbivorous insects

Plant growth and productivity are strongly constrained by herbivorous insects, which reduce both yield and quality. Over the past two centuries, extensive efforts have been devoted to identifying natural insect-resistant traits and genes that have evolved in plants. Here, we first review key milestones and advances, including empirical observation, mechanism onset, theoretical emergence, gene identification, and breeding application. Then, we categorize research on plant defenses for insect resistance into four major types: physical, chemical, ecological modulation, and behavioral defenses, and integrate them to highlight the coordination and synergy among different defenses. Finally, we propose priority areas and future directions for research to advance studies on plant–insect interactions and support effective and sustainable pest management.