Predator-cue induced plasticity of defensive morphology and behavior in planthoppers facilitate the survival from predation

Predators can induce morphological plasticity in prey through selection driven by predation risk. However, defense plasticity is rarely reported in insects, let alone trans-generational plasticity, the underlying mechanisms and attention of such plasticity devoted to pest control and ecosystem evolution. Here we examined the morphological plasticity of small brown planthoppers (SBPHs), <i>Laodelphax striatellus</i>, elicited by caged predators, <i>Paederus fuscipes</i> in the parent or F1 generations and uncover the risk cues mediating these effects. We also uncovered the survival outcomes in SBPHs with predator-induced defensive morphological traits by examining their survival probability and behavioral plasticity. Results showed caged predators or predator odor cue could enhance a higher proportion of long-winged, female SBPHs in the parent and F1 generation, but the proportion of males neither short- nor long- winged forms were affected. The visual cue from predators elicited weaker effects. Surprisingly, we discovered these long-winged forms suffer a lower predation rate when attacked by <i>P. fuscipes, </i>owing to an enhanced agility level. Our results suggest the within- and trans-generational plasticity of induced defenses may cause profound effects on SBPH population dynamics and prey-predator interaction. Understanding this interaction and mechanisms may illuminate the context of ecosystem evolution, help to predict pest dispersal or migration, which contributes to pest control.

捕食者可通过捕食风险介导的选择作用，诱导猎物产生形态可塑性（morphological plasticity）。然而昆虫中的防御可塑性鲜有报道，跨代可塑性（trans-generational plasticity）更是如此，且这类可塑性在害虫防治与生态系统演化领域的潜在机制与研究关注度均未得到足够重视。本研究以笼养捕食者褐足隐翅虫（Paederus fuscipes）为胁迫源，探究亲代与F1代灰飞虱（small brown planthopper，SBPH，学名Laodelphax striatellus）的形态可塑性，并解析介导该效应的风险信号因子。本研究同时通过检测灰飞虱的存活概率与行为可塑性，明确了携带捕食者诱导的防御性形态性状的灰飞虱的存活结局。结果表明，笼养捕食者或其气味信号可提升亲代与F1代雌虫中长翅型灰飞虱的比例，但雄虫的翅型比例，无论长翅或短翅型，均未受影响。捕食者的视觉信号则仅能引发较弱的调控效应。令人意外的是，本研究发现这类长翅型个体在遭遇褐足隐翅虫捕食时的被捕食率更低，这源于其运动敏捷性的提升。本研究结果表明，诱导型防御的代内与跨代可塑性可对灰飞虱种群动态以及猎物-捕食者互作产生深远影响。深入解析这类互作关系与潜在机制，可为生态系统演化研究提供新的理论视角，助力预测害虫的扩散与迁飞规律，进而为害虫防治工作提供理论支撑。