Data from: Herbivory-induced volatiles function as defenses increasing fitness of the native plant Nicotiana attenuata in nature

From an herbivore’s first bite, plants release herbivory-induced plant volatiles (HIPVs) which can attract enemies of herbivores. However, other animals and competing plants can intercept HIPVs for their own use, and it remains unclear whether HIPVs serve as an indirect defense by increasing fitness for the emitting plant. In a two-year field study, HIPV-emitting N. attenuata plants produced twice as many buds and flowers as HIPV-silenced plants, but only when native Geocoris spp. predators reduced herbivore loads (by 50%) on HIPV-emitters. In concert with HIPVs, plants also employ antidigestive trypsin protease inhibitors (TPIs), but TPI-producing plants were not fitter than TPI-silenced plants. TPIs weakened a specialist herbivore’s behavioral evasive responses to simulated Geocoris spp. attack, indicating that TPIs function against specialists by enhancing indirect defense.

当植食性动物首次啃食植物时，植株会释放植食诱导植物挥发物（herbivory-induced plant volatiles，HIPVs），这类挥发物可吸引植食者的天敌。然而，其他动物以及存在种间竞争关系的植物可截获HIPVs以供自身利用，目前学界仍未明确HIPVs是否可通过提升释放植株的适合度，从而发挥间接防御功能。在一项为期两年的野外研究中，释放HIPVs的N. attenuata植株所产生的芽与花数量，是HIPV沉默植株的两倍，但该现象仅在本地大眼蝽属（Geocoris spp.）天敌将HIPV释放植株上的植食者负载量降低50%时才会显现。与HIPVs协同发挥作用的是，植株还会合成抗消化型胰蛋白酶蛋白酶抑制剂（antidigestive trypsin protease inhibitors，TPIs），但合成TPIs的植株并未比TPI沉默植株拥有更高的适合度。TPIs会削弱专食性植食者对模拟大眼蝽属天敌攻击的行为逃避反应，这表明TPIs可通过增强间接防御来对抗专食性植食者。