Data from: How to fight multiple enemies: target-specific chemical defences in an aposematic moth

Animals have evolved different defensive strategies to survive predation, among which chemical defences are particularly widespread and diverse. Here we investigate the function of chemical defence diversity, hypothesising that such diversity has evolved as a response to multiple enemies. The aposematic wood tiger moth (Arctia plantaginis) displays conspicuous hindwing colouration and secretes two distinct defensive fluids, from their thoracic glands and abdomen. We presented fluids from lab-reared moths to two biologically relevant predators, birds and ants, and measured their reaction in controlled bioassays (no information on colour was provided). We found that defensive fluids are target-specific: thoracic fluids, and particularly the 2-sec-butyl-3-methoxypyrazine (SBMP) which they contain, deterred birds, but caused no aversive response in ants. In contrast, abdominal fluids were particularly deterrent to ants, while birds did not find them repellent. Our study is the first to show evidence of a single species producing separate chemical defences targeted to different predator types, highlighting the importance of taking into account complex predator communities in studies on the evolution of prey defence diversity.为应对捕食胁迫，动物演化出了各异的生存防御策略，其中化学防御手段尤为广泛且多样。本研究旨在探究化学防御多样性的功能，提出假说：此类多样性的演化是针对多类天敌的适应性响应。 本研究的实验对象为具有警戒色（aposematic）的木虎蛾（Arctia plantaginis），该物种成虫拥有醒目的后翅色彩，并可分别从胸部腺体与腹部分泌两种不同的防御体液。 我们将实验室饲养的木虎蛾所产出的防御体液，施加于两种生态相关的捕食者——鸟类与蚂蚁，并在可控的生物测定（bioassay）实验中记录二者的行为反应（实验未提供体色相关信息）。 研究结果表明，防御体液具有靶标特异性：胸部体液及其所含的2-仲丁基-3-甲氧基吡嗪（2-sec-butyl-3-methoxypyrazine, SBMP）可有效驱避鸟类，但对蚂蚁未产生驱避效应；与之相对，腹部体液对蚂蚁具有显著的驱避作用，而鸟类并未表现出排斥反应。 本研究首次证实单一物种可产生针对不同捕食者类群的专属化学防御，凸显了在猎物防御多样性的演化研究中，纳入复杂捕食者群落视角的重要性。