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...

为抵御捕食、得以存续，动物演化出了多样的防御策略，其中化学防御手段尤为普遍且形式丰富。本研究聚焦化学防御多样性的功能，提出假说：这类多样性的演化是动物应对多类天敌的适应性结果。本研究的对象为具有警戒色的木虎蛾（Arctia plantaginis），其后翅色彩醒目，且可从胸部腺体与腹部分泌两种截然不同的防御体液。我们将实验室饲养的木虎蛾所分泌的防御体液，分别施加给两种具有生态相关性的捕食者——鸟类与蚂蚁，并在可控的生物测定实验中记录二者的反应（实验未提供体色相关信息）。我们发现防御体液具有靶标特异性：胸部腺体分泌的体液，尤其是其中含有的2-仲丁基-3-甲氧基吡嗪（2-sec-butyl-3-methoxypyrazine，SBMP），可驱避鸟类，但对蚂蚁未引发厌恶反应。与之相反，腹部分泌的体液对蚂蚁具有显著驱避效果，而鸟类则未表现出排斥反应。本研究首次表明……