Reduced palatability, fast flight, and tails: Decoding the defence arsenal of Eudaminae skipper butterflies in a Neotropical locality

Prey often rely on multiple defences against predators, such as flight speed, attack deflection from vital body parts, or unpleasant taste, but our understanding on how often and why they are co-exhibited remains limited. Eudaminae skipper butterflies use fast flight and mechanical defences (hindwing tails), but whether they use other defences like unpalatability (consumption deterrence), and how these defences interact, has not been assessed.

We tested the palatability of 12 abundant Eudaminae species in Peru, using training and feeding experiments with domestic chicks. Further, we approximated the difficulty of capture explained by flight speed and quantified by wing loading. We performed phylogenetic regressions to find any association between multiple defences, body size, and habitat preference.

We found a broad range of palatability in Eudaminae, within and among species. Contrary to current understanding, palatability was negatively correlated with wing loading, suggesting that faster butterflies tend to have lower palatability.

The relative length of hind wing tails did not explain the level of butterfly palatability, showing that attack deflection and consumption deterrence are not mutually exclusive. Habitat preference (open or forested environments) did not explain the level of palatability either, although butterflies with high wing loading tended to occupy semi-closed or closed habitats.

Finally, the level of unpalatability in Eudaminae is size dependent. Larger butterflies are less palatable, perhaps because of higher detectability/preference by predators. Altogether, our findings shed light on the contexts favouring the prevalence of single vs. multiple defensive strategies in prey.

猎物通常会依托多重防御策略抵御捕食者，例如提升飞行速度、偏转针对身体要害部位的攻击，或是生成难闻的异味（即拒食性），但学界目前对这些防御策略的共现频率及其背后动因的认知仍十分有限。花弄蝶亚科（Eudaminae）的弄蝶已被证实会借助快速飞行与机械防御手段（后翅尾突）抵御天敌，但它们是否会采用拒食性这类其他防御策略，以及这些防御策略间的相互作用机制，目前尚未得到系统研究。

本研究以家鸡雏为实验对象，通过驯化与饲喂实验，评估了秘鲁境内12种常见花弄蝶亚科物种的适口性；此外，我们基于飞行速度估算了猎物被捕获的难度，并以翼载荷（wing loading）作为量化指标；同时通过系统发育回归分析，探究了多重防御策略、体型大小与栖息地偏好之间的关联。

研究结果显示，花弄蝶亚科物种内部及物种间的适口性存在广泛差异。与当前学界的主流认知相悖的是，适口性与翼载荷呈负相关关系，这表明飞行速度更快的弄蝶往往适口性更低。

后翅尾突的相对长度与弄蝶的适口性并无显著关联，这说明攻击偏转防御与拒食性防御并非互斥的策略。栖息地偏好（开阔或森林生境）同样无法解释适口性的差异，尽管翼载荷较高的弄蝶往往栖息于半封闭或封闭的生境中。

最后，花弄蝶亚科的拒食性水平与体型大小相关：体型更大的弄蝶适口性更低，这可能是因为捕食者更易发现此类个体，或是对其存在捕食偏好。综合来看，本研究的发现为阐释猎物偏好采用单一防御策略还是多重防御策略的情境条件提供了新的理论视角。