Mimicry with a difference

Butterfly imitates wasps to fake his role models

Almost perfect similarity: wasp (left) and butterflies are almost indistinguishable. © Michael Boppré
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Textbook opinion incomplete: A small butterfly reveals that mimicry can work quite differently than previously thought. Because this bear moth disguises itself as a wasp, but does not rely on the deterrent effect. Instead, he wants to deceive his role model: the wasps themselves. Because these do not attack conspecifics - and thus not the little butterfly.

Mimicry - the imitation of poisonous or highly fortified species - is a common strategy in the animal kingdom. For example, a cockroach in Vietnam mimics the black and yellow warning defensiveness of sturdy ground beetles, hoverflies imitate wasps and some harmless snakes mimic venomous relatives.

According to popular doctrine, this mimicry serves above all to deter eating enemies. These antagonists, so the theory established for about 150 years, learn from bad experience, for example, with stinging wasps and therefore avoid similar-looking animals.

A butterfly as a pseudo-wasp

But this idea is obviously not true for all cases of mimicry - the theory is incomplete, as Michael Boppré from the University of Freiburg and his colleagues found the example of some Bärenspinner. These diurnal moths mimic wasps: they are patterned yellow-black, have wasp waists and their wings are transparent and folded like wasps.

"Especially in flight, the role models and their imitators are hardly distinguishable even for experienced eyes, " says Boppré. For him, therefore, the question arose why the moths have developed this almost perfect imitation and who they dupe with it. Because to keep predators at bay, an imperfect similarity is sufficient. display

Deception of the wasps as a target

By observing the moths in nature, the researchers came up with an amazing answer to their mimicry question: With the wasp-look, the moths do not want to deceive birds, but their role models - the wasps. Because these hunt other insects and thus the bear moths. But an innate inhibition prevents the wasps from attacking other wasps.

The moths therefore do not imitate the wasps because of the deterrent effect, but so that they are kept by the wasps for conspecifics - and thus protected from attacks. "This new explanation may seem like a small detail at first glance, but the idea alone has far-reaching consequences, " emphasizes Boppré.

Textbook must be supplemented

According to popular doctrine, mimicry is based on a learning effect of predators - which is why it works only if the role models occur at least temporarily more often than their counterparts. The imitators must therefore not be too frequent, which means a disadvantage for them.

In the case of the bear moth, however, this is not the case: "Mimicking wasps that do not attack their imitators innately does not require that price, " says the researcher. The usual theory must therefore at least be supplemented. (Ecology and Evolution, 2017; doi: 10.1002 / ece3.2586)

(Albert-Ludwigs-University Freiburg im Breisgau, 28.02.2017 - NPO)