Last week Kiran Gadhave wrote about “The Curious Case of the Large Blue Butterfly,” and he described how the butterfly larvae fool ants into taking them into their colonies, where they then eat the ant grubs.
Now researchers may have discovered how the caterpillars fool the ants by making sounds that mimic the ant queen. The study was recently published in the journal PLOS ONE.
Ants have evolved a complex set of signals that allow colony members to distinguish between residents and intruders. The social parasitic Maculinea butterfly uses chemical and acoustic adaptations to trick ant signaling defenses, and manages to spend most of its life cycle inside the ant nest.
To better understand the potential role of acoustic signals in butterfly larvae integration and adoption by ant colonies, scientists compared two populations of parasitic butterflies — a predatory species that feeds on ant broods, and a cuckoo species that is fed directly by the worker ants. The eggs of both species are laid outside of ant colonies, and then they are eventually adopted by the ants.
The researchers recorded and analyzed acoustic emissions from butterfly larvae before and after their adoption by the ant colonies, and from worker and queen ants. They then played the sounds and observed the ants’ behavior.
In the first recording experiment, the authors found that butterfly larval acoustic emissions were more similar to those of queen ants than to those of the worker ants, although the larval acoustic sounds varied between and within butterfly species. Playback experiments showed ant workers responding the most strongly to sounds from post-adopted cuckoo larvae and from predatory larvae sounds recorded pre-adoption.
These results suggest acoustic signals may play a role in parasite integration and adoption into the colony.
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