Maculinea butterflies have a good thing going. As larvae they hang out in Myrmica ant nests, feeding on the ant’s own larvae in safety and comfort. Room, board and three squares a day, the only thing that could mess it up is if those pesky ants got wise to the scam and, oh, tore the butterfly larvae apart and ate it.
So why don’t they? Part of it is that the larvae use chemical signals to fool the ants, but scientists have also recently discovered that parasitic Maculinea species, commonly known in their adult forms as Large Blue butterflies, have also learned to mimic ant voices and “talk” to the ants, letting them know that everything is cool man and that they’re going to get a job and have their half of the rent next week.
“Acoustic signals convey quite complex information, not only between worker ants while outside the colony, for example during foraging, but also within the nest and between castes,” said Francesca Barbero, the lead researcher on the recent study from the University of Turin, Italy. “We aimed at understanding whether some ant social parasites, such as butterfly larvae, could interfere with their host ant communication system.”
The researchers recorded and observed the sounds parasitic butterfly larvae made and played them back to ant nests to see how the sounds impact ant behavior. Other researchers had found earlier that parasitic butterflies can influence ants by making baby ant “begging” sounds and secreting chemicals that make them smell like ant larvae.
However, that’s by no means the end of their acoustic tricks. As Barbero’s team found, once inside the nests they also mimic the unique sounds made by the colony’s queen, tricking the ants into giving them the royal treatment and taking care of them at the expense of their own offspring.
Some species of larvae actually adapt a “cuckoo” strategy in which the ants actually feed and clean them. Researchers found those larvae were more forceful in their cries, while the predatory larvae simply did enough to not get noticed.
“This is consistent,” Barbero said. “Once inside the host nest, the main difference between the two life strategies is that cuckoos need to be considered as colony members, predatory species need not to be discovered by ants.”
[Source: Acoustical Society of America]
Image by Marco Gherlenda/University of Turin