Some caterpillars have evolved a remarkable ability to communicate with ants – not through chemical signals, as previously understood, but through rhythmic vibrations that mimic the ants’ own communication methods. A study published on , in the Annals of the New York Academy of Sciences, reveals that certain caterpillars can produce vibrations with a complexity that appears to facilitate a close, and sometimes parasitic, relationship with ant colonies.
Many caterpillars belonging to the gossamer-winged butterfly family exhibit “myrmecophily,” meaning they have a fondness for ants. This relationship varies; some caterpillars receive protection or food from their ant hosts, while others are fully integrated into the ant nest, even exploiting it by feeding on ant larvae. Researchers have long known that these caterpillars sometimes mimic ant chemical cues to gain acceptance. However, recent research suggests a more sophisticated form of communication is at play.
“Research had hinted that some caterpillars were copying the way ant queens vibrate to communicate with their colony,” explains Chiara De Gregorio, an ethologist at the University of Warwick in England. This led to the hypothesis that caterpillars might be “exploiting existing communication systems within the ant colony.”
De Gregorio and her team investigated this possibility by collecting nine caterpillar species and colonies of two ant species from across Northern Italy. They categorized the caterpillars based on the degree of their relationship with ants, ranging from those with no association to those completely reliant on ants for survival. Using sensitive microphones, the researchers recorded and analyzed the vibrations produced by both caterpillars and ants as they traveled through materials like dirt. This allowed for a detailed examination of the tempo and regularity of these buzzing signals.
The analysis revealed that both caterpillars and ants generate vibrations with a regular, metronome-like pattern. However, a key finding emerged: only the caterpillars most dependent on ants were capable of producing rhythmic patterns that matched the complexity of the ants’ vibrations. This included maintaining consistent pauses between pulses and alternating between long and short intervals. This precise rhythmic language appears crucial for establishing a strong partnership with the ants.
“Across many animal species, rhythm is increasingly recognized as an important component of communication,” De Gregorio notes. “It’s not only what is communicated that matters, but also how.”
The researchers believe the ants already utilize these vibrations for their own communication purposes. Caterpillars capable of mimicking this vibrational language likely receive increased attention and care from the ants, effectively integrating themselves into the colony. This suggests a form of vibrational mimicry, where caterpillars are essentially “speaking the language” of their ant hosts.
The implications of this research extend beyond the specific caterpillar-ant interactions studied. Luan Dias Lima, an entomologist at the University of São Paulo in Brazil, suggests that similar studies on metalmark butterflies – another group of caterpillars known for their close relationships with ants – could reveal whether a “global universal rhythm” exists for ant-butterfly communication. Comparing these independently evolved relationships could provide valuable insights into the evolution of interspecies communication.
De Gregorio finds the level of rhythmic complexity particularly striking, especially considering her background in primate studies. While primates possess sophisticated brains, the ability to generate and recognize rhythm is relatively rare, observed in only a few species like humans, indri lemurs, and gibbons. The discovery of comparable rhythmic organization in ants and caterpillars suggests that the capacity for rhythmic communication may be more widespread in the animal kingdom than previously thought.
“Observing comparable levels of rhythmic organization in ants was genuinely mind-blowing,” she says. The findings raise the possibility that keeping a beat – a fundamental aspect of communication – may be a more basic and widespread ability among animals than previously appreciated. This research opens new avenues for understanding the evolution of communication and the intricate relationships between species.
The study highlights the often-overlooked complexity of insect communication and the remarkable adaptations that allow species to thrive through interspecies interactions. Further research will be needed to fully understand the nuances of this vibrational language and its role in shaping the ecological dynamics between caterpillars and ants.
