A Strange Butterfly-Ant Relationship Discovered in Peru
By Aaron Pomerantz
Phil Torres and I recently described the never-before-seen life history of Adelotypa annulifera, a metalmark butterfly in the family Riodinidae. While many riodinid butterfly species are known to have a symbiotic relationship between their caterpillars and ants, this appears to be the first documented case where the adult butterflies co-exist with ants.
Since we knew little about this butterfly species beyond dead specimens, Phil and I decided to collaborate, as I was making a return trip to the same field site in southeastern Peru. After hours of hiking through the Tambopata rainforest, I was finally able to uncover the larvae of this butterfly.
The life history for any species belonging to this genus was completely unknown until now. Eggs of Adelotypa annulifera are laid at the tips of new-growth bamboo culm sheaths bearing extrafloral nectary sites where adult butterflies and ants gather to feed.
The immature caterpillar stages are actively tended by multiple species of ants, including the bullet ant Paraponera clavata, and were observed feeding on the extrafloral nectaries of the bamboo. Pupation of A. annulifera then occurs on the host plant near the base of the bamboo.
We also observed the butterflies stealing bamboo sap secretions from the ants, a potential form of kleptoparasitism which was previously unknown to occur with these adult butterflies.
Perhaps the butterflies are utilizing a pheromone from their larval stage, potentially allowing the caterpillars to take advantage of the ants, which would normally attack other invading insects. The three red spots on the butterfly wing also look strikingly like the red ants that they associate with, and perhaps this wing pattern serves as a form of mimicry (if a butterfly looks like red ants that bite and sting, a bird may be less inclined to eat it). This is just a hypothesis at the moment, and future work should test this putative mimicry wing pattern and chemical signals. We hope to continue investigating this fascinating species, because there certainly seems to be more to this tropical butterfly than meets the eyes.
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