AsianScientist (Aug. 31, 2015) – Researchers have discovered that butterfly larvae can control dopamine secretion in ants by supplying them with nectar. The results of this study, published in Current Biology, provide novel insight into the phenomenon of symbiosis and give clues about the physiological functions of dopamine.
Lycaenid butterflies and ants are representative examples of mutualism, in which different species benefit from the activities of the other. The larvae of lycaenid butterflies secrete a nectar rich in sugars and amino acids, thereby supplying ants with a source of nutrition, whereas the ants in turn protect the larvae from their natural enemies.
However, these benefits are not necessarily balanced because the ants can find alternative sources of food, whereas the larvae are completely dependent on the ants for protection.
Therefore, assistant professor Hojo Masaru of Kobe University and joint research groups at the University of the Ryukyus and Harvard University hypothesized that the larvae possessed some mechanism to keep the ants from leaving.
Using Narathura japonica and Pristomyrmex punctatus, the group investigated the behavior of the two species under the following three conditions: ant-only, larvae and ants (with nectar) and larvae and ants (no nectar).
A reduction in locomotor activity was observed only in ants that ingested nectar, making them stay around the larvae longer. In addition, the researchers discovered that these ants were more aggressive.
Measuring brain chemicals in ants that ingested the nectar revealed a decrease in the levels of dopamine, a neurotransmitter which modulates various behaviors in animals. Moreover, a similar reduction in movement activity was observed in ants administered a drug that suppresses dopamine release (reserpine).
This study suggests that the mutualistic relationship between lycaenid butterfly larvae and ants is maintained through the selfish manipulation of behavior by the larvae.
Hojo said, “We would like to further study the benefits to the ants of taking the nectar from the larvae.”
The article can be found at: Hojo et al. (2015) Lycaenid Caterpillar Secretions Manipulate Attendant Ant Behavior.
———
Source: Kobe University; Photo: Bob Peterson/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
