This post marks the beginning of something I've been meaning to start for a long time: blogging about peer-reviewed research. The Research Blogging site has some cool features for doing this, and so this is a bit of an experiment into how all of that works.
The first paper is on ants, an invertebrate certainly, but not one I'm an expert on. The reason it appealed to me, I think, boils down to seeing a talk by Bert Hölldobler (of Hölldobler & Wilson fame) recently at the Natural History Museum. I was also once a physicist, and we like such things.
First some background, the 'blue butterflies' are in the family Lycaenidae. This family is well known for its association with ants. The caterpillars actually live as social parasites within the nests of ants (they get the ants to feed them, they don't feed on the ants).
Ants primarily communicate with each other via chemicals (hydrocarbons) and physical contact (Hölldobler's talk showed some fascinating videos of physical interactions). The caterpillars can replicate the chemical signals used by the ants, causing the ants to carry them into their nest and feed them as they would their own young.
But that's not the whole story. If an event happened which required the ants to rescue their larvae, they would actually rescue the blue butterfly caterpillars over their own children. Indeed if food becomes scarce the ants will kill and feed their own larvae to the caterpillar. The queens of the ant nests may treat the invader as a rival, whilst the workers treat it as royalty. This paper explains how this happens.
The species of ant used in the study, Myrmica schencki, can make stridulatory noises that vary between workers and queens. It is by mimicking these noises that the butterfly caterpillar, and pupa, persuades the worker ants of its high value to the colony (by sounding more like a queen than a worker).
There are probably aroun 10,000 different species that parasitise ant nests, so there is plenty of scope for further work to see how widespread this phenomenon is.
Francesca Barbero, Jeremy A Thomas, Simona Bonelli, Emilio Balletto, Karsten Schönrogge (2009). Queen Ants Make Distinctive Sounds That Are Mimicked by a Butterfly Social Parasite Science, 323