On a recent camping trip near Payson, Arizona, I found ants in a pine tree. They seemed to be defending a crack in the tree filled with resin.
The area looked like this:
I was interested in what they were doing, because I have read/seen conflicting information about the effects of pine resins on ants.
For example, in Tom Eisner's For Love of Insects, he gives anecdotal evidence that ants are repelled by pine resin. Scientists have reported that stingless bees cover their nests with plant resins in response to ant attacks, suggesting the resins repel ants. One of the components of certain plant resins, limonene, is touted as a natural insecticide effective against ants (limonene is also found in citrus fruit peels).
The ants I had observed didn't seem to be repelled by the resin. They were walking all over it, and apparently had a nest nearby.
I had also seen the video, Ants: Nature's Secret Power. In this section, wood ants are shown carrying resin back to their nest, at some cost to themselves. Take a look:
Experiments have shown that wood ants, Formica paralugubris, use pine resins as antibiotics, that is, as protection against pathogens.
Is this a case of one ant's poison being another ant's medicine? It seems likely that different species of ants would have different reactions to resins. Also, resins are not all identical. Some contain different terpenes, or higher levels of resin acids, which could change the level of repellency or antibiotic properties.
Seems like a relationship that needs further investigation. What do you think about ants and resins?
For further information:
Michel Chapuisat, Anne Oppliger, Pasqualina Magliano, and Philippe Christe. (2007). Wood ants use resin to protect themselves against pathogens. Proc. R. Soc. B. 274: 2013–2017.
Published online 29 May 2007
Paper is available online for free
Lisette Lenoir, Jan Bengtsson, and Tryggve Persson. (2003). Effects of conifer resin on soil fauna in potential wood-ant nest materials at different moisture levels. Pedobiologia. 47 (1): 19-25.
Sara Diana Leonhardt and Nico Blüthgen. (2009). A Sticky Affair: Resin Collection by Bornean Stingless Bees. Biotropica. 41 (6): 730 - 736.