I have watched video on youtube where guy pours molten aluminium into fire ant colony to make casing. In the comments below there's huge discussion on is that a right thing to do. I am on the side that one should not exterminate colony of living things to get aluminium shape of questionable artistic value.
I believe every living organism (even single cell ones) experience pain somehow, because it is important to stay alive. The scientific answer depends on how you define pain...
Evidence suggests that some, if not all, invertebrates have the potential to suffer through current practices that do not take into consideration that invertebrates may experience something like pain and stress and have the capacity for advanced and unexpected cognitive abilities.
Genetic analysis of nociceptive behaviors in the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster has led to the discovery of conserved sensory transduction channels and signaling molecules. These are embedded in neurons and circuits that generate responses to noxious signals. This article reviews the neurons and molecular mechanisms that underlie invertebrate nociception. We begin with the neurobiology of invertebrate nociception, and then focus on molecules with conserved functions in vertebrate nociception and sensory biology.
Just to mention fire ants you possibly meet are invasive species, so you should not protect them.
The red imported fire ant, Solenopsis invicta Buren, is an invasive pest that has become widespread in the southern United States and Caribbean after accidental introduction from South America in the 1930's. This species, which has diverse detrimental impacts on recipient communities, was recently discovered in Australia and New Zealand and has the potential to colonize numerous other regions.
- Figure 1 - fire ants worldwide - source