Fire ants cover inaccessible surfaces with particles to aid food search (2020)

You're right, my mistake! I didn't play the video today before I linked it, and I didn't remember it had sound! That was definitely not a GIF! :)

I've now updated my original comment to read "video" instead of "GIF" to fix the error.

You can try it for yourself. I've tried killing fire ants before with sticky poison and they intentionally "clog" it up, just like in the gif.

If you scroll down the Twitter thread, there's another gif that highlights an individual worker.

Watching her makes it pretty clear that it's intentional, not just dropped or random.

> They pick this thing up based on pure instinct, or chemical programming, and they get stuck on the sticky surface so they abandon their item. Could be as simple as that until we see more evidence.

Intentional paving is also based on pure instinct or chemical programming.

The experiment did include trials with either food or non-food items in the prepared patches, and "significantly more particles were relocated on viscose and paraffin-smeared surfaces in the presence of food than in the presence of non-food objects." The abstract does not say whether, in the absence of particles to relocate, such areas received sufficiently more traversal attempts to account for this difference, and I am disinclined to drop $20 for the full article.

One could also wonder why the ants are picking up and moving non-food particles in the first place. The process you describe is one that could have driven selection for picking-up-and-carrying: perhaps it was selected for because it helped foraging in the way you suggest.

Is there evidence for or against the proposition that ants are just as likely to pick up and carry these particles whether or not sticky patches are nearby? Do they move them at the same rate in all directions when there is a sticky patch nearby? Under your hypothesis, we might expect the particles to spread equally in all directions, in accordance with some form of the diffusion equation, until they reach the sticky edge, and that's not what seems to be happening in the video.