The part from the paper which is so interesting is why the ant bites the trap in the first place. The paper suggests that the spider puts out a pheromone that attracts the ant and triggers the ant to aggressively bite the snare, but the pheromone only does this for the spider's target species, the green tree ant. The researchers watched three other ant species check out the snare, go "meh", and move on, unharmed, without showing any aggression towards the snare.
Ultimately, it's probably due to the rate of encounter with this species and the evolution of the pheromone towards the most consistent and intense response from that particular species. It's likely that a more general pheromone wouldn't induce such a consistent response, since it would be a less specific and reliable cue from the ant's perspective. So if you encounter lots of different ant species, a more general pheromone with a 50% response rate could work, but if you primarily encounter this ant species, a more specific pheromone with a 90% response rate is going to confer a greater fitness advantage.
Could be due to the rate of encounter with this species vs. other species, could also be due to the consistency of response with more general vs. specific pheromones. You start with spiders with silk/pheromones that ants are a little more aggressive towards, then variance in that chemical makeup leads to fitness advantages. If the pheromone confers a strong advantage in a specific ant,
> but the pheromone only does this for the spider's target species
Isn't this concluded through observational studies? Is it possible that its just not universally true, like it still impacts, idk, 0.01% of this ant's species due to gene diversity?
Yeah, that is pretty crazy. I wonder what it smells like? Has to be an enemy specific to that ant species right?
that's a good question -- the paper describes it triggering aggression in the ant within milliseconds of it probing the snare with its antenna. I don't know the basis for it, but that's some down-to-the-metal ant programming right there
You should read up on manipulative parasites too! Things like wasp larvae developing inside an insect and changing its behavior through chemical manipulation of neural pathways. Some really remarkable specialization!