Earlier quoted context omitted.
I actually don't care at all if an insect lives or dies. Insects do not have emotions; no other insects mourn if one dies. This makes them markedly different from humans and other animals; insects are little more than machines and from a moral perspective much closer to bacteria than, say, mice. The only reason I care is because of the broader ecological effects. I don't care whether my gut microbes live or die eithe…
Ants are certainly smarter than mice. Ants also have a complex range of psychological responses. (Not sure I'd call them "emotions" since we're obviously too distantly related to them to have a meaningful reference here, but whatever.)
Ants can response to their environment, but are they even "psychological responses" or just a piece of machinery responding in a pre-programmed way? When I played the Sims 20 years ago my characters would respond in certain pre-programmed ways. None of can truly know what it's like to be an ant, but given the tiny size of their brains compared to higher animals I think it's fair to say the machinery for any kind of emotion just isn't there.