I never implemented this, but I thought of a few things to try.
If a lone enemy ant is near your hill, wouldn't it be best to just suicide into it and prevent multiple ants from being distracted?
If a lone enemy ant is near your ant out gathering food, wouldn't you just want to jockey for position and keep your ant alive for more food gathering?
At the beginning of the game, wouldn't each ant be worth a lot more, so your economy can grow, and towards the end, wouldn't it be worth less so that you can suicide to overwhelm an enemy hill?
I'm curious as to how people valued their ants and what worked well.