After playing around with the force composition again last night and watching Rayalot72's video, a few things comes to mind regarding what's necessary for a successful 3.2 Insane run:
1. Composition: A ratio of 1:1:1 worker warrior major works surprisingly well, however as TerrificTimmeh said might be too slow to win with. Still, a sizable investment in early taunt majors would most likely be best for killing the army ants, as well as dealing with adult mantis/cricket ambushes with minimal loss of food. I think getting an early couple of majors, about 20 workers (including nest groups), 30 warriors and the rest in majors should work the best right now.
2. An alternative harvesting route might involve getting the big plants from islands further away on the first couple of days before the day/night spawn rate gets too much, then harvesting the ones easier to get on the right side of the map (i.e. the uncontested bottom right corner one) on later nights. Haven't tried this yet to see how effective it can be.
3. Army ants must be attacked starting from Day 2 onwards to push them decisively back to the middle lane, finishing them by Day 3-4 on the leftmost lane close to the bottom side of the map.
4. Should the adult whip spider be killed on Night 3? I couldn't really capitalise on the space created until Day 4, since I gobbled up all the leaves on the right side first in my last few runs, and there's too many whip spiders etc. patrolling along the middle.
5. Selling warrior ants to get 1000+ more leaves on Day 4 for the final push. Feasible?