Major spoilers for the challenge, read at your own risk
I beat Challenge 3 on my 2nd attempt, no guides, I had 18 of each ant (including worker) at level 3 sitting in the tube while 3 groups of lebel 2 and 3 workers stayed in the nest to quickly replace eggs. With Royal Guard and the confusion one any Mole Cricket could be dealt with and I could fall back to deal with the Manti. When the enemy stopped sending ants out I sent my attack force into the nest to summon the enemy royal guard, after that I retreated back to the tube and waited for avout 2-3 minutes before attacking again. After that I won.
Stun Leaf cutter
Mortar Rufa
Aggressive Broad Worker
Meat-shield Fusca