After missions 1.1 and 1.2 I've found myself in formicarium without worker ants. There are 7 + 1 soldier ants and no workers so I can't get any food.

Oh, I've just realized that these ants are actually workers, but they don't have that hammer icon next to them so I took them for soldier ants by mistake.

Soldiers are able to harvest food. The only way an ant wouldn't be able to would be if their control group had it turned off.