Hey I keep manica rubida too.
I'd really try to give them fruit flies if you haven't yet.
Since I give mine flies they don't take anything else.
Do you have one queen or multiple?
I know they are polygynous at a larger colony size but I wonder at what size you can add a queen there's not too much on Google about them.
How old, and how many workers have your colony?
My colony is 2 years old, about 300 workers. I think I'll try to add another queen in a year or two, but I don't know if it'll work. Colonies are oligogynus, so queens occupy different, distant chambers, without direct contact with each other. At least theoretically, and I don't really know what it's like. The problem may be the origin of the queens. In nature, probably fertilized queens return to their home nest, but I'm not sure that either.
good opportunity to update the journal ; )
IMG_20200606_153851 by Hubert Kozaczuk, on Flickr
Screenshot_20200606-154033 by Hubert Kozaczuk, on Flickr