I don't have any personal experince with this type of ant, but I have heard that the best way to get the colony going is just leaving them alone. Trying as best you can to not disturb them and when giving food try to be the least disturbing that you can. I have also heard that they do much better in a more natural setup rather than a test tube.
As far as diet they should be good with accepting insects like mealworms and crickets and other feeder insects as well as honey/sugar water. I don't believe that diet would play much of a role in this issue though.
Heat is important however I have never heard of an ant needed a specific heat to do well, besides either being generally warmer or generally colder depending on the environment they come from. As long as they are fairly warm and not cold but also not cooking where condensation forms on the walls of the test tube, they should be comfortable.
I hope this information helped although don't assume it is completely correct as I have never had any personal experince with these ants and most of this information comes from other people or assumptions based on other ants. I hope all goes well and your ants have a successful comeback.
Edited by Karma, January 18 2018 - 4:57 PM.