I see a lot of your colonies randomly curl up and die 40-50 workers a week in some cases, well there may be an answer, something that as ant keepers you are over looking.
Aspartame A.K.A. E955, this is an additive used in loads of foods but something I found interesting is the fact it is used in thousands of vitamin supplement tables, drinks and powders. Adding the vitamin supplements to your ant colony that contain E955 will cause weird deaths in ants. Aspartame is a neuropoison which will cause the ants to act very weird, in sense paralyzing them causing brain malfunctions, slowing them down until they come to a total stop and then die.
Aspartame is deadly to ants Equal, NutraSweet, Splenda and Canderel are all examples of sweeteners that use it and it is used in over 6000 bought foods and drinks. If anything has Aspartame in it then DON'T feed it to any species of ants, in fact there are a lot of roomers that it harms humans too
DON'T GIVE ANTS FOODS OR VITAMINS CONTAINING ASPARTAME
Sourced from: Wikipedia, Own research into aspartame, Girlfriends biology knowledge.
Regards
MrNixy