Please correct me if I'm wrong, but I didn't think that infertility resulted in a lack of workers. I thought that the queen would still lay eggs and raise them, but the offspring would be males. Perhaps my misunderstanding is that both scenarios happen. It would seem more beneficial for the queen to have males in this case than no offspring a all.
Regardless, I have Brachymyrmex depellis in test tubes from last fall. I'm pretty sure that they have a very tiny pile of eggs that's almost indistinguishable from the cotton. Are you sure that their brood isn't on the cotton? It actually took me a good bit of time to determine that there actually was a brood. Oddly, they seem to be far behind my other colonies that were in a similar predicament.
Good advice for a tiny species. You are also right about male offspring, but it's possible that since this queen still has her wings and is maybe not mated, she does not recognize herself as an independent queen.
In experiments with social parasite colony founding, in order to collect the number of queens necessary for statistical analysis, the queens are often taken straight out of their original nest, wherein they sit around to be cleaned and fed and not lay eggs. The researchers remove their wings by hand and suddenly they act like foundress queens, even though they never had a nuptial flight and never mated. It's possible that queens must experience certain triggers to carry out the responses involved with colony founding.
Oftentimes a dealated queen will try to found a colony whether or not she has mated, unless she finds conditions unsuitable. I would speculate that an alate queen like this is missing her behavioral triggers.
If you've enjoyed using my expertise and identifications, please do not create undue ecological risk by releasing your ants. The environment which we keep our pet insects is alien and oftentimes unsanitary, so ensure that wild populations stay safe by giving your ants the best care you can manage for the rest of their lives, as we must do with any other pet.
Exotic ants are for those who think that vibrant diversity is something you need to pay money to see. It is illegal to transport live ants across state lines.
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Black lives still matter.