Scientists have developed a breakthrough food supplement that could help save honeybees from devastating declines. By engineering yeast to produce six essential sterols found in pollen, researchers provided bees with a nutritionally complete diet that boosted reproduction up to 15-fold. Unlike commercial substitutes that lack key nutrients, this supplement mimics natural pollen’s sterol profile, giving bees the equivalent of a balanced diet.
I’m with you, it’s confusing. But I think what it means is this:
The study ran for 90 days. Non-sterol bees had stopped doing bee sex by then. Sterol bees were doin it all the way up to the end of the 90 days - and then the study ended. We can therefore assume they wanted to continue having freaky beedsm sex for even longer.