Not sure what all the extra question marks are for. When CCD was first named in 2006, they had a very specific set of symptoms in mind. The hives in question had lots of healthy looking brood, very few bees and the queen remained. The other bees did not seem to be inclined to rob, though this may have been due to the weakened state of all the hives.
In other words, it appeared that most of the bees had simply left -- or died -- leaving the queen and the hatching brood. No overt symptoms such as lots of mites, were apparent. As the years went by, this was seen less and less, and the cause was never identified. In fact, it was never clear if it was anything more than a freak occurrence which defied explanation.
Some pathogens seemed to correlate with CCD, but it was never established that these were causative. Probably they were opportunistic infections of hives with some other problem. The most likely candidate is a virus or a combination of viruses. Disappearing diseases of various sorts have been observed for more than a hundred years, far predating the age of pesticides.