MaryAnn Frazier from Penn State has tested a couple hundred samples of CCD comb. No one particular neonicotinoid or other systemic pesticide was found in all samples. The highest non-beekeeper introduced chemical tested out in about 30% of the CCD samples. Neonicotinoids are not being found in levels to suggest "coincides".
What was found, was 100% of the samples tested for the chemicals in Apistan and Checkmite, and the off label brands of these same chemicals also used by many commercial beekeepers.
The thing with chems, is that many are tolerated by bees at somewhat low safe levels(not an endorsement). But when you mix these same somewhat non-impacting chemicals in the hive, they have a far higher multiplication factor making them deadly. On a scale of 1 to 10, if you take two chemicals rated as 1 (1 being the lowest impacting chems on the scale), then the combination of these chems often does not add up to a 2. When mixing chems, 1 plus 1 often results in 5, 8, or even 10 (being the deadliest).
What was found in all CCD hives, was an average of (If I remember) 7 or 8 different chems, with the highest being in the high twenties. But remember, only two chems were found in EVERY sample. Both being beekeeper approved chems and used off-brand by many at levels far exceeding anything in a couple of strips.
It's the power and damage of having multiple chems feeding off each other.
Keeping all chems out of the hives is best. I don't use sugar treatments. But feel they are one of the safest soft treatments out there.
I personally do not use any acid treatments. Many I see use them late in the year after the fall brood cycle is complete, and mites have already done their damage. My personal opinion is that there is a fine line between enough acid to kill a mite, and NOT harm a bee. That's why using these acid treatments prior to the fall flow should be encouraged, if used. That way, you knock the mites down prior to the fall brood cycle so that you have healthy bees unaffected by both mites and acid treatments. (This of course does not acount for the queen's health)
Keeping beekeeper induced chemicals out of the hive, rotating out comb (to keep chemical buildup from whatever the source), and other approaches will keep many from ever having problems with CCD. (I'll add...IF this is CCD). Which by the way is what most commercial guys do not do.
Not sure if I'm convinced about worrying about chems in sugar. More concerned about the average homeowner and the hundreds of products they can buy at the local hardware store.