There's a troubling aspect of this thinking, and that's that people expect there to be a single smoking gun and either the pesticides are it, or there aren't.
Living beings don't fit neatly into that. They process a large variety of inputs and can adapt to a number of stressors and heal; in fact, in machine culture we seem to take it for granted that living systems are at 100% because we're used to machines that are either working or very conspicuously broken.
Bees have been shipped about fields, worked harder than even their natures. They're exposed to crops now genetically modified to include pesticides in their pollen. The sprays being used are increasingly pushed into use for profit without review. This leaves them in such a weakened state that if a mite finishes them off, you can't say it was just one factor.
If you want a resilient system, you've got to pay attention to all of these factors.