Yes they are safe. The amount of dichlorvos is miniscule and the development of resistance is no more than anything else used to combat the mites.
Wikipedia is the most bullshit place to find accurate information and if you ever believe the government, well then keep believing them I guess but...
I just finished wiping them out of my closet and tent with Hot Shot No Pest Strips. Hang one or two in a tent, they will gass off over the time. Your scumbag mites will be gone. Do some research lots of blades have been using them for years. They're safe too.
In answer to the OP's original question, Blackstrap Molasses at 1tbls per gallon of water. Natural nutrient. I usually use it 2 or 3 times during the last 5 weeks.
Read any of of the 378,983,365,125 Google search results to understand how it works.