Hi all
Tarpy and Rangel already showed that miticides can lower sperm viability, which could lead to unfertilized eggs being laid by an apparently normal queen. 

> Sperm viability analyses showed that queens raised in miticide-free beeswax contained 44% higher total number of sperm cells stored, compared to queens raised in miticide-laden beeswax. Likewise, the amount of live sperm cells contained in the spermathecae was higher by approximately 64% in queens raised in miticide-free beeswax, compared to queens raised in miticide-laden beeswax.  

>  Although our study is the first one to report sperm counts and sperm viability in the spermathecae of queens raised in beeswax contaminated with fluvalinate, previous results obtained by Collins et al. (2004 ) found that queens that were exposed to coumaphos during development had a significantly lower number of sperm in the spermatheca.

Juliana Rangel & David R. Tarpy (2015) The combined effects of miticides on the mating health of honey bee (Apis mellifera L.) queens, Journal of Apicultural Research, 54:3, 275-283

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