Trevor asks,
"Just for clarification, is it that varroa do not reproduce in queen cells
or
is it that varroa are never found in queen cells?"

My understanding is that Varroa simply do not go into queen cells.  I always
assumed it was because the chemical enticements (phereomones. etc.) are not
present in queen cells.  However, I cannot cite studies or sources for this
information other than stating that is how I've come to understand the
interactions between Varroa and queens based on numerous sessions and
presentations I've attended over the years.  This is probably not sufficient
to satisfy the original query, but I am confident it is the correct answer
and studies exist to support the assertion.  I guess this last statement
makes me guilty of hearsay.  I would look to the work done in Baton Rouge by
John Harbo and company.  Perhaps also Tibor Szabo.

Sincerely,
Aaron