Mites are referred to as the 'vectors', i.e., capable of 'spreading' the
viral particles from one host to another.

In the field, Varroa are highly effective vectors of Deformed Wing Virus
(DWV). DWV has been found in concentrations within adult female mites at
many times the level in their host honeybee's blood. The hypothesis is that
the DWV survives and replicates within the mite. This is very interesting,
if validated. The effect of 'concentration' of viral particles as a
consequence of mite feeding should not be ruled out. However, some
researchers appear convinced that concentration effects do not account for
the excessive virus titers in the mites.

Another interesting virus is Acute Bee Paralysis Virus (ABPV). This virus is
spread by adult bee salivary secretions. There is an association with ABPV
and Varroa. Bee colonies under very high infestation pressure by Varroa will
experience losses of adult and larvae. ABPV causes rapid death, so
establishment within bee colonies is difficult. Is Varroa a vector for ABPV?
Likely.

Most of the honeybee viruses belong to a group of nameless insect RNA
viruses. There's quite a few and likely many more yet to be isolated. Why so
many? It could be that there were multiple evolutionary pathways of
infectability within this group, co-evolutionary relationships, or perhaps a
generalization for insect hosts evolved independently amongst group members.

It should be noted that bees can carry viral loads with NO disease. Humans,
too.

Best regards,

Richard Goetze

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