I am new to this ListServ, but it has been brought to my attention that
this group has been discussing the use of fungi to control varroa mites,
so I thought I would give you an update as to where the USDA is on this
research.

I am a Research Entomologist (Insect Pathologist) at the USDA
Agricultural Research Service's Bee Biology and Systematics Lab in
Logan, UT.  I am currently working on developing a microbial control for
varroa mites, that means, yes, the use of fungi for controlling varroa.
As with any chemical control, we are concerned about the safety of this
type of control, and we are concerned about it's effectiveness, also.
It takes years to develop a new control method, but we are now at the
point of doing field tests in collaboration with Dadant to determine
effective doses and methods for application.  The biggest problems
associated with marketing such a product are actually getting EPA
registration, which is very expensive, and developing a cost effective
production method for the fungi.

Two different fungi have been patented (or patent pending) in the U.S.
At the USDA, we have screened several fungi to come up with our choices.
It is true that most fungi that infect insects will not infect at hive
temperatures (too warm), but we have selected species and strains that
will.

The truth of the matter is, it is unlikely that these fungi hang around
in a hive forever once they are introduced.  It would be nice, but not
likely to happen.  These fungi just are not able to survive and grow
that well in the hive environment. In order for the fungus to stay in
the hive for years, it would need a large number of live hosts (varroa)
to transmit the disease.  Although you might think you have a lot of
mites, if the fungus works as well as we would like it to, it will kill
off it's hosts, and then it will die as well.  For this reason, the
fungus will have to be reapplied to the hive again.  We have not
determined the frequency that this needs to be done, but it likely will
be similar to chemical applications - say once or twice a year.

I stared this research at the Beneficial Insects Research Laboratory in
Weslaco, TX, but about 2 years ago, I moved to the Logan Bee Biology and
Systematics Laboratory.  UC Davis and the USDA-ARS laboratory in France
have also recently begun collaborating with us on this research.

Rosalind James, PhD

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