There has been much talk & some success with Metarhizium anisopliae
(M.a.) which is definitely a promising candidate for development as a
biocontrol for Varroa.  However, I would like to perhaps shed some hard
cold reality to the prospects of M.a. being the silver bullet for mite
control.  I believe if M.a. can bridge the numerous hurdles that are
required to develop, test, document efficacy & safety, register and
successfully market it as a product that it may provide another
potential tool in controlling outbreak populations of Varroa but I
doubt it will be the end all to our mite problems.

It may not be the efficacy of M.a. that causes failure of product
development it may in fact be the safety & marketing aspects of M.a.
Certainly these Entomopathogenic fungi are very interesting and often
display dramatic epizootics in nature.  We have a cryogenic culture
collection here in our research group holding around 7000 individual
specimens of pathogenic fungi (or thought to be pathogenic) to insects
& other arthropods.  Very few have ever been studied fewer utilized and
only a couple have been selected for commercial development.  The
several that have,  have not generated commercial success even though
they  appeared to be very virulent to the target organism yet safe for
humans & relatively safe for non-targets.

There are basically two ways to utilize these fungal pathogens.  One is
classic biological control where an organism is released into the
environment with the hopes it will establish itself & provide control,
particularly in large population centers.  No commercial gain here!
Once established there is no longer anyone willing to by the stuff as
it works on its own--think Entomphaga maimaiga & Gypsy Moth in the NE.
The other method is to develop a mycoinsecticide, a product developed
from the organism used to control source populations much like an
insecticide would be used.  Spray & pray!  This could be used to
control the pest in areas the fungus was not already or in too low a
concentration to be effective.   There is economic incentive here to
develop & market a product that can be sold to generate a profit.  It
would need to be repeatedly reintroduced so the end user would need to
keep buying product for re- application.

The difficulty of developing a working product is probably much easier
& less expensive than proving safety, efficacy & insuring to your
financier that a profit will be worth the early investments. The costs
of doing the requisite testing for registration may be excessive.
Here is where several products have failed to materialize, not on the
lab bench where the organism proves worthy but on the market competing
with more effective cheaper chemical insecticides that are being pumped
out.  These new chemistries are amazingly effective.  I've tested some
agricultural products that at 1 tenth the labeled rate have provided
better control than twice the rate of fungal insecticide.

My suggestion is to hold tight, keep an eye on this product.  Poking
this down a termite nest in your foundation is a lot different from
potentially putting in your food supply.  This product while on the
market for one insect will require lots of study to become a tool for
beekeepers.

I hope it makes it!  After about 20 years of studying these organisms
they certainly seem to have great potential, its just that relatively
few successes have yet emerged from the use of fungi.  Market forces
are changing & the organic revolution is changing the landscape,
insecticides developed from very poisonous chemicals are being seen for
what they are moving to biologics will take time but I think that it
may be coming.

Mike Griggs
Entomologist/ Support Scientist

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