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Date: | Tue, 12 Aug 2008 10:26:27 -0400 |
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Entomopathogenic fungi are notoriously difficult to work with.
Somewhere in the 19teens an entomopathogenic fungus was introduced in
Mass. to help control Gypsy Moth. It apparently disappeared.
However, in 1989 an unusually cool damp summer in the NE it was found
to be causing mortality across NY. The fungus was possibly
misidentified for years, but was spreading with the Gypsy Moth
populations. In 1990 a Grasshopper fungus was introduced into Alaska
in attempt to control a grasshopper population that had exploded near
Delta Junction--again--the introduction was thought to be a failure
until in 2000(ish) calls came back to our lab of huge epizootic in the
area of release.
In a hive there are huge barriers to overcome. Temperature, matching
fungus to host, humidity concerns and activity of the bees all need to
be factored. One might find a hot isolate that works well in lab &
field tests but slow growth in commercial culturing may make it
infeasible for production.
A common practice in our lab is to pass the fungus through the host
several times--this increases virulence sometimes several fold.
Because the host organism is biological in nature and the control
organism is also there are very specific timing, environmental and
host activity (hygienic) that can reduce the effect. Looking at the
history of using insect pathogenic fungi for control of insects --
progress is slow but progress is being made. After 20 years of work
with these fungi I have seen many failures but am optimistic that
progress is being made such that products are making it to market.
Example--I was talking to a neighbor that produces thousands of bales
of hay for the equestrian markets in the area. He is using a hay
amendment (fungal antagonists) to reduce the build up of mold in bales
of too much moisture. This research was started more than 15 years ago.
Note: isolate selection (or species) will be the biggest first step.
unfortunately, we have very little information on the genetics of
pathogenic fungi to really understand the processes to select
candidates for best control. Currently, labs use isolates that are
"hot" work in the lab and are easy to grow. This may not be the best
criteria for selecting something that works in the field under
commercial beekeeping conditions.
Mike Griggs
Entomologist/ Support Scientist
Biological Integrated Pest Management Unit
President Finger Lakes Beekeepers
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