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Informed Discussion of Beekeeping Issues and Bee Biology <[log in to unmask]>
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Tue, 26 Oct 2004 23:57:08 EDT
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Hi all: Since it was mentioned soft skin insects  might not be hurt by Jim
Fischer I decided to look around. It is said here:  "It has been reported to
infect approximately 200 species of insects and  other arthropods."
Wonder what these 200 species of insects are?  Think I will look around!
By the way, below...mosquitoes.....are they hard shell? And we are talking
spiracles  again for effective treatment???? Wow......
Regards,

Dee A. Lusby
_http://www.entomology.wisc.edu/mbcn/kyf607.html_
(http://www.entomology.wisc.edu/mbcn/kyf607.html)
Metarhizium anisopliae, formerly known as  Entomophthora anisopliae, is a
widely distributed soil-inhabiting  fungus. The first use of M. anisopliae as a
microbial agent against  insects was in 1879, when Elie Metchnikoff used it in
experimental tests to  control the wheat grain beetle, Anisoplia austriaca. It
was later used to control the sugar beet curculio,  Cleonus punctiventris. A
member of the Hyphomycetes class of fungi,  M. anisopliae is categorized as a
green muscardine fungus due to the  green color of the sporulating colonies.
It has been reported to infect  approximately 200 species of insects and other
arthropods. Although M.  anisopliae is not infectious or toxic to mammals,
inhalation of spores  could cause allergic reactions in sensitive individuals.
M. anisopliae generally enters insects  through spiracles and pores in the
sense organs. Once inside the insect, the  fungus produces a lateral extension
of hyphae, which eventually proliferate and  consume the internal contents of
the insect. Hyphal growth continues until the  insect is filled with mycelia.
When the internal contents have been consumed,  the fungus breaks through the
cuticle and sporulates, which makes the insect  appear "fuzzy." M. anisopliae
can release spores (conidia) under low  humidity conditions (<50%). In
addition, M. anisopliae can obtain  nutrition from the lipids on the cuticle. The
fungus can also produce secondary  metabolites, such as destruxin, which have
insecticidal properties on moth and  fly larvae.
Some insects have developed physiological mechanisms  to reduce infection by
fungi such as M. anisopliae. For example, the  desert locust produces
antifungal toxins, which can inhibit the germination of  spores. In addition, insects
can escape infection by molting rapidly or  developing a new integument before
the fungus can penetrate the cuticle.
The successful mass culture of M. anisopliae  and development of methods of
mass-producing infective spores has led to the  commercial development of this
fungus as a microbial insecticide. M.  anisopliae is grown on a large scale in
semi-solid fermentation-- similar  to that used in the production of
_Bacillus  thuringiensis_ (http://www.entomology.wisc.edu/mbcn/fea207.html) --and the
spores can then be  formulated as a dust. The fungal spores can also be grown
on sterilized rice in  plastic bags for small-scale production. M. anisopliae
is sensitive to  temperature extremes; spore viability decreases as storage
temperatures increase  and virulence decreases at low temperatures.
Bioblast is a commercially available formulation of  M. anisopliae that is
used to control termites such as Reticulitermes sp. The  fungus is applied into
wood known to contain active termite galleries. Termites  in these galleries
are exposed to direct contact with the fungus. In addition to  direct contact
with the fungus, infection of other termites in the colony occurs  when
grooming individuals exposed to the fungus spread the pathogen to healthy,
non-infected individuals in the population. Laboratory studies have shown that  death
occurs within 4 to 10 days, depending on temperature.
No other products containing M. anisopliae  are currently registered, but the
fungus has controlled many other insect pests  in experimental trials,
including Japanese  beetle, black vine  weevil, and mosquitoes. Sprayable
formulations have been used to  control meadow spittlebug  on sugar cane and coffee
leafminer and the  froghopper, Tomaspis saccharina, in Trinidad and Grenada. M.
anisopliae is highly pathogenic to many species of ticks, and is being
considered as a  microbial control agent for the management of ticks and Lyme disease.
However, this fungus may  also infect and kill beneficial organisms. In
laboratory assays, the thrips predator _Orius  insidiosis_
(http://www.entomology.wisc.edu/mbcn/kyf101.html)  showed a high rate of susceptibility to  M.
anisopliae.
- Raymond A. Cloyd, University of Illinois
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