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Honey bees are hosts to the pathogenic large
ectoparasitic mite Varroa destructor (Varroa mites).
These mites feed on bee hemolymph (blood) and can
kill bees directly or by increasing their susceptibility
to secondary infection with fungi, bacteria or viruses. |
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Little is known about the natural defenses that keep
the mite infections under control.
Pyrethrums are a group of flowering plants which
include Chrysanthemum coccineum, Chrysanthemum
cinerariifolium, Chrysanthemum marschalli, and |
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related species. These plants produce potent
insecticides with anti-mite activity. The naturally
occurring insecticides are known as pyrethrums.
A synonym for the naturally occurring pyrethrums is
pyrethrin and synthetic analogues of pyrethrums are |
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known as pyrethroids. In fact, the human mite
infestation known as scabies (Sarcoptes scabiei) is
treated with a topical pyrethrum cream.
We suspect that the bees of commercial bee
colonies which are fed mono-crops are nutritionally |
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deficient. In particular, we postulate that the problem
is a diet deficient in anti-mite toxins: pyrethrums,
and possibly other nutrients which are inherent in
such plants. Without, at least, intermittent feeding on
the pyrethrum producing plants, bee colonies are |
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susceptible to mite infestations which can become
fatal either directly or due to a secondary infection of
immunocompromised or nutritionally deficient bees.
This secondary infection can be viral, bacterial or
fungal and may be due to one or more pathogens. |
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In addition, immunocompromised or nutritionally
deficient bees may be further weakened when
commercially produced insecticides are introduced
into their hives by bee keepers in an effort to fight
mite infestation. We further postulate that the proper |
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dosage necessary to prevent mite infestation may be
better left to the bees, who may seek out or avoid
pyrethrum containing plants depending on the
amount necessary to defend against mites and the
amount already consumed by the bees, which in |
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higher doses could be potentially toxic to them.
This hypothesis can best be tested by a trial
wherein a small number of commercial honey bee
colonies are offered a number of pyrethrum
producing plants, as well as a typical bee food source |
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such as clover, while controls are offered only the
clover. Mites could then be introduced to each hive
with note made as to the choice of the bees, and the
effects of the mite parasites on the experimental
colonies versus control colonies. |
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It might be beneficial to test wild-type honey bee
colonies in this manner as well, in case there could be
some genetic difference between them that affects the
bees’ preferences for pyrethrum producing flowers.
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