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Bt
Crop Spraying:
Bt has been used in organic farming for over 50 years
as a microbial pest control agent (MCPA). Bt strains account
for nearly 90% of the world MPCA market. Most of the Bt products
contain insecticidal crystal proteins (ICP) and viable spores (spores
that can produce live bacteria). The ICPs are responsible for insect toxicity.
ICPs are usually biologically inactive within hours or days. A few products
contain inactivated spores.
Typical agricultural formulations include wettable powders,
spray concentrates, liquid concentrates, dusts, baits, and time release
rings. Bt formulations may be applied to foliage, soil, water
environments or food storage facilities. There are many different strains
of Bt used, each specific to different insects. Because Bt
is species specific, beneficial and non-target insects are usually not
harmed.
Popular Bt Strains used
Bt Strain |
Effective against |
Bt kurstaki (Btk) |
types of lepidopterous insects gypsy moth cabbage looper |
Bt aizawai (Bta) |
wax moth larvae in honeycombs |
Bt israelensis (Bti) |
mosquitoes, blackflies, midges |
Bt san diego |
certain beetle species, bool weevil |
Bt
is effective only when eaten by the insect as a larva, Bt is
ineffective against adult insects. Since Bt is applied topically,
insects that attack the roots or the insides of a plant will not be affected.
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