The information in this profile may be out-of-date. It was last revised
in 1996. EXTOXNET no longer updates this information, but it may be useful
as a reference or resource.
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E X T O X N E T
A Pesticide Information Project of Cooperative Extension
Offices of Cornell University, Oregon State University, the
University of Idaho, and the University of California at Davis
and the Institute for Environmental Toxicology, Michigan State
University. Major support and funding was provided by the
USDA/Extension Service/National Agricultural Pesticide Impact
EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade names include Acrobe, Bactospeine, Berliner (variety
kurstaki), Certan (variety aizawai), Dipel, Javelin, Leptox,
Novabac, Teknar (variety israelensis), Thuricide, and Victory.
Bacillus thuringiensis is also known at B.t.
This microbial insecticide was originally registered in 1961 as a
General Use Pesticide (GUP). It is classified as toxicity class
III - slightly toxic. Products containing B.t. bear the Signal
Word CAUTION because of its potential to irritate eyes and skin.
Bacillus thuringiensis (B.t.) is a naturally-occurring soil
bacterium that produces poisons which cause disease in insects.
B.t. is considered ideal for pest management because of its
specificity to pests and because of its lack of toxicity to
humans or the natural enemies of many crop pests. There are
different strains of B.t., each with specific toxicity to
particular types of insects: B.t. aizawai (B.t.a.) is used
against wax moth larvae in honeycombs; B.t. israelensis (B.t.i.)
is effective against mosquitoes, blackflies and some midges; B.t.
kurstaki (B.t.k.) controls various types of lepidopterous
insects, including the gypsy moth and cabbage looper. A newer
strain, B.t. san diego, is effective against certain beetle
species and the boll weevil. To be effective, B.t. must be eaten
by insects during their feeding stage of development, when they
are larvae. B.t. is ineffective against adult insects. More than
150 insects, mostly lepidopterous larvae, are known to be
susceptible in some way to B.t.
B.t. forms asexual reproductive cells, called spores, which
enable it to survive in adverse conditions. During the process of
spore formation, B.t. also produces unique crystalline bodies.
When eaten, the spores and crystals of B.t. act as poisons in the
target insects. B.t. is therefore referred to as a stomach
poison. B.t. crystals dissolve in the intestine of susceptible
insect larvae. They paralyze the cells in the gut, interfering
with normal digestion and triggering the insect to stop feeding
on host plants. B.t. spores can then invade other insect tissue,
multiplying in the insect's blood, until the insect dies. Death
can occur within a few hours to a few weeks of B.t. application,
depending on the insect species and the amount of B.t. ingested.
Typical agricultural formulations include wettable powders, spray
concentrates, liquid concentrates, dusts, baits, and time release
agricultural formulations include wettable powders, spray
concentrates, liquid concentrates, dusts, baits, and time release
- Acute toxicity: B.t. is practically
non-toxic to humans and animals. Humans exposed orally to
1000 mg/day of B.t. showed no effects . A wide range
of studies have been conducted on test animals, using
several routes of exposure. The highest dose tested was
6.7 x 10^11 spores per animal. The results of these tests
suggest that the use of B.t. products causes few, if any,
negative effects. B.t. was not acutely toxic in tests
conducted on birds, dogs, guinea pigs, mice, rats, and
humans. No oral toxicity was found in rats, or mice fed
protein crystals from B.t. var. israelensis . The
LD50 is greater than 5000 mg/kg for the B.t. product
Javelin in rats and greater than 13,000 mg/kg in rats
exposed to the product Thuricide [147,148]. Single oral
dosages of up to 10,000 mg/kg did not produce toxicity in
mice, rats, or dogs . The dermal LD50 for a
formulated B.t. product in rabbits is 6280 mg/kg. A
single dermal application of 7200 mg/kg of B.t. was not
toxic to rabbits . B.t. is an eye irritant; 100
grams of formulated product applied in each eye of test
rabbits caused continuous congestion of the iris as well
as redness and swelling . Very slight irritation
from inhalation was observed in test animals. This may
have been caused by the physical rather than the
biological properties of the B.t. formulation tested .
Mice survived 1 or more 1-hour periods of breathing mist
that contained as many as 6.0 x 10^10 spores B.t. per
- Chronic toxicity: No complaints were
made by 8 men after they were exposed for 7 months to
fermentation broth, moist bacterial cakes, waste
materials, and final powder created during the commercial
production of B.t. . Dietary administration of B.t.
for 13 weeks to rats at dosages of 8400 mg/kg/day did not
produce toxic effects . Some reversible abnormal
redness of the skin was observed when 1 mg/kg/day of
formulated B.t. product was put on scratched skin for 21
days. No general, systemic poisoning was observed .
- Reproductive effects: There is no
indication that B.t. causes reproductive effects .
- Teratogenic effects: There is no
evidence indicating that formulated B.t. can cause birth
defects in mammals [143,148].
- Mutagenic effects: B. thuringiensis
appears to have mutagenic potential in plant tissue.
Thus, extensive use of B.t. on food plants might be
hazardous to these crops . There is no evidence of
mutagenicity in mammalian species.
- Carcinogenic effects: Tumor-producing
effects were not seen in 2-year chronic studies during
which rats were given dietary doses of 8400 mg/kg/day of
B.t. formulation . It is unlikely that B.t. is
- Organ toxicity: There is no evidence of
chronic B.t. toxicity in dogs, guinea pigs, rats, humans,
or other test animals.
- Fate in humans and animals: B.t. does
not persist in the digestive systems of mammals that
ingest it .
- Effects on birds: B.t. is not toxic to
birds [8,150]. The LD50 in bobwhite quail is greater than
10,000 mg/kg. When autopsies were performed on these
birds, no pathology was attributed to B.t. Field
observations of 74 bird species did not reveal any
population changes after aerial spraying of B.t.
- Effects on aquatic organisms: B.t. is
practically nontoxic to fish . Rainbow trout and
bluegills exposed for 96 hours to B.t. at concentrations
of 560 and 1000 mg/L did not show adverse effects. A
small marine fish (Anguilla anguilla) was not negatively
affected by exposure to 1000 to 2000 times the level of
B.t. expected during spray programs. Field observations
of populations of brook trout, common white suckers, and
smallmouth bass did not reveal adverse effects 1 month
after aerial application of B.t. formulation .
However, shrimp and mussels may be affected adversely
- Effects on other organisms: Applications
of formulated B.t. are not toxic to most beneficial or
predator insects . Treatment of honeycombs with B.t.
var. aizawai does not have a detrimental effect upon
bees, nor on the honey produced . Very high
concentrations (108 spores/ ml sucrose syrup) of B.t.
var. tenebrionis, which is used against beetles such as
the Colorado potato beetle, reduced longevity of honey
bee adults but did not cause disease . B.t. applied
at rates used for mosquito control may cause the death of
some non-target species . Users of B.t. are encouraged
to consult local officials or the nearest EPA regional
office responsible for protecting endangered species
before using B.t. products in counties where susceptible
endangered species of Lepidoptera are known to be present
. It did not have negative effects on frogs and
- Breakdown in soil and groundwater: B.t.
is a naturally-occurring pathogen that readily breaks
down in the environment. Due to its short biological
half-life and its specificity, B.t. is less likely than
chemical pesticides to cause field resistance in target
insects. B.t. is moderately persistent in soil. Its
half-life in suitable conditions is about 4 months .
B.t. spores are released into the soil from decomposing
dead insects after they have been killed by it. B.t. is
rapidly inactivated in soils that have a pH below 5.1
. Microbial pesticides such as B.t. are classified
as immobile because they do not move, or leach, with
groundwater. Because of their rapid biological breakdown
and low toxicity, they pose no threat to groundwater.
- Breakdown in water: The EPA has not
issued restrictions for the use of B.t. around bodies of
water. It can be effective for up to 48 hours in water.
Afterwards, it gradually settles out or adheres to
suspended organic matter .
- Breakdown in vegetation: B.t. is
relatively short-lived on foliage because the ultraviolet
(UV) light of the sun destroys it very rapidly. Its
half-life under normal sunlight conditions is 3.8 hours
. It is not poisonous to plants and has not shown
any adverse effect upon seed generation or plant vigor
- Appearance: The insecticidal action of
B.t. is attributed to protein crystals produced by the
bacterium. The vegetative cells of B.t. are approximately
1 micron wide and 5 microns long, and are motile .
The commercial product contains about 2.5 x 10^11 viable
spores per gram. B.t. products lose some of their
effectiveness when stored for more than 6 months .
B.t. is incompatible with alkaline materials. Formulated
products are not compatible with captafol, dinocap, or,
under some conditions, leaf (or foliar) nutrients .
- Chemical Name: Bacillus thuringiensis
- CAS Number: (B.t. variety kurstaki)
- Molecular Weight:
- Water Solubility: Not Applicable
- Solubility in Other Solvents: Not
- Melting Point: Not Applicable
- Vapor Pressure: Not Applicable
- Partition Coefficient: Not Applicable
- Adsorption Coefficient: Not Applicable
- ADI: Not Available
- MCL: Not Available
- RfD: Not Available
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
Sandoz Agro, Inc., and Abbott Laboratories
1300 E. Touhy Ave.
Des Plaines IL 60018
Chem. and Agric. Prod. Div.
1401 Sheridan Rd.
North Chicago, IL 60064
- Phone: 708-699-1616 ; 708-937-2739
- Emergency: 708-699-1616; Not Available
References for the information in this PIP can be found in
Reference List Number 10
information in this profile does not in any way replace or
supersede the information on the pesticide product labeling or
other regulatory requirements. Please refer to the pesticide