Som Phytopharma INDIA Ltd.

LIPEL - SP Biopesticide - Generic Information

What is Bt- k? Bacillus thuringiensis kurstaki (Bt-k)

Bt- k is widely used to control moth and butterfly (Lepidoptera) pests as it specifically affects the larvae (caterpillars) of some of these species. Large quantities of Bt-k have been used over the past 30 years, especially to control gypsy moth populations. Natural epizootics (widespread insect disease) caused by Bt-k have been observed only very rarely in the natural environment, and usually when caterpillars are in a confined environment.

How does Bt-k work?
The protein crystal produced by Bt- k includes a substance known as a delta-endotoxin which is toxic to members of the Order Lepidoptera (moths and butterflies). Endospores of Bt-k are also toxic to the caterpillars of many moths and butterflies. The spores and endotoxins in the protein crystal are known as the "active ingredients" in Bt-k formulations, because it is these ingredients which kill the insects. However, the protein crystal is not toxic until it is swallowed by a caterpillar - it must be present on a leaf & eaten by a caterpillar before it takes effect. Once the crystal is eaten by the caterpillar it is activated by the specific conditions found in the caterpillar gut (namely, alkaline conditions & the presence of certain digestive enzymes). The toxin works by attacking the gut lining.

This causes paralysis of the gut and the caterpillar stops feeding as little as two minutes after eating the Bt-k.

Formulation

Generic Information

Specifications

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The caterpillar will die of starvation two to five days later, depending on environmental conditions. Vegetative growth of Bt-k within the caterpillar and septicaemia caused by Bt-k may also help to kill the caterpillar.

Is Bt-k safe for humans?
Bt has no known toxic effects on humans or other mammals, plants, birds, fish, honeybees, or other beneficial insects. Its safety record, and the results of more than 30 years of Bt investigation around the world, have led many countries including Canada, the United States and most other countries where Bt products are currently registered to declare it exempt from pesticide residue tolerances on food crops.

Bt-k is used to control caterpillars pests in the production of many food crops. Organic food growers also use this biological insecticide. Unlike many pesticides, Bt-k can be used right up to the time of harvest because it is not toxic to humans. Any sprayed fruits or vegetables should be washed before they are eaten.

Even though there is no evidence of harm to humans from Bt-k, persons with respiratory ailments or other health concerns may wish to reduce their exposure to the product during the spray operation. To deal with this, close windows the evening before aerial spraying takes place and stay indoors until the Bt-k product has had time to dry (which takes a few hours).

The spray does not cause damage to automobile, house, boat or trailer paints or finishes. If it is left to harden, the spray can be removed with water but may require more effort. The sooner it is washed off the easier it is to remove.

How long does Bt-k last in the environment?
Bt-k breaks down quickly in the environment in about three to seven days. Sunlight will help to break the product down. For the most effective use of Bt-k, it is usually applied more than once in infested areas. This is because the caterpillars must be in an early larval stage in order for the Bt-k to work. Unfortunately, not all caterpillars hatch at the same time. Because the product breaks down quickly, it will not be available to caterpillars that hatch after the first spraying, unless several applications are made.

Will the pests develop resistance to Bt-k?
After 25 years of use, there are no known instances of target insects developing resistance to Bt.

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