Monsanto India

Biotech Basics 1: Bacillus thuringiensis

Bt stands for Bacillus thuringiensis (Bt), a common soil bacterium, so called because it was first isolated in the Thuringia region of Germany.

The bacillus produces a protein which, when ingested by the larva of the targeted moth, like the Bollworm, attacks the inner lining of its alkaline digestive system and incapacitates it. This prevents the moth from feeding further.

Bt is easily cultured by fermentation. For over 40 years, it has been widely used as a pesticide. Growers have been spraying dried forms of Bt onto crops. The protein is a major component of pesticides used against the lepidopteran group of insects (scaly winged insects with a proboscis). These include the butterfly, moth and about 300 such insects.

But Bt powder is only effective in dry protected environments like warehouses. In the open, it does not spread enough to be effective. Sunlight and rain cause it to lose its effectiveness.

The most interesting aspect of Bt is that while it is effective against 300 pests of the lepidopteran order, it is harmless to birds, bees, fish, many beneficial insects, animals and human beings. The protein is biodegradable, unlike chemical pesticides which also kill indiscriminately and move up the food chain.

Many plants have in-built resistance to various pests -- some have thorns, others secrete alkaloids. Unfortunately, the plants on which the world depends for food and fibre lack such protection and resistance. Food crops fall prey to any number of pests and diseases. To control crop losses, currently running at Rs 30,000 crores annually, farmers are compelled to use pesticides with disastrous results on human beings and the environment.

One alternative to chemicals is biological pesticides. But these have their own drawbacks in terms of costs of production and the fact that they are easily washed away.

That is why scientists working to overcome these problems found a solution in Bt. They took the gene responsible for the production of the protein and incorporated it in plants. These plants thus have an in-built mechanism of protection against targeted pests, with minimal use of pesticides. The protein produced by the plants does not get washed away, nor is it destroyed by sunlight. The plant is thus protected from the bollworm, round the clock regardless of the weather.

Scientists have thus tapped nature to contain harmful pests that destroy millions of tonnes of precious grain each year, grain that can feed millions of hungry people.

Copyright 2001 Monsanto India All Rights Reserved