BOTANY Higher Secondary Second Year - Textbooks Online

3. They also bring about considerable damages to living organisms
because of their hazardous effects in the environment. There was an
enmasse killing of more than 4,000 people, many animals and plants,
when methyl isocyanate (MIC) gas leaked out in the night of 2nd and 3rd
December, 1984 from the underground reservoir of Union Carbide Factory
at Bhopal. This is mentioned as Bhopal Tragedy. Many of the people
exposed to this poisonous gas are suffering even today.
4. Majority of microorganisms such as viruses, bacteria, fungi,
protozoa and mycoplasma are known to kill insect pests. The suitable
preparations of such microorganisms for control of insects are called as
‘microbial insecticides’. These are non-hazardous, non-phytotoxic and
are selective in their action. They are eco-friendly not responsible for
environmental degradation. The most frequently used bio-control agent
is Bacillus thuringiensis and Pyrethrum extracted from the inflorescence
of Chrysanthemum belonging to Asteraceae.
Bacterial pesticides
B. thuringiensis is a widely distributed bacterium. It is a saprophytic
bacterium and can be isolated from soils, litters and dead insects. It is a
spore-forming bacterium and produces several toxins such as exotoxins
and endotoxins in crystallized forms. The bacterium is harmful to
lepidoptera insects. After infection of spore, larvae are damaged due to
the secretion of a single large crystal in the cell. This crystal (toxin) is
proteinaceous in nature.
6.3. Genetically modified food
The greater concern in food biotechnology is the integration of both
modern biological knowledge and techniques and current bioengineering
principles in food processing and preservation. Modern biotechnological
techniques will have considerable importance in influencing trends in the
food market, namely cost, preservation, taste, consistency, colour and
above all, health aspects.
Every year more than a million children die and another 3,50,000 go
blind from the effects of vitamin A deficiency. Employing genetic
engineering techniques, Potrykus of Switzerland and Peter Beyer of Germany
transferred genes that make carotene in daffodils into Oryza sativa. Ordinary
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