question_answer

(a) Write about microbial control of insects/pests.

(b) What is IPM.

OR

Explain gene therapy with example.

 

Answer:

(a) The insects and pests cause harm to the crop plants affecting their productivity. We use several kinds of chemical pesticides and insecticides to control them. These chemicals are toxic and harmful to man and animals. They enter in our food chain and cause various diseases. They pollute fruits, vegetables and soil also decreasing its fertility. So, there is necessity to develop biological methods to control pests and insects. Another important aspect of this is to became familiar with various life forms in a field which could help in biocontrol.

(i) Lady bird (Beetle) and Dragonflies are useful to get rid ofaphids and mosquitoes.

(ii) To control butterfly caterpillars, the dried spores of Bacteria Bacillus thuringiensis (Bt) are mixed with water and sprayed on vulnerable plants such as Brassica and fruit trees. In the gut of larvae the toxin is released and the larvae get killed. Now a days with the help of genetic engineering scientists have introduced B. thuringiensis toxin genes into plants. Such plants are resistant to insect pests, e.g., Bt-cotton.

(iii) Trichoderma is free-living fungi that are very common in root ecosystems. They are effective biocontrol agents.

Baculoviruses are pathogens that attack insects and other arthropods. The viruses of genus Nucleopoly- hedroviruses are used in bio control.

(b) Integrated Pest Management (IPM) Programme involves use of different pest control methods which are ecologically sound like crop rotation, sanitation, growing of target crop away from major crop, use of very low concentration of chemicals which does not cause pollution.

OR

In gene therapy, genes are inserted into the cells and tissues of an individual to correct certain hereditary diseases. It involves the delivery of a normal gene into the individual or embryo to replace the defective mutant allele of the gene. Viruses which attack the host and introduce their genetic material into the host are all used as vectors.

The first clinical gene therapy was given in 1990 to four year old girl with adenosine deaminase (ADA) deficiency. This disease is an autosomal recessive disease caused by receiving a deficient ADA (adenosine deaminase deficiency) gene from the parents.

The ADA gene codes for the enzyme adenosine deaminase that is essential for the proper functioning of human body's immune system. ADA deficiency can be cured by bone marrow transplantation in some children but it is not completely curative.

For gene therapy, lymphocytes from the blood of the patient were grown in culture outside the body. A functional ADA cDNA is then introduced into these lymphocytes. These lymphocytes are then transferred into the body of the patient; the patient requires periodic infusion of such genetically engineered lymphocytes. If a functional gene is introduced into the bone marrow cells at early embryogenic stage; it would be a permanent cure.