"Genetic engineering increases our options for non-chemical control of pests"



In 1953, Watson and Crick discovered that DNA present in all cells contains a code that is used by cells as a "recipe" for how an organism will function.

In all organisms, the code is made up from a four letter alphabet (A, C ,G, T) which usually contains between 1,000 and 100,000 letters.

The entire recipe, called the genome, may contain between 4 million (simple bacteria) and 3 billion (human) letters or more. The genome contains many different types of genes which carry out varied functions. For example, the colour of your eyes are determined by specific genes.



How does genetic engineering work?

One of the great discoveries of this century is that DNA from any organism will function if it is properly transferred into any other organism! A whole new technology has arisen out of this single discovery.

Genetic engineering is the process whereby genes which carry out specific tasks in a cell are cut from one organism and glued into another. This confers a new ability on the organism that has received the gene.



There are a number of tools required for this process:
DNA is cut using restriction enzymes.
Genes (groups of DNA) are transported around on plasmids
• Ligase is an enzyme that glues DNA particles together

Genes which have a trait wanted for another organism are cut using a restriction enzyme
                
                                  
These genes are inserted into plasmids by first cutting the plasmid with restriction enzymes
                
                                  
These genes are inserted into plasmids by first cutting the plasmid with restriction enzymes

           
                                  
The gene is now a part of the plasmid.
                               
                                  

The plasmids are often located in a bacteria like Agrobacterium. Once the plasmid in the bacteria has the new gene, they are cultured to make many copies of the plasmid and then placed next to plant cells.

Plasmids of Agrobacterium have the property of being able to jump from one cell to another, and so move into the plant cell.
                      
                                  
The plant cells are grown into mature plants using a process called tissue culture.

These plants will contain the new gene in their cells which will give them the new, desired trait.

                        
                                  
       

The centre row of potatoes has been genetically engineered to resist pest attack. The others have not.



How is genetic engineering use in pest control?
For pest control, different types of genes are inserted into plants to give them some ability to fight off or avoid pests.

*Genes are inserted which produce a natural or synthesized toxin to kill or ward off pests (See section on IPM - Integrated Pest Management).
*Genes are inserted which contain a specific resistance gene which makes organisms immune to the pest (See IPM - Integrated Pest Management).
*It is also possible to insert genes into crop plants which confer resistance to a herbicide which would have once killed the plants. The advantage of this is one herbicide can be used to control all the weeds in that crop.
Genetic Engineering is used as a pest control strategy because 
1. it can replace some pesticides 
2. it is safe for humans and the environment
3. it is inexpensive in the long term
Genetic Engineering is not always used because
1.It is expensive to set up (cost of research)
2. it takes a long period of research to make sure that the genetically engineered organism is safe to release
3. pests are controlled using other control strategies


Go to the Careers sectionto meet some people who are looking for ways to control pests using Genetic Engineering.