DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) was originally synthesized in 1874 but its insecticidal properties were not discovered until 1942.  Herman Muller is credited with this discovery and in 1948 he was awarded the Nobel Prize in physiology and medicine for his work with DDT.

        DDT possessed a variety of unique properties which set is apart from earlier insecticides.  First, it was a potent neurotoxin which stimulated the uncontrolled release of nerve impulses resulting in spontaneous muscle contraction and death.  Second, it was very stable in the environment and therefore maintained its insecticidal properties longer than its predecessors.  The stability of DDT was derived from its low volatility, its resistance to microbial degradation, as well as its insensitivity to UV-light and elevated temperatures.  In addition to the use of DDT as a crop protection agent, it was also employed to reduce the spread of infectious diseases such as malaria and typhus.  Insect vectors such as mosquitoes (malaria) and lice, mites, or fleas (typhus) transmit both of these diseases.

Transgenic Plants History

        The problems created by the widespread use of synthetic insecticides (insect resistance, environmental dilemmas, and health crises) lead researchers to search for an alternative means of pest control which might bypass some or all of these problems.  The solution was derived from the observation that the bacteria Bacillus thuringiensis possessed a gene which coded for a toxin with powerful insecticidal properties—the Bt toxin.  The Bt toxin exerts its effects by binding to and facilitating the lysis of insect epithelial cells.  By using recombinant DNA technology, researchers isolated the gene for Bt toxin and spliced it into various plant genomes.  In many cases, the application of this new technology enabled crops to synthesize Bt toxin and thereby protect themselves from insect pests.   This technique was applied with considerable success in corn plants.  The transgenic corn plants were able to synthesize Bt toxin and markedly reduce damage caused by the European corn borer, an insect that had been particularly difficult to control because of its ability to burrow within the corn plant.