Using Genetically Altered Insects to Reduce Disease and Benefit Agriculture
Posted December 10, 1998
By Linda Lundren
With more than one million species of insects identified, the class Insecta dominates the world of living things in terms of numbers. Many species, such as the honeybees
that pollinate ten billion dollars worth of agricultural crops, are an asset to humans. However, many other species transmit disease and destroy crops.
The use of insecticides is the current trend in preventing crop damage and the spread of disease by insects. Yet, complications have occurred with this type of chemical
control. When applications of insecticides are not monitored closely, organisms that do not pose a threat can easily be destroyed along with the targeted pest. Other control methods
include physical barriers such as bed nets to keep insects away and vaccines to prevent the spread of disease from insect bites. All of these efforts have had only limited success. As
a result, studies have been conducted to find a new and improved technique to isolate and destroy harmful insects. One alternative involves genetic control.
Transgenic Insects
Integrating the DNA from one species into the DNA of another species can confer new traits. The plant or animal that carries the new traits is called a transgenic
organism. By creating transgenic organisms the incidence of a certain insect transmitted disease can be reduced or even eliminated. For example, the Aedes aegypti mosquito is
responsible for 50 million cases of dengue (DENG EE) fever each year. Scientists transformed the Aedes aegypti into a transgenic mosquito. This was accomplished by inserting a
housefly gene into the mosquito. First, the gene was attached to a virus that does not cause disease. The mosquito was then infected with this virus. When this gene became incorporated
into the DNA of the mosquito, it prevented the dengue virus from replicating in the body of the mosquito. As a result, the dengue virus can not be transmitted in a bite from a transgenic
mosquito because viral replication has ceased.
Transgenic technology has the potential to reduce the use of chemical insecticides in agriculture. More than 183 species of insects and arachnids targeted by chemical
pesticides have developed resistance to pesticides. Insecticides may also kill beneficial insects and produce toxic by products as they breakdown in water and soil. Scientists have developed
insecticide-resistant insects that can be used to biologically control harmful insects. For example, researchers developed an insecticide-resistant predatory mite that feeds on spider
mites known to destroy almond trees. Use of biological controls in agriculture will reduce the amount of chemical control necessary.
Concerns Regarding Transgenic Engineering
With almost every new scientific experiment comes fear and doubt. This was found to be true after several trial runs were made with genetically altered insects. Some
issues raised were that plants containing pesticide genes could affect non-target organisms that are considered beneficial. Ecosystems could also be damaged due to the spreading of genes
from one species to another closely related species. For instance, a transgenic crop releases pollen, which carries the transgenic genes. Pollen can travel great distances and could
easily fertilize other wild plants creating an entire bloom of herbicide-resistant weeds.
Even though certain questions have been raised about the overall benefits of transgenic insects, the importance of decreasing chemical pesticide use seems to outweigh
the negative views on genetic engineering. Most scientists agree that the introduction of genetically engineered organisms should be slow and controlled in order to alleviate many of
the problems that could arise.
Activity
Use the Internet to locate 3 articles on insects that have been genetically altered. Present your findings to the class. Be sure to include the advantages and disadvantages of each transgenic
insect. Also, describe which finding you feel has the most significance for improving agriculture or reducing disease.
References
Building the Better Bug. David A. O'Brochta and Peter W. Atkinson in Scientific American, Vol. 279, No.6, pages 90-95, December 1998.
The Ecology of Agricultural Pests: Biochemical Approached. Edited by W.O.C. Symondson and J.E. Liddell. Chapman and Hall, 1996.
Genetic Modifications of Mosquitoes. Frank H. Collins and Anthony A. James in Science and Medicine, pages 52-61; November/December 1996.
An Important Step Forward in the Genetic Manipulation of Mosquito Vectors in Human Disease. Margaret G. Kidwell and Alice R. Wattam in Proceedings of the National
Academy of Sciences USA, Vol. 95, No.7, pages 3349-3350; March 31, 1998.
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