Genetic Engineering to Exterminate the Parasite

Bugs in the System? Issues in the science and regulation of genetically modified insects

A Report Prepared by the Pew Initiative on Food and Technology

January 2004

This report gives a very in-depth analysis of genetically modified insects and the issues surrounding their development, approval, employment, and regulation. As mentioned in a previous blog post, genetically modified insects may be a potentially successful strategy to combat the spread of Chagas' disease. Currently the most supported method is to create paratransgenic kissing bugs, in which the actual insect remains unchanged but its gut symbionts - the bacteria that it depends upon to get essential nutrients from its food - would be altered in such a way as to kill the insect as they travel through the digestive tract. This type of genetically modified organism can be created by giving the insect a substrate with bacteria that carry the desired transgenes, which may be lethal or may function to make the insects sterile or unable to infect hosts. While the use of genetically modified insects may appear a solution with a high potential to halt the Chagas disease epidemic, the use of this type of technology does not have a large precedent and raises several complex and possibly dangerous concerns.

Use of genetically modified insects in a variety of realms has a wide range of potential benefits. This article recounts several instances in which employing these organisms may be economically beneficial, such as eradicating a cash crop pest. In the context of Chagas' disease, creating a paratransgenic kissing bug would directly interfere with disease propagation and thus should cause a reduction in incidence. This result would obviously bring about a huge public health benefit, improving the quality of life for many people especially in endemic areas. It would also provide an economic benefit by easing the financial burden of treating this disease and losing part of the workforce to its symptoms.

Introduction of genetically modified insects into the environment is not risk-free, however. Altering a characteristic of the organism to change one trait may affect other parts of the insect's biological fitness as well. Changing the genetic make-up of the insect may alter its tolerance to certain environmental conditions, its ability to reproduce, its interactions with other animals, etc. Thus not only could genetically modifying an insect change one targeted trait, but it might throw off the delicate enviornmental balance and affect an entire ecosystem. Introducing this type of organism to an environment may have unintended consequences on non-target flora and fauna, both direct and indirect. Also, the stability of the introduced genetic construct is important to consider. Both horizontal and vertical gene transmission may occur, transferring the material within the original species and among other species as well. If the construct is more prone to mutation or recombination, serious consequences may ensue.

Also, regulation of genetically modified insects poses a challenge. In the history of genetic modification, the precedent established has been to regulated the altered material as the original product would have been regulated based on its intended function and not on its origin. For instance, a genetically modified crop would be subject to the same regulations as an unaltered crop. For insects, however, it is more difficult to find an analogous unaltered form for comparison. Current thought suggests that different genetically modified insects, depending on their potential uses, may be subject to regulation by the Environmental Protection Agency, the Food and Drug Administration, and the United States Department of Agriculture. Unlike other genetically modified products, insects are not neatly confined within national boundaries, so international legislation and regulation may be necessary.

Thus while genetically modified insects may have potential to effectively combat the Chagas' disease epidemic, the use of this biotechnology raises several important concerns about public health, environmental effects, and regulation. These issues must all be addressed adequately and thoroughly before implementing this type of measure, as recalling the introduction of a genetically modified insect into an environment would be extremely difficult, if not entirely impossible.

http://www.pewtrusts.org/uploadedFiles/wwwpewtrustsorg/Reports/Food_and_Biotechnology/pifb_bugs_012204.pdf