(Beyond Pesticides, November 6, 2012) In efforts to stamp out the deadly disease Dengue fever, officials in Brazil are in the process of releasing millions of genetically engineered (GE) mosquitoes into the environment. However, some in the environmental community are concerned about the possible non-target effects of this experiment, and urge additional research in the lab before releasing the insects into the natural world.
According to the Los Angeles Times, the experiment is taking place in the small town of Itaberaba, in Brazil’s Bahia state. The company overseeing the release, London-based Oxitec, also developed the GE insects. GE mosquitoes are raised in the laboratory, where the eggs of female mosquitoes are injected with a gene that produces sterile male mosquitoes. The modified male mosquitoes are then released into the environment en masse where they crowd out native males and mate with available females. The offspring from these mosquitoes are supposed to die before they hatch.
In the town of Itaberaba, 84% of mosquito larvae now carry the modified gene, and the state government has approved an expansion of the program into five additional neighborhoods. GE mosquitoes have previously been released into uninhabited areas of India and Malaysia, and future plans include a release of the insects in the Florida Keys; though local officials are waiting on a U.S. Food and Drug Administration (FDA) analysis before moving forward. Farther south, the Los Angeles Times indicates, “Scientists in Brazil are waiting for permission to take the next step: the carpet bombing of an entire city, Jacobina, with the male zombie mosquitoes.”
While much talk has focused on the grand possibility for GE mosquitoes to eliminate all mosquitoes worldwide, some in the environmental community are concerned that Oxitec is rushing into these experiments without seriously considering the possible risks associated with their work. British-based environmental group Genewatch is issuing an alert over the release of modified mosquitoes in Brazil, indicating that there is a possibility of some next-generation mosquitoes mutating further and surviving into breeding age. Genewatch is concerned because GE mosquitoes rely on the antibiotic tetracycline to act as a chemical switch, allowing the GE larvae to develop under lab conditions. The organization cites confidential company documents that show 15% of GE insects surviving to adulthood in the presence of low levels of tetracycline contamination. These results imply that the modification may only provide a temporary reduction in the spread of the disease, with further unknown human and environmental health effects as a result. Dr. Helen Wallace, director of Genewatch, notes in an interview with The Financial Times, “Staff would be better employed using the well-established public health approach of removing mosquito breeding sites [water containers] rather than in placing GM mosquito larvae at intervals across a site. Plans to scale up releases of GM mosquitoes in dengue-endemic Brazil should be halted. Authorities in other places where releases are planned, such as Florida and Panama, should also stop and think again.”
Researchers involved in the experiment respond to these claims by stressing that the potential benefits of their work outweigh the risks. They claim that no mosquitoes have survived so far, and that even if they did, it would be unlikely to cause problems because the altered gene is nontoxic and not spread by saliva. Although, as Genewatch revealed, the gene doesn’t necessarily have to be toxic in order to cause adverse effects. Professor Anthony James from UC Irvine compares the use of GE mosquitoes to the widespread use of pesticides, stating to the Los Angeles Times, “Most of the concerns are about some unintended off-target effects [involving species beyond the Aedes], but we know exactly what the off-target effects of insecticide are.”
While insecticides are surely not the answer to mosquito borne illnesses, given the current evidence on GE mosquitoes, Beyond Pesticides continues to recommend cultural controls as the main method for stopping mosquito borne disease. As a result of the massive West Nile virus outbreak this year, the issue of GE mosquitoes will surely not retreat by next summer. It is therefore of utmost importance that regulators and government officials not only assess hazards, but also consider alternatives when reviewing proposals to introduce gene altered insects into the open environment. In terms of biological controls, New Jersey’s Cape May County provides an excellent example of a low-risk alternative to employing insecticides or introducing GE species. Cape May relies on mosquitoes’ natural predators, tiny copepods that eat the larvae of the mosquito. Through education of proper cultural controls, and least-toxic and cost effective biological alternatives, there shouldn’t be a need to choose between GE mosquitoes or toxic chemicals.
For more information on safer mosquito control, see Beyond Pesticides program page on mosquito management.
Source: LA Times
All unattributed positions and opinions in this piece are those of Beyond Pesticides.