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Op-Ed: Hallelujah! GM mosquitoes and some doubts!

By Paul Wallis     Nov 1, 2011 in Science
Sydney - Yes, your dreams have come true! Genetically altered mosquitoes with a percentile chance of creating a whole new range of problems are here! Not that the problems are intentional. The idea is to control dangerous mosquitoes, but...
The idea is that swarms of male mosquitoes carrying a lethal gene are released in the wild, decimating the native mosquito population. This works with fruit flies and other pests, but there are issues with the technique when used on mosquitoes.
The New York Times
…In particular, critics say that Oxitec, the British biotechnology company that developed the dengue-fighting mosquito, has rushed into field testing without sufficient review and public consultation, sometimes in countries with weak regulations.
Previous experiments by Oxitec have had some success, including a rumoured but unconfirmed 80% population reduction in one series of tests. The trouble is that the methodology itself is in question in some crucial areas.
The worries are practical:
…The Oxitec technique, however, is not foolproof.
Alfred M. Handler, a geneticist at the Agriculture Department in Gainesville, Fla., said the mosquitoes, while being bred for generations in the lab, can evolve resistance to the lethal gene and might then be released inadvertently.
Todd Shelly, an entomologist for the Agriculture Department in Hawaii, said in a commentary published on Sunday by Nature Biotechnology that 3.5 percent of the insects in a lab test survived to adulthood despite presumably carrying the lethal gene.
Environmental issues
There’s another problem from the environmental point of view- Mosquitoes are also prey for a very large part of the food chains in which they live. A crash in predator populations could lead to the surviving mosquitoes having fewer or no natural controls. They can recover their numbers far more rapidly than their predators, which would either have to die or leave the areas affected to survive.
Mosquitoes populations could be exposed first one and then another lethal gene, and the pattern could repeat. In effect, this could be a “superbug” process, with progressively more widely resistant mosquitoes evolving after exposure to genetic controls. That’s not too drastic a leap of logic, given that mosquito populations are gigantic. That 3.5% survival rate could result in billions of resistant mosquitoes in a few years.
The most likely risk with GM mosquitoes is actually based on population statistics. It’s axiomatic in epidemiology that in all large populations, there will be at least a few resistant specimens. That’s why even plague diseases never wipe out whole species, even in areas where the populations haven’t been previously been exposed to the disease. Any organism which breeds in billions per year must have a residual population of mutants and genetically resistant specimens. If the disease carrying mosquitoes become multiply-resistant, they could be a far worse problem than they are now.
The pity of it is that genetic methods are definitely a safer option in theory than pesticides and other chemical options which are potentially long term environmental hazards. As usual with GM products, the lack of generational studies and population monitoring is lacking.
Future diseases- A self-inflicted problem for humanity?
A more academic problem for the future is that GM organisms and multiply-resistant survivors of genetic controls may be able to carry a whole different range of diseases, which themselves could become multiply-resistant. There’s no indication of this process currently occurring, but a macro-ecological picture needs to be drawn regarding possible evolution of risk species.
In nature, successful survival is as much an immunological process as eating and drinking. Really tough organisms like rats, cockroaches, fleas, ticks, lice and bedbugs have survived all-out attempts to destroy them in the past. They’ve survived control methods to which they developed progressively increasing levels of resistance, like resistance to poisons to the extent they’ve all now come back to high population levels.
If we create organisms which are able to pass on genes and evolve their way into a “poly-immune” condition to genetic controls, pest control is likely to become a lot harder.
Any action has consequences. It’d be a lot better if we could be sure what those consequences are.
This opinion article was written by an independent writer. The opinions and views expressed herein are those of the author and are not necessarily intended to reflect those of
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