# 6035
When it comes to deadly creatures on this planet, few can compare with the lowly mosquito.
Malaria is believed to sicken 200 million people every year, and claim nearly a million lives (cite). Dengue fever has seen an explosive spread over the past 50 years, and infects tens of millions of people every year.
Add EEE (Eastern Equine Encephalitis), West Nile Virus, Chikungunya, and a handful of other arboviral encephalopathies into the mix, and you have in mosquitoes a very efficient vector of death and disease.
Global Spread of Dengue
The burden of disease carried by mosquitoes is truly staggering, and many places once thought safe from these mosquito borne scourges are now threatened.
In 2009, after an absence of nearly 6 decades, Dengue fever was once again reported in Florida. While the number of cases was small (just over 60 cases in 2010), the concern is that this once-eradicated disease will re-establish itself in the sunshine state.
In order to spread, Dengue requires the right mosquito vector. And the two species best suited to transmit the virus are the Aedes aegypti and Aedes albopictus mosquitoes, which also can spread such diseases as West Nile, Malaria, Yellow Fever, and Chikungunya.
Map showing the distribution of dengue fever (red) and the distribution of the Aedes aegypti mosquito (cyan) in the world, as of 2006. Agricultural Research Service of the US Department of Agriculture.
Map showing the native habitat (blue) and recent spread (green) of the Aedes albopictus mosquito.
Complicating matters, as these species continue to encroach on new populations, many are developing signs of resistance to insecticides and insect repellants (see Declan Butler On Growing Mosquito Insecticide Resistance & From the `Nature Bats Last’ Dept).
Which has led many scientists to look for novel ways to control mosquitoes without the use of potentially dangerous chemicals.
Over a year ago I wrote about the controversial release of genetically modified mosquitoes (see The Cayman Island Mosquito Trials) by the Oxitec company in a bid to learn how to reduce these Dengue vectors.
Oxitec’s genetically altered terminator mosquitoes have been bio-engineered to carry a lethal gene that the males can pass on to their progeny that causes them to die in the larval stage.
And the early results were very promising.
An 80% reduction of mosquitoes in a 25 acre test area after 19,000 males mosquitoes were released over a 4-week period in 2010.
Now, according to a report yesterday in The Key West Citizen, there are plans to conduct a similar test in the city sometime in 2012.
While still awaiting federal and state approval, already the battle lines are being drawn between those in favor of trying these novel control methods, and those opposed.
BY TIMOTHY O'HARA Citizen Staff
tohara@keysnews.comAn environmental group is questioning the Florida Keys Mosquito Control District's plan to introduce sterile mosquitoes into the Keys to battle the spread of dengue fever.
The plan is to release between 5,000 and 10,000 modified mosquitoes into an undisclosed 36 acre block near the Key West Cemetery. These male mosquitoes would be dusted with a florescent powder to enable tracking.
But some environmental groups, like Friends of the Earth, are vehemently opposed, claiming that this planned release of GMO mosquitoes could have unintended consequences on the local ecosystem.
The FOE Blog on December 21st warned:
Floridians face genetically engineered mosquito threat
The Florida Keys Mosquito Control District counters these concerns with a FAQ of their own on the dangers of Dengue, and the planned sterile male release project.
I’ve a few excerpts posted below.
Frequently Asked Questions
What are the likely impacts on the environment and on humans?
The main impact on human health will be to reduce the number of Aedes aegypti mosquitoes that can spread dengue.
There is no permanent change to the wild mosquito population and therefore unlikely to have any impact on the environment compared to the currently used alternatives.
Aedes aegypti is not originally native to Key West, though it has been present on and off in the last few decades. It is not a keystone species, there are no birds, fish or other insects that feed exclusively on it and therefore reducing the number of Aedes aegypti is most unlikely to have any impact on the environment. Additionally, the released mosquitoes will die in the environment and their progeny will die so this is a 'self limiting' approach. i.e. there is no permanent change to the wild mosquito population.
Oxitec has a short FAQ page on their technology, which you can access here. Oxitec’s GM process isn’t the only bid to modify mosquitoes to reduce disease transmission.
Earlier this year in A Mosquito STD To Fight Dengue I wrote about a project to infect mosquitoes with Wolbachia, a bacteria commonly found in fruit flies that – for reasons that aren’t entirely clear - inhibits a mosquito’s ability to transmit Dengue Fever.
Nearly a year ago in Queensland, Australia researchers began releasing thousands of Wolbachia infected mosquitoes each week into the remote communities of Gordonvale and Yorkeys Knob.
Within a matter of a few months the Wolbachia infected mosquitoes overran the uninfected mosquito population in these two test environments.
Although extremely encouraging, more tests are needed, including confirmation that this process works against all dengue serotypes. The Gates Foundation is providing further funding to support the release of Wolbachia mosquitoes in Australia, Vietnam and Thailand.
While it has required impressive skill and technology to bring these `Brave New Mosquitoes’ to the point of being ready for field tests, the bigger challenge may well lie in getting an increasingly wary and skeptical public to accept their release.
