17 September 2011

A Deadly Enemy Older than Man: The Buzz of Death

Mosquitoes transmit disease to over 700 million humans a year, with a resulting death toll in the millions (wikipedia). To this point, the insect repellant DEET is the most effective defensive weapon against these disease vectors, other than thick clothing and strong netting. But humans are slowly beginning to decode the language of mosquito smell rceptors.

Scientists at UC Riverside are discovering an array of common chemicals that can inhibit, blind, or lead astray the CO2 receptors of mosquitoes.

Vanderbilt University researchers have gone further, and developed an entirely new class of insect repellant which is thousands of times more effective than DEET.

But now that genetic engineers have become interested in the mosquito problem, we are beginning to see new strategies which are more clever than ever. The illustration above reveals two contrasting approaches to species eradication -- the sterile male technique vs the autocidal technique.
...if autocidal technology lives up to its promise, it could be about as environmentally friendly as pest control can get. It could largely or entirely replace pesticides, and it affects only the target species. Last but not least, it is hard to see what could go wrong. _NewScientist
The autocidal technique produces females which either die before maturation, or which are physically disabled and unable to mate.

Generally, genes that cause a reproductive disadvantage will tend to disappear from the population over time. But there are a number of factors which could alter that Darwinian equation.

If the autocidal mosquitoes were also given traits that conferred a reproductive advantage for themselves -- super powerful sexual attractant pheromones for example -- as part of an overall genetic package, the autocidal trait would spread more quickly.

Likewise, if automated stations were set up in the wild to periodically release new batches of autocidal males, the process could be reinforced over an extended period of time.

If the autocidal trait caused sterility in females, rather than death or disability, the process of species extermination would be accelerated.

And so on. It is easy to imagine dozens of ways to augment, accelerate, or perpetuate such a process of ongoing extermination.

Alert readers will have recognised the return to the New Scientist article on species extinction, applied here specifically to mosquitoes.

But as noted in the NS article, similar techniques could be applied to virtually any species that reproduces sexually. Also as noted in the NS article, the genetic engineers have just begun to think of different approaches to the mosquito problem. This ball has just begun to roll down the hill.


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Blogger Stephen said...

I hope they can use some of these techniques on bedbugs.

Saturday, 17 September, 2011  
Blogger Cheryl Pass said...

Sounds very interesting...just wondering what happens to birds and bats who eat the mosquitoes. Maybe that is a dumb question...not a bio-scientist here.

Thanks for the hope, though!!

Saturday, 17 September, 2011  
Blogger Unknown said...

Does look very promising. But thinking that animals like spiders that feeds on these insects, would it not cause instability in the food chain?

Saturday, 17 September, 2011  
Blogger al fin said...

Stephen: Yes, NYC could use some of this type of help.

Cheryl: The genetic attacks are targeted toward specific species. If by chance those species are obliterated, other species are likely to fill the niche the extincted one vacated. But hopefully not as disease vectors.

SMK: See note to Cheryl above. These are not broad-spectrum attacks against all mosquitoes or all flies etc, just specific species. The overall food chain shouldn't be seriously affected, since other species tend to fill in the niches rapidly.

Saturday, 17 September, 2011  
Blogger Cleanthes said...

It won't be long before these techniques find a use on human populations. Genocide made easy.

Saturday, 17 September, 2011  
Blogger J said...

Releasing mutated males would cause fewer females each generation. Any organized society would find out immediately that something is happening. BTW, the effect would be similar to what is happening in India and China, an excess of males babies born. From the perspective of a genocidically inclined environmentalist, what is happening in the world is a dream come true.

Saturday, 17 September, 2011  
Blogger neil craig said...

World malaria deaths were down to 50,000 before, following the Silent Spring propaganda, weastern governments insisted on DDT bans.

In fact DDT has never been shown to harm a single human being, even the claims it thinned eggshells are largely debunked. On the other habd the lack of DDT kills 1.5-2 million annually, but mainly African kids so the econazis don't mind.

Sunday, 18 September, 2011  
Blogger PRCalDude said...

DDT has to be used sparingly or the mosquitos develop resistance to it just as all the other insecticides. I'm all for the use of DDT, but the Africans will eventually need to come up with better solutions. This is extremely unlikely.

Sunday, 18 September, 2011  
Blogger sds said...

I’m picking up a lot of unique or good facts here. lovely article post. Thank you for publishing this article and thanks for improving my knowledge.

Monday, 19 September, 2011  
Blogger Jez said...

The autocidal technique sounds all find and good, but surely there is a huge flaw. It relies on there being NO mutation that allows these immature mosquitos to actually mature slightly quicker, and hence breed.

The technique is very different to the sterile insect approach, and assumptions from one technique can not be assumed valid for the other.

Suppose that even 1 in a billion of them do mature just early enough to breed, as is likely in such a large population. You will have successfully created an even faster breeding mosquito. We are seeing similar things with the fish stocks around the world - take away the mature ones and the immature ones start to become mature sooner.

This experiment seems to be one of the most dangerous attempts at control of a species, and the autocidal technique, as applied in this case, seems extremely risky.

I suspect there will be a short term reduction, followed by a resurgence of more rapidly maturing mosquitos that will be worse than the original problem.

Monday, 19 September, 2011  
Blogger J said...

Fighting living, evolving organisms by genetic manipulation is sure to backfire. With organisms that exchange genes like bacteria and virus, it is "madness".

Monday, 19 September, 2011  

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