From: Anders Sandberg (asa@nada.kth.se)
Date: Sat Jul 12 2003 - 05:44:58 MDT
[ Inspired by the mosquitos of New Haven and Kalix :-) ]
What to do about mosquitos? Besides being terribly irritating, in many
places they transmit dangerous diseases. While chemical repellents work
to some extent they might be too costly for the thrid world, have toxic
side effects and need to be applied regularly. Insecticides work better,
but often cause ecological disruption . mosquitos are an important part
of the ecosystem. Spreading sterile mosquitos to cause a decline in
population is costly, since the numbers of mosquitos are so large.
On the more radical side, it ought to be possible to genetically
engineer mosquitos to avoid humans. But how to introduce such genes into
the mosquito population and make them dominant? A possible approach
would be evolutionary: introduce an evolution pressure on the mosquitos
to avoid humans.
My suggestion is along these lines: many people take pills that contain
a substance that acts as a mosquito contraceptive. Mosquitos that bite
such people will be less fertile, and hence not pass on their genes to
the next generation. Mosquitos that tend to avoid humans will have more
offspring and become more common. Over the next generations mosquitos
will become increasingly human-friendly.
Will this work? It depends on whether it is possible to create a cheap
substance acting as an insect contracpetive that stays relatively long
in the human body and does not cause side effects. Enough people need to
take it to make the fitness of human-biting mosquitos less than
human-avoiding mosquitos (human-avoiding mosquitos probably currently
have a slightly smaller fitness since humans are common, large and
well-fed mammals in most environments). The larger the fitness decrease,
the faster the evolution towards the avoiding form. The behavior also
needs to be changeable; this seems likely since many insect parasites
are species-specific.
Some drawbacks are: There might be an evolution towards contraceptive
resistance rather than non-biting. Ideally different pills should
contain different contraceptives making such resistance unlikely and
evolutionary harder than evolution towards non-biting.
Humans need to continue taking the pill to keep the selection pressure
up. If they stop human-biting mosquitos will start to increase again.
There will also be an influx of such mosquitos from regions where the
pill is not commonly used (while non-biting mosquitos will move into
these regions). This might lead to a tragedy of the commons problem, as
mosquito protection is a public good but the slight discomfort/cost of
the pill makes people want to avoid it . unless of course taking the
pill can also be made to benefit them too. Maybe the mosquito
contraceptive should be packaged together with a nutrient supplement of
some kind? In general the logistics and the economics of this
evolutionary approach to mosquitos needs to be studied a bit more
closely. The principle seems to be fairly simple and robust, but the
actual implementation might be done in many different ways.
What do you think?
-- ----------------------------------------------------------------------- Anders Sandberg Towards Ascension! asa@nada.kth.se http://www.nada.kth.se/~asa/ GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y
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