Evolutionary fix of mosquitos

From: Anders Sandberg (asa@nada.kth.se)
Date: Sat Jul 12 2003 - 05:44:58 MDT

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    [ 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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