Just because you can, does that mean you should?

Well, whine-not (sorry) start with something on a grand scale?  An article in today’s news describes the success, in localised trial runs, of releasing genetically modified (GM) mosquitoes into wild populations:

“You first release a few thousand males to see if they will mate, then you move to a control programme. In the Cayman Islands we released 3 million over a few months over 16 hectares. We effectively brought the overall mosquito population down by 80% in three months” –  Oxitec’s CEO Haydn Parry

Male mosquitoes are released; when they mate with normal females, they produce offspring genetically programmed to die before reaching maturity.

Aedes aegypti during blood mealI have heard people say before that mosquitoes are the one animal they would remove from existence, if they were endowed with such powers (I’ve also heard this said about cockroaches, though they are decidedly less bitey).   Indeed, on hot nights in South East Asia with 20-odd bites burning with the fury of a thousand flaming suns, I’ve been inclined to agree; and that’s not considering the major issues of disease transmission.  Although malaria is most commonly cited, the focus here is dengue fever, carried by Aedes mosquitoes.

The article rather skips over the fact that although mosquitoes carry these diseases, they are not themselves the disease, not the problem to be solved.  Is it naive to think that time would be better spent developing a vaccine (on which progress has been made in recent years) than wiping out mosquitoes?  I say this with no real love for mosquitoes, but in the recognition that a species that may be a threat to us might be a food-source for something else: a few immediate examples are dragonflies, birds and (of course) bats.

The worldwide death rate from dengue fever, incidentally, is 2.5% of the 500,000 people infected each year.  Without wanting to seem unsympathetic, this method seems a tad destructive – and the long term consequences cannot, surely, be known?

If we’re sticking with biological-poking-and-prodding, I prefer the Australians’ idea of introducing the bacteria Wolbachia to mosquito populations. Common amongst insects, one of Wolbachia‘s more notable features is that it effectively blocks the mosquitoes’ ability to transmit the dengue virus.  Not only does this mean the mosquito populations aren’t affected, but in theory it would spread faster than the dodgy genetics, because its carriers wouldn’t be dying left, right and centre.

Do you think that wiping out the vector of a disease is the best way to combat it?  Can we be sure that our well-intentioned interventions won’t have negative consequences elsewhere?  Given how many species become extinct each year, does it matter if we add mosquitoes to the list?  I’d like to know what you think.

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One thought on “Just because you can, does that mean you should?

  1. The Crow says:

    My first thought would be that, if the released mosquitoes’ offspring are not viable, the GM phenotype would be selected against to such a degree that it would be very quickly bred out of the population? I would imagine it wouldn’t take long for the remaining 20% from Haydn Parry’s quote to drastically increase in number again, and I bet they’ll never wipe out the population entirely. It seems like a very round-about attempt at a solution.

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