Monday, October 10, 2005

 

My Ecophilosophical Quandry

As I dump accumulated rainwater wherever I find it in my garden I have often wondered whether mosquitos would have defenders if they arrive on the endangered species list. Would they? Should they? Could they? Idle ethical speculation, no doubt. But what if we had the option?

Mosquitos transmit deadly diseases. Malaria, for instance, kills an estimated 2.7 million people this year. Dengue fever is less extensive, but spreading, and no vaccine is available. A recent article on the spread of dengue fever explained: mosquito bites infected person then bites an uninfected person a little while later, in countries with mosquitos. In countries with mosquitos, I thought? Are there countries without mosquitos? But they probably meant the "city-dwelling Aedes aegypti" in particular, not just any mosquitos.

I do not live in a climate where malaria and dengue fever are a hazard, except possibly near international airports when stowaway bugs in air cargo fruit bite someone once in a blue moon. We'll see whether this changes as winters warm.

Nevertheless, I dislike mosquitos. I have disliked them for a long time, as long as I can remember. I suppose I belong to the group of people who smell particularly delicious to them, for I am bitten if anyone is. In Texas, where everything is bigger (so they say) mosquitos bit me through my sleeping bag. In Corsica, they descended on our bed from the walls and ceiling of our hotel room in such numbers that they fairly spoiled our honeymoon. I now choose my hours and weather for gardening much more carefully to minimise the number of itchy bumps with which I'll end up. Wouldn't the world be a better place without them?

Imagine my delight when I read in the Guardian this morning:

Scientists create GM mosquitoes to fight malaria

Science: Mosquito with flourescent testicles could save thousands of lives.


Part of the proposed technology has been around for years and has been used successfully to combat other types of insects: basically, you release a lot of sterile individuals and severely reduce reproductive yield, possibly to a tipping point below which the attractor becomes zero. The difficulty with mosquitos has been the difficulty of separating the males from the females to avoid releasing females at all; sterile or not, they transmit disease. The new part is using genetic modification to enable effective and efficient sorting: "the males expressed a fluorescent green protein in their sperm."

This project has learned from past failures and anticipated objections very well. In particular,
  1. knowing that only female mosquitos bite, they would release only males to ensure that nobody will be bitten by a genetically modified bug.
  2. the released males will be sterile, so no genetically modified genes will enter the wild pool.

Sounds good, but how many sigmas out is zero defects? What happens if a female or two are released along with the males? Presumably they will have been exposed to radiation, too, but will the same dose sterilise females? What happens to the modified genes if and when the mutants are eaten by their natural preditors (they must have some, mustn't they?) How long will it take natural selection to endow the females with a preference for males whose testicles don't glow? Have the researchers patented this process? If not, why not? If so, who profits and who pays?

Other than the GM aspects, is there a reason to preserve mosquitos? No doubt they provide an essential link in some part of the food chain; I vaguely recall that some kinds of bats eat them, but perhaps not the Anopheles stephensi, and I'm not as pro-bat as I used to be since they've been identified as a reservoir, vector, or both, of some of the nastiest emerging diseases of our times--ebola and sars, to wit.

Finally, before letting the prospect of a mosquito-free world dominate our concern about releasing GM bugs, one last question: if we succeed in eradicating mosquitos (or at least some of the more dangerous types of mosquitos), could something worse take their place?




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