In recent months an outbreak of the Zika virus, a usually unremarkable cousin of the more dangerous and more common Dengue fever virus, has quickly spread across both the physical landscape of South America and the media landscape of the rest of the world. This is yet another disease spread by our old enemy. No, I'm not talking about the Scots, I'm talking about the Mosquito. In light of these recent reports, I'm left asking myself, once again, why we haven't wiped the mosquito from the face of the planet. Forget the War on Terror, or the War on Drugs, or the War on [insert noun here] ... what about the War on Vampire Flies?
Here's a little back story of Zika: it was first identified in a caged monkey in 1947, and by 1968 we had directly observed transmission of Zika to humans via the Aedes mosquito. Since then, examination of human antibodies indicates that people have been fighting off this disease at least as far back as 1951. The symptoms, thus far, were pretty run-of-the-mill: a fever that usually lasts just over a week, skin rashes, conjunctivitis, muscle pain ... Basically, you'd feel rubbish for a bit, but you'd get over it.
Now, though, we have reports of wide-spread infection in South America, and, more importantly, a sudden rise in rare, debilitating disorders. For example, in 2014 there were only 147 reported cases of Microcephaly - a disease that inhibits development in the womb, colloquially known as shrunken-head syndrome, which, if the child survives birth, leads to a host of life-long debilitations and a lower life expectancy. In 2015, as Zika spread, that number shot up to around 4000. In the babies that didn't survive, the Zika virus was repeatedly found in brain tissues, amniotic fluid, placental tissues ... All the places you'd think to look if searching for a viral culprit. The Zika virus is, so far, the best explanation for this 25-fold rise in Microcephaly, but why this connection hasn't been seen before isn't all that clear. It could be a recent mutation in the virus genetics, or it could just be the numbers; with an outbreak on such a large scale, the connection to these rare side effects could just be becoming more obvious.
As we all know, the spread of disease by mosquito bites is nothing new. Multibillionaire and all-round-nice-guy Bill Gates has dedicated himself to the cause of finally beating malaria, a disease that killed half a million people in 2013 alone. There's no shortage of money behind this drive, but malaria is just one disease spread by mosquitoes, as the recent Zika outbreak is reminding us. There's also: Dengue and Yellow fevers, both cousins to Zika and endemic to specific parts of the world; Japanese Encephalitis, found commonly near pig farms, and whose prognosis is a terrifying 1/3 recover, 1/3 are paralyzed, 1/3 die; the West Nile virus, which is usually mild, but in rare cases leads to neurological disorders ... And so on.
It's hard to wipe out a virus, but it's possible. Smallpox was once a blight on the face of mankind - literally - that in the 18th century alone killed an estimated 400,000 Europeans per year. Through vaccination this virus has been more-or-less completely eradicated from the planet. If it still lives at all, it is in small pockets (or in a super-villain's fridge), and is very unlikely to ever get a stranglehold on human civilization again. There are thousands of known viruses and parasites though, so curing them all individually is difficult work, particularly given that they're prone to mutating their way past our drugs. Luckily, some diseases can't get about on their own, they need a carrier to take it from Andy to Shanise, and this carrier is known as a disease vector. If we can't defeat the diseases listed above directly, maybe the simplest thing is to go after their carrier.
Here's a fact you probably already know - the mosquito is believed to be responsible for more human deaths than all wars combined. Wait ... Did I read that right? Ah, no, I didn't. The actual fact is that female mosquitoes are responsible for more deaths than all wars combined. The males don't drink our blood at all, they just go about their day, looking for lady mosquitoes to mate with, wishing the ladies would find another way to produce their eggs than by making an enemy of humans. Don't they know that humans are mental? Keep this little fact about the females in mind, it'll be important later.
Insecticides have failed spectacularly at destroying mosquito populations for the same reason bacteria are developing defences against antibiotics: evolution. No, not the David Duchovny film, I mean the process of evolution by natural selection, but that's a mouthful. Spray a million insects with toxins, and most will die. But if only a handful have some weird mutation, a genetic variant that allows them to resist the toxin, those survivors will repopulate the area with that variant, eventually leading to millions of toxin-resistant insects, rendering the insecticide less than useless. With genetic modification, however, we may be able to out-think evolution.
One private company in the UK has developed a novel tool for doing this. Instead of suggesting we spread mosquito killing toxins far and wide for miles and miles and miles, these scientists have genetically engineered male mosquitoes that, when released, mate with the local females to produce offspring that die in the larval stage. The idea is to eradicate the mosquitoes by preventing the next generation from ever happening. This has been field-tested in Brazil, Malaysia and Panama, and has brought down local mozzy populations by as much as 90%. Another group, this time in America, have devised a similar solution: genetically engineered mosquitoes that produce flightless females and healthy males. This, quite frankly, is ingenious. The line of males continue on to pass on their tampered genetics around, but the broken females never get off the ground, never bite a human, and never reproduce. In cage tests, this effectively brought mosquitoes to extinction.
Then there's the Star Wars Mosquito Defense System. That's not a joke ... Well, it is, but it's not my joke. If genetic rewiring is difficult to evolve around, how about a laser that shoots mosquitoes out of the sky?! Don't believe me? Watch. This laser is guided by a sophisticated piece of tech that pinpoints mosquitoes and destroys them at up to 100 mozzies per second up to 30 metres away. Your ears might be able to pick a mosquito apart from a house fly by that distinctive annoying sound it makes, but this Moz-Gun can tell a mosquito apart by the frequency of its wing beats, so friendly bees in the neighbourhood remain unharmed (save the bees!). It has, of course, received some criticism for being expensive and not viable in areas without electricity. To me this just seems like a matter of time until the price drops and energy storage technology catches up, then they'll be stocking shoulder-mounted Moz-Guns in the hiking section of your nearest Argos catalogue.
So we're close to having the technological and biological tools to bring our old enemy to its knees. Obviously rendering mosquitoes harmless to humans would be preferable to wiping them out entirely, and treatments do exist for many of the diseases they spread - malaria, for example, is far from a death sentence in the western world. The problem is that the infrastructure for disseminating these treatment en mass in poorer areas of the world does not, so lives are being lost while we dilly-dally over costs. Further, as Zika has shown, our predictive power of what plague the mosquito will spread next is far from perfect, so can we really afford not to wipe out the mosquito? Before rushing into such a big decision, we need to answer a couple of questions. Firstly, what would the ecological impact of driving the various mosquito species to extinction be? We've seen in the past that our meddling, intentional or not, can have dire consequences on local ecosystems. Would the Earth sorely miss these little disease vectors? Secondly, and possibly more importantly, would wiping them out be ethical?
Generally speaking, if you bring down the population of one species in a food chain, a bigger species that usually eats it will go hungry, and reduce in number, and then the species that eats that will go hungry, and so on and so on, all the way up the food chain to me. Nature, the top-dog journal which I laid to waste in my last blog (I hope it has recovered), put this problem to the world's leading ecologists. The somewhat surprising conclusion they made was that the biggest impact would be in the Arctic tundra, where migratory birds nest and eat up all those delicious mosquitoes during a brief time in which mosquitoes mate so successfully they form literal insect clouds. If all that bird food were to disappear, what would happen? Bruce Harrison of the North Carolina department of Environment and Natural Resources estimates that 50% of those migratory birds would go hungry if the mosquitoes were to vanish, but Cathy Curby, wildlife biologist at the US Fish and Wildlife Service in Fairbanks, Alaska, points out that the stomachs of these birds show that they much prefer the taste of midges, and only dabble in mosquitoes. So will anyone really care if the mosquitoes disappear?
It seems that, while there are many species that eat mosquitoes (or mosquito larvae), nothing eats them exclusively. Nor are mosquitoes good pollinators, or useful in any other way. Mosquitoes do not fill a role in the ecosystem (a niche) that wouldn't be replaced by something else, given time. As entomologist Joe Conlon says, mosquitoes "don't occupy an unassailable niche in the environment," ... "if we eradicated them tomorrow, the ecosystem where they are active will hiccup and then get on with life". Unlike bees, whose disappearance would have a million and one disastrous knock on effects, mosquitoes could just go away.
Now onto the trickier question ... Is it ethical? In terms of deciding whether all the thousands of human lives lost to mosquito carried diseases are more valuable than the billions of lives of mindless insects, there is no question. Save the humans, kill the insects. One wouldn't turn back the clock and protect the smallpox virus from extinction (though, some would argue a virus isn't technically alive, but I digress), so should we hesitate when offered the opportunity to wipe out this disease ridden pest? A pest that is estimated to be responsible for over half of all human deaths throughout history?
I think hesitating, and then carrying on with the task, is exactly what we should do. We should take a long look at ourselves and recognize that we're making a decision never made before in human history: intentional extinction of a fellow Earthling. It apparently has a word - speciecide. Sure, we've intentionally wiped out local populations, and incidentally driven other species to extinction, but this is an altogether different decision. This is a calculated, strategic effort to say "you my friend, are going the way of the dinosaur". If we do this, we should be careful not to make this option all to easy to go to when we have future disagreements with our Earthly neighbours. Sharks, for example, are routinely culled following a tragic death of a swimmer/surfer/astronaut, and it would be incredibly tragic if it became all too easy to press the "remove all" button during a media frenzy. We will be stepping into the role of ultimate adjudicator of whether a species deserves to survive on our planet, and the smarter we get, the more potent our death rays will become.
This thought makes me pretty uncomfortable, but it doesn't make me want to save the mosquito. The mosquitoes (at least the species that carry diseases), in my opinion, absolutely need to be gone. We just need to step cautiously into our new roles as gods.
Or we could just drink more gin and tonic. Apparently it works great.