While living in Mozambique I have seen first-hand the tremendous suffering caused by mosquitoes and the diseases that they transmit, especially in children. Friends have lost children to malaria and, in this rainy season especially, neighbours are frequently coming down with the disease. According to the Gates Foundation, malaria, transmitted by the mosquito Anopheles gambiae, caused 627,000 deaths in 2012. It’s a scourge to the human race. When you add in dengue and chikungunya, two other mosquito-borne diseases, and the strong (but not yet conclusive) association between the zika virus and microcephaly, mosquitoes become the animal incarnation of the Grim Reaper.
Nevertheless, I was shocked to read an article in the Guardian in which so many ecologists, entomologists, parasitologists would have no problems with “wiping them off the face of the earth”.
A few quotes:
- Professor Steve Lindsay, a public-health entomologist at the University of Durham agrees: “I have no problem with taking out the mosquito.”
- Professor Hilary Ranson, head of vector biology at the Liverpool School of Tropical Medicine. “I spend most of my time trying to keep them alive and study them, but that’s in order to try to kill them. Ultimately I wouldn’t be too sentimental.”
- Jules Pretty, professor of environment and society at the University of Essex: “Here you can ask the question: if there was a loss of a whole species, would there be a human benefit? And in this case, the human benefit is so great that I think you have to say: ‘OK, I can hold these two thoughts at once.’”
These are really quite strong statements. And for the most part I see where they are coming from. The human argument against mosquitos (or the diseases that they carry) is very strong – you only have to look at the number of deaths they cause, the suffering from the diseases, the long term effects of the disease. The economic argument is strong, at least in terms of man-hours and productivity loss because of illness – estimated at billions of dollars every year.
An estimated 207 million people suffered from the disease in 2012, and about 627,000 died. About 90 percent of the deaths were in Sub-Saharan Africa, and 77 percent were among children under age 5.
If we did eradicate them, wouldn’t ecology suffer? A pitcher plant in the north east of America, benefits from the micro-community including mosquito larvae that lives in its leaves, as they make nutrients such as nitrogen available for the plant. The mosquitofish Gambusia affinis, a specialised predator of mosquitoes, could go extinct without mosquitos to feed on. This loss could have major effects up and down the food chain. A primary food source of insects, spiders, salamanders, lizards and frogs would be lost and the migratory birds that fly through the Arctic tundra would no longer benefit from the vast summer swarms of mosquitoes. Also, mosquitoes do pollinate plants. But, in most cases, the ecological role played by mosquitoes is actually small, and according to a report in 2010, other species could fill in – birds would switch to other swarming flies that would fill that niche, and other organisms could step in to process detritus in water systems. The evidence suggests that ecology wouldn’t suffer that much, unlike if, for example, bees go extinct. So the ecological argument for keeping mosquitoes is not strong. As one article is titled, “What Purpose Do Mosquitoes Serve? It’s hard to justify the existence of these annoying critters.”
It seems very clear: eradicating mosquitoes isn’t just a good thing to do for humanity, it also isn’t too bad for the world either.
A couple of thoughts:
One. It isn’t the mosquitoes that kill people, it is the diseases they carry. Malaria kills people, not Anopheles gambiae. The Gates Foundation defines malaria eradication as “removing the parasites that cause human malaria from the human population. Simply interrupting transmission is not sufficient to achieve eradication”. Sure, it might be easiest to eliminate malaria by eliminating A. gambiae but we should bear in mind that it’s not A. gambiae that kills. I can testify to how annoying they and how much their bites itch (and Aedes aegypti‘s bites are even more painful) but that isn’t a reason to eradicate them.
Two. A comment on the Guardian article: “If we eradicate the mosquito what vehicle will death find to replace it?”. If other species will fill in mosquitoes ecological role with ease, then other species will surely become the vectors of deadly diseases. A Conversation piece on the eradication of mosquitoes concludes with the same thought.
Three, and perhaps my strongest objection to the sentiment in the Guardian article. Even if mosquitoes were, as far as we could work out, ecologically ‘useless’ and even if it was guaranteed that eradicating them would also eradicate malaria, Dengue and zika, would it still be right to purposefully ensure entire species go extinct? Do we have the right to wipe that species off the face of the earth? I’m not sure. What would that mean for other ‘undesirable’ species? It’s a very dangerous place to go if we start rating which species we can eradicate. Who gets to make that decision? What checks and balances would there be? What do you think? Please make comments at the bottom of the page – I’m interested in your thoughts.
After all, “The ecological effect of eliminating harmful mosquitoes is that you have more people. That’s the consequence,” says entomologist Daniel Strickman, programme leader for medical and urban entomology at the US Department of Agriculture in Beltsville, Maryland. If you’re talking about species that are a menace to other species, serve little ecological ‘purpose’, and have done great damage to the ecosystems around them, then Homo sapiens should be worried.
ADBScience 
7 responses to “Do we have the right to eradicate species?”
Over 50 years ago we were taught that to control mosquitoes remove rubbish eg tin cans old tyes and other possible breeding grounds. Fish in ponds to eat larvae , cannot remember whether it was a drop of oil or detergent to reduce surface tension and drown the larvae.? Also hearsay evidence about banning the plantation of plants such as banana in city area of dar es salaam reduced the incidence of infection
I remember Geography lessons about malaria control, like releasing river water from dams to wash out stagnant water ponds downstream. I suppose humans have always locally displaced/eradicated species – see conflicts between humans and lions/elephants in parts of rural Africa – so mosquito control near cities is a proportional response. But releasing modified mosquitoes that have the potential to eliminate mosquito populations worldwide through genetic drive is a different level of response, and one I think needs more thought than the articles I quoted seem to give.
What about a couple of other examples:
1) guinea worm, which we’re very close to eradicating: would anyone argue that we shouldn’t?
2) smallpox, which while a virus, of course has been eradicated outside a couple of labs. One could equally ask if we “had the right” to wipe smallpox off the earth.
And another thought: is it worse to purposefully eradicate a species (as in this case) or do so accidentally as we’re doing with countless species through global warming etc?
Good examples and I was just talking to Joanne on a similar line. Because of course, malaria (Plasmodium falciparum) is a living organism. And then dengue and zika are viruses. Where do you draw the line? Self-replicating self-sustaining organisms? That would rule out parasites and viruses.
I thought about whether it’s worse to be deliberate or accidental but chose not to include it in the blog. I think it’s worse to deliberately eradicate a species – the intent is the thing that sways me. But then again, we’re ‘accidentally’ causing extinction as you say, and I don’t think that is an excuse. I suppose you could draw parallels with murder vs manslaughter – murder carries a longer sentence but is manslaughter actually any less bad? I’m sort of going by gut feeling, but realise that gut feelings differ between people.
In Nature recently – about President Carter’s work to eradicate Guinea worm http://www.nature.com/news/a-good-precedent-1.19323
Which kills more humans, malaria or other humans I wonder? I can’t remember which bit of sci-fi it was, but there is piece about humans being incapable of living peacefully and protecting themselves, and actually the best thing for the longevity of the planet would be to wipe us out.
Great read though, and interesting dilemma.
Also, I’d agree with you about the intent in relation to deliberate vs. accidental extinction – once you’ve done one thing like mosquitoes and malaria, where do you stop?
According to Wikipedia, intentional injuries (suicide, homocide, war etc.) causes more deaths than malaria – 26 deaths per 100,000 vs 20 deaths per 100,000 but of those 26 deaths per 100,000, suicide is 14. So malaria kills more people than people kill other people. .
I was also thinking that there was something in sci-fi that talked about wiping out humans. Perhaps I’m thinking of Agent Smith and his ‘humans are viruses’ lines from the Matrix. When looking for that quote I actually found a Wikipedia page about the movement for the voluntary extinction of humankind. Maybe that’s a bit extreme, but it’s interesting that there is thought out there about our impact on the planet.