Would the world really be better off without mosquitoes?
Do mosquitoes serve any purpose, and given the opportunity, should we eradicate them?
If you could get rid of any animal, what would it be?
If you put enough thought into it, it’s a pretty difficult question. Nature is a complex web of interactions, and it’s hard to take anything out without a cascade of unpleasant consequences. You might hate spiders, but without them we’d be overrun by all manner of pests, harming crop production and spreading disease.
I’ve always said the animal I’d choose to get rid of would be mosquitoes. But this week, I found myself wondering whether my answer was really all that wise.
Why mosquitoes are the worst animals (statistically)
Let me start by explaining my reasoning. According to the WHO, mosquito-borne diseases kill 725 000 people a year. That makes mosquitoes the deadliest animals on Earth by some margin. Snakes, the second deadliest animals (if you don’t count humans themselves), kill between 81 000 and 138 000 humans per year.
Mosquitoes spread a variety of deadly diseases, including Zika, dengue, yellow fever and West Nile fever. The most deadly disease of all is malaria, which was responsible for 627 000 deaths in 2020. Malaria may have killed half the people who have ever lived. Most deaths occur in children under 5 years of age.
From these facts, it seems clear that the world would be a much happier place without mosquitoes.
But before we press the hypothetical button that wipes them out, let’s double-check — do mosquitoes serve any purpose?
A light snack
Mosquitoes do in fact have an important ecological role to play — they’re delicious.
Plenty of species subsist on mosquito larvae. These include insects (dragonflies), amphibians (eastern red-spotted newt) and reptiles (freshwater turtles). Other animals prefer to dine on adult mosquitoes, such as the common nighthawk, hummingbirds and some species of bat.
Getting rid of mosquitoes could leave us with less of their predators and more of the other animals those predators eat or compete with. Hummingbirds and bats are both pollinators, so declines in their populations could negatively affect plant reproduction.
And there’s worse news — mosquitoes are pollinators too.
Pollination
Female mosquitoes only drink blood when they’re preparing to lay eggs, while male mosquitoes are strict vegetarians. A mosquito’s primary food source is actually nectar.
Like other pollinators, the mosquito takes pollen from the anthers of one flower as it feeds. It then transfers this pollen to the stigma of another flower, yielding fruit and seeds. Animal pollination is important to the sexual reproduction of most wild plants, while 35% of crop production is at least partially dependent on insect pollination.
The majority of a mosquito’s meals are harmless, or even beneficial to us and the planet.
Due to habitat destruction, increased use of pesticides and climate change, pollinators are already in crisis. Could we really afford to get rid of a pollinator on purpose?
What if we swatted every mosquito?
Mosquitoes may do the planet some good, but would we still be better off without them? The natural world is too complex for us to know for sure.
Getting rid of mosquitoes might not be a disaster for food webs and pollination long-term. 99% of species that have ever evolved on Earth have now gone extinct. We’re not left with a void every time one disappears. If mosquitoes disappeared, another insect would likely come to fill a similar niche in the ecosystem.
The problem is that this replacement could be just as bad, or even worse, than mosquitoes. It could carry worse diseases, transmit them more effectively and spread further across the globe. Then again, it might not. It would, after all, be hard for something to cause more damage that the world’s current deadliest animal.
Science writer David Quammen approaches the question from a different perspective. He argues that mosquitoes could be viewed as protecting the Earth from humans. Forests are home to more than 75% of life on land, and hundreds of millions of people depend on them for subsistence and income. A billion acres of forest have been lost since 1990. In an essay titled Sympathy for the Devil, Quammen suggests that rainforest destruction may be even worse if it weren’t for mosquitoes.
Resident forest peoples have acquired some immunity to mosquito-borne diseases and engage in lifestyles that minimise exposure to mosquitoes. Non-natives, on the other hand, are more vulnerable. Quammen says that mosquitoes make large swathes of rainforest uninhabitable, and this limits the damage we can inflict upon these areas.
It’s a tough argument to consider, and you’ll have to make up your own mind. Ideally, of course, we’d be able to stay away from rainforests without the threat of serious illness, but that isn’t the world we live in.
Although I think Quammen is correct to suggest mosquitoes limit the impact of humanity on rainforests, this isn’t enough to make me feel thankful for the mosquito. 725 000 deaths a year, most of which are in young children, is a high price to pay for anything.
The ethics of wiping out a species
We’ve considered the consequences of getting rid of mosquitoes, but how about the ethical argument? Is it morally correct to eradicate a species on purpose?
The concept of intrinsic value represents the idea that nature has inherent value, independent of any benefit or harm it may confer on us. Attributing intrinsic value to all species would give us a moral obligation to preserve them, regardless of whether we’re better off without them.
Yet there must be a limit to the kinds of organisms we’re willing to assign intrinsic value to. An alternative to eradicating mosquitoes would be eradicating the disease-causing microorganisms they carry. Would anyone argue that these bacteria and viruses have intrinsic value? Probably not. You’d be hard-pressed to find anyone who mourns the loss of smallpox.
So what quality does the mosquito possess that a Plasmodium bacterium doesn’t, and why should it matter to us?
Verdict
With all these facts and viewpoints to consider, would I still elect to get rid of mosquitoes? Probably. But I’d be a lot less certain than before that I was making the correct decision.
Which species have intrinsic value and what that should mean to us is an ethical dilemma with no clear answers. And from a practical perspective, we just don’t know what long-term effects the loss of mosquitoes would have on the world around us.
But the question of whether we should aim to wipe out harmful species is no longer so hypothetical. By infecting mosquitoes with a bacterium that reduces their ability to reproduce, researchers have nearly eliminated populations of two mosquito species on two islands in Guangzhou. Tsetse flies, which spread sleeping sickness and African animal trypanosomiasis, have also been targeted by eradication campaigns.
Maybe it’s time to think a little harder about whether we want these bugs around or not.
