The outbreak of Zika in Latin America has renewed the often-heard call to “get rid of mosquitoes.” That’s a naïve and foolish idea. It would also be hard — if not impossible — to do.
There are more than 3,000 species of mosquito. Several hundred species bite humans. Of these, three are primarily responsible for transmitting human disease.
It would be foolish to get rid of all mosquitoes. They inhabit various niches in ecosystems. Mosquito larvae help recycle nutrients and provide food for fish and other aquatic organisms. Some adult mosquitoes pollinate flowers. They’re also food for birds, bats, and other animals.
The idea that we can eradicate even one mosquito species underscores our ignorance about the way natural ecosystems work. We just don’t know enough about most ecosystems to predict how they would respond to the disappearance of a single species.
The potential for collateral damage to other insects and non-insect species is quite real. That’s the classic story of DDT. Thinking it would be a magic bullet, farmers liberally used this indiscriminate insecticide to stop insects from eating crops. That worked for a time. But they also nearly eliminated an array of bird species.
It’s naïve to assume that we can intentionally eradicate mosquitoes. When this has been attempted in the past, it didn’t work. Instead, these efforts did fantastic jobs of selecting for insecticide-resistant mosquitoes. I can’t imagine that a similar sort of selection won’t occur following the release of genetically modified male mosquitoes.
Instead of getting rid of mosquitoes, what we need is a better understanding of their natural history and their places in various food webs. Such information would let us build accurate models that could tell us how a particular web would respond to the absence of mosquitoes. My guess is: not well. More significantly, a better understanding of food webs would provide key insights into better ways to control mosquito abundance and reduce the risk from vector-borne diseases.
Andrew P. Dobson, DPhil, is professor of ecology and evolutionary biology at Princeton University. His research focuses on the ecology of infectious diseases.