Over the Labor Day weekend, I went backpacking in the Catalina Mountains with some friends. It was a beautiful night, with a nearly new moon and Jupiter gleaming brightly in the sky, so most of us left our tents in the car and slept outside. Or in my case, lay around outside, stiff as a board, fearing one of the rattlesnakes or scorpions we had run into earlier would try to snuggle up in my sleeping bag with me.
But the real trouble started for me just as it began to get light and I started to relax. A slight whining noise increased in volume until it reached screaming pitch and I realized a mosquito was dive bombing straight into my right ear. I took immediate evasive maneuvers, and managed to thwart the attack. But it was either a very nimble insect, or prepared with hefty backup, because no sooner had I declared the immediate vicinity of my head a Green Zone but a double strike was ordered on my left ear. Again I warded off insect penetration of my blood supply – or so I thought. The game of cat and mouse continued until it became too bright to continue the charade of sleep, whereupon I found the facial squadrons had been mere decoys to distract me from the devastation being wrought upon my arms and ankles. I have been painfully avoiding scratching in the days since.
Back in July, intern Janet Fang of Nature wrote a brief news article on the research and development of large scale mosquito eradication efforts. She asked several researches what might be the impacts of eradicating all 3,500 or so species of mosquitoes worldwide (of which a couple hundred bite humans and a handful of those carry disease, like malaria). Unlike other pesky bugs, like no-see-ums, mosquitoes are not the exclusive pollinators of cacao or other any other valuable crops. They do not by themselves support any endangered species that we are aware of. In fact, the brief survey of research in the Nature article made it sound like mosquitoes are mostly generalists (as opposed to specialists) and that theoretically, their disappearance would allow competitors to take their place with little ecological impact.
This is the kind of near-term thinking we humans are good at. If there are no immediately obvious consequences, we deem it relatively harmless. As long as no people live right where we dump the rocket fuel or test the nuclear weapons, it should be okay, right? We forget that it might migrate into the water table and travel. As long as no one dies of carbon dioxide poisoning, we see little harm in burning fossil fuels, and miss the slow and insidious creep of average temperatures and extreme weather events. If farm workers fail to die from pesticide exposure, it is hard to claim damages for their children’s IQ being lowered by 30 points due to impeded mental development. But studies of larger scale can sometimes capture these indirect impacts.
Likewise, a species’ mere presence can restructure the ecological community around it. I have been doing some theoretical research (read: math) on how hiding from predators affects two competitors’ ability to coexist. (More on that soon, I’m meeting with my advisor tomorrow!) For example, grasshoppers change which leaves they hang out on depending on whether they are hunted by ambushing spiders or by roaming spiders, and that has cascading effects on what plants thrive there (Schmitz 2008). Aldo Leopold wrote about what happened in the mountains of Arizona and New Mexico when the wolves were extirpated there. Although he thought the mountainsides were stripped by deer no longer consumed by wolves, he would have found poetry in the notion the damage was worse because they were no longer hiding from wolves either. Just because we cannot predict the effects of wiping out mosquitoes does not necessarily mean there will be none. In fact, maybe I will try my hand at that after this predator avoidance project.
I should mention there is also an ethical dimension to this. An entire field has emerged, known as Conservation Biology, that really holds at its core the preservation of biological diversity. Back to Leopold again – he writes of the killing of what may have been the last grizzly in Arizona. The world afterwards seems a smaller, sadder place. Barbara Kingsolver (a Tucson homegirl) also makes more explicit and practical, though no less impassioned, arguments for biodiversity.
What do you think? Would it be wrong to erase all mosquito species from the face of the earth instead of slapping them one by one like I did all night? Would it be a good idea? After all, we did it with smallpox. I don’t think it will be a matter of “can” for long, but “should.”