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Invasive Mosquitoes Spread by Riding On America's Highways

America's highways are the source and subject of myth, the exit strategy in case of a hydrogen bomb, and a boon for the invasive Asian tiger mosquito.

by Ben Richmond
Oct 28 2014, 10:00am

Image: CDC/Wikimedia

America's highways are the source and subject of myth, the exit strategy in case of a hydrogen bomb, and a boon for the invasive Asian tiger mosquito.

Since arriving aboard a shipment of tires in Texas in 1985, the Asian tiger mosquito, or Aedes albopictus, has spread all the way up to Maine. They're aggressive day-time biters, which would be bad enough, but they're also vectors that spread West Nile, dengue fever, and chikungunya, a virus that we didn't even have in the United States until last year.

And just as they arrived on the continent by riding human transportation, the mosquitoes spread across almost all of the Eastern United States by hitching rides on our highways, according to research published in the journal Molecular Ecology.

The Asian tiger mosquito's expanding range. Image: Kim Medley

Before we lavish praise on the mosquito for mastering the highway system at least as capably as people from Massachusetts, it's worth acknowledging that the team of University of Central Florida researchers managed to do something really difficult by tracking mosquitoes across the country.

"Even Darwin, in the 1800s, was interested in how species travel from point A to point B," study lead author Kim Medley said in a press release. "But measuring dispersal rates by hand is nearly impossible...You can dust mosquitoes and release them and then try to recapture them, but capturing enough of the releases to reach any solid conclusion is really difficult."

So rather than tracking down the same mosquitoes, the researchers genotyped the mosquitoes and caught up with their descendants later.

Naturally, to collect their specimen, the researchers headed to cemeteries, where abandoned flower vases provided the tiger mosquitoes with just the right amount of water for breeding.

The gene flow of mosquitoes through America was correlated with two things: bodies of water and highways. Turns out the mosquitoes, which typically only fly a single kilometer in their life, spread by riding on semi-trailers and cars. The bodies of water only really factored in as evidence of the environment being damp enough to refill the mosquito-breeding wells on trucks and cars, since according to a New Jersey mosquito control official, "this mosquito can breed in a bottle cap."

Oddly, one barrier to the tiger-mosquito takeover was found in typically mosquito-friendly forests, although that seems to be because the tiger mosquitoes couldn't displace the native treehole mosquitoes.

You've got to hand it to those treehole mosquitoes, that stand up to their invasive competitors, unlike we people, who, however unwittingly, chauffeured them across the country.