The 2019 mosquito population will likely be just as feisty as any other year, despite bitter blasts of cold over the previous winter. Washington University in St. Louis researchers have found one particular mosquito’s ability to adapt to climate change and other threats has actually increased the problem in the St. Louis area. They tell the story of that Asian Tiger mosquito, which wasn’t even on this continent forty years ago.
In a remote wooded area outside of Eureka, Missouri, a small group of buckets put in place by Washington University researchers may hold new answers about these hated backyard nemesis. And if you’re hoping this past winter’s polar vortex sent the critters packing for this year, scientists here quickly dash those hopes.
“They lay eggs in the fall that are incredibly resilient to extreme cold,” Tyson Research Center Director Kim Medley says. “So we suspect that even though we had a really deep freeze for a few days, that these mosquitos will likely do just as well this year as they did for the last.”
Findings here at the Tyson Research Center have taught scientists that mosquitos not only can adapt to different temperatures, but that they can do it very quickly.
“These mosquitos can rapidly adapt to changes in climate. And particularly for the Asian Tiger mosquito, they have adapted over a matter of three decades to northern winters,” Medley says.
The story of the Asian Tiger mosquito is a story of a major change in the bugs here in St. Louis over the past few decades. You see, the most prevalent mosquito in St. Louis wasn’t even in the United States until the 1980’s. It begins with a shipment of recycled tires from halfway around the world.
“It was accidentally introduced to the area around Houston, Texas in the early eighties. Presumably through the transport of used tires from Japan to that area,” Medley explains. They quickly spread from Texas, all the way north to New Jersey, in a couple of years really. Five years or so after they were introduced.
“In the temperate latitudes of the US, particularly in the urban and suburban areas, they are definitely the dominant species of mosquito.”
All that because of what happens when the larvae begin to grow. The Asian Tiger mosquito is stronger, and tends to dominate and push out other species. Survival of the meanest in this case.
The Asian Tiger mosquito, once it was in the St. Louis area, replaced some of the native mosquitos that were much less aggressive biters. There were fewer of them. So now that we have the Asian Tiger mosquito, we have more annoying biters and more of them.
They haven’t just adapted to the cold. In some cases, they’ve even evolved into resisting chemicals we use to destroy them.
“Some mosquitos have evolved resistance to certain management techniques,” Medley said. “They have a short lifespan which is one of the key requirements to being able to adapt quickly. They go through a number of generations in a very short period of time.”
The one bit of good news is the fact the Asian Tiger, while more annoying, is a less likely carrier of diseased like zika.
All this brings us back to the buckets. Out in Tyson’s woods, they actually don’t have too many mosquitos. That’s because the bugs need containers, natural or man-made, for their eggs to grow and hatch. So Asian Tiger or otherwise, if you get rid of those containers full of water around your house, you’ll do what bitter cold and even chemicals can’t always do.
“There many strategies out there to manage mosquito populations,” Medley says, “but the best way to do it for containers mosquitos is to eliminate their habitat and dump out those containers.”