Hand Sanitizer Is Great at Preserving Insect DNA


Scientists have discovered that hand sanitizer is a really good preservative of insects like this bark beetle. Kschulze/Ullstein Bild/Getty/HowStuffWorks

For the last decade, armies of bark beetles have been devastating forestlands in California and other places, and scientists are fighting back. To do so, they need citizen scientists — aka the general public — to trap the tiny bugs, which are as small as a grain of rice, and mail them back to their labs for DNA studies.

The only problem? People don't keep laboratory-grade preservatives at home. So how could  the beetles' DNA remain intact until it reached their labs? The answer, researchers found, resided in two common household products: hand sanitizer and automobile antifreeze.

According to a new survey, published in Invertebrate Systematics, inexpensive alcohol-based hand sanitizer and ethylene glycol-based automobile antifreeze can preserve bark beetle DNA for a week, making them appropriate substitutes for lab-grade preservatives.

During the study, conducted by researchers at the University of Florida, 33 ambrosia beetles were left for two or seven days in either 95 percent ethanol (the control); hand sanitizer; or propylene- or ethanol-based automobile antifreeze. The scientists set the samples outside where they would receive direct outdoor exposure. Afterward, the researchers checked the beetles' intact DNA and found that all methods worked equally well for preservation.

During the study, conducted by researchers at the University of Florida, 33 ambrosia beetles were left for two or seven days in one of these:

·         95 percent ethanol (the control)

·         hand sanitizer (the brand Purell for instance is 63 percent ethanol)

·         propylene- or ethanol-based automobile antifreeze

The scientists set the samples outside where they would receive direct outdoor exposure. Afterward, the researchers checked the beetles' intact DNA, and found that all methods worked equally well for preservation.

"This is great for citizen science projects," says entomologist Sedonia Steininger, one of the study's authors, as it will hopefully increase the number of projects and participation. "But [it's also great news] for researchers who may be out in remote locations without access to their usual suite of preservatives." The results could mean professionals will be able to sample more freely, while incurring lower costs.

Steininger says the group was "happily surprised" that both of the substitute preservatives not only worked, but worked for a full seven days: "To our knowledge, no one else has ever looked at the preservation efficacy of these household products for storing DNA."

She thinks that not many insect studies are being done today that require the mailing in of actual specimens, as preservation is a real issue when it comes to conducting molecular analysis. Thus, the finding that hand sanitizer and antifreeze will preserve insect DNA may prompt more studies with actual specimens.

The findings couldn't come sooner for those working on the bark beetle infestation. More than 2,000 species of bark beetles are found around the world. While many species attack already-stressed and weakened trees, helping to clean up dead wood, nonnative bark beetles also attack healthy trees, sometimes wiping out entire tree species. But even native bark beetle species can wreak havoc on forests. 

In the last decade, bark beetle outbreaks have been increasing, due to the warmer weather associated with climate change. This has devastated certain tree populations. In British Columbia, for example, 80 percent of the pine trees have been killed from bark beetle infestation. And in the U.S., millions of acres of forestland have been affected by the tiny insects, mostly in the Rocky Mountains and Western United States, including Colorado, Wyoming and drought-stricken California.

The Backyard Bark Beetle venture is a citizen science project run by researchers at the University of Florida. The project uses volunteers who trap bark beetles in their yard, then send them to the researchers, who study the beetles' distribution and diversity. Researchers instruct volunteers how to create a low-cost bark beetle trap using a plastic bottle into which hand sanitizer (or antifreeze) is inserted. Here's a video showing how to make the beetle bottle trap used in the Backyard Bark Beetle project.



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