Want to rid your backyard of pesky mosquitoes and stop them from spreading dangerous diseases? Here's a tip: Serve them coffee.
Regular or decaf will do.
To prevent spreading the mosquito-borne La Crosse virus, which can cause encephalitis, primarily in children, Radford University Assistant Professor of biology Justin Anderson conducted a two-year research project to determine whether coffee extracts interfere with the replication of the virus or simply kill the pestiferous mosquitoes.
"Other researchers are working on ways to kill the virus, and others are working on ways to kill mosquitoes. We decided to look into doing both, to block virus transmission and to kill a bunch of mosquitoes, too," Anderson explained.
To begin the research, Anderson along with Nicole Eastep and Rachel Albert, both 2011 biology graduates who studied in Anderson’s lab, mixed the La Crosse virus with various coffee concentrations and infected cultured cells with the virus. The researchers then examined the virus’s ability to infect those cells and replicate.
"It turned out the coffee killed the virus to a certain level—not completely, but it did a pretty reasonable job of inhibiting the ability of the virus to infect the cells," Anderson said. "Both regular and decaffeinated coffee demonstrated significant reductions in the La Crosse infection in direct antiviral assays."
Next, it's time for the mosquitoes to taste the coffee.
Anderson, barista to the mosquitoes, and his researchers hatched mosquito larvae and reared them in various coffee concentrations, then looked for changes in their developmental time or mortality. "The coffee pretty much killed the mosquito larvae at really high concentrations, basically at almost the concentration at which you would drink," he said.
The research group did not test straight coffee, Anderson said, "mostly because we couldn't see the mosquitoes in it."
Subsequently, the research group used a coffee concentration of 25 percent, and almost all of the mosquitoes perished. When the concentration was cut to 12 percent, Anderson and his crew found a higher mosquito survival rate. Later, they settled on a concentration between 12 percent and 25 percent, then infected mosquitoes with La Crosse virus.
The team's findings showed that "mosquitoes reared in the coffee replicated the virus to a lower level than did mosquitoes reared in water," Anderson said. "That was a new finding. No one had shown anything like that before, to manipulate the mosquito like that using a plant extract."
An article by Anderson and his colleagues explaining their findings appears in a special edition of the journal Frontiers in Physiology. The issue is dedicated to global change and human vulnerability to vector-borne diseases.
In terms of his research, but not personally, Anderson is finished with coffee but not mosquitoes. Up next is pokeweed, which has a protein called pokeweed antiviral that has been shown to inhibit every virus it has been tested against, he said.
Anderson is working with Radford University students Nikki Holland and Madison Gardner on the pokeweed research.
"We’ve cloned the pokeweed antiviral protein gene, and we're trying to express that protein in some bacteria and expose it to mosquitoes to see if it kills the mosquito," Anderson said. "We'll look to see if it works against the two viruses, La Crosse virus and dengue virus, that we're working with now and see if we can engineer bacteria to express it and give it to the mosquitoes."