Since those first specimens were found, scientists in Washington State and British Columbia have set up a network to monitor for more V. mandarinia, and have found a few, but they’ve also done a different type of investigation, using genetics to figure out whether the hornets in BC and Washington were related. Their results were published in September in the Annals of the Entomological Society of America.
The scientists specifically looked at the DNA found in the hornets’ mitochondria—the “power plants” that turn nutrients into energy in the cells of eukaryotes (plants, animals, fungi, and a host of other organisms that aren’t bacteria or archaea). Mitochondria are the remains of a long-ago event: a bacterium found its way into another organism and, through a series of evolutionary changes, became part of that organism. Consequently, mitochondrial DNA differs from that found in the rest of the cell. It is also matrilineal, passed down from mother to offspring without input from the father, and therefore shows much less change from one generation to the next than the DNA in the rest of an organism. This relative constancy makes mitochondrial DNA a useful tool for tracking lineages.
For the Vespa mandarinia study, the scientists sequenced the mitochondrial DNA of the British Columbia and Washington specimens, along with specimens from Japan and South Korea, and found that the North American imports do not have the same mother. While the Washington state specimen shared 99.5 percent of its mitochondrial DNA with the one from South Korea, the Canadian and Japanese specimens shared a bit more than 60 percent of their DNA. Lead author Telissa Wilson, with the Washington State Department of Agriculture, writes in an email, “We were all surprised that the U.S. and Canada samples were from different lineages when the locations were in such close proximity.”
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