GWINNETT COUNTY, Ga. — New research on Joro spiders by Georgia Gwinnett College found the invasive critters carry a bacteria that can cause them to go sterile.
Wolbachia, a common bacteria found in about half of all insects on the planet, was detected as members of GGC’s biology department were studying the genetic makeup of Joro spiders found in the state.
Joros have been in Georgia for about 10 years after traveling to the United States from east Asia.
Dr. James Russell, a professor of biology at GGC, was testing the genes of Joro spiders to see if there was any genetic diversity. While extracting genes from the spiders with a student, Nicholas Mizera, Russell said they found Wolbachia.
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So what is Wolbachia?
“Wolbachia is considered by some the most infectious bacteria in the world, of insects,” according to GGC.
“There was very little genetic diversity, so on a whim, we decided to look for the presence of Wolbachia,” Russell said. “It’s a common bacteria found in about half of all insect species, like butterflies, moths and bees. We found that Joro spiders are infected with Wolbachia.”
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Once Russell and Mizera discovered the Wolbachia, the professor said they had two questions to ask, and answer.
First: “Can Joro spiders transmit Wolbachia to humans?” Russell says no, they cannot.
Second: How does Wolbachia affect Joro spiders.
On that topic, Russell said he hadn’t confirmed it but had an idea.
“We hypothesize it creates reproductive barriers and incompatibility issues for the spider, but more detailed experiments are needed to test that hypothesis,” Russell said.
Russell’s hypothesis predicts that when the Wolbachia bacteria infects a male spider and they mate with an uninfected female spider, the female spider is made sterile, or cannot reproduce or lay eggs. That means the female is unable to fill the egg sacs they normally leave in the wild around this time of year.
GGC said Joro spiders lay eggs in mid-October and each white silk sac contains as many as 500 spider eggs.
While a pairing of an infected male spider and an uninfected female spider could cause infertility, if both the male and female are infected with Wolbachia, they are able to reproduce. Russell said only the female spiders can pass the bacteria along to their offspring.
“This particular Wolbachia effect can potentially be used to control populations,” according to Russell.
He said the research could show scientists a way to control insects known to harm humans but in a better and less harmful way, such as controlling mosquito populations.
It’s an idea being tested as a mosquito control technology by the U.S. government.
The U.S. Environmental Protection Agency identifies Wolbachia as a naturally occurring bacteria that is currently being used to infect mosquitoes in an effort to shrink their populations. According to the EPA, this involves genetically modified mosquitoes.
“Modified male mosquitoes carry a gene that results in female offspring not surviving. One Experimental Use Permit (including one product amendment and extension) has been issued,” the agency said.
Now, Russell and Mizera are putting together a research paper to present their findings to the scientific world.
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