In 1882, there was an epidemic sweeping vineyards in the Los Angeles Basin of California. Named after plant pathologist Newton Pierce, it was known as a mysterious plant disease that turned green leaves brown, shriveled grapes, and killed a grapevine within three years. It would take about a century for scientists to figure out what was causing the disease—a bacteria named Xylella fastidiosa—and who was spreading it: a leaf hopping insect called the glassy-winged sharpshooter.
Despite best efforts to eradicate the half-inch long insect, Pierce’s disease still ravages vineyards today. There’s a fear climate change will exacerbate the problem and make Xyella infections intractable. But there is one glimmer of hope on the horizon—and it involves hacking the glassy-winged sharpshooter’s DNA.
In a new study published May 3 in the journal Nature Scientific Reports, researchers at the University of California Riverside managed to successfully use the gene-editing tool CRISPR to change the eye color of the insect, an alteration that was passed on to its progeny. This may not seem like much, but this proof-of-concept shows that it’s possible to modify the glassy-winged sharpshooter with specific mutations and ensure those mutations stick and aren’t lost to future generations. It means scientists might have the perfect tool to end the insect’s bacteria-spreading reign of terror and save countless vulnerable vineyards from infection.
“Our team established, for the first time, genetic approaches to controlling glassy-winged sharpshooters,” Peter Atkinson, an entomologist at UC Riverside and the study’s co-author, said in a press release.
Since 2014, scientists have been using CRISPR—a technology developed from bacteria that allows precise edits to specific genetic sequences—to eradicate diseases like malaria and control pests.
“This is a great technology because it can be so specific to one insect, and not cause off-target effects on other insects, animals or humans,” Inaiara de Souza Pacheco, an entomologist at UC Riverside and lead study author, said in the press release. “It’s a much more environmentally friendly strategy for insect control than using chemicals.”
Using CRISPR, the researchers were able to modify the genes that control the sharpshooter’s eye color, changing it from brown to white or cinnabar. They discovered that these genes are not passed down based on gender, like if white eyes were only passed down to only males or females. Instead, nearly 100 percent of the insect eggs modified by CRISPR gave rise to insects with different eye colors, and better yet, these new traits were passed down three or more generations.
“It’s absolutely amazing because the success rate in other organisms is often 30 percent or lower,” Linda Walling, a plant biologist at UC Riverside and study co-author, said in the press release. “The high rate of gene editing success in glassy-winged sharpshooters bodes well for our ability to develop new methods of insect control, as well as understanding the basic biology of this devastating pest.”
This success means the researchers are ready to home in on their real target: the glassy-winged sharpshooter’s mouth. That's how the X. fastidiosa bacteria is typically spread.
“We’re using CRISPR to try and modify the mouth parts of the sharpshooter so they can’t pick up the bacteria that causes Pierce’s Disease,” Rick Redak, an entomologist at UC Riverside and study co-author, said in the press release.
If this proves successful, not only will CRISPR be saving California’s $58 billion wine industry by saving grapevines from an early death, it could also become a popular approach to controlling bothersome insect populations that ravage agricultural crops and spread destructive diseases.
“It’s looking like sharpshooters will become a model organism for the Hemiptera, this big category of piercing, sucking insects,” said Redak. “Our model of using CRISPR for them could blow open our ability to control diseases they transmit to plants and possibly, to humans as well.”