Study suggests invasive spider tolerates urban landscape better than most native spiders

The Jorō (Joro) spider was first spotted in the United States around 2013 and has since been spotted throughout Georgia and the Southeast. New research from the University of Georgia has found more clues as to why the spider was able to spread.

The study found that the invasive orb-weaving spider is surprisingly tolerant of the vibrations and noise common in urban landscapes.

In this new study, published in ArthropodsResearchers examined how Joro spiders can live near busy roads, which are particularly stressful environments for many animals.

Researchers found that while Joro spiders located near busier roads are somewhat less likely to attack simulated prey, they do not appear to suffer from it and weigh about the same as their counterparts living in places less frequented. This suggests that the species can successfully compensate for its human-dominated landscape.

“If you’re a spider, you rely on vibrations to do your job and catch insects,” said Andy Davis, corresponding author of the study and a research scientist at UGA’s Odum School of Ecology. “But these Joro webs are everywhere in the fall, including right next to busy roads, and the spiders seem to be able to make a living there. For some reason, these spiders seem tolerant in urban environments.”

Busy roads do not affect the health and weight of the Joro spider

Joro spiders are regularly seen in areas where Georgia’s native spiders do not inhabit.

They build their golden webs between power lines, over stoplights, and even over the pumps at local gas stations, none of which are particularly peaceful places.

This is what led Davis and his team to study their behavior along roadsides.

Davis and a team of Odum School undergraduates used a tuning fork to simulate the vibrations caused by prey when it was caught in a spider’s web, then observed whether the spiders attacked. In more than 350 trials, the Joro spiders attacked the simulated prey 59% of the time.

Web spiders near busy roads attacked about half the time, while those near low-traffic areas pounced 65 percent of the time.

Despite this slight difference, it does not appear to affect the body mass or health of the spiders.

“It appears that Joro spiders won’t hesitate to build a web under a red light or in an area where you wouldn’t imagine a spider to be,” said Alexa Shultz, co-author of the study and third year ecology student. student at UGA. “I don’t know how happy people are going to be about it, but I think spiders are here to stay.” Her undergraduate co-authors, Kade Stewart and Caitlin Phelan, agreed.

Joro spiders likely to spread beyond the southeast

In their native Japan, the East Asian Joro spider colonizes most of the country. Japan also has a very similar climate to the United States and is at roughly the same latitude.

The current study builds on previous work from Davis’ lab that showed that Joro spiders are well-equipped to spread across much of the East Coast because of their high metabolism and heart rate. Spiders are also cold tolerant, surviving brief freezes that kill many of their orb-weaving cousins.

Their hardiness is one of the traits that has allowed spiders to explode in population in the United States, with numbers easily in the millions now. The new research suggests that the Joros’ tolerance for urban vibrations and sounds is likely another factor in the species’ exponential growth.

But their spread should not be too alarming, researchers say. Spiders are rather shy.