The looming invasion of the joro spider, known for its distinctive black and yellow coloring, is stirring excitement among wildlife enthusiasts, though it may not be as welcoming to those with arachnophobia.
Researchers recently uncovered intriguing behavior among these famous parachuting spiders, revealing that they can engage in violent confrontations, even cannibalism, under the right conditions.
Leading joro spider researcher Andy Davis from the University of Georgia’s Odum School of Ecology noted, “We watched what would happen if the spiders were together in a container, and it sometimes would lead to a battle to the death.”
Interestingly, despite previous assumptions that joro spiders exhibit a shy demeanor, Davis explained, “So we believe they have a shy personality, but they apparently can be aggressive to each other.”
The study further emphasizes this unexpected behavior after initial observations in the wild suggested that joro spiders can trap one another in their webs.
In laboratory tests conducted by the University of Georgia scientists, two female joro spiders were placed in a container, allowing researchers to monitor their interactions.
In about 40% of trials featuring two spiders of similar sizes, one female would attack the other and, in some instances, consume it.
In cases where the females varied in size, fights occurred 18% of the time, with the larger does not always being the aggressor.
The researchers confirmed instances of cannibalism even in field trials, noting an occurrence where one female killed and wrapped another in her silk web.
The findings were published in the journal Arthropoda in a paper titled, “It’s a Spider-Eat-Spider World: Observations of Nonsexual Cannibalism in the Invasive Joro Spider.”
The research indicates that female joro spiders may exhibit aggressive behavior towards one another primarily when provoked or stressed.
Moreover, the implications of these findings could extend to how researchers might control spider populations, as Davis stated, “Given that they’ll eat each other, it implies that if their densities get really high, they may kill off their own competition.”
As joro spiders continue to proliferate in the Southeast, some areas have reported declines in native spider populations, prompting worry about the ecological impact of these invaders.
Massachusetts saw its first confirmed joro spider sighting last year, with a giant female observed in Beacon Hill, marking the furthest north these spiders have been spotted.
Davis has noticed hundreds of joro spiders residing in his backyard, indicating that their population is thriving in Georgia.
The research team, including University of Georgia students Kade Stewart, Caitlin Phelan, and Alexa Schult, documented these episodes of nonsexual cannibalism, contributing unique insights into the behavior of this invasive species.
As the joro spider continues to spread along the East Coast, Davis noted that it wouldn’t be surprising to see an influx into the Northeast this year.
The East Asian joro spider, officially named Trichonephila clavata, made its way to the U.S. around 2013, likely hitching a ride on a shipping container from its native regions of Japan, Korea, Taiwan, and China.
While they might be alarming in appearance, Davis reassured the public that they pose little threat to humans: “They’re no more dangerous than any backyard garden spider.”
Joro spiders are beneficial predators, known for consuming various pests including flies, mosquitoes, and even native pollinators such as bees.
As this fascinating invasion unfolds, wildlife enthusiasts and researchers alike are keen to observe how the interactions among these large spiders could influence both their population dynamics and the ecological landscape they inhabit.
image source from：bostonherald
