Parasitic nematodes have developed a unique way to locate and attach to their insect hosts in midair, according to new research from scientists at the University of California, Berkeley and Emory University. Rather than jumping at random, these tiny worms use static electricity to increase their chances of reaching prey.
Victor Ortega-Jiménez, assistant professor of integrative biology at UC Berkeley, led experiments testing whether electrical attraction helps nematodes find and capture food. Ortega-Jiménez previously found that spider webs use electrostatic forces to catch charged insects, and ticks are drawn to the static charge generated by furry animals. This prompted him to investigate if similar mechanisms are at play with nematodes.
“We live in an electrical world, electricity is all around us, but the electrostatics of small organisms remains mostly an enigma,” Ortega-Jiménez said. “We are developing the tools to investigate many more valuable questions surrounding this mystery.”
To test their hypothesis, researchers used tethered fruit flies connected to a battery that imparted an electrical charge. High-speed cameras recorded attempts by Steinernema carpocapsae nematodes—less than a millimeter long—to leap onto the flies. The worms can jump up to 25 times their body length.
“I believe these nematodes are some of the smallest, best jumpers in the world,” Ortega-Jiménez said.
Emory physicist Justin Burton developed a mathematical model for postdoctoral fellow Ranjiangshang Ran to analyze. Their findings showed that static charges commonly produced by flying insects significantly increased the likelihood of successful midair attachment by the worms. When only 100 volts were applied, less than 10% of jumps hit their target; with 800 volts, success rose to 80%. Slight wind improved outcomes further.
“Our findings suggest that, without electrostatics, it would make no sense for this jumping predatory behavior to have evolved in these worms,” Ran said.
If unsuccessful in landing on a host, the worm risks drying out or being eaten while airborne. Upon successful attachment, it enters its host through a natural opening and releases bacteria lethal to insects within two days. The worm then feeds on multiplying bacteria and tissue before laying eggs inside the cadaver; several generations may develop before juvenile worms emerge.
“Using physics, we learned something new and interesting about an adaptive strategy in an organism,” Ran said. “We’re helping to pioneer the emerging field of electrostatic ecology.”
The study was published on October 14 in Proceedings of the National Academy of Sciences (link). More information is available from Emory University.
