Scientists have identified a virus responsible for a widespread die-off of superworms, which are widely used as food for birds, reptiles, pets, and increasingly, humans seeking alternative protein sources. This discovery has led to the development of a new approach for detecting and identifying emerging viruses and pathogens in humans, plants, and animals.
Researchers at Rutgers University-New Brunswick have uncovered a virus that triggered a significant decline in superworm populations, which are a popular food item for a variety of animals, including birds, reptiles, and now, more frequently, humans as a protein alternative. This finding has also introduced a novel method for the detection and identification of emerging viruses and pathogens that affect humans, plants, and animals.
Through the use of ground-up beetle bodies transformed into a slurry and an electron microscope cooled with liquid nitrogen, the team announced today in Cell the identification of a virus they named Zophobas morio black wasting virus. The name is inspired by the virus’s lethal impact on Zophobas morio, a species of darkling beetle, particularly during its larval phase when it hatches as a sizable, brown superworm. This species earned the nickname “superworm” due to the remarkable size of its larvae, reaching about 2 inches long, making them larger than other insect larvae raised for food.
The protein-rich larvae of Z. morio, essential food for captive exotic reptiles, birds, fish, and amphibians globally, began to perish inexplicably in 2019, leading to confusion among pet food suppliers and owners.
Jason Kaelber, a co-author of the study and an associate research professor at the Institute for Quantitative Biomedicine (IQB) at Rutgers-New Brunswick, collaborated with Judit Penzes, the lead author and a postdoctoral associate at IQB.
“Judit was investigating the reasons behind beetle farmers losing their superworm colonies because of a severe disease, while I aimed to develop methods for discovering new viruses that don’t rely on DNA or RNA sequencing,” Kaelber explained. “Together, we identified the virus responsible for the widespread deaths among superworms.”
The research commenced over a year ago when Penzes, a molecular virologist, was approached by beetle farm owners reporting alarming mortality rates among their superworms. Penzes was already recognized in the field for her previous work isolating a virus that was impacting crickets, another insect commonly used for pet food.
To begin her research, she collected superworms from pet shops in New Jersey. “Every time I visited a pet store, I headed straight to the feeder insect aisle to check out the worms,” she said. “They were all infected. I informed the store owners about my research and asked for samples. They were more than willing to assist, allowing me to take as many as I needed.”
Back in her lab, she blended the worm carcasses using a Magic Bullet blender at high speeds to create a beetle juice slurry, which she underwent a virus purification process to isolate the virus based on its density. In the final phase, she illuminated the centrifuge tube with a fluorescent light, revealing the virus by making it glow blue.
“When I saw it glow, I thought, ‘I’ve got you,'” Penzes commented. “At that moment, I knew it was indeed a virus.”
Penzes then collaborated with Kaelber, an electron microscopist, to explore the virus using a cryo-electron microscope, enabling a three-dimensional view of the virus, including its internal structure.
“This method involves rapidly freezing a virus, a protein, or a cell, preventing the water from forming ice crystals,” Kaelber noted. “This approach allows us to determine the amino acid sequence of the protein without needing to analyze the DNA, simply by examining the 3D structure, thanks to our high-resolution capability.”
They compared the viral protein structure with the data of known proteins from Rutgers’ Protein Data Bank and found it resembled a virus that affects cockroaches, though it wasn’t identical and belongs to a family of viruses known as parvoviruses.
“It’s a novel virus, distinct from anything previously sequenced or imaged,” Penzes added.
The researchers also expressed appreciation to superworm farmers across the country who willingly provided samples when they learned about the study. “The willingness of farmers to assist in our virus research significantly contributed to the development of this published study,” Penzes remarked.
According to Kaelber, this project established a “proof of concept” that cryo-electron microscopy can be used to identify and analyze new pathogens directly.
“In the event of a significant outbreak in the future, we will want to utilize every tool at our disposal for investigation,” Kaelber noted. “We hope to normalize diagnostic cryo-electron microscopy for scenarios involving unknown infectious diseases, allowing us to identify the causative agent swiftly.”
Cryo-electron microscopy has gained traction in recent years as a method for 3D analysis of known samples. Yet, this study at Rutgers marks the first instance where this technique has been applied to an unidentified pathogen.
Following the identification of the virus, the researchers tested a method to immunize the Z. morio beetles against the disease by injecting a closely related virus from another species that does not cause symptoms. They are creating a vaccine based on this research.
“This discovery holds significance for two reasons,” Kaelber explained. “First, beetle farmers can use this knowledge to safeguard their colonies and understand how to effectively manage the outbreak. Second, the superworm epidemic served as a real-world application test for the technology we hope will be beneficial in swiftly investigating future outbreaks affecting humans, plants, or animals.”
Scientists Martin Holm from the Rutgers Institute for Quantitative Biomedicine and Samantha Yost of REGENXBIO Inc. in Rockville, Maryland, also contributed to this study.
