How beetle juice led to the discovery of a virus and solved the mystery of a superworm die-off
Rutgers University-New Brunswick scientists have discovered a virus that caused a nationwide die-off of superworms, a common food for birds, reptiles, other pets and, more and more so, even for humans as an alternative protein ...
Using chopped up beetle carcasses forming a slurry and an electron microscope cooled by liquid nitrogen, the scientists report in Cell that they have discovered what they have titled Zophobas morio black wasting virus.
The name is derived from the virus's deadly effect on a species of darkling beetle, Zophobas morio, native to the subtropics, particularly in the insect's immature larval stage when it emerges from its eggs as large, brown superworms. This species was named "superworm" because its larvae are bigger, at about 2 inches in length, than any others grown as feed.
The protein-rich larvae of Z. morio, which are dietary staples for captive, often exotic reptiles, birds, fish and amphibians worldwide, mysteriously began dying off in 2019, puzzling pet food suppliers and pet owners.
Jason Kaelber, an author of the study and an associate research professor at the Institute for Quantitative Biomedicine (IQB) at Rutgers-New Brunswick, worked with Judit Penzes, the first author of the study and a postdoctoral associate at IQB.
"Judit was looking to identify the reason beetle farmers were losing all their superworm colonies to a deadly disease and I was looking to develop ways of discovering new viruses that don't depend on DNA or RNA sequencing," Kaelber said. "We ended up discovering the virus that has been sweeping the country and killing superworms."
Insect virologist and virus co-discoverer Judit Penzes displays infected, dead superworms (at left) and healthy worms. Credit: J. Penzes
Healthy superworms have been in rare supply for several years because of a mysterious die-off of the popular pet food source. Rutgers scientists have pinpointed the cause of the illness and are developing a vaccine. Credit: Judit Penzes