Can a caterpillar species actually digest polyethylene and point the way to a new solution to litter problems?
That question demands further investigation, according to German researchers questioning a study published in April, as well as the scientists who conducted the original research.
The April report generated global headlines, many touting the ability of the wax worms, which are really caterpillars of the greater wax moth Galleria mellonella, as a potential solution to plastic litter.
Now researchers at Johannes Gutenberg University report they are not convinced caterpillars were eating and degrading a PE bag. They did a control study and said spectroscopic signatures noticed by the original researchers did not support the earlier findings. They reported their research in the Aug. 7 issue of Current Biology.
The original researchers disputed the German scientists' work in a correspondence published alongside the German report in the peer-reviewed journal.
Both groups say more research is needed to solve the issue.
One way to resolve the dispute involves putting a kind of chemical label on the carbon atoms in the polyethylene and seeing if the caterpillar's digestive system breaks down the material. Labeling would be done by inserting carbon 13 into PE and following it through the caterpillar's metabolism to see if the carbon-carbon bonds of PE are broken in the caterpillar's digestive system.
Carina Weber and her team at JGU reported that spectroscopic signatures of pure ethylene glycol don't match well with what Federica Bertocchini's team reported. Weber and her colleagues in Mainz, Germany, said spectroscopic profiles highlighted by Bertocchini and her group could have been caused by contamination.
In her response to Weber's report, Bertocchini disputed the JGU results but agreed that labeling studies are needed to determine what is going on metabolically with the caterpillars munching on PE.