A caterpillar that costs Brazilian farmers millions of dollars in destroyed crops might also hold a key to solving one of the world's worst pollution problems.
Researchers at two universities in São Paulo, Brazil, have discovered fungi living inside the gut of the Helicoverpa armigera caterpillar — a notorious pest that devours soybean, cotton, and corn — that can break down polystyrene, the plastic commonly known as Styrofoam. The team, led by biologist Flavio Henrique Silva at the Federal University of São Carlos (UFSCar), isolated four types of fungi from the caterpillar's intestines and tested each one on thin plastic films over 60 days.
"If the fungus was able to grow on that film, it's because it used the film as a carbon source — that is, a food source," Silva explained.
The study, published in the journal BMC Microbiology, divided the caterpillars into three groups. One group ate only polystyrene blocks. A second group consumed a mixed diet with up to 50 percent polystyrene. A third group ate a normal diet. The researchers found that caterpillars fed polystyrene developed more diverse fungal communities in their guts, suggesting their digestive systems were adapting to process the plastic.
The four fungi that showed promise were Aspergillus, Talaromyces, and two species of Penicillium. Two of these proved especially efficient at degrading the polymer surface.
This discovery adds to growing research on nature's ability to clean up human pollution. The same UFSCar lab previously found that bacteria from another crop pest — the sugarcane weevil — could also break down polystyrene. The researchers are now studying whether the caterpillars fully digest the plastic or merely break it into smaller pieces called microplastics.
The team is also studying another insect: the Zophobas morio beetle larva, informally called the "giant mealworm." Unlike the delicate sugarcane weevil larvae that die easily in lab conditions, giant mealworms can survive for weeks eating nothing but Styrofoam — a remarkably resilient appetite that makes them especially interesting for future research.
Silva says much work remains to identify which specific microorganisms, genes, and proteins are responsible for the degradation process. "We need to determine which microorganisms are most efficient," he said.
But the implications are exciting. Each year, millions of tons of polystyrene waste pile up in landfills and oceans, where it can persist for centuries. Finding natural organisms that can safely break down this stubborn material could one day offer a cleaner way to tackle plastic pollution.