Darkling beetle larvae can degrade plastic in their gut

Darkling beetle larvae have the potential to help tackle the issue of plastic pollution, according to a new study led by experts in the Department of Chemical Engineering at POSTECH. 

The researchers have discovered for the first time that the larvae of the darkling beetle P. davidis can consume polystyrene and reduce both its mass and molecular weight. 

“We have discovered a new insect species that lives in East Asia – including Korea – that can biodegrade plastic through the gut flora of its larvae,” said study co-author Professor Hyung Joon Cha.

By 2017, 8.3 billion tons of plastic waste had been produced across the globe, but only nine percent of this waste was recycled. The issue of plastic waste is made much worse by the fact that plastics can take as long as hundreds of years to decompose. 

For example, a floating island of waste called the Great Pacific Garbage Patch has accumulated an estimated 80,000 tons of plastic particles in the North Pacific Ocean and continues to grow.

In collaboration with Professor Intek Song of Andong National University, the POSTECH team has determined that a species of darkling beetle larvae can decompose polystyrene, a material that is difficult to break down due to its unique molecular structure.

The researchers isolated the bacteria Serratia in the intestinal tract of the beetle larvae. When polystyrene was fed to the larvae for two weeks, six times the amount of Serratia appeared in the gut flora. 

Unlike that of other known polystyrene-degrading insects, the gut flora of beetle larvae was found to consist of a very simple group of six species. This combination of bacterial strains could ultimately be used in the development of a polystyrene-decomposing flora.

The research also suggests that polystyrene could be broken down by other insects besides darkling beetles that also feed on rotten wood. 

“If we use the plastic-degrading bacterial strain isolated in this study and replicate the simple gut floral composition of P. davidis, there is the chance that we could completely biodegrade polystyrene, which has been difficult to completely decompose, to ultimately contribute to solving the plastic waste problem that we face,” said Professor Cha.

The study is published in the journal Applied and Environmental Microbiology.

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By Chrissy Sexton, Earth.com Staff Writer