Are There Worms That Eat Plastics?
The discovery of larvae or worms that eat plastics is shrouded in illusion and skepticism. According to experts, each year, more than 320 million tons of plastic are consumed around the world. In fact, almost all sectors of the population use this material in one way or another.
In this sense, it is estimated that between the 1950s and 2015 the generation of plastic waste was 6.3 billion tons worldwide. The use of plastic led to its accumulation, becoming an important pollutant of land, rivers, lakes and oceans.
With this panorama, the discoveries of animals that can exert plastic biodegradation were highly expected. Next, we’ll show hopeful data on the subject.
Plastic-eating worms: a new hope
Since the 1950s, many researchers have studied the ability of insects to eat plastics and damage packaging materials.
Beetles and larvae that exhibited this behavior were identified in the family Tenebrionidae , the family Anobiidae, and the family Dermestidae . However, these studies lost interest over time.
Subsequently, in the early 1970s, many research groups studied the biodegradation of polystyrene (PS) in soils, sea water, landfill sediments, activated sludges and compounds.
Thus, scientists have determined that some insects with jaws can chew and eat plastic packaging, including polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP) packaging films. However, until recently, little was known whether the ingested plastic could biodegrade in the insect’s intestines.
What are the worms that eat plastics?
Recently, a group of Chinese scientists reported that the larvae of the Indian Flour Moth (or Plodia interpunctella ) are able to chew and eat PE films, and two bacterial strains, isolated from their intestines, are able to degrade them. .
The same group also found that the larvae, the larvae of the beetle Tenebrio molitor, which are much larger than the larvae of the Indian Flour Moth, can eat Styrofoam as their only diet.
In addition, a research group at the University of Cantabria reported the biodegradation of PE by the larvae of the great wax moth, Galleria mellonella . Finally, this ability to eat plastic is also recognized in the so-called superworms, larvae of Zophobas morio , also in the Tenebrionidae family .
Allies or enemies?
In general, these worms are the second stage of an insect that has four stages of life : egg, larva, pupa and adult. They are considered a pest because they parasitize honeycombs (wax larvae) or grain deposits (flour larvae), causing great economic losses.
On the other hand, mealworms are also considered a resource. These larvae are a lucrative animal food, available at many insect markets and pet stores.
Larvae are mass-produced as food for birds, reptiles, amphibians and fish using bran, an agricultural by-product, as the main food. In general, they can be easily grown on fresh oats, wheat bran or grains with potatoes, cabbage, carrots or apples. In addition, the manure generated by the flour larvae is sold as fertilizer.
What is the mechanism that allows the biological degradation of plastic?
In 2015, a group of Chinese researchers showed that a strain of flour larvae from Beijing, China, could survive only on plastic for a month.
When the worms were treated with antibiotics, this ability disappeared, suggesting that digestion was mediated by the microbial activity of the intestinal flora. These studies were expanded with the use of strains of worms from the United States.
Therefore, it is now known that the ability to degrade plastic is widespread among different strains of worms. It is noteworthy that progress has been made in knowing that PS degradation rates significantly improve when supplementing the worms’ diet with a conventional source of nutrition.
Furthermore, scientists have also established that mealworms fed this mixed diet can reproduce and give birth to a second generation capable of degrading PS.
The microbiome is nature’s secret weapon
The same group of researchers who are developing this line of research carried out an analysis of the intestinal microbiome of the Tenebrio molitor larva . So far, scientists have managed to reveal the existence of two groups of bacteria ( Citrobacter sp . and Kosakonia sp .) strongly associated with the biodegradation of PE and PS.
In addition, they were able to identify other bacterial groups that are uniquely associated with the biodegradation of each of the plastics. These results suggest an adaptability of the worm’s gut microbiome, allowing it to break down chemically different plastics.
The study of plastic-eating worms confirms that rapid biodegradation of PS is possible in the larval intestine. Thus, the presence of a promising plastic degradation process is indicated, which may prove useful in improving environmental pollution levels.
