Are There Worms That Eat Plastic?

The discovery of worms that eat plastic is not new, but no one thought we could use them to break down materials because they worked so slowly. However, new reports have sparked new hope.
Are there worms that eat plastic?

The discovery of larvae and worms eating plastic has spread both hope and skepticism. According to experts, we use  over 320 million tonnes of plastic globally every year. In fact, almost all sectors of society use plastic in one way or another.

Between 1950 and 2015, it has been calculated that we accumulated approximately 6.3 billion tonnes of plastic waste globally. Excessive plastic use has long polluted all the world’s land masses, rivers, lakes and seas.

So finding animals that can help with the decomposition of plastic has ignited the flame of hope. Here we tell you more about this.

Worms that eat plastic: New hope

Since the 1950s, researchers have studied the ability of insects to eat plastic and break down packaging. The beetles and larvae that have shown this behavior mainly belong to the families Tenebrionidae, Anobiidae  and Dermestidae. However, over time, most people lost interest in these studies.

Later, in the early 1970s, many researchers instead began studying the degradation of polystyrene (PS) in soil, seawater, sediment from landfills, excess sludge and compost. As a result, researchers determined that certain insect-chewing insects can chew and eat plastic packaging, including polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP). However, it was not known until recently whether eaten plastic could be broken down in the insects’ intestines.

Mask against white background

Which worms can eat plastic?

Recently, a group of Chinese researchers reported that Indian mealworm ( Plodia interpunctella) has the ability to chew and eat PE plastic. They also found two bacterial strains, isolated from their intestines, that have the ability to break it down.

The same group also discovered that mealworms can eat polystyrene as their only food. Flourworms are the larval form of the flour beetle Tenebrio molitor , which is much larger in size than Indian mealworm.

In addition , a group of researchers from the University of Cantabria reported that the larval form of larger wax moths could also break down PE plastic.

This ability to eat plastic is also found in the larval form of the beetle Zophobas morio, also from the family Tenebrionidae. 

Friends or foes?

These plastic-eating worms are usually in the second stage of four life stages: egg, larva, pupa and adult. Experts consider them a pest because they attack honeycombs (Indian mealworms) as well as crops and grains (mealworms), leading to large economic losses.

However, mealworms can also be a resource. These larvae are a cost-effective food source for animals and can be bought in most pet stores. They are bred as food for birds, reptiles, amphibians and fish. The larvae eat mainly bran, an agricultural by-product. It is usually easy to raise them in fresh oatmeal, bran or barley along with potatoes, cabbage, carrots or apple.

The worm compost that mealworms generate is also sold as a fertilizer.

What enables biodegradation of plastic?

In 2015, a group of Chinese researchers proved that a strain of mealworms from Beijing, China, could survive with plastic as the only food for a month.

When they treated the worms with antibiotics, this ability disappeared, which would indicate that it is their microbiotic intestinal flora that enables the degradation of plastic. These studies have been based on the use of worm strains from the United States.

Therefore, we now know that the ability to break down plastic is found in several different strains of worms. It is also worth noting that it has been discovered that the degradation of polystyrene (PS) is significantly improved by supplementing the worms’ diet with a conventional nutrient source.

Finally, researchers also determined that mealworms with this diet can reproduce and give birth to a new generation with the same ability to break down PS.

The bacterial flora is nature’s secret weapon

The same group of researchers has also analyzed the intestinal flora of the mealworm Tenebrio molitor, and has succeeded in detecting two bacterial groups ( Citrobacter sp. And Kosakonia sp.) That are  strongly associated with the degradation of PE and PS.

They could also identify other bacterial groups, each of which could be associated with the degradation of a particular type of plastic. These results suggest that it is the adaptability of the intestinal bacteria that enables these worms to break down different types of plastic with different chemical compositions.

Larva next to pupa

The research that has been done on these worms that eat plastic confirms that their intestines enable the rapid decomposition of different types of plastic. This suggests that there is a chance for a promising plastic decomposition process –  one that may prove useful for improving the environment.

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