5 Worms That Can Help Us Getting Rid Of Our Plastic Waste
And which eats a plastic bag quickest
Plastic pollution is recently causing one of the most serious environmental issues. This is because a lot of plastic is not biodegradable, and breaks down into tiny pieces called micro-plastics. These pieces stay in nature for a very long time. And even when plastic is biodegradable, when it ends up in nature it doesn’t always degrade, it can still affect many life forms, natural habitats, and even the economy (more about Why Biodegradable Plastic is Not Always Biodegradable).
That is why more environmentally friendly alternatives are important. Some possibilities are:
- recycling plastic
- using bioplastic
- preventing plastics from reaching rivers and oceans
- removing plastics from rivers and oceans
Another alternative is to use insects that help with the biodegradation of plastic. Such insects can digest the plastic and convert it into harmless materials. Several worms can break down plastic. For each type of worm is described how long they need to eat this plastic bag:
1. Wax worm
The first type of worm that can break down plastic are wax worms (Galleria mellonella), which grow into moths. Wax worms normally live in beehives and are seen as pests, as they eat the beeswax. When they are given polyethylene to eat, which is often used for plastic bags, plastic films, and bottles, holes start to appear after forty minutes.
One wax worm can eat 1.84 mg (0.000064 ounces) of plastic per day, so it would take 100 wax worms 22 days to eat the plastic bag shown above.
Wax worms are able to digest plastic because the mechanism to digest beeswax can be used for polyethylene as well. This is because beeswax and polyethylene have structural similarities. To digest plastic, their salivary first transforms the polyethylene into other materials, which then later can be degraded by microorganisms in their gut.
In this video, you can see wax worms at work and that their plastic-eating skills were proven by squashing them:
2. Indian mealworm
The second type of worm that can break down plastic are Indian mealworms (Plodia Interpunctella), which grow into moths. Indian mealworms are, like wax worms, seen as pests, as they normally live in stored products. They love all kinds of dry foods, including grains, nuts, dry beans, dried fruits, dried flowers, cereals, and crackers. I think I used to have them in my rice when I was living in a student home. Only the larvae feed themselves, as the adult moth focuses on mating and laying eggs.
One Indian mealworm can eat 0.13 mg (0.0000046 ounces) of plastic per day. So, it would take 100 of these worms 308 days to eat the plastic bag shown above. Like wax worms, Indian mealworms have certain microorganisms in their gut, that can break down the plastic. After digestion, only water-soluble products are left.
3. Rice mealworm
Valmir Duarte on YouTube)
The third type of worm that can break down plastic are rice mealworms (Corcyra cephalonica), which grow into moths. Like Indian mealworms, they are normally seen as pests in stored dry foods, such as rice, wheat, maize, coffee, spices, and cocoa beans, especially in the tropics.
One rice mealworm can eat 0.05 g (0.0018 ounces) of low-density polyethylene per day. One difference between low-density polyethylene compared to high-density polyethylene is that the low-density version is flexible plastic and the high-density plastic is semi-rigid or tough. So, it would take 100 rice mealworms about 19 hours to eat the plastic bag shown above.
To decompose the plastic, not only microorganisms in the gut are at work, but also enzymes that are produced by the gut. Enzymes are substances in a body that speed up chemical reactions, without being changed by these reactions.
4. Mealworm
The fourth type of worm that can break down plastic are rice mealworms (Tenebrio Molitor), which grow into beetles. These worms are used as human food in some parts of the world, as they contain a large number of amino acids, essential vitamins, minerals, and fibers. Amino acids are needed to build proteins, which together are the building blocks of life.
Mealworms normally live on and eat stored plant food, but are also able to digest polyethylene, polystyrene (also called Styrofoam), polypropylene, and polyvinyl chloride (PVC). One mealworm can eat 0.23 mg (0.0000081 ounces) of polyethylene per day. So, it would take 100 rice mealworms about 174 days to eat the plastic bag shown above. Mealworms are also able to digest plastic because of bacteria and enzymes in their gut.
5. Super worm
The fifth type of worm that can break down plastic are super worms (Zophobas atratus), which grow into beetles. They normally eat bran, which is the broken seed coats of cereal grain that are left after graining to create flour or meal. They are being sold as food for animals around the world.
Super worms can not only eat polyethylene, but also polystyrene and polyphenylene sulfide (PPS), which are for example used as packaging foams. Microorganisms in their gut are able to degrade these materials.
One super worm can eat about 59 mg (0.0021 ounces) of low-density polyethylene per day. So, it would take 100 super worms about 16 hours to eat the plastic bag shown above.
Conclusion
So, wax worms, Indian mealworms, rice mealworms, mealworms, and super worms are able to digest plastic. Super worms digest plastic fastest.
About the author
Dr. Erlijn van Genuchten is a an internationally recognized environmental sustainability expert. She is a science communicator, helpings scientists in the fields of nature and sustainability increase the outreach of their results and allowing us all to put scientific insights into practice and contribute to a sustainable future. Erlijn has inspired thousands of people around the world — for example — by supporting the United Nations with her expertise, her book “A Guide to A Healthier Planet” published by Springer Nature, and her posts on social media.
- More about her book “A Guide to a Healthier Planet”
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Related articles
- Why Biodegradable Plastic is Not Always Biodegradable
- How Food Waste Can Be Used to Reduce Plastic Pollution
- How Plastics Can Be Removed From Our Rivers And Oceans
- How To Prevent Plastics From Reaching Rivers and Oceans
- How Excavated Waste Can Become Tomorrow’s Resource
You can find all plastic related articles on my plastic reading list and all animal related articles on my animal reading list.
Credit
This article is based on these scientific publications:
Other sources:
General:
Wax worms:
- Bombelli, P., Howe, C. J., & Bertocchini, F. (2017). Polyethylene bio-degradation by caterpillars of the wax moth Galleria mellonella. Current biology, 27(8), R292-R293.
- Karsten, P. (2002). Raising Waxworms as Food Insects for Birds and Reptiles. AFA Watchbird, 29(4), 37–38.
- Yang, J., Yang, Y., Wu, W. M., Zhao, J., & Jiang, L. (2014). Evidence of polyethylene biodegradation by bacterial strains from the guts of plastic-eating waxworms. Environmental science & technology, 48(23), 13776–13784.
Indian mealworm
- Ren, L., Men, L., Zhang, Z., Guan, F., Tian, J., Wang, B., … & Zhang, W. (2019). Biodegradation of polyethylene by Enterobacter sp. D1 from the guts of wax moth Galleria mellonella. International journal of environmental research and public health, 16(11), 1941.
- Bombelli, P., Howe, C. J., & Bertocchini, F. (2017). Polyethylene bio-degradation by caterpillars of the wax moth Galleria mellonella. Current biology, 27(8), R292-R293.
Rice mealworms
- Allotey, J., & Azalekor, W. (2000). Some aspects of the biology and control using botanicals of the rice moth, Corcyra cephalonica (Stainton), on some pulses. Journal of stored products research, 36(3), 235–243.
- Kesti, S. S. K., & Thimmappa, S. C. T. (2019). First report on biodegradation of low density polyethylene by rice moth larvae, Corcyra cephalonica (stainton). The holistic approach to environment, 9(4), 79–83.
- Lo, M., Diome, T., Thiaw, C., & Sembéne, M. (2020). Study of the development parameters of Corcyra cephalonica (Stainton) according to the type of food substrate. International Journal of Zoology Studies, 5(1), 35–41.
Mealworms
- Brandon, A. M., et al. (2018). Biodegradation of polyethylene and plastic mixtures in mealworms (larvae of Tenebrio molitor) and effects on the gut microbiome. Environmental science & technology, 52(11), 6526–6533.
- Siemianowska, E., Kosewska, A., Aljewicz, M., Skibniewska, K. A., Polak-Juszczak, L., Jarocki, A., & Jedras, M. (2013). Larvae of mealworm (Tenebrio molitor L.) as European novel food.
Super worms
