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Very hungry caterpillar eats Earth’s plastic pollution

Staff writers, March 5, 2020 7:45AM Kids News

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Eric Carle’s illustration of the caterpillar from his famous book The Very Hungry Caterpillar. media_cameraEric Carle’s illustration of the caterpillar from his famous book The Very Hungry Caterpillar.

science

Reading level: green

A very hungry caterpillar can eat a lot of plastic bags.

Scientists have been feeding caterpillars called waxworms polyethylene — one of the most common plastics used in shopping bags — and found that just 60 little caterpillars can eat more than 30sqcm in a week.

The scientists’ findings, published in the journal Proceedings of the Royal ­Society B this week, suggest that armies of hungry caterpillars could be put to work to eat waste plastic.

In just days, their feasting could digest what would otherwise take hundreds of years, helping solve Earth’s big plastic pollution problem.

media_cameraA caterpillar on a plastic bag during an earlier scientific experiment in Spain in 2017, exploring the possibility of using worms to eat plastic. Picture: AFP PHOTO/CSIC/Cesar Hernandez

The caterpillars are the larvae of the greater wax moth. In nature, the caterpillars get into beehives and eat the wax the bees use to make honeycomb. Honeycomb and polyethylene have a similar structure when you look at them both under a microscope.

“They are really avid* ‘plastivores’,” Christophe LeMoine of Brandon University, Canada, who led the study, told The Times.

“We think it is quite phenomenal* that these insects are able to survive for weeks on a diet made entirely of plastic.”

Supplied Editorial Wax worm media_cameraA wax worm chews a hole through plastic. Polyethylene debris can be seen attached to the caterpillar. Federica Bertocchini, a developmental biologist at the University of Cantabria in Spain, first noticed the possibility as she cleaned out her backyard bee hives several years ago. Picture: Federica Bertocchini, Paolo Bombelli, Chris Howe

Scientists studied the gut bacteria of the waxworms and believe the bacteria is key to their special pollution-smashing talent.

The study found that when the caterpillars were given antibiotics* to reduce the bacteria in their gut, they were not able to digest the plastic as easily. When caterpillars were fed only polyethylene they ended up with more bacteria in their gut than if they had a normal diet without plastic.

The scientists found that some gut bacteria (kept alive outside the body of a caterpillar) could survive for a year if it was fed only plastic, but that plastic broke down faster if it was inside the body of a caterpillar rather than outside.

“There appears to be a synergy* between the waxworm and its gut bacteria that accelerates* plastic biodegradation*,” Dr LeMoine said. “A better understanding of how this works may guide future efforts to design the ‘perfect’ ­plastic biodegradation system.”

More work needs to be done on what to do with caterpillar poo, which is toxic* when the caterpillar has been eating plastic.

Dumpsters being full with garbage media_cameraPlastic bag bans in Australia is helping slowed how much polyethylene is going to landfill, but we still have to find a way to treat what already exists. Picture: iStock

GLOSSARY

  • avid: keen
  • phenomenal: remarkable
  • antibiotics: medicine to kill bacteria
  • synergy: two things working together
  • accelerates: speeds up
  • biodegradation: break down using nature
  • toxic: poisonous

EXTRA READING

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Kids feeling eco-anxiety about plastic waste

Human poo study finds microplastics

QUICK QUIZ

  1. What sort of caterpillar is this?
  2. Name the type of plastic mentioned in the story.
  3. What in the caterpillar’s digestive system breaks down the plastic?
  4. Why are bees mentioned in this story?
  5. What is wrong with the caterpillar’s poo?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. What do you think?
Scientists are working hard to solve the problems caused by plastic. Some people think plastic should be banned.  Write reasons for and against this idea. Then, choose which side you agree with. Use the reasons to help you to design a poster that will help convince other kids to agree with you.

Time: allow 40 minutes to complete this activity
Curriculum Links: English, Science, Health and Physical Education, Geography, Visual Communication Design, Personal and Social Capability   

2. Extension
Can you think of a solution to the problem of what to do with the toxic caterpillar poo? 

Time: allow at least 15 minutes to complete this activity
Curriculum Links: English, Science, Critical and Creative Thinking

VCOP ACTIVITY
Verb adventures
With a partner see if you can identify all the doing words/verbs in this text. Highlight them in yellow and then make a list of them all down your page. Now see if you and your partner can come up with a synonym for the chosen verb. Make sure it still makes sense in the context it was taken from.

Try to replace some of the original verbs with your synonyms and discuss if any are better and why.

HAVE YOUR SAY: What is the best way to deal with Earth’s plastic problem?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.

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