Styrofoam Biodegradation: Comparing the capabilities of mealworms, woodlice, and millipedes Dominic Polycarpou Sleepy Hollow High School

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Styrofoam: A Global Problem • Difficult to degrade • Not recyclable • Mild carcinogen • Moves up food chain

Retrieved from: https://medium.com/age-of-awareness/why-styrofoam-expanded-polystyrene-should-be-banned-everywhere-in-the-world-4101552f5e2b 2

Degradation Methods

Degradation uses a lot of: • Time • Heat/Energy • Harsh Chemicals Styrene Molecule

Retrieved from: https://en.wikipedia.org/wiki/Styrene 3

Biodegradation • Certain fungi (w/ help from Fenton’s reagent) • Mealworms -> Eat polystyrene (Styrofoam) • Limited in scope/potential

Yellow Mealworms Retrieved from: https://www.rainbowmealworms.net/1000-mealworms/

Fenton’s reagent Retrieved from: https://chemdemos.uoregon.edu/demos/Household-Fentons-Reagent 4

My Prior Research • Fed polystyrene to mealworms • Degraded by 20% over 2 weeks • Polystyrene eaten, not broken down • Research very new, more needed

Photos taken by student 5

Other methods • New field of research, not studied much • Other organisms may have biodegradative abilities • Very few tested, some local organisms may be useful

Other Organisms • Wood lice (Oniscidea spp.) eat polyethylene/starch mix • Greenhouse millipedes (Oxidus gracilis) are common decomposers

Greenhouse millipede Retrieved from : https://en.wikipedia.org/wiki/Greenhouse_millipede

Woodlice Retrieved from: https://www.discoverwildlife.com/animal-facts/insects-invertebrates/facts-about-common-rough-woodlouse/

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Hypothesis If greenhouse millipedes and common woodlice can biodegrade polystyrene, then the weight of the polystyrene will decrease over time, comparable to mealworm biodegradation.

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Methods

6 trial groups

Mealworm

Millipede

Woodlice

Control

Polystyrene

Control

Polystyrene

Control

Polystyrene

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Container details • 34.6 cm x 21 cm x 12.4 cm plastic container • Bedding of leaf litter, dirt • Polystyrene chunks placed on surface • Given apples every 3 days • Misted every day • Kept in semi-dark room •Avg pH = 6.73 (SD = 0.312)

Photos taken by student 9

Measurement Procedure

Gather containers from storage location

Every day: • Weigh polystyrene

Every 3 days: • Count & weigh

organisms

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Mealworm Weight Change

• PS trial started smaller

• Groups did not diverge

• Mealworms trended

downwards

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0.260.270.280.29

0.30.310.320.330.340.35

Average Mealworm Weight

MWC MWPSDate Av

erag

e w

eigh

t

Millipede Weight Change

• No significant variance

• Measurements small/sensitive

to other variables

• Not indicator of health

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0

0.02

0.04

0.06

0.08

0.1

Average Millipede Weight

MPC MPPSDate Av

erag

e w

eigh

t

Woodlice Weight Change

• No significant variance

• Measurements

small/inaccurate

• Small sample size

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00.020.040.060.08

0.10.12

Average Woodlice Weight

WLC WLPSDate Av

erag

e w

eigh

t

Mealworm Mortality

• Mortality similar in both

groups

•Some death expected

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05

101520253035

# of Mealworms Alive

MWC ALIVE MWPS ALIVEDate #

Aliv

e

Millipede Mortality

• Mortality same in both

groups

•Some millipedes disappeared

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25262728293031323334

# of Millipedes Alive

MPC ALIVE MPPS ALIVEDate #

Aliv

e

Woodlice Mortality

• Similar mortality

• Small numbers in each group

• Most woodlice survived

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01234567

Woodlice Mortality

WLC ALIVE WLPS ALIVEDate #

Aliv

e

Polystyrene Weight Change

• Variance due to water misting

• Groups generally similar

• No indication of degradation

•No negative weight change

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05

10152025303540

Polystyrene Weight Change

MWPS MPPS WLPSDate

Wei

ght C

hang

e (%

)

Discussion • Mealworms decreased instead of increasing in weight • May be unhealthy due to excess water from misting • Polystyrene not shown to be degraded • Millipedes aware of polystyrene, didn’t eat • Small number of wood lice, results unreliable

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Sources of Error • Small sample sizes • Scale may be inaccurate • Short experiment time • Misting changed weight of polystyrene (uncontrolled variable) • Dirt/leaf litter adhered to polystyrene

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Conclusion • Millipedes and woodlice did not degrade polystyrene • Mealworms did not degrade polystyrene (different from prior research) • Degradation limited by different habitat • Mealworms are limited in degradative abilities

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Future Focus • Effect of environment on mealworm degradation • Test other secondary decomposers • Test mealworms in compact mesocosms

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Acknowledgements I’d like to thank: • Dr. Danielle Begley-Miller and Dr. Mike Rubbo • My science research teachers • TESA students • My family

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Any Questions?