Post on 06-Jul-2021
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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?