Mealworm consumption of Expanded Polystyrene

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Day 2 of the Mealworm colony.

In a 2015 study by Stanford University and a team of Chinese researchers, it was found that Mealworms eat Expanded Polystyrene (EPS), and produce viable fertiliser as a result.[1] This is a significant finding as only a small portion of EPS currently produced is recycled[2] and any additional methods for breaking down the material may provide a solution for the material going to waste. Mealworm recycling may solve a number of issues present with current recycling processes such as the discarding of EPS contaminated with food or fire retardants.[3]

Raising mealworms in order to consume EPS is a relatively simple procedure, requiring some space in the shade, live mealworms, a suitable container and some food. Instructions for creating a mealworm farm are plentiful online, and applicable where EPS is used as food.

Sourcing mealworms[edit]

Mealworms are a common food for domestic and agricultural animals such as chickens and pet lizards and as a result are commonly sold at pet shops. However mealworms that have fed off of EPS for a generation appear to have improved rates of consumption of the plastic.[4] As a result, it may be preferable to find someone already processing EPS in this way to start your farm. It may also be necessary over time to continue to source new groups of mealworms to avoid the effects of interbreeding in your colony.[5] Other potential sources of mealworms can include people breeding them for their own animals.

Mealworms in a container of bran.

Building a mealworm farm[edit]

A basic farm can be built using a flat container, with air holes poked in it, and a bed of grain. The more air holes provided for the worms, the better the flow of air, which can prevent mold. Some mealworm farm designs call for the use of a flywire mesh. EPS can be added right from the start in chunks. This starting point will allow the mealworm larva to begin eating and growing. Over time nutrients rich in protein and other vitamins can be added, and a source of moisture should be provided. Common sources of moisture suggested in other guides include water gels, and scrap vegetables. Vegetables will need to be kept separate from grains, and changed when they become moldy. Over time, some mealworms should begin their metamorphisis into pupae and then finally into adult beetles. During the pupa stage, the worms are particularly vulnerable to cannibalism from other worms that are dehydrated. Creating a second tier for the adult beetles, on top of the original farm, with a fine mesh for eggs to fall through will prevent the adults from cannibalising Pupa.[6]

Toxicity in EPS[edit]

Historic processes for producing EPS as insulation for building materials included the use of known carcinogenic fire retardants, in particular Hexachlorobenzene and Hexabromocyclododecane. Both were banned by the Stockholm Convention on Persistent Organic Pollutants, and while the time period for implementation of this convention has expired, it is likely that products made prior to this are still contaminated.[7][8] However, HBCD has been found to be excreted by mealworms within 48 hours of consumption in contaminated EPS, meaning that where this pollutant exists, they are still safe feed for other animals.

Products created by EPS mealworm farms.[edit]

Sugar Gliders eating Mealworms.
  1. Mealworms as animal feed
  2. Mealworm excrement as fertiliser

Note that fertiliser produced from contaminated EPS may contain those contaminants.

The European Union has approved mealworms for human consumption. However, mealworms fed EPS should be considered not food safe until further studies have been conducted.[9]

External Links[edit]

A similar process for polyurethane with fungi

Scientists Discover Plastic-Eating Worms That Digest Styrofoam