Waxworm: How can they Reduce Plastic Pollution?

What are Waxworms?

Waxworms are the caterpillar larvae of wax moths, which belong to the family Pyralidae (snout moths). Two closely related species are commercially bred the lesser wax moth (Achroia grisella) and the greater wax moth (Galleria mellonella).

They belong to the tribe Galleriini in the snout moth subfamily Galleriinae. Another species whose larvae share that name is the Indian meal moth (Plodia interpunctella), though this species is not available commercially.

The adult moths are sometimes called “bee moths”, but, particularly in apiculture, this can also refer to Aphomia sociella, another Galleriinae moth that also produces waxworms, but is not commercially bred.

Waxworms are medium-white caterpillars with black-tipped feet and small, black or brown heads.

In the wild, they live as nest parasites in bee colonies and eat cocoons, pollen, and shed skins of bees, and chew through beeswax, thus the name. Beekeepers consider waxworms to be pests. Galleria mellonella (the greater wax moths) will not attack the bees directly but feed on the wax used by the bees to build their honeycomb.

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Their full development to adults requires access to used brood comb or brood cell cleanings these contain protein essential for the larvae’s development, in the form of brood cocoons. The destruction of the comb will spill or contaminate stored honey and may kill bee larvae or be the cause of the spreading of honey bee diseases.

When kept in captivity, they can go a long time without eating, particularly if kept at a cool temperature. Captive waxworms are generally raised on a mixture of cereal grain, bran, and honey.


Biodegradation of Plastic

Two species of waxworm, Galleria Mellon Ella and Plodia interpunct Ella have both been observed eating and digesting polyethylene plastic. The waxworms metabolize polyethylene plastic films into ethylene glycol, a compound that biodegrades rapidly.

This unusual ability to digest matter classically thought of as non-edible may originate with the waxworm’s ability to digest beeswax as a result of gut microbes that are essential in the biodegradation process.

Two strains of bacteria, Enterobacter asburiae, and Bacillus sp, isolated from the guts of Plodia interpunct Ella waxworms, have been shown to decompose polyethylene in laboratory testing. In a test with a 28-day incubation period of these two strains of bacteria on polyethylene films, the films’ hydrophobicity decreased.

In addition, damage to the films’ surface with pits and cavities (0.3-0.4 μm in depth) was observed using scanning electron microscopy and atomic force microscopy.

Placed in a polyethylene shopping bag, approximately 100 Galleria Mellon Ella waxworms consumed almost 0.1 gram (0.0032 ounces) of the plastic over the course of 12 hours in laboratory conditions.

Studies carried out in 2020 by Bastian Barton at the Fraunhofer Institute for Structural Durability and System Reliability (LBF) in Darmstadt, Germany, disproved the ability of Galleria melon Ella caterpillars to digest and biologically degrade polyethylene.

Even though the waxworms would eat holes into polyethylene bags, they ingested only a small proportion, excreted the polyethylene unaltered, and showed significant loss of body weight.

Who is Discover wax worms as Plastic Biodegradation?

Ms. Federica Bertocchini is now a beekeeper and it is to her credit; the discovery of plastic-eating worms is too.  Professor Bertocchini, who belongs to the Institute of Biomedicine and Biotechnology of Cantabria in Spain, was so annoyed to see her beehives infected with the caterpillars.

So, while cleaning the beehive she put all these worms into a plastic bag and made sure that the beehive is safe from infections. But to her astonishment, all the worms were out of the plastic bag within a little time leaving behind the plastic bag with many holes.

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Bertocchini, along with the researchers of Cambridge University checked this with 100 wax worms in a plastic bag. They could make out that within 40 minutes the plastic bag was reduced by 92mg.

Polyethylene was known for its hardness and the nature of non-biodegradable nature. Breaking down this within 24 hours’ time is such a cool update for humankind.

These wax worms were observed very closely and found that these worms excrete within 24 hours of consuming the plastic and these stools were tested to see any plastic particles appear in the excrete. The scientists were pretty confused with the fact whether these worms are merely cutting down the plastic into small bits.

But it was really amazing to know that these excretes dis not have any plastic in it. Thus, it was confirmed that the plastic consumed by these is being digested by these worms completely. Excrete of these appear and was compared to that of rabbit’s excrete and was also found that those are good for the soil fertility and also biodegradable.

Waxworms as a food source

Waxworms are a commonly used food for many insectivorous animals and plants in captivity. These larvae are grown extensively for use as food for humans, as well as live food for terrarium pets and some pet birds, mostly due to their high-fat content, their ease of breeding, and their ability to survive for weeks at low temperatures.

They are recommended for use as a treat rather than staple food, due to their relative lack of nutrients when compared to crickets and mealworms. Their high fat and calorie density can also contribute to obesity in captive animals if they are fed waxworms too often, especially in animals with low metabolisms, such as reptiles.

Most commonly, they are used to feed reptiles such as bearded dragons (species in the genus Pogona), the neon tree dragon, geckos, brown anole, turtles such as the three-toed box turtle, and chameleons. They can also be fed to amphibians such as Ceratophrys frogs, newts such as the Strauch’s spotted newt, and salamanders such as axolotls.

Small mammals such as the domesticated hedgehog can also be fed with waxworms, while birds such as the greater honeyguide can also appreciate the food. They can also be used as food for captive predatory insects reared in a terrarium, such as assassin bugs in the genus Platymeris, and are also occasionally used to feed certain kinds of fish in the wild, such as bluegills.

Solving the Mystery

Bertocchini teamed up with fellow scientists Paolo Bombelli and Christopher Howe to find out how wax worms spread on plastic.

When they placed the worms on polyethylene plastic, they found that each worm was making an average of 2.2 holes per hour. 100 waxworms decomposed 92 milligrams of a plastic bag overnight. At this rate, it would take those 100 worms nearly a month to completely break down an average 5.5-gram plastic bag.

To prevent the jaws from being chewed as the cause of the degradation, the team applied a soupy mix of recently deceased worms to the plastic and waited. Sure enough, they found that the liquid larvae could also eat holes in the plastic. This is what Bertocchini and colleagues said an enzyme in the worms or the bacteria that live in and on their bodies will break down the plastic.

This enzyme converted polyethylene into ethylene glycol, a chemical commonly used in antifreeze. Bertocchini hopes to be able to identify the exact enzymes that break down polyethylene in future work.

Looking for a solution

For decades, scientists have been looking for a way to biodegrade plastics, says Uwe Bornscheuer, a biochemist at the University of Greifswald in Germany.

“Plastic pollution is a big global problem,” said by Bornscheuer.

In 2014, Wu and colleagues from Stanford University discovered that an intestinal bacterium in a different species of wax worm can break down polyethylene, although it has different by-products. A 2016 study identified the enzymes in a type of bacteria that could break down a type of plastic called poly (ethylene terephthalate).

“There are probably many other types of worms that can break down plastics,” he said.

For Woods Hole Oceanographic Institute marine biologist Tracy Mincer, the solution to plastic pollution must focus on producing less and recycling more.

“Polyethylene is a high-quality resin that can be recycled in a variety of ways, and it rakes in as high as $ 500 per ton,” he said in an email. “In my opinion, while this is an amazing natural history and a wonderful academic exercise, it is not a solution to the disposal of polyethylene because it is throwing away money.”


What are Waxworms?

Waxworms are the caterpillar larvae of wax moths, which belong to the family Pyralidae (snout moths). The adult moths are sometimes called “bee moths”, but, particularly in apiculture, this can also refer to Aphomia sociella, another Galleriinae moth that also produces waxworms, but is not commercially bred.

What Do Waxworms Eat?

1. As their name implies, waxworms eat beeswax, as well as honey.
2. Adult waxworms (wax moths) don’t eat or drink.
3. Captive-bred waxworms are generally raised on a mixture of cereal grain, honey, and sometimes glycerin.
4. Generally speaking, you don’t need to feed your waxworms.

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