MOTH SPIT V PLASTIC

In her bee hives, Cecilia Betts used to find little caterpillars eating the honeycombs. These are well known to beekeepers and not at all popular because they eat the wax honeycomb cells in hives, preventing the bees from using them, leaving a trail of frass (the name for caterpillar faeces) behind them. These caterpillars are the larvae of the wax moth (a museum specimen illustrated), Galleria mellonella (Linnaeus, 1758). This is a pyralid micro-moth, a member of the Pyralidae family, which has a wide distribution around the world wherever there are apiaries.

Enter microbiologist Dr Federica Bertocchini of the Spanish National Research Council in Madrid. She also had problems with wax moths in her bee hives but noticed that, when she collected the offending larvae in plastic bags, they ate their way out, not just be chewing the bag but actually digesting the polyethylene plastic. Dr Bertocchini found that the caterpillars possessed an enzyme that digested the plastic and, importantly, worked at ambient hive and room temperature. This is very exciting because, as we all know, plastic pollution is a planet-wide plague, so the ability to use enzymes to clean up polyethylene, which is difficult to treat and represents about a third of plastic waste, would be revolutionary. The present difficulty is because current methods of recycling polyethylene are mechanical and only produce lower grade plastic products and digesting processes today require a lot of heat. The waxworm digestive enzymes from G. mellonella and other pyralid microlepidoptera, though, can be readily synthesised and the hope is that this will lead to bulk treatment of the plastic waste without high temperatures and simply in water at neutral pH.

This won’t make beekeeping any easier, however, and it seems that beekeepers will have to continue to pick out the wax moth caterpillars, keep their hives clean and, for serious infestations, use a fumigant such as carbon dioxide against this moth’s attacks.

You can read an interesting review paper on this at https://bit.ly/3CJjNwaxwormdoc.

Betts Ecology keep up to date with biological research and when this is relevant to our site or consultancy work, we apply it to help our residents and clients. 

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