There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.
You can buy this lab book for $23 at amazon.com or lulu.com. It will take 1-2 weeks to get to you -- Order Now. It’s a great resource, especially with the 2016-2017 science budget being used up!
*Some of you have already purchased my lab book – be sure to check out Page 141 !
“A developmental biologist and amateur beekeeper has come up with a new way to get rid of used plastic bags: Make waxworms eat them. The larvae of the greater wax moth (Galleria mellonella), these caterpillars thrive on beeswax. While cleaning out empty hive boxes that were infested with these caterpillars, Federica Bertocchini of the Institute of Biomedicine and Biotechnology of Cantabria in Spain put them in a plastic grocery bag. To her surprise the waxworms quickly ate their way out, leaving the bag riddled with holes. It turns out the caterpillars can break down the bag's polyethylene into ethylene glycol, which can be readily converted into useful substances such as antifreeze… Polyethylene is very hard to break down, making the 80 million tons produced a year a big recycling challenge.”
“Researchers in Europe have found that the larvae of a common insect have an unusual ability to digest plastic, a discovery that could lead to biotechnical advances that help deplete the continual buildup of one of the world’s most stubborn pollutants.”
“Experiments show the insect can break down the chemical bonds of plastic in a similar way to digesting beeswax.
Each year, about 80 million tonnes of the plastic polyethylene are produced around the world.
The plastic is used to make shopping bags and food packaging, among other things, but it can take hundreds of years to decompose completely.
However, caterpillars of the moth (Galleria mellonella) can make holes in a plastic bag in under an hour.”
Some scientists question the conclusions about the larvae.
“Ramani Narayan from Michigan State University, who looks for ways of degrading plastics, isn’t convinced. He says the evidence that the waxworm paste was producing ethylene glycol is ‘tenuous at best,’ and could be explained by other chemical changes. And even if Bertocchini is right about the degradation, Narayan says that it’s unlikely to have practical use. An army of bag-chewing caterpillars might consume a lot of plastic, but they would also end up releasing small fragments or microplastics into the environment, which can “pick up toxins like a sponge, transport these toxins up the food chain, and can cause harm to the environment and human health,” he says. ‘Biodegradation isn’t a magical solution to plastics waste management.’
Susan Selke, director of the Michigan State University School of Packaging, adds that caterpillars wouldn’t survive in the oxygen-free conditions within landfills, and it’s unclear if they would go for plastics over, say, other sources of food nearby. ‘There’s a long way between demonstrating that biodegradation can occur and the development of a system that provides benefit from biodegradation,” she says.’ “
“On closer examination, Dr Bertocchini and her colleagues discovered that their caterpillars each ate an average of 2.2 holes, three millimetres across, every hour, in the plastic film. A follow-up test found that a caterpillar took about 12 hours to consume a milligram of shopping bag. Such bags weigh about three grams, so 100 larvae might, if they spent half their lives eating, consume one in a month.
Whether releasing wax moths on the world’s surplus plastic really is sensible is not yet clear. For one thing, it has not been established whether the caterpillars gain nutritional value from the plastics they eat, as well as being able to digest them. If they do not, their lives as garbage-disposal operatives are likely to be short—and, even if they do, they will need other nutrients to thrive and grow. Another question is the composition of their faeces. If these turn out to be toxic, then there will be little point in pursuing the matter. Regardless of this, though, the discovery that wax-moth larvae can eat plastic is intriguing. Even if the moths themselves are not the answer to the problem of plastic waste, some other animal out there might be.”
“...Bertocchini says the next step isn’t to use the wax worms themselves, but to find the enzyme in their digestive systems that’s being used to break up the plastic in the first place. If scientist could isolate that, it could be used as a treatment in landfills. That would certainly be easier than dealing with millions of wriggly caterpillars.”
*This Blog contains several entries that would be helpful to your chemistry classroom. Check out the Topic List to help you to find past Blog entries.
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