According to a paper by two Drexel University professors, erythritol, used as a semi-sweet and low-calorie bulking agent in some sweeteners, is both appealing and toxic to fruit flies. Because it is safe for humans to consume at far higher doses than those that are toxic to the flies, it may have application as a safe but effective pesticide.
The paper, “Erythritol, a Non-Nutritive Sugar Alcohol Sweetener and the Main Component of Truvia, Is a Palatable Ingested Insecticide,” was published June 4 in primary research journal PLOS ONE.
The senior co-authors of the study were Sean O’Donnell, associate head of the Department of Biodiversity, Earth & Environmental Science and Daniel Marenda, associate professor in the Department of Biology.
Three years ago, curious findings by Marenda’s son, Simon Kaschock-Marenda, prompted further investigation. While researching the health effects of various sweeteners and sugars for a sixth-grade science project, Kashock-Marenda found that Truvia-brand sweetener killed the fruit flies on which he was experimenting. With his father, he repeated the experiment with similar results and they called in O’Donnell’s expertise.
O’Donnell and Marenda were assisted by biology doctoral student Kaitlin Baudier.
“The three of us brainstormed what we would do and I was the primary person who carried out most of the experiments, along with a couple of undergraduates as well,” she said, referring to biology majors Nirali Patel and Katherine Diangelus.
Baudier is currently in Costa Rica studying the habitat of Ecitoninae army ants.
She described the difficulty in designing experiments that would build off of Kashock-Marenda’s initial findings.
“We were faced with a couple of problems … how to test this in a very skeptical way so that we could publish it and actually have these results brought to the scientific community,” she said.
The project compared the effects of sweetener brands Truvia, Equal, Splenda, Sweet’N Low and PureVia on Drosophila melanogaster, the common fruit fly.
“Twice a week we would change the fly food to make sure they were getting fresh food. Every day the amount of dead flies were recorded and every other day a climbing assay was performed to see the effects of the sugars on their climbing abilities,” Diangelus wrote in an email.
Only Truvia, the only sweetener tested in which erythritol is the main ingredient, showed a very strong effect on the flies that consumed it. The flies suffered decreased motor control and lived for a mean of 5.8 days, compared to a mean longevity between 38.6 and 50.6 days for flies living on other foods. Both Truvia and PureVia contain extracts of Stevia rebaudia, or sweetleaf. A further experiment with erythritol, Truvia and PureVia confirmed erythritol and not sweetleaf products as the killer.
Finally, experiments showed that erythritol was not only readily consumed by the flies but significantly preferred over table sugarThis both eliminated food avoidance as a cause of death and exposed its potential application as a pesticide.
How erythritol causes death in fruit flies was not investigated, though in the paper’s conclusion the researchers conjecture that “ingestion of erythritol may alter nutrient and/or water absorption and/or efflux.” They caution erythritol has so far only been tested on fruit flies and not other insects, some of which are known to produce small doses of erythritol themselves. Fruit fly mortality was dependent on dose, so it may only be toxic to other insects in high doses.
“Once I get back from the field I’ll be working on testing it on a few other species as well,” Baudier said.
She summed up the potential application, “If there is a way that it can be feasibly used as a pesticide and sprayed on our food, then the idea is it would at least be human-safe.”
The FDA considers the sugar alcohol “generally recognized as safe” for use in food, and a 2007 paper suggests the only effect of consuming as much as 50 grams (1.8 oz) is stomach rumbling and nausea. Truvia’s manufacturer lists a mere 3 grams of erythritol per serving, which makes the risk of exposure to harmful levels of erythritol low.
“I was surprised to see what conclusions this data led to because the original thought was that Truvia could possibly be dangerous to humans since flies could not handle it,” Diangelus said. “But I think it’s remarkable that erythritol could be used as a palatable pesticide because current pesticides are not safe for humans or the environment.”
While the researchers further investigate the effects of the substance, they intend to apply for a patent on the use of erythritol in pest control. According to Baudier, “It would benefit our research, and the hope is that if we get a patent it would fund further research into use of this possibly interesting pesticide.”