Discarded Aloe Peels Could Make a Sustainable Agricultural Insecticide, Study Finds

The peels of the aloe vera plant — as aloe barbadensis is commonly called — are routinely thrown away as agricultural waste, but scientists have found that these rinds can ward off bugs, acting as a natural insecticide for crops.

The aloe plant has been used for millennia in the treatment of wounds, skin problems and to promote healthy digestion, but this new use could be a turning point in the management of insects that feed on crop vegetation.

“It’s likely that millions of tons of aloe peels are disposed of globally every year. We wanted to find a way to add value and make them useful,” said Debasish Bandyopadhyay, Ph.D., who was the primary investigator on the project, in a press release from the American Chemical Society (ACS).

The team of researchers from the University of Texas Rio Grande Valley will present the results of their study at ACS’ fall meeting.

The possible use of the rinds of the aloe plant as an insect repellent first piqued Bandyopadhyay’s interest when he went to a local aloe production center with a colleague and observed bugs attacking plants, but not the leaves of the aloe vera.

After checking with the company’s CEO, Bandyopadhyay took some of the aloe rinds back to the lab.

Home gardeners have been using aloe vera gel along with garlic and onions as a natural insecticide, but don’t always use the aloe peels. On an industrial scale, the peels are processed as agricultural waste and used in the creation of biomass, which has the ability to improve the quality of the soil at aloe farms. This isn’t entirely without environmental consequences, however, since when agricultural waste rots, it releases methane and other polluting greenhouse gases into the atmosphere, which contribute to climate change.

“By creating an insecticide that avoids hazardous and poisonous synthetic chemicals, we can help the agricultural field,” said Bandyopadhyay, as Earth.com reported. “But if the peels show good anti-mosquito or anti-tick activity, we can also help the general public.”

Bandyopadhyay has been looking at the potential of recycling aloe peels and making them into a natural pesticide that could help farmers in places like India, Africa and parts of the Americas that are tropical and subtropical, the press release said.

The development of the pesticide could also mean an alternative disposal method for the peels that is not only environmentally friendly but gives aloe producers other sources of revenue.

“The goal is to recycle this waste in a meaningful way while making aloe production greener and more sustainable,” said Bandyopadhyay in the press release.

In their study of aloe peels’ potential insecticidal properties, Bandyopadhyay and the research team began by drying out the peels at room temperature in the dark in order to keep the plant’s bioactivity intact. They then produced a variety of extracts using dichloromethane (DCM), hexane, methanol and water. The finding that hexane extract contained a compound called octacosane that had properties known to kill mosquitoes had been previously reported by the research team.

The DCM was found to be a more effective insecticide than hexane extract in newer experiments, so the team decided to analyze it further.

The team came up with more than 20 compounds contained in the rinds of the aloe vera, many of which proved to have antifungal, antibacterial or other health benefits. They also found that six of the compounds — arjungenin, dinoterb, octacosanol, nonadecanone, subenniatin B and quillaic acid — had insecticidal properties. The compounds were also nontoxic, so they didn’t present any significant safety concerns.

Next, the researchers will perform field tests to see how the insecticidal compounds work against insects that feed on agricultural plants. Bandyopadhyay and some of his colleagues are looking into whether the compounds have anti-tick or anti-mosquito properties that could have the potential to be used in the development of a repellant for consumers.

“By creating an insecticide that avoids hazardous and poisonous synthetic chemicals, we can help the agricultural field,” Bandyopadhyay said. “But if the peels show good anti-mosquito or anti-tick activity, we can also help the general public.”