The stemless, cactus-like aloe vera plant can also be used as an organic pesticide, recent research shows.
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Aloe vera peels could fight staple food crop pests

Aloe vera peels have bioactive compounds that can ward off bugs, a recent study shows. The findings may offer a new use for peels that are usually discarded as waste and could be catalyst for organic farming and traditional medicine.

Globally, between 20 and 40 per cent of crop yields is lost to pests, which has a direct impact on food security and nutrition, according to the British organisation CABI international (CABI).

Aloe vera is a stemless, cactus-like plant that is widely cultivated in Australia, China, India, Jamaica, Mexico, South Africa, Tanzania and the USA. Its gel-like substance is used to heal wounds, sunburns and skin diseases, and to prevent baldness.

However, aloe vera peels or rinds are considered worthless and usually disposed of as agricultural waste.

“It’s likely that millions of tonnes of aloe peels are disposed of globally every year,” says Debasish Bandyopadhyay, an assistant professor in chemistry at the University of Texas Rio Grande Valley, USA, and principal investigator on a study to find ways to add value to aloe while reducing waste.

At a meeting of the American Chemical Society (ACS) last August, Bandyopadhyay and his colleagues showed how aloe vera peels can act as a natural insecticide, staving off insects from crops such as maize or millet. “We proved that [aloe] vera rinds’ derived extracts act as a feeding deterrent and eventually kill agricultural pests,” Bandyopadhyay tells SciDev.Net. He explains that insects do not like aloe vera peels as they contain phytochemicals (chemicals produced by plants) that are toxic for them.

“Insects may be harmed or killed by natural substances contained in aloe peels,” he adds. “Exposure to these compounds can cause discomfort, illness or even disruptions in an insect’s ability to travel, eat and reproduce.”

Insects leave aloe leaves alone and attack the leaves of other plants instead

The researchers became interested in the potential use of aloe peels as an insecticide after visiting a site where they noticed that insects left aloe leaves alone while attacking the leaves of other plants. They hypothesised that aloe peels have specific defence chemicals.

To investigate, they collected and dried out the peels and then produced extracts from them with substances such as dichloromethane (DCM), hexane and methanol.

Their experiments showed that the DCM extract of aloe peels had substantial insect-killing properties against farm pests, as did six other compounds from the peels.

Significantly, the compounds did not show toxic properties, suggesting that aloe-peel-based insecticide wouldn’t have significant safety concerns for people.

“By repurposing the leftover aloe peels that are currently discarded, aloe production can be made more sustainable and contribute to achieving the UN Sustainable Development Goals,” Bandyopadhyay tells SciDev.Net, citing Zero Hunger as an example.

Economic potential in organic farming

Chiranjib Chakraborty, a professor at the School of Life Science and Biotechnology, Adamas University in Kolkata, India, believes the findings have huge economic potential and could help promote organic farming and traditional plant medicines. He believes the research findings could support a shift to a more sustainable farming and replacement of chemical-based practice in millions of farms devoted to rice, wheat, maize and millet.



More information:

See also press release by ACS

Link to YouTube presentation by University of Texas


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