When earthworms soil themselves, everyone wins

December 10, 2019 at 9:13am

Daphne Sugino Souffront went in search of safer, earth-friendly alternatives to pesticides. She found the answer in — wait for it — earthworm poop!

Earthworms are small, but mighty — hungry. In a day, they eat half of their body weight. They aren’t picky either. They munch on kitchen scraps and chow down on cardboard. They will even devour a pair of jeans, only leaving behind bits of elastic, metal grommets and zippers. Their hunger makes them one of the world’s best recyclers. That’s because everything an earthworm eats is eventually eliminated. When their waste, called ‘castings,’ interacts with bacteria, it becomes nutrient-rich vermicompost that can be used as organic fertilizer.

Several studies have shown that vermicompost also appears to help plants ward off pests. However, there’s been no evidence on why this happens. Sugino Souffront, a graduate research assistant in FIU’s Department of Earth and Environment, wanted to uncover how vermicompost could be doing this.

Under the guidance of professor Krishnaswamy Jayachandran and assistant professor Diego Salazar-Amoretti, she got to work. But, there was a problem. Sugino Souffront needed plants. Lot of them. So, in FIU’s organic garden, she used 238 feet of soil to plant 1,350 seeds. After 104 days, she had 450 tomato plants. Then, she held a tea party for the plants. A vermicompost tea party, that is.

Sugino Souffront is a Fall 2019 Worlds Ahead Graduate.

To read the story of how she survived Hurricane Maria when it hit her home in Puerto Rico, please click here.

With 240 pounds of vermicompost, she “brewed” three different strengths of tea with varying amounts of the vermicompost and water. Then, using gas chromatography–mass spectrometry — a method often used to detect cocaine in drug tests — Sugino Souffront discovered vermicompost was causing plants to make important chemical changes to ward off pests. It specifically targeted terpenes, which act as the first line of defense against pests. The process works like antibodies fighting off disease-causing viruses in a person’s immune system.

Today, farmers primarily rely on pesticides to ward off crop-destroying insects and funguses. These types of agrochemicals provide short-term protection with long-term environmental impacts.

“Pesticides pollute soil and water, as well as contribute to the loss of important pollinators, like bees. Given what’s we know about the impact they have on the planet, we have to work to find alternatives,” she said. “And what better way than vermicomposting? It’s sustainable, easy, accessible to anyone and very cheap.”

Sugino Souffront believes the always-hungry, underappreciated earthworms may provide a promising alternative to agrochemicals, especially for Florida’s tomato industry, where more than 80 percent of farmers use pesticides. She will be sharing her findings with tomato farmers in Florida and across the world.

Sugino Souffront's research was supported by a USDA Hispanic Serving Institution BASE grant.