From Deep Look.
Two tiny mites duke it out on strawberry plants throughout California. One is a spider mite that sucks the juices out of the delicious crop and destroys it. The other, persimilis, is a crafty predator that growers drop by the thousands from high-tech drones to protect their fields.
DEEP LOOK is an ultra-HD (4K) short video series created by KQED San Francisco and presented by PBS Digital Studios. See the unseen at the very edge of our visible world. Explore big scientific mysteries by going incredibly small.
Individual spider mites are barely visible, about the size of a grain of salt, but together they cause huge damage to crops around the world. They suck sap from the leaves and stems of crops and houseplants, leaving yellow or dry rusty leaves and tangles of fine silk.
Farmers can use pesticides to knock them back, but spider mites quickly develop resistance, making them particularly stubborn pests.
So many farmers turn to biological control agents. One of the most popular is another type of mite commonly called persimilis. This predatory mite hunts down spider mites and their eggs.
But spreading the tiny hunters over vast agricultural fields is a challenge, so some growers are turning to companies like Parabug to disperse the predators by air using drones.
Now, entomologist Christian Nansen and engineer Zhaodan Kong at UC Davis are looking at ways to automate this entire process of crop protection. They’re developing a strategy using drones armed with special cameras to detect changes in the way sunlight bounces off plants’ leaves.
Software using machine learning algorithms would then read the subtle changes in the leaves’ reflectance and come up with a diagnosis about what was causing the stress. If the system suspects a spider mite infestation it could then summon a second drone, packed with predatory mites. The team is working on developing software to accurately drop the predators right on the trouble areas.
“The idea is that these natural predators are like tiny paratroopers coming in on the drones,” said Nansen, “with a special eye in the sky that sees exactly where they need to go.”
— What are spider mites?
Spider mites are not insects. They’re arachnids, more closely related to spiders and ticks.
— How do I get rid of spider mites?
One of the best ways to get rid of spider mites on houseplants and garden crops is to spray the plant with water to knock the mites off. There are pesticides that will kill them, but spider mites have a knack for becoming resistant. Oils are also used to smother the mites. Biological control agents like predatory mites can be particularly effective.
—+ Find additional resources and a transcript on KQED Science:
—+ More great Deep Look episodes:
Samurai Wasps Say ‘Smell Ya Later, Stink Bugs’ | Deep Look
How Ticks Dig In With a Mouth Full of Hooks | Deep Look
🏆Congratulations🏆 to these 5 fans on our Deep Look Community Tab for identifying the sharp mouthparts of the Persimilis mite – chelicerae!
—+ Thank you to our Top Patreon Supporters ($10+ per month)!
Chris B Emrick
Elizabeth Ann Ditz
Shelley Pearson Cranshaw
Joshua Murallon Robertson
Roberta K Wright
—+ Follow KQED Science and Deep Look:
—+ About KQED
KQED, an NPR and PBS affiliate in San Francisco, California, serves Northern California and beyond with a public-supported alternative to commercial TV, radio and web media.
Funding for Deep Look is provided in part by PBS Digital Studios. Deep Look is a project of KQED Science, the largest science and environment reporting unit in California. KQED Science is supported by The National Science Foundation, the Dirk and Charlene Kabcenell Foundation, the Vadasz Family Foundation, the Gordon and Betty Moore Foundation, Campaign 21 and the members of KQED.