Scientists found a desert-adapted pest-fighting mite that could help protect crops across the world's driest regions

Researchers at Arturo Prat University in Iquique, Chile, led by Dr. Víctor Tello, discovered a population of the predatory mite Phytoseiulus persimilis in farmland in Chile’s Tarapacá region, according to Diario El Longino. That discovery has resulted in a scientific paper, ‘First record of Phytoseiulus persimilis in the Tarapacá Region, Chile,’ now in peer review. The story behind it could matter to American growers just as much as it does to Chilean ones.

Meet the bug that farmers already rely on
Phytoseiulus persimilis is not a household name, but many farmers know it. According to Diario El Longino, this predator specialises in the hunting of red spider mites, such as the desert red spider mite that damages alfalfa and melon crops and the two-spotted spider mite that causes major crop losses in vegetables and fruit around the world. Instead of spraying chemicals, growers release these predators into a field or greenhouse, where they hunt down the pests without touching the plants themselves.

According to Cornell University’s NYSIPM program, this species is already one of the most widely used biological control agents in the world. In fact, it has even been found establishing itself naturally in parts of the southeastern United States, in areas where it hadn’t been recently released. It’s a tool that American greenhouse and produce growers already depend on to reduce pesticide use.

Why this specific find is so strange
Here's what makes the Tarapacá discovery odd. According to the University of California Statewide Integrated Pest Management Program, Phytoseiulus persimilis requires high relative humidity to thrive, and humidity levels below 70% reduce molting, and its growth almost stops when humidity levels drop to between 25 and 30 percent. Tarapacá is in one of the driest deserts on Earth, nowhere near that kind of moisture. Dr. Tello’s team is now investigating whether this population has adapted to survive in low-humidity and high-heat conditions, which hasn’t been documented before for this species. Diario El Longino notes that the work comes from a university research project, UNAP Consolida SINCPROYEXT-0075, which tested the mite’s behavior in the laboratory after feeding it different species of red spider mites.

The heat math behind why this matters
The other half of the puzzle is temperature tolerance. A 2025 study published in the journal Insects found that the species generally thrives best between about 62.6 and 82.4 °F, and that steady temperatures of 95 degrees or higher keep young mites from ever reaching adulthood. In the review, the authors describe the species as a specialist predator of spider mites that is already used in greenhouse and field biocontrol, but note that its performance drops sharply outside a narrow thermal window. They also flag a practical gap: most laboratory work has focused on short-term lethal thresholds, leaving little guidance on how sustained heat and humidity swings affect survival, development and prey consumption

For an agricultural industry facing longer heat waves and tighter water budgets, a naturally hardier version of a predator already in commercial use would constitute a genuine upgrade, not a brand-new gamble.

That’s a US problem as well. According to Sound Horticulture’s grower guidance, growers often mist plants or walkways when conditions become dry to help meet the predator’s humidity needs. In drought-stressed growing regions across the American West, anything that lessens the requirement for additional water to keep a beneficial predator alive is worth paying attention to.

From a research project to a possible new industry
The work isn't stopping at documentation. Dr. Tello is raising the mites on two-spotted spider mites to observe how the desert population behaves under different humidity levels. The project has led to a teaching project in which students of agronomy at the university are directly involved in the research. Two of those students are Francisca Rojas Barraza and Iván Morgado Suárez, who are studying how the mite reacts to different levels of humidity.

If the desert adaptation survives further testing, Dr. Tello has said the population could eventually be duplicated and assessed for use in arid farming areas elsewhere because this species is already one of the most widely traded biological control agents on the planet. That includes drought-prone growing regions here in the US, where a heat-tolerant strain of a predator that growers already trust could translate to less reliance on irrigation just to keep it alive.

The takeaway
None of this is confirmed yet. The underlying research is still undergoing peer review, and Dr. Tello himself has called it a research line that is “just beginning,” not a breakthrough that has been achieved. But it’s a reminder that even a well-studied, commercially traded organism can still surprise scientists, and that the next low-chemical tool for farming through hotter, drier summers might already be crawling around a desert field, quietly disproving the textbooks.