Phytoseiulus persimilis–Predatory Mite

Biocontrol Agent Factsheet

Phytoseiulus persimilis is an ideal candidate for spider mite biocontrol because of its diet specialization, short life cycle and ability to traverse spider mite webbing. Although it can be used inside and outside, this article focuses on outside use.

Common Names

None

Relative effectiveness

Adult Phytoseiulus persimilis has the highest consumption rate of all biocontrol predatory mites available against Tetranychus web-spinning spider mites. However, Phytoseiulus persimilis is highly dispersive if prey availability is low and they have a low tolerance for cold temperatures. Thus, they should not be used to prevent infestation, or expected to persist in the environment after prey is managed or over multiple seasons in cooler climates. However, in the southeastern US, populations can be found in areas where they have not been recently released, indicating establishment. Phytoseiulus persimilis can be used for both indoor and outdoor applications, but multiple releases are likely necessary outdoors where dispersal and re-infestation rates by spider mites are high.

Where to use

Many edible and ornamental crops, inside and outside; can be used on tomatoes

Where spider mites are present, especially in hot spots to prevent spread

Under sufficiently warm (62-80°F) and humid (50-70% relative humidity) conditions

About Phytoseiulus persimilis

Phytoseiulus persimilis is among the most popular predators produced and sold globally. It is a highly selective predator of Tetranychus web-spinning spider mites in more humid areas of North America. Its diet specialization, short life cycle and ability to traverse spider mite webbing makes this species an ideal candidate for spider mite biocontrol. Phytoseiulus persimilis will also readily disperse if there are few prey nearby. However, they cannot overwinter in temperate climates. They are therefore not appropriate for preventative biocontrol and must be applied when prey are present each season.  

  • Native/Non-native: Non-native 
  • Preferred climate: humid, temperate, mediterranean, sub-tropical
  • Region: Released throughout North America
  • Established: Yes
  • Where established: Phytoseiulus persimilis populations have naturally established in parts of the southeastern U.S., but they are commercially available to purchase in all regions. 

Phytoseiulus persimilis Appearance

Small (0.5 mm), but observable using a 10X hand lens. Adults are pear-shaped and red to orange in coloration. Like other predatory mites, they lack eyespots and dense body hair compared to herbivorous mites. They can be distinguished from other predatory mite genera by their coloration and relative leg length. Phytoseiulus spp. generally has a larger leg length: body length ratio compared to common Neoseiulus spp. of mites. 

Two orange-colored Phytoseiulus persimilis adults present against a green leaf surface. This image is magnified using a microscope.

Two Phytoseiulus persimilis adults.

How to Use Phytoseiulus persimilis

Biocontrol category: Augmentative–must be released/applied repeatedly 

When to use: Phytoseiulus persimilis should be released when spider mites are first detected during the growing season, and at least 4 weeks after a broad-spectrum insecticide application to reduce exposure to harmful pesticide residues. 

Rate: It is recommended that prior monitoring of spider mites is conducted to determine these areas. See instructions on how to monitor for spider mites (YouTube). Recommended application rates vary by crop and infestation levels. Generally, numbers of spider mites decrease when pest:predator ratios reach 5-10:1. For strawberry, releases should be made when 2 spider mites per leaflet are detected, or when 25-35% leaflets are infected with spider mites. More generally, common release rates on strawberry are 20,000 P. persimilis per acre for low to moderate infestations, and 200,000 when webbing is present or when spider mite populations have reached “outbreak levels”. This translates into 1-3 predators per square foot for preventative management, 5 predators per square foot for low to moderate infestation, and 10+ predator mites per square foot for high infestations. For recommendations on specific crops, contact distributor.

Maximizing effectiveness: Predatory mite performance is highly influenced by prey availability, plant structural characteristics, i.e., the presence of leaf hairs, and plant connectedness. For P. persimilis, performance generally decreases with increasing density of plant hairs and increased plant spacing. Optimal plants have a smooth, non-waxy leaf surface and are touching in some way to allow predator dispersal within the crop.

Pest stage: Phytoseiulus persimilis prefers to feed on eggs and larvae of twospotted spider mite (Tetranychus urticae). 

Mode of action: Predator 

Conservation: Conserving this predator in the environment is not practical in areas with cold winters. Repeated applications are more likely to provide better control during a growing season. In the southeastern U.S., conservation may be possible through limiting use of broad-spectrum insecticides. This predator can be difficult to conserve because it will disperse when spider mites are no longer present. 

Compatibility: Predatory mites are most sensitive to insecticides, insecticide/miticides and to a lesser extent some herbicides compared to selective miticides or fungicides. In general, less harmful insecticides for predatory mites include diamides, Bacillus thuringiensis, diflubenzuron, methoxyfenozide, and pymetrozine, while etoxazole, bifenazate, spiromesifen, hexythiazox, and cyflumetofen are the most compatible miticides. Phytoseiulus persmilis is considered to be moderately sensitive to pesticides compared to other predatory mite species. Specific products to avoid when releasing P. persimilis include bifenthrin, fenpyroximate, and acequinocyl. It is important to note that nearly all products have non-lethal effects on predatory mites that may negatively impact their performance. Products should be used only when necessary to promote biocontrol success.

See Schmidt-Jeffris 2021, Bergeron 2020, Biobest Side Effects App, IOBC-WPRS Pesticide Side Effect Database and Koppert - Side effect  for more details on pesticide compatibility.  

Any time you use a pesticide, you must read and follow the label directions and comply with all applicable laws and regulations related to pesticide use. Also be sure that any pesticide used is approved for use in your country and state/province.

Risk: No known harm to environmental or human health.  

Commercially available: Yes

Pests Targeted by Phytoseiulus persimilis

  • Twospotted spider mite (Tetranychus urticae Koch
    Location: Global, very common
  • Strawberry spider mite (Tetranychus turkestani)
    Location: Global
  • Dark-red spider mite (Tetranychus ludeni)
    Location: Tropics
  • Carmine spider mite (Tetranychus cinnabarinus)
    Location: Subtropics
  • Pacific spider mite (Tetranychus pacificus)
    Location: Western U.S. and Canada

Twospotted spider mites

Twospotted spider mites feed on more than 900 plants globally, many of which are economically important crops. Using its piercing and sucking mouthparts, spider mites suck out cell contents on the undersides of leaves, leaving chlorotic spots on upper leaf surfaces. Twospotted spider mites are distinguished by their red eye spots, hairs on their body and legs, and the presence of dark markings on both sides of their body (i.e., the two spots). Note these markings are variable and can be absent or spread across the whole body.

Spider Mite Damage

Spider mite damage will first appear on the surface of leaves. It resembles regular chlorotic spots, white-yellow in coloration on the leaf surface. This type of damage is called “stippling”. In some fruit-bearing crops, direct feeding on fruit may result in similar damage on the fruit itself, such as “gold fleck” in tomatoes.

In the background, the underside of a bean leaves including veins and leaf hairs. In the foreground, four spider mite individuals grouped near each other. Spider mite eggs are also scattered throughout the image. The eggs are spherical and white. Arrows indicate eggs and adult spider mites, including a male guarding a female.

Several spider mite individuals and spider mite eggs observed on the underside of bean leaves with magnification.

Strawberry leaf with signs of damage by spider mite feeding. The damage appears as regular chlorotic spots, white-yellow in coloration on the leaf surface. This type of damage is called stippling.

Example of two-spotted spider mite damage on strawberry leaf, also called “stippling” or chlorotic spotting.

Author

  • Samantha Willden
    Cornell AgriTech, Department of Entomology 
  • Rebecca Schmidt-Jeffris
    USDA-ARS, Temperate Tree Fruit and Vegetable Research Unit, Wapato, WA
  • Gregory Loeb
    Cornell AgriTech, Department of Entomology

Date: December 2022

  • Bergeron, P.E. and Schmidt-Jeffris, R.A. Not all predators are equal: miticide non-target effects and differential selectivity. Pest Management Science, 76: 2170-2179 (2020).
  • Escudero, L. A. & Ferragut, F. Life-history of predatory mites Neoseiulus californicus and Phytoseiulus persimilis (Acari: Phytoseiidae) on four spider mite species as prey, with special reference to Tetranychus evansi  (Acari: Tetranychidae). Biological Control 32, 378–384 (2005).
  • McMurtry, J. A., Moraes, G. J. De & Sourassou, N. F. Revision of the lifestyles of phytoseiid mites (Acari: Phytoseiidae). Systematic and Applied Acarology 18, 297–320 (2013).
  • Navajas, M. Host plant associations in the spider mite Tetranychus urticae (Acari: Tetranychidae): Insights from molecular phylogeography. Experimental and Applied Acarology 22, 201–214 (1998).
  • Knapp, M., van Houten, Y., van Baal, E. & Groot, T. Use of predatory mites in commercial biocontrol: current status and future prospects. Acarologia 58, 72–82 (2018).
  • Vanas, V., Enigl, M., Walzer, A. & Schausberger, P. The predatory mite Phytoseiulus persimilis  adjusts patch-leaving to own and progeny prey needs. Experimental and Applied Acarology 39, 1–11 (2006).
  • Hoque, M. F., Islam, W. & Khalequzzaman, M. Life tables of twospotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) and its predator Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae). Journal of Bio-Science 16, 1–10 (1970).
  • Skirvin, D. & Fenlon, J. Of mites and movement: the effects of plant connectedness and temperature on movement of Phytoseiulus persimilis. Biological Control 27, 252–250 (2003).
  • Stavrinides, M. S. & Skirvin, D. J. The effect of chrysanthemum leaf trichome density and prey spatial distribution on predation of Tetranychus urticae (Acari: Tetranychidae) by Phytoseiulus persimilis (Acari: Phytoseiidae). Bulletin of Entomological Research 93, 343–350 (2007).
  • Trumble, J. T. & Morse, J. P. Economics of integrating the predaceous mite Phytoseiulus persimilis (Acari: Phytoseiidae) with pesticides in strawberries. Journal of Economic Entomology 86, 879–885 (1993).
  • Bilbo, T. & Walgenbach, J. Compatibility of bifenazate and Phytoseiulus persimilis for management of twospotted spider mites in North Carolina staked tomatoes. Journal of Economic Entomology 113, 2096–2103 (2020).
  • Schmidt-Jeffris, R. A., Beers, E. H. & Sater, C. Meta-analysis and review of pesticide non-target effects on phytoseiids, key biological control agents. Pest Management Science 77: 4848 – 4862 (2021).
  • Two Phytoseiulus persimilis adults. Photo by S. Willden.
  • Two spotted spider mite (top) and Phytoseiulus persimilis (bottom) development time at 20°C (68°F) within growth chambers. See Hoque et al. 2008 for seasonal variation in life cycle. Data from Sabelis 1981 and artwork by S. Willden.
  • Several spider mite individuals and spider mite eggs observed on the underside of bean leaves. Photo by S. Willden.
  • Example of twospotted spider mite damage on strawberry leaf, also called “stippling” or chlorotic spotting. Photo by S. Willden
Portrait of Amara Dunn
Amara Dunn-Silver

Senior Extension Associate

NYS Integrated Pest Management

Amara Dunn-Silver
Man in field smiles.
Gregory Loeb

Professor

Department of Entomology

Cornell AgriTech

Gregory Loeb