Amblyseius swirskii–Predatory Mite

Biocontrol Agent Factsheet

Amblyseius swirskii (sometimes called the Swirski mite) is a species of mite that feeds on a wide variety of economically important pests including mites, thrips, psyllids, and whiteflies. This article focuses on the use of this predator in outdoor environments.

Overview

Pests Targeted: Mites, thrips, psyllids, whiteflies
Pest Stage: Eggs, immatures and adults. Eggs and immatures are the best stages to target with biocontrol agents.
Commercially Available? Yes
Scientific Name: Amblyseius swirskii
Biocontrol Agent Type: Predator

Photo of an A. swirskii specimen when plated and viewed under a microscope. The image background is light blue and the specimen in the foreground is contrasted from the background by dark outlines of the external and internal body structures. — Amblyseiulus swirskii specimen viewed under a microscope. Photo by R. Schmidt-Jeffris.

Common Names

Swirski mite

Relative effectiveness

Amblyseius swirskii can be used to control thrips and whiteflies simultaneously, unlike other predatory mites used for biological control. Several studies have also indicated that A. swirskii is more effective at managing thrips compared to N. cucumeris. Amblyseiulus swirskii is less effective at controlling spider mites compared to specialist predators like Phytoseiulus persimilis, Neoseiulus fallacis, and Neoseiulus californicus. It is also less effective at providing quick knockdown of high-density pests of any species compared to specialist predators and performs best as a preventative measure. Like N. cucumeris, A. swirskii can be released before pests are detected if non-prey resources such as pollen and nectar are available.

Where to use

Many edible and ornamental crops, inside and outside

May require higher release rates on plants with many hairs on their leaves. This predator is likely ineffective on tomato due to the glandular trichomes on the leaves. (See ‘How to Use’ section)

About Swirski Mites

Amblyseius swirskii is a relatively new biocontrol agent that was first discovered in the Mediterranean. Since 2005, it has been commercially released in more than 50 countries for whitefly, thrips and mite control. Amblyseius swirskii has gained huge success in recent years because it can control thrips and whiteflies simultaneously. In fact, nearly all sweet pepper growers in Spain converted from chemical control to biological control of onion thrips and western flower thrips using A. swirskii (Calvo et al. 2015). Another benefit of releasing A. swirskii is that it can persist well in the environment without prey if non-prey resources including pollen, nectar or honeydew is available. Growers may wish to provision A. swirskii with commercially available supplementary foods to improve its performance. This includes cattail pollen and brine shrimp cysts. Amblyseius swirskii is best used for preventative control, but larger and more frequent releases can be made for curative measures against small to moderate pest infestations.

Native/Non-native: Non-Native
Preferred climate: Humid, temperate, mediterranean, sub-tropical
Region: Not naturally found in North America but it is effective when released in all regions above 20 °C (68 ° F) .
Established: No

Swirski Mite Appearance

Amblyseius swirskii can be found on the underside of leaves or inside flowers where prey or non-prey resources are available. This species is indistinguishable from Neoseiulus fallacis, Neoseiulus californicus and Neoseiulus cucumeris (other predatory mites) without a microscope. Neoseiulus and Amblyseius spp. are small (0.5-1.0 mm), pear-shaped, and cream-yellow colored. They are roughly the same size as spider mites but can be distinguished from them by lack of eye spots and dense body hair. They are also highly active compared to plant-feeding mites when viewed using a hand lens. Eggs are 0.15 mm, oval and cream-colored, and laid on the underside of leaves.

Amblyseiulus swirskii specimen viewed under a microscope.

A. swirskii adult

Life Cycle

An illustration comparing the life stages of A. swirskii. Time spent in development was averaged between A. swirskii reared at 25°C (77°F) and 70% RH on two different prey species: Tetranychus urticae and Bemisia tabaci.

General appearance and description of A. swirskii at each life stage. Text below each image describes each life stage: Egg (oval 0.14 mm) 1-2 days; larva (cream colored, 6 legs) 1 day; nymph (proto and deuto stages combined, cream-yellow coloration with occasional darker markings) 3 days; and adult (0.5-1.0 mm, cream-yellow coloration with occasional dark markings) 19-25 days. Total development time from egg-adult is 6-7 days at these conditions. — The life stages of A. swirskii. Time spent in development was averaged between A. swirskii reared at 25°C (77°F) and 70% RH on two different prey species: twospotted spider mite and whitefly. Data by Seiedy et al. 2017 and artwork by S. Willden

How to Use Swirski Mites for Biocontrol

Biocontrol category:

Augmentative - must be released/applied repeatedly
Conservation - attract and protect from the surrounding environment

When to use: Releases of A. swirskii can be made during the spring and summer when average temperatures are > 20°C (68°F). For preventative control, release A. swirskii before the pest is detected, especially if non-prey resources (pollen and nectar) are available. To build populations, release during the peak flowering season. Note that A. swirskii has a low cold tolerance and will not overwinter on outdoor crops in cold climates.

Where to use: Amblyseius swirskii can be applied on many indoor and outdoor-grown plants where prey and/or non-prey plant resources (pollen and nectar) are available. Although navigation by A. swirskii may be slowed on plants with dense leaf hairs, these structures often provide a hospitable environment and refuge from other predators. For short-term management, it may be necessary to increase release rates on crops with high leaf hair density to ensure that predators are able to navigate plant structures in time to reach prey hot spots.

Rate: Release predators at 25 mites per 1 m2 (2 mites per 1 ft2) for preventative control before pests are present, and 50 mites per m2 (4 mites per 1 ft2) when pests are first detected. Release 100-300 mites per 1 m2 (20-30 mites per 1 ft2) on pest hot spots. In the open-field, 20-40 mites per plant were effective in providing curative control of melon thrips on cucumber, but the researchers speculated that earlier applications at lower dosages could have prevented pest infestation at a lower cost (Kakkar et al. 2016).

Maximizing effectiveness: Multiple release systems are available for distributing A. swirskii. Mass releasing from bottles or blowers are effective if predators are distributed in crop settings with food resources. If food resources (i.e., prey and/or pollen) are not available, it is recommended to release using breeding sachets that provide non-harmful prey mites for A. swirskii to eat. Ideal temperatures for A. swirskii are are between 20-32°C (68-86°F). Release during peak flowering, even if pests are not present. If releasing on a pollen-poor plant, consider providing banker plants, such as peppers, that provide additional pollen or nectar for A. swirskii and other biocontrol agents.

Pest stage: Eggs, immatures and adults. Eggs and immatures are the best stages to target with biocontrol agents.

Mode of action: Predator

Conservation: Although A. swirskii is not found naturally in North America, it is a good candidate for conservation biocontrol during the growing season when temperatures are favorable. Because A. swirskii can effectively feed and reproduce on plants that offer non-prey resources like nectar and pollen, planting companion plants near target areas that are rich in pollen or nectar can help to conserve A. swirskii. If companion planting is not possible, sprinkling supplemental cattail or apple pollen on target plants can also conserve A. swirskii during the growing season.

Compatibility: Broad-spectrum pesticides can have serious non-target effects on predatory mites, even if they are labeled as selective. In general, the ‘most selective’ insecticides that have reduced toxicity to predatory mites include diamides, Bacillus thuringiensis, diflubenzuron, methoxyfenozide, and pymetrozine. Compatible miticides include hexythiazox, etoxazole, bifenazate, spiromesifen and cyflumetofen. A recent study found that Sulfoxaflor, flonicamid, flubendiamide, metaflumizone, methoxyfenozide, spiromesifen, and spirotetramat are compatible insecticides for A. swirskii. This study also identified abamectin, deltamethrin and spinosad as harmful to A. swirskii and these products should therefore be avoided.

Amblyseius swirskii can be released with other biocontrol agents to manage whiteflies, thrips and spider mites. However, it does readily consume eggs from the aphid-feeding gall midge Aphidoletes aphidimyza that could disrupt aphid biocontrol. There is also high potential for A. swirskii and the generalist predator N. cucumeris (used for thrips management) to eat each other if released together. (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.)

See Schmidt-Jeffris 2021, Fernández et al. 2017, Biobest Side Effects App, IOBC-WPRS Pesticide Side Effect Database and Koppert - Side effect for more details on pesticide compatibility.

Risk: There is no evidence of harm to human or environmental health.

Commercially available: Yes. This species is widely available from multiple distributors.

About Pests Targeted by Swirski Mite

Amblyseius swirskii has a highly varied diet and performs best when a diversity of food resources are available. The primary target pests for A. swirskii are often thrips and whiteflies, but this predator can feed on broad mites, spider mites, eriophyid mites and in some cases psyllids in protected systems. Amblyseius swirskii should not be purchased to control spider mites, but may assist with spider mite management at low densities. It is not able to navigate spider mite webbing. Aphids, scales or mealybugs are not appropriate targets for A. swirskii.

Pest species targeted

Twospotted spider mite (Tetranychus urticae)
Western flower thrips (Frankiniella occidentalis)
Broad mite (Polyphagotarsonemus latus)
Asian citrus psyllid (Diaphorina citri)
Onion thrips (Thrips tabaci)
Silverleaf or tobacco whitefly (Bemisia tabaci)
Greenhouse whitefly (Trialeurodes vaporariorum)
Chilli thrips (Scirtothrips dorsalis)
Tomato russet mite (Aculops lycopersici)
European red mite (Panonychus ulmi)
Carmine spider mite (Tetranychus cinnabarinus)
Melon thrips (Thrips palmi)

Targeted Pest Damage

Amblyseius swirskii is a generalist predator that feeds on many small, soft-bodied invertebrates. Preferred prey includes whiteflies, thrips and broad mites. Whitefly damage results from nymphs and adults feeding on plant phloem. This damage can appear as premature yellowing, shriveling and dropping of leaves. Adult whiteflies can also transmit bacteria, pathogenic fungi and viruses that cause plant disease. Thrips damage appears as irregular sections of chlorotic leaf tissue that is the result of adults and nymphs feeding on plant cells using their piercing and sucking mouthparts. This damage is often accompanied by dark flecks of thrips frass (aka feces). Spider mite damage is similar to damage by thrips, but chlorotic sections are smaller, roughly the size of a pinprick. Spider mite damage is commonly called “stippling”. When spider mites reach high densities, damage will likely be accompanied by webbing between leaves. In some fruit-bearing crops, direct feeding on fruit by spider mites may result in similar damage on the fruit itself, such as “gold fleck” in tomatoes. However, A. swirskii is not the best choice for biocontrol if spider mites are the primary pest. Pests in the Tarsonemidae family (includes broad mites) produce discolored, brittle and deformed leaves and petioles, leading to stunted growth. Fruits and vegetables can also be damaged resulting in smaller, deformed and “tanned” fruit.

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 on the underside of bean leaves.

Western flower thrips (Frankliniella occientalis).

A whitefly nymph. The nymph is oval-shaped with many fine hairs around the edge.

A whitefly nymph. Photos by Bohne and Mikhaltsov.

An adult whitefly with simple wing venation, and a white-powdery appearance

Adult whiteflies have simple wing venation, and a white-powdery appearance.

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.

A colony of whiteflies present on the underside of a green leaf. Whiteflies are distinguished from the leaf background by their white-powdery appearance.

typical feeding damage by thrips on a leaf. The damage appears as white or bleached splotches against the green leaf surface. Black flecks of frass also speckle the leaf.

Thrips feed by piercing the epidermal layer of host tissue and sucking out cell contents. This damage results in bleached and irregularly shaped spots variable in size on the leaf surface. This damage is also accompanied by thrips feces or “frass” that appears as dark flecks.

Authors

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: January 2022

References

Abou-Awad, B.A., Metwally, A.M., and Al-Azzazy, M.M. Typhlodromis swirskii (Acari: Phytoseiidae) a predator of eriophyid and tetranychid mango mites in Egypt. Acta Phytopathologica et Entomologica Hungarica, 45: 135 – 148 (2010).
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).
Buitenhuis, R., Shipp, L. and Scott-Dupree, C. Intra-guild vs extra-guild prey: effect on predator fitness and preference of Amblyseius swirskii A. (Athias-Henriot) and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae). Bulletin of Entomological Research, 100: 167 – 173 (2010).
Buitenhuis, R., Shipp, L., and Scott-Dupree, C. Intra-guild and extra-guild prey: effect on predator fitness and preference of Amblyseius swirskii (Athias-Henriot) and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae). Bulletin of Entomological Research, 100: 167 – 173 (2010).
Buitenhuis, R., Murphy, G., Shipp, L., and Scott-Dupree, C. Amblyseius swirskii in greenhouse production systems: A floricultural perspective. Experimental and Applied Acarology, 65: 451 – 464 (2015).
Calvo, F.J., Knapp, M., van Houten, Y.M., Hoogerbrugge, H., and Belda, J.E. Amblyseius swirskii: What made this predatory mite such a successful biocontrol agent? Experimental and Applied Acarology 65: 419 – 433 (2015).
Doğramaci, M., Kakkar, G., and Kumar, V. Featured Creatures: Amblyseius swirskii. University of Florida (2013).
Mar Fernández, M., Medina, P., Wanumen, A., Del Estal, P., Smagghe, G., and Viñuela, E. Compatibility of sulfoxaflor and other modern pesticides with adults of the predatory mite Amblyseius swirskii. Residual contact and persistence studies. BioControl, 62: 197 – 208 (2017).
Juan-Blasci, M., Qureshi, J.A., Urbaneja, A., and Stansly, P.A. Predatory mite Amblyseius swirskii (Acari: Phytoseiidae), for biological control of Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae). Florida Entomologist, 95: 543 – 551 (2012).
Kakkar, G., Kumar, V., Seal, D.R., Liburd, O.E., Stansly, P.A. Predation by Neoseiulus cucumeris and Amblyseius swirskii on Thrips palmi and Frankliniella schultzei on cucumber. Biological Control, 92: 85 – 91 (2016).
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).
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).
Messelink, G.J., van Maanen, R., van Steenpaal, S.E.F., and Janssen, A. Biological control of thrips and whiteflies by a shared predator: Two pests are better than one. Biological Control, 44: 372 – 379 (2008).
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).
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).
Seiedy, M., Soleymani, S., and Hakimitabar, M. Development and reproduction of the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) on Tetranychus urticae Koch (Acari: Tetranychidae) and Bemisia tabaci Gennadius (Heteroptera: Aleyrodidae). International Journal of Acarology, 43: 160 – 164 (2017).

Photos and Illustrations

Amblyseiulus swirskii specimen viewed under a microscope. Photo by R. Schmidt-Jeffris.
Magnified image of a A. swirskii adult on a leaf surface. Image by R. Schmidt-Jeffris.
Amblyseiulus swirskii specimen viewed under a microscope. Photo by R. Schmidt-Jeffris.
An illustration comparing the life stages of A. swirskii. Time spent in development was averaged between A. swirskii reared at 25°C (77°F) and 70% RH on two different prey species: Tetranychus urticae and Bemisia tabaci. Data by Seiedy et al. 2017 and artwork by S. Willden.
Color photo taken under a microscope at 20X. The photo background is the underside of a bean leaf that includes veins and leaf hairs. In the foreground, four spider mite individuals are grouped near each other. Spider mite eggs are also scattered throughout the image. Individual spider mites and their eggs are indicated by white arrows, including a male spider mite that is guarding a female. Photo by S. Willden.
Western flower thrips (Frankliniella occientalis). Photo by D. Kirkeby.
Trialeurodes vaporariorum, or the greenhouse whitefly nymph (top) and adult (bottom). Adults have simple wing venation, and a white-powdery appearance. Photos by Bohne and Mikhaltsov.
Example of two-spotted spider mite damage on strawberry leaf, also called “stippling” or chlorotic spotting. Photo by S. Willden.
Whitefly infestation confirmed by visual inspection on the underside of leaves.
Thrips feed by piercing the epidermal layer of host tissue and sucking out cell contents. This damage results in bleached and irregularly shaped spots variable in size on the leaf surface. This damage is also accompanied by thrips feces or “frass” that appears as dark flecks.