Amblyseius swirskii is a small, predatory mite that has become an important tool in biological pest control within agricultural settings. Originating from the Eastern Mediterranean region, this generalist predator readily consumes various small, soft-bodied insect pests, as well as alternative food sources like pollen or plant exudates. Its ability to effectively suppress pest populations has led to its widespread commercial use in greenhouse and nursery crops across Europe and North America since 2005.
Understanding Amblyseius Swirskii
Amblyseius swirskii belongs to the Phytoseiidae family of predatory mites. Adult mites are 0.4-0.5 mm in length, with females larger than males. They possess a pear-shaped, translucent to pale yellow body, which can change to a reddish hue depending on their diet. These mites have eight legs, with their front pair pointing forward, and a limited number of hairs on their back. They are highly mobile, often found on the underside of leaves or within flowers, and can be difficult to spot without magnification.
The life cycle of Amblyseius swirskii includes five stages: egg, larva, protonymph, deutonymph, and adult. Eggs are oval, white, and about 0.14-0.15 mm, typically laid on the underside of leaves near veins. Larvae have six legs and do not feed, while nymphs develop eight legs and are whitish-yellow. At 25°C, the entire life cycle from egg to adult completes in about five days. A single female lays 1.5 to 2 eggs daily, totaling 30 to 40 eggs over her lifespan, contributing to its rapid effectiveness.
Pests Controlled by Amblyseius Swirskii
Amblyseius swirskii targets a variety of small, soft-bodied arthropod pests. Its primary targets include different species of thrips, such as the western flower thrips (Frankliniella occidentalis), and various whitefly species, including greenhouse whitefly (Trialeurodes vaporariorum) and tobacco whitefly (Bemisia tabaci). The mite actively seeks out and preys on young larvae of thrips and the eggs and early larval stages of whiteflies, consuming multiple life stages of these pests.
Beyond thrips and whiteflies, Amblyseius swirskii also preys on other pest mites like broad mites, cyclamen mites, and tarsonemid mites. While it can feed on spider mites, including the two-spotted spider mite (Tetranychus urticae), it is less effective against them compared to specialized spider mite predators. This mite is not an appropriate control for pests such as aphids, scales, or mealybugs. Its ability to feed on pollen and plant exudates allows it to establish and persist in crops even before pest populations become high.
Deployment in Pest Management
Amblyseius swirskii is commonly acquired and released using several methods. It is often supplied in bottles containing adult mites mixed with a carrier like bran or vermiculite, which can be sprinkled directly onto plants. Another common method involves slow-release sachets, where the mites multiply within the sachet and gradually disperse into the crop over several weeks. These sachets provide a continuous release of mites, making them suitable for long-term preventative control.
The ideal timing for introducing Amblyseius swirskii is often preventatively, before pest populations become established. However, it can also be introduced as soon as the first pest mites are detected. Release rates vary depending on the crop, climate, and pest density, ranging from 25 to 300 mites per square meter. For preventative control, a rate of 25 mites per square meter is often recommended, increasing to 50 mites per square meter when pests are first detected. For localized pest hotspots, a higher rate of 100-300 mites per square meter may be applied.
Once released, Amblyseius swirskii actively searches for prey on plant surfaces, particularly the undersides of leaves where pests often reside. They pierce their prey and suck out the contents. This predatory behavior, combined with their ability to sustain themselves on pollen, makes them a valuable component of Integrated Pest Management (IPM) strategies. IPM uses a combination of methods, including biological control, to manage pests sustainably and reduce reliance on chemical pesticides.
Optimizing Environmental Conditions
The effectiveness and survival of Amblyseius swirskii are influenced by environmental factors. Optimal temperatures for their activity and reproduction range from 20 to 32°C (68 to 90°F), with reproduction and survival highest around 25°C. They can tolerate temperatures between 15°C and 36°C, but their activity decreases below 18°C. These mites do not undergo diapause, a dormant state induced by short day-lengths or low temperatures, allowing for their use late into the fall and winter in indoor environments.
Humidity levels influence their success; Amblyseius swirskii is sensitive to relative humidity below 60%. Maintaining a microclimate humidity of around 70% on the leaf surface is beneficial for their performance and establishment. Enclosed release methods help create a favorable microclimate with higher humidity and temperature, supporting mite survival and establishment for several weeks. Access to water is also important for these mites.
Compatibility with chemical pesticides is an important consideration when using Amblyseius swirskii. Certain pesticides, such as abamectin, deltamethrin, and spinosad, are harmful to these mites and should be avoided to ensure their survival. While Amblyseius swirskii can be used alongside other biological control agents, caution is advised when co-releasing with species like Aphidoletes aphidimyza (an aphid-feeding gall midge) or Neoseiulus cucumeris, as antagonistic interactions can occur where they might prey on each other or their eggs.