Amblyseius (Transeius) montdorensis

Common information

Amblyseius or Transeius Montdorensis (also known as Tyhlodromips montdorensis) is a predatory mite, an acariphage, first described in 1994 in Australia. They eat small insects and mites, with a lack of victims, they can feed on pollen and honeydew. They have proven themselves as effective biocontrol agents for many agricultural crops and are now used all over the world. Transeius (Amblyseius) montdorensis mainly feeds on eggs and the initial larval stages of thrips and whitefly, which makes them the best means of preventing the reproduction of these pests. Although indirectly, but at the same time no less effectively control the population of spider mites and some other species of phytophagous mites.

Description and life cycle

Montdorensis is a small, less than 1 mm pear—shaped mite, pale (translucent) in colour. The life cycle consists of 5 stages of development: egg, larva, pronymph, deutonymph, adult. The eggs are transparent and oval-shaped. The egg develops for 1-2 days, after which it passes into the larva stage. The acariphage carries out oviposition in safe places, preferring the reverse side of the leaf (usually hairs — trichomes). At 25 °C, the full life cycle (from egg to adult) is less than 7 days. All mobile stages are active predators. A female mite kills an average of 14 thrips larvae per day.

Target pests

Montdorensis are mainly used to control thrips and whitefly. They also provide secondary suppression of other pests, including spider mites. The main target pests are:

1. Tobacco (onion) thrips
2. Tomato trips
3. Western Flower trips
4. Greenhouse (glasshouse) whitefly
5. Tobacco (silverleaf) whitefly

Advantages of acariphage

• Rapid population growth on pollinated crops
• Polyphagia (a wide range of victims)
• Ability to survive at low victim density (alternative food sources)
• Preventive use
• Habitat and growth conditions

Transeius montdorensis is successfully used for growing many crops, such as peppers, aubergines, cucumbers, strawberries in greenhouses. They can also be used outdoors, provided that the temperature does not fall below 10 °C for a long time.

Montdorensis prefers warm conditions, and its activity stops at temperatures below 11 °C. Adults can tolerate temperature increases up to +45 °C in greenhouses, but eggs and young individuals die at the same time. The optimal temperature range is 20-30 °C. Acariphages do not enter diapause when daylight is reduced. As long as the average daily temperature is within the permissible norm, the predator will be active regardless of the time of year.

Recommendations for the introduction

Biological protection agents, unlike chemical agents, can be used in large quantities without harm to plants. But we all know how to count, so we set a goal to optimize costs as much as possible. Of course, it is necessary to take into account many factors, such as the economic component, the degree of pest damage and the volume of its population, as well as the presence of other entomophages. Therefore, an analysis of a specialist is necessary for accurate calculations.

As our practice shows, it is better to introduce a predator with repetitions 2-4 times, in smaller quantities than once, but a lot at once. Thus, we reduce the risk of population degeneration, increase the percentage of its survival rate and create several generations of the mite.

The frequency of repeated introduction of a predator varies depending on the culture and the degree of infection. We provide a general, introductory, scheme of using Montdorensis, for more accurate calculations, a specialist’s consultation is required

1. Preventive — 10-25 mites / m2, the number of issues is 3. The interval between releases is 2 weeks.
2. At the first signs of a pest — 50-100 mites / m2, the number of releases requires analysis. The interval between releases is 1-2 weeks.
3. With an increased pest population density of 100-200 mites / m2, the number of releases requires analysis. The interval between releases is 1-2 weeks

The best time to implement

Amblyseius montdorensis is recommended to be introduced at the beginning of the pest emergence cycle to prevent the growth of whitefly and thrips populations. To monitor the pest, adhesive traps should be used and the entomophage should be released at the first signs of their appearance. On pollinated crops, maximum results are achieved with the preventive introduction of Montdorensis.

As additional agents of biocontrol of thrips, predatory bugs Orius (feed on all stages of thrips) and predatory mites Hypoaspis living in the soil (destroy the pupae of thrips in the soil) should be noted. Among the additional agents of biocontrol of whiteflies, parasitoid wasps of Encarsia formosa should be noted.

After implementation

Transeius (Amblyseius) montdorensis are actively hunting and quickly change location in search of prey, so during the first week after the introduction, it is quite problematic to detect them. It should be noted the places of release of acariphage, especially with a large number of pests. These areas should be regularly checked to assess the number of pests and acclimatization of predatory mites. Initially, the number of harmful organisms may continue to increase while the predator takes root.

Compatibility with chemicals

Although some pesticides are not harmful to predatory mites, many of them are directly toxic or have a sublethal effect. This may interfere with the rooting of predators and/or reduce their effectiveness.

If there is absolutely no way to do without pesticides, then you should definitely check for side effects and choose products that are least harmful to montdorensis and other bioagents used.

Some insecticides (for example, synthetic pyrethroids, organophosphates and neonicotinoids) may have residual toxicity that affects Montdorensis for a long time. Fungicides usually have low toxicity to predatory mites, but some of them (for example, mankoceb and chlorothalonil) have a strong destructive effect.