Amblyseius andersoni

Amblyseius andersoni is an entomophagous mite in the family Phytoseiidae. It is widespread in Europe and North America.  A. andersoni controls phytophagous mites, including the spider mite Tetranychus, as well as the gall mites Eriophyidae and  Panonychus mites. It is often used both on fruit and berry crops: apple, pear, grapes, raspberries, and on vegetables: pepper, cucumber, tomato, aubergine, etc. In recent studies conducted in the Netherlands, Amblyseius andersoni has shown itself as a promising predator on ornamental crops: rose, gerbera, chrysanthemum. The ability to feed on pollen and larvae of thrips allows the entomophage to survive when populations of harmful mites decrease.

Description and life cycle

This is a small mite (up to 1 mm) of pale beige translucent colour. The eggs are also translucent, oval and up to 0.25 mm in size. The life cycle is characteristic of parasitomorphic mites and consists of several stages: egg, larva, protonymph, deutonymph and imago. As soon as the mites acquire the ability to move, they become active predators and feed on spider mites.

The female lays eggs singly on the underside of the leaf, and after 2-3 days the larvae come out of them. The total number of eggs that a female can lay during the life cycle is up to 50. At an optimal temperature of 20-25 °C and humidity above 65%, an adult Amblyseius andersoni develops from an egg in 8-11 days.

As the temperature drops and the days get shorter, the mites enter diapause in early autumn, but they will be active again as soon as the average temperature rises above 10 °C. In summer, the entomophages are effective at temperatures up to 40 °C.

Application

The product is supplied in the form of sachets, as well as in tubes of 25 thousand mites and in five litre buckets of 125 thousand individuals. The sachet device ensures the further reproduction of mites and their release to culture for a period of several weeks. The sachet can be applied to any suitable parts of the plant, such as leaf stalks, shoots or small branches. On crops growing with the help of supports or whose growth is directed along the trellis ropes, sachets can be placed on these structures, but must always be protected from direct sunlight. 

Amblyseius andersoni is considered a preventive agent against spider mites and other phytophagous mites. The best way would be to apply it before the pest population reaches a high level. If the pest population is very large and there is obvious damage to the crop, then alternative means, such as acaricides, should be used before introducing this predator.

In situations where the use of acaricides in outbreaks of spider mites is unacceptable, use increased rates of introduction of such predatory mites as Phytoseiulus persimilis or Amblyseius californicus.

The sachet is hung on plants in an amount of 0.25-1 per sq.m. It can be placed on the petioles of leaves or hung in the middle of foliage on a trellis.   

On tomato culture, where this product is used against Aculops lycopersici, the sachet is placed as high as possible on the plant. This is caused by two reasons:

• According to the technology, the lower leaves of the tomato are systematically removed and along with them, the sachets located at the bottom of the plant are also removed. Therefore, the placement of sachets in the upper part of the vegetative mass ensures their long-term presence on the plant.
• Aculops lycopersici forms large populations that climb the stem of plants in the form of a mass with a rusty colour. Individual mites are detected 20 centimetres ahead of the whole pressing wave. Placing a sachet over this mass allows predators to destroy mites as they advance before they can cause significant damage. Placing the sachet at the bottom would lead to the fact that predators would catch up with the phytophages population from below, and it turned out that they would destroy the pest after it damaged the culture.

Chemical compatibility

It is considered that Amblyseius andersoni is one of the first species of predatory mites that populate fruit and berry crops after insecticidal treatments.

Races that are used in commercial applications do not undergo special selection to obtain stability, so you should always be careful when using plant protection products. The structure of the sachet protects the tick colony from many treatments, so even if the mites die on the leaf, new young predators emerge from the sachet to replace the dead.