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They are tiny and yet highly effective in pest control: predatory mites, small arachnids that feed on all sorts of other animals of their size. Thus, they make an enormous contribution to pest control and are also on a large scale (especially in viticulture) to be worth protecting beneficial organisms.
Predatory mites (Gamasina) are a large group and only a few species have been studied in detail so far. Their small habitats are very diverse. Many species live epigean, d. H. on the soil surface, some endogaeic (in the upper layers of soil), others hunt in the vegetation, for example on leaves of trees for food. They are usually very nimble and can also kill prey animals, which are a lot bigger than themselves.
Among the most well-known predatory mites are species of the genera Phytoseiulus, Amblyseius, Hypoaspis and Typhlodromus. The exact determination of the species is done microscopically. In addition to the genera mentioned, there are now other species in breeding, which can be specifically used against pests.
- Phytoseiulus persimilis and Typhlodromus pyri are leaf dwellers and are used against spider mites, preferably in the greenhouse
- most Amblyseius species are well-suited for controlling thrips and white flies. Amblyseius barkeri is also used against soft-skin mites
- Hypoaspis miles and Hypoaspis aculeifer are epizaphoric species that are used to control mosquitoes whose eggs and larvae develop in the soil, such as: B. Mourning gnats
The above mentioned species and some others can now be easily ordered online. Delivery is by post, in special packaging or in substrate. Normally, a magnifying glass with good magnification is sufficient to check the health of the animals.
Depending on the area of application, the animals are then transferred with the brush to the appropriate substrate. More detailed instructions are usually attached to the shipment.
Husbandry and breeding on the example of Typhlodromus pyri
Some species, such as Typhlodromus pyri, are relatively easy to grow at room temperature. For feeding you only need pollen. Especially birch pollen is suitable because it can be easily harvested in larger quantities. Optionally, you can order pollen from the feeding supplies for a small fee. However, since its composition is unknown, it is difficult to predict whether and how well the animals will accept it.
The animals are kept in 0.25 l containers, which are known as meat salad pancakes. These are poured to about one-third with gypsum, which is mixed with activated carbon. The ground should have enough time to dry, then the animals can already be put on and some food can be added with a fine brush. The lid must be sufficiently perforated, but a certain humidity should always be maintained. If the black color of the activated carbon fades (which is usually the case after a few days at the latest), it is time to re-wet what is best done with a pipette on the edge of the cup. Feeding is on demand, once or twice a week. T. pyri can also be supplied with live food. Good results are feeding with leaf gall mites or curling mites.
After a certain time (about 1 month) the container has to be changed. The animals are transferred again by brushing.
For breeding, a small Plexiglas roof is placed in the container. Underneath, the females lay their eggs, which are brushed off after 1-2 days or transferred together with the roof in a new shell. Depending on the temperature, the hatchlings hatch already after 2-4 days and become sexually mature within about two to three weeks.
Of course, no exhaustive description of the keeping and breeding of various predatory mites can be given here. It is always best to look at the practice of an experienced breeder.
Effects of predatory mites
If the apple variety is already poisoned by the red spine, the sugar content is very much reduced. Flowering in the following year is reduced. Of course you can work with pesticides. However, the funds then attack the healthy fruit.
Ecologically useful would be the onset of predatory mites. These animals feed on red spiders. Predatory mites are available in garden shops or on the Internet. The predatory mites are delivered on bean leaves. The leaves contain the females as well as eggs. Per delivery there are about 1,000 animals. The eggs are exposed directly to the plant. Make sure that it is not too hot when exposed. Therefore, it makes sense in the evening or in the morning or in cloudy weather to put the eggs to the plants.
Predatory mites eat 5 spider mites or about 20 spider mite larvae per day. Only when all pests have been eliminated, the predatory mite migrates on to other plants where there are also spider mites. Predatory mites are definitely safer than chemistry.The animals are neither harmful to humans nor to other animals such as pets. If there are no more spider mites on the plants, the predatory mites eat themselves. Or they starve after a few days.