Hypoaspis miles / Stratiolaelaps scimitus

  This predatory mite has been called Hypoaspis miles for a long time, but according to the latest changes in taxonomy, it was given a different name Stratiolaelaps scimitus. However, among biological control specialists, the name Hypoaspis miles is still more convenient and common.

  In its natural habitat, Hypoaspis feeds on various soil insects and their larvae. This predator is interesting for agricultural production, since among its victims are larvae of fungus gnats, brine flies and thrips, as well as soil aphids.

  The predator has a size of up to 1 mm and a brown body color. In nature it populates the topsoil (up to 4 cm deep), and also occurs on the surface of plant residues. In production conditions, it moves on an artificial substrate, as well as on the surface of pots, stacks, etc.

  Oviposition is carried out in moist soil, peat or a layer of organic residues. Therefore, the presence of such a substrate in the production area is obligatory if the agricultural producer plans to create a stable and long-term population of this predator.

  The growth rate of its population depends on temperature conditions. At 10 °C and below, the development of the mite stops. At 15 °C, it stretches for a period of up to 5 weeks, and at 24 °C, the development cycle is shortened to 2 weeks. However, the temperature from 32 °C and above causes slowdown of the population development.

  In the process of development, the predator goes through three nymphal stages. After oviposition at a standard temperature of 20 °C, the larvae of the first stage hatch after 6 days. A couple of days later, the second stage occurs - protonymph, followed by the third - deutonymph. This interval of two stages takes about 10 days and during this period young mites actively feed. At 20 °C, the total period of development from egg to adult is 17-18 days in the presence of a sufficient number of prey.

  An adult hypoaspis is capable of destroying up to 8 first stage sciarid larvae per day. But when hunting for more mature larval stages, its effectiveness decreases. For example, a predator is capable of infecting no more than one larva of the 4th stage per day.

  An important characteristic of hypoaspis is its ability to infect thrips larvae that fall for pupating on substrate. Among its prey there is the western flower thrips (Frankliniella occidentalis). It is important to remember, however, that thrips control is a complex process and the hypoaspis is one of its elements. But it is convenient in this regard, since its use is easily combined with other biological agents for thrips control, including parasitic nematodes.

  Since the bulk of pesticides is applied by the vegetative mass, and the hypoaspis lives in the substrate, the probability of its contact with them is low. This peculiarity makes it possible to combine it with the use of many chemical remedies, but it is not compatible with soil preparations.

   Hypoaspis application rates are very wide, they depend on the situation on the crop and can vary from 100 to 1000 individuals per m².

- The standard preventive dosage is considered to be 50-100 individuals per m².

- If thrips or other pests are detected on the crop, the release rate will be 250-300 individuals per m².

- If there is a high level of populations, then the application rate can reach 500-1000 individuals per m².

  It is best to apply the predator preventively or when the pest population is low. It is applied to the substrate, compost or simply to a cube of mineral wool, where it immediately begins to search for prey. If there are open areas of soil or other substrate under the stacks, then a predator should also be evicted on them, since pests can populate it.

  The stability of the hypoaspis population is explained by the high life span of the predator, which can be several months. Even in the absence of a food resource, individuals of the hypoaspis are able to live up to 7 weeks. It is convenient to use on plants with a long cultivation period, for example, on ornamental crops.

  Hypoaspis preparations are stored for a short time, usually no more than 48 hours after delivery, at 12-18 °C. Hypoaspis is a moisture-loving mite, therefore, in order to avoid drying out, it should be kept at high humidity.

  In recent years, there have been attempts to use Hypoaspis in beekeeping to control the parasites of the honey bee, varoid mites. In short, the potential of this predator is still far from being revealed, and further technological developments will still find new applications for it.