Target Pests: Fungus gnats (Bradysia spp.), Western flower thrips (Frankliniella occidentalis), Root Aphids, Mites
Description: Stratiolaelaps (Hypoaspis) is a native species of soil-dwelling mite, which feeds on small insects and mites (e.g. springtails, root mealybug crawlers, and spider mites). Adults are tan in color, less than 1 mm long (1/20th in.) and move rapidly over the soil surface. They live, eat, and reproduce in the soil medium and walkways on the greenhouse floor.
Use in Biological Control: Stratiolaelaps are used primarily to control young larvae of fungus gnats in the soil or planting media. They also help control soil stages of thrips and may account for up to 30% of thrips control. They do not control shore flies or moth flies, but will feed on other soil organisms, such as springtails and root mealybugs. They have been used successfully in bedding and potted plant production, seedling and cutting propagation, and poinsettia stock. Stratiolaelaps adapt well to the various growth media and capillary mats used in plant production, but do not survive freezing or flooding conditions.
Life Cycle: The complete life cycle takes about 18 days at 68°F (20°C). The sex ratio is an equal 1:1, females to males. Eggs hatch in 2-3 days into young nymphs, which are also fierce predators that consume eggs and small larvae. Each adult Stratiolaelaps will consume 1-5 prey per day. It can also survive as a scavenger in the absence of pests, feeding on algae and plant debris. Populations will naturally fluctuate throughout the growing season.
For Best Results: Do not mix predators into the growth media before potting plants because they do not survive. Apply Stratiolaelaps shortly within the first few weeks of planting and before fungus gnat levels reach more than 20 adults per trap, per week. To control high numbers of fungus gnats, use of Stratiolaelaps can be integrated with insect parasitic nematodes, which control the larval stage of fungus gnats.
Release Rates: Stratiolaelaps is most effective when applied before fungus gnat populations become established or when numbers are still low (below 10 per trap, per week). Two applications of Stratiolaelaps per crop cycle are usually sufficient if used early in the season. The second application should be made 2-3 weeks after the first.
Soil Culture: Apply 5 Stratiolaelaps per square foot to the soil at the time of planting (repeat in 2-3 weeks). Be sure to treat wet, exposed areas of soil where fungus gnats are likely to breed.
Sawdust Bag or Rockwool Culture: Apply 5 Stratiolaelaps per square foot, or 250,000 per acre. Apply 1 tsp. per every 2nd bag or rockwool slab (repeat in 2-3 weeks).
Pot Culture: Apply 1 liter bottle of Stratiolaelaps (25,000 ea.) per 2,000 square feet of bench area. Treat the floor of the greenhouse weekly if it provides wet conditions for fungus gnats to breed, and occasionally treat the perimeter of the greenhouse. It is not necessary to apply mites to every flat of bedding plants if applications are done early, at a full rate, to allow them time to spread to all flats. Mites can also be applied to propagation media before striking cuttings.