Hypoaspis miles (= Stratiolaelaps scimitus)
Living in the top layers of the soil, Hypoaspis mites are highly active and voracious predators that will tackle a wide range of soft-bodied organisms. They are particularly useful predators of fungus gnats and also feed on thrips that drop to the soil to pupate. Hypoaspis miles is a widely used predator around the world and plays an especially important role in greenhouses and nurseries where fungus gnats are a serious threat.
At 25°C these mites complete a generation in just under two weeks. Hypoaspis are able to survive for lengthy periods without food if necessary and can live for several months under favourable conditions.
- Fungus gnats (including Sciarid flies)
- Thrips pupae (including Western Flower Thrips)
Hypoaspis mites do particularly well in nursery and greenhouse environments. They prefer moist but well drained and porous soil or potting mixes and do best in a temperature range between 20 and 30 °C.
It is always good to establish beneficial insects and mites early before pest problems develop. Start your release program at (or preferably before) the first hint of fungus gnats. Close monitoring is advised to determine frequency and numbers for follow up releases if required.
Hypoaspis mites arrive in cardboard cylinders (tubes) containing a minimum of 20,000 living stages (including eggs and young mites). They are supplied within a mix of cocoa peat and vermiculite and should be distributed evenly across pots or bedding for best results. Ensure that the contents of the tube is evenly mixed immediately prior to release.
Recommended release rates
|Preventative||1 tube per 150 m2 bedding||1 tube per 300 x 6” pots|
|Curative||1 tube per 100 m2 bedding||1 tube per 200 x 6” pots|
A note on release rates: Unlike chemicals which generally exhibit a clearly defined dose response curve, with beneficial insects, more is always better. However, they are costly to produce and the goal should be to achieve the best results at minimal cost. We are constantly trying to strike a balance between cost and efficacy. There are many factors that should be considered including the value of the crop, the magnitude of the pest population and the activity (or otherwise) of naturally occurring beneficial species. Also unlike chemicals, where it is common to respond to pest populations that have already exceeded some ‘economic threshold’, we recommend establishing beneficials early in the life of the crop before pest populations reach threatening levels. In most cases our releases are inoculative and we anticipate that our beneficials will establish and breed up within the crop to give long term control. As a general principle, 2-3 releases of modest numbers is better than a single large release – this reduces risk, improves establishment and accelerates the development of multiple overlapping generations of the beneficial species.
Monitor the population of fungus gnats using yellow sticky traps and by visual inspection of the potting mix. Also check visually (with a handlens) for presence and abundance of Hypoaspis mites. Additional follow up releases may be advised to accelerate establishment and improve chances of effective control.
Cultural practices to aid establishment
Hypoaspis are considered robust and can cope with a range of conditions. It is best to follow watering practices that maintain adequate soil moisture without over-wetting.
Hypoaspis mites are quite hardy and will survive many commonly used pesticides. We do however suggest you consult the Biobest Side Effects Manual for an indication of potential harmful effect on your newly established soil borne predators before applying any potentially toxic materials. Be particularly cautious about pyrethroid sprays and soil drenches.
Hypoaspis mites are despatched by express post or overnight courier and should be received within 48 hours. They should be released as soon as possible after arrival – preferably during the cooler hours of morning or dusk. If necessary they can be stored for one or two days in a cool, dark place (10-15°C is ideal).