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Phytoseiulus persimilis

Predatory Mite of Spider Mites

Identification and Biology : Shiny  red-shapped predatory mite (0.5 mm) with long legs.  P. persimilis moves faster than spider mites.  Eggs are oval and twice as big as spider mite eggs.  Larvae and nymphs are pale pink to light red.   It is sensitive to temperatures above 30°C, and at 35°C will stop feeding altogether.  A humidity of 60% or lower has a negative effect on the hatching of the eggs and development of P.  persimilis.

Mode of action: The nymphs and adults of  P. persimilis feed on all stages of the spider mite.   P. persimilis does not perform well under dry, warm conditions.  .  Because the predatory mite’s development rate is roughly twice as fast as that of the spider mite, the number of predatory mites increases rapidly, and will quickly reduce the spider mite population by predation.  The predatory mite population can decline dramatically in the absence of spider mites so reintroductions may be needed.

Introduction method and release rates: P. persimilis is not introduced preventatively.  Curative:  2-4 mites/m2.  Hotspots:  20-50 predatory mites/ m2Persimilis leaf:  distribute bean leaves on infected plants.  Leaves should remain on crop for al least 2 days to allow eggs to hatch.  One unit (250 mites) covers up to 5 medium plants.

Storage: Introduce the beneficials as soon as possible after receipt. If storage is necessary, keep them at 8 – 10 °C (46 – 50 °F).