A parasitoid is an insect whose young develop in or on one host and kill it. UC IPM explains they are called parasitoids rather than parasites because they kill the host. Most used in greenhouses are small wasps, for example Aphidius on aphids, Encarsia and Eretmocerus on whiteflies, Leptomastix and Anagyrus on mealybugs and Trichogramma on moth eggs.
In practice
Parasitoids are often host-specific, so the species must match the pest; the wrong Aphidius for the aphid present does little. Their own development time sets how long control takes, often two to three weeks before mummies appear. Most are harmed by broad-spectrum sprays and some are caught on sticky cards, so plan both around releases.
Don't confuse with
- Predator: eats many prey, e.g. predatory mites and lacewing larvae.
- Parasite: lives on a host without necessarily killing it.
Integrated pest management: preventing and controlling pests by combining monitoring, prevention, cultural, biological and, as a last resort, chemical tools against set action thresholds.Tiny parasitic wasps of the genus Aphidius that lay eggs inside aphids; the larva kills the host from inside, leaving a swollen tan mummy.Small soft-bodied sap-sucking insects of the family Aphididae that cluster on stems and leaf undersides, excrete sticky honeydew and multiply rapidly by live birth.Small white-winged sap-sucking insects of the family Aleyrodidae, mainly Trialeurodes vaporariorum and Bemisia tabaci, that fly up when disturbed and coat leaves in honeydew.Soft-bodied sap-sucking insects of the family Pseudococcidae, covered in white waxy filaments, that hide in stem joints and roots and excrete honeydew.A coloured card coated in non-drying glue that catches flying insects, used mainly to monitor pest trends: yellow for gnats, whiteflies and aphids, blue for thrips.Mites, mostly of the family Phytoseiidae, released as biological control to eat pest mites, thrips larvae, whitefly eggs or fungus gnat larvae.Insects of the family Chrysopidae, mainly Chrysoperla species, whose larvae are general predators of aphids, thrips, mite eggs and young caterpillars.Using living natural enemies, such as predators, parasitoids, nematodes and microbes, to suppress pests and diseases instead of, or before, chemical sprays.A non-crop plant kept in the grow to host harmless alternative prey or pollen, breeding beneficial insects continuously so they are ready when pests arrive.
