Greenhouse Whitefly

Trialeurodes vaporariorum — the greenhouse whitefly — is the SINGLE MOST DAMAGING PEST OF GREENHOUSE PRODUCTION worldwide and one of about 1,500 species in family Aleyrodidae (the whiteflies — small sap-sucking insects with pollen-like white wax covering the wings). The species is native to Mexico and the southwestern US but has spread globally with greenhouse vegetable and ornamental production over the past century. Adults are 1.5-2 mm long, with the species' diagnostic features: clear wings covered in white pollen-like waxy powder (the source of the 'whitefly' family name), pale yellow body, and distinctive 'snowflake' clouds when whitefly populations are disturbed. Larvae are 0.5-1 mm long, oval flat soft-bodied 'crawlers' that attach to the underside of host plant leaves and feed in fixed positions through subsequent instars (only the first instar is mobile; later instars are sessile and look like small white-or-pale scale insects). The species is a major pest of GREENHOUSE PRODUCTION — tomatoes, cucumbers, peppers, lettuce, herbs, ornamental flowers (especially poinsettias, gerbera daisies, hibiscus), and many other greenhouse crops. The species is essentially impossible to eliminate from greenhouse production once it establishes — the warm protected greenhouse environment provides optimal conditions for continuous reproduction (multiple generations per year, with rapid population growth), and the small body size and underside-of-leaf habit make detection and control difficult. Damage includes direct feeding (sucking plant sap, weakening plants), HONEYDEW EXCRETION (sticky sugary excretion that coats plant surfaces and supports growth of black sooty mold fungi that further damage plants), and VIRUS TRANSMISSION (whiteflies are vectors of multiple plant viruses including Tomato yellow leaf curl virus and others — though greenhouse whitefly is a less efficient virus vector than the related sweetpotato whitefly Bemisia tabaci). The species is one of the most successful examples of MODERN BIOLOGICAL CONTROL. The parasitoid wasp ENCARSIA FORMOSA was discovered as a greenhouse whitefly parasitoid in 1926 by Speyer (in greenhouses near London, UK) and was one of the FIRST INSECTS COMMERCIALLY MASS-REARED for biological pest control. Commercial Encarsia formosa production began in the 1970s and has grown into a multi-billion-dollar global biocontrol industry — the wasp is now mass-reared and shipped worldwide for greenhouse pest control. Encarsia formosa is the FOUNDATIONAL MODEL for modern greenhouse biological control programs, which now use dozens of beneficial insect species (parasitoid wasps, predatory mites, predatory bugs) to control diverse greenhouse pests. The species is harmless to humans but is the foundational case study in modern biological control.