AbstractIn autumn 1987, the first observations were made in the Netherlands of a whitefly species identified as type ‘B’ of the sweet potato whitefly,Bemisia tabaci(Gennadius), on the host plant poinsettia,Euphorbia pulcherrimaWilld. ex Klotzsch. Although an eradication programme was initiated, total eradication was not obtained. Over the yearsB. tabacihas persisted on poinsettia and slowly spread to other crops like Begonia, Bouvardia, Gerbera and Hibiscus. Vegetables like tomato, cucumber and egg plant have also become infested.B. tabacioften develops extensively during the summer season due to its better adaptation to temperatures of ⩾25°C compared with the greenhouse whitefly, which develops more readily at 20°C. During the poinsettia growing season, high population numbers ofB. tabaciwill not develop, but any plants showing visible signs of infestation, such as an empty pupal case, are rejected at the auction. The integration of biological and chemical control is expected to show better potential than the use of insecticides, as insecticide resistance has already been observed. Several natural enemies, such as certain strains of the parasitoidsEncarsia formosaGahan andEretmocerus californicusHoward, as well as the predatorsDelphastus pusillusLeconte andMacrolophus caliginosusWagner, are being tested in green‐houses. Research is also carried out regarding the use of insectpathogenic fungi such asAschersoniaspp.,Verticillium lecanii(Zimm.) Viegas andPaecilo
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