Whiteflies are an increasing problem in ornamental crops using Integrated Pest Management. According to the growers, the available beneficials are particularly lacking efficacy in the wintertime at lower greenhouse temperatures. The parasitoid Encarsia tricolor shows potential for crops grown at low temperatures in the wintertime like gerbera and poinsettia. The species was collected in 2009 in a strawberry crop grown in greenhouse and reared at Wageningen UR Glastuinbouw. This species parasitizes the cabage whitefly, the tabacco whitefly and the greenhouse whitefly. The rearing of E. tricolor was enlarged for cage trials in 2010 in which the parasitism rate of the species was compared with those of Encarsia formosa, Eretmocerus eremicus and Eretmocerus mundus. The trials took place at two temperature regimes: a constant temperature of 20 oC and a day/night regime of 18/15 oC on gerbera with Trialeurodes vaporariorum and at the day/ night regimes 21/18 oC and 16/14 oC on poinsettia with Bemisia tabaci. Eretmocerus mundus and Eretmocerus eremicus were the least effective species at high temperature regimes. Encarsia tricolor performed as well as Encarsia formosa. At the lowest temperature regimes none of the parasitoids controlled the pest. The parasitism rates varied from 2 to 18%.
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