Weiße Fliege an Schnittgerbera: Biologische Bekämpfung mit Schlupfwespe oder Raubmilbe?

Biological control of the whitefly Trialeurodes vaporariorum on cut Gerbera under protected conditions is still risky. Up to now the parasitoids Encarsia formosa and Eretmocerus eremicus are the most frequently used antagonists to control this pest. Additionally, the recently rediscovered predatory mite Amblyseius swirskii is promoted efficient beneficial especially for whitefly control. We conducted a series of experiments to characterize and compare the efficiency of these beneficials under greenhouse conditions. Therefore, we infested gerbera plants artificially with start populations of whiteflies and released parasitoids or the predatory mite in separate experimental units. Treatments without release of antagonists served as control. Results show that parasitoids as well as predatory mites led to a sufficient whitefly control. After release of the recently promoted predatory mite A. swirskii we found no whitefly larvae on the gerbera plants throughout the experimental time. In contrast, after release of the parasitoid species Encarsia formosa or Eretmocerus eremicus whitefly larvae were frequently found on the plants at least in the beginning of the experiments. Nevertheless parasitized whitefly larvae were detected soon after parasitoid introduction and whitefly population build up was not observed. In conclusion, all tested beneficials are valuable antagonists for whitefly control in cut gerbera. Therefore, either time consuming intensive monitoring of whitefly infestation level or preventive antagonist release is obligate in cut gerbera. Biological control strategies for gerbera production are discussed in detail.