Field applications of entomopathogenic fungi against Rhagoletis cerasiC.DanielauthorE.WyssauthorTwo myco-insecticides, Naturalis-L (Beauveria bassiana) and PreFeRal®WG (Paecilomyces fumosoroseus), were applied against adult R. cerasi (Diptera: Tephritidae) in two orchards in north-western Switzerland in summer 2006. Both products were applied at a concentration of 5.75x104 CFU / ml. With four applications at seven day intervals the whole flight period of R. cerasi was fully covered. During this period (5th June – 6th July) the temperature averaged 19.2°C, total precipitation was 60 mm. Under these conditions Naturalis-L significantly reduced the number of damaged fruit (efficacy: 69-74%), whereas damage was not significantly reduced with PreFeRal®WG (efficacy: 27%). Fungus infested flies were found on the yellow sticky traps proving that the myco-insecticides worked as predicted. Climatic conditions were different in 2007: temperature averaged 15.9°C (16th May – 4th July), total precipitation was 281 mm. In 2007 only Naturalis-L was tested: with five applications an efficacy of 73% and 78% was obtained on the cherry varieties Langstieler and Dolleseppler, respectively. However, for the latest ripening and most infested variety Schauenburger only an efficacy of 18% was observed. In these cherries a high number of young larvae were found indicating that the efficacy was low at the end of the treatment period. In conclusion a control of R. cerasi with myco-insecticides seems possible. However, application regime still has to be improved and should not only be adapted to the flight period of R. cerasi, but also to the cherry varieties.Crop health, quality, protectionFruit and berries2008Conference paper, poster, etc.