Field applications of entomopathogenic fungi against Rhagoletis cerasi

Summary

Two myco-insecticides, Naturalis-L (Beauveria bassiana) and PreFeRal®WG (Paecilomyces fumosoroseus), were applied against adult R. cerasi Loew (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 the relative humidity averaged 66.3% (5th June – 6th July), the temperature averaged 20.5°C. Under these conditions only Naturalis-L significantly reduced the number of damaged fruit (efficacy: 69-74%), whereas damaged fruits were not significantly reduced with PreFeRal (efficacy: 27%). For B. bassiana living fungal propagules were still detectable seven days after application, while the fungal propagules of P. fumosoroseus remained only three days. A control of R. cerasi with myco-insecticides seems possible under field conditions. However, application regime still has to be improved.