Field applications of Beauveria bassiana to control the European cherry fruit fly Rhagoletis cerasi

Field experiments with foliar applications of Beauveria bassiana ATCC 74040 (product Naturalis-L) were conducted to control the European cherry fruit fly Rhagoletis cerasi Loew (Diptera: Tephritidae), a major pest of cherries in Europe. Naturalis-L was applied at concentrations of 250 ml per 100 l in 7-day intervals during the flight period of R. cerasi. Flight activity monitored by yellow sticky traps was only slightly affected by treatments. Infection and mycosis of adult cherry fruit flies was shown to be possible under field conditions. Fruit infestation was assessed at harvest. The number of infested fruits was significantly reduced by 65% with foliar applications of Naturalis-L. These results were obtained from five experiments in 2 years with considerably different weather conditions (wet vs. dry) and in different orchards with different flight intensities of R. cerasi (low vs. high) and different cherry varieties (early ripening vs. late ripening). In conclusion, the application of Naturalis-L is a suitable and economically feasible strategy for controlling R. cerasi in organic cherry production. The product Naturalis-L is currently registered for cherry fruit fly control in Italy and Switzerland.