Promising field and semi field results forcherry fruit fly control using Neem

The European cherry fruit fly, Rhagoletis cerasi (Diptera: Tephritidae), is the major pest species in cherry orchards throughout Europe. Adequate control measures are lacking to date, especially in organic fruit growing. In our prior studies the proof has been given for neem (a.i. azadirachtins) to interfere with ovary development and impede successful reproduction in R. cerasi. In fruit fly control under field conditions, however, it usually failed. To our belief the latter is mainly founded in the unsuitable layout of these field trials. Three main conditions have to be fulfilled to apply neem successfully under field conditions: First, females have to be detained from immigrating from the control to the treated area. Second, the application of neem products has to be started together with the first detections of flies on Yellow Traps. Third, the active ingredient has to be present in the field constantly. Taking these precautions into account, we here present semi field and field trials we carried out with neem in bait spray and semi field trials with cover spray. The tested baits and the cover spray contained NeemAzal-T which is an oil-free formulation. Beforehand, we compared acceptances of bait containing either the latter formulation or, the already licenced oily formulation NeemAzal-T/S under laboratory conditions. In laboratory studies R. cerasi preferred the oil-free formulation in bait. In semi field and field trials infestation rates were significantly reduced by all bait treatments as well as the cover spray. Infestation in the treated trees was below the economic threshold. The outcome of the study reveals the high efficacy of neem under exclusion of immigration of mature females and is essential in decision making regarding preconditions of orchards necessary for a successful application of neem products for cherry fruit fly control.