Experiences of integrated management of European Cherry Fruit Fly (Rhagoletis cerasi) and how to utilize this knowledge for Sea Buckthorn Fly.

Summary

The genus Rhagoletis Loew includes about 65 known species distributed throughout Europe, Asia and America. Most species are oligophagous, attacking only a few closely related host plants. The European cherry fruit fly R. cerasi is the economically most important pest species in Europe. R. batava and R. alternata can also cause economic damage in Europe. In addition to these species, the American cherry fruit fly species R. cingulata, R. indifferens and R. fausta, as well as the apple maggot R. pomonella, the blueberry maggot R. mendax, and the walnut infesting species R. completa and R. suavis are pest insects of high economic importance. R. cingulata and R.completa were recently introduced to Europe and are currently spreading in Central Europe. A lot of research was conducted on integrated control of the European cherry fruit fly R. cerasi during the past hundred years. For the monitoring of flight period of R. cerasi yellow sticky traps are used. This method was shown to give reliable results for the timing of application. However, an economic threshold cannot be determined with yellow sticky traps, because fruit infestation is also influenced by crop load and weather conditions during oviposition period of flies. Chemical control (Insecticides) of R. cerasi is currently impeded by the withdrawal of “old” organophoshporus compounds (Dimethoate) and the debate on side-effects of neonicotinoids. Attract-and-kill strategies are available or under development: food baits (based on yeast hydrolysate and sugar) are mixed with the organic insecticides Spinosad or Neem. The baits attract the flies, stimulate feeding and thus increase uptake of the insecticide. However, the efficacy of attract-and-kill strategies strongly depends on the attractiveness of the bait which is influenced by climate conditions. Mass trapping by yellow sticky traps combined with baits is used for cherry fruit fly control in home-gardens. However, due to the high number of traps needed to achieve good control, this strategy is too expensive for commercial production. The use of kaolin as mechanical barrier on the fruit surface to prevent oviposition was shown to be effective against R. indifferens and R. mendax. Because kaolin treatments leave white residues on fruit, this method is not used against cherry fruit fly. Recently, it was shown that oil products can also prevent oviposition by creating a slippery layer on the fruit surface. A biocontrol method using the entomopathogenic fungus Beauveria bassiana has been developed and is currently registered in serveral European countries (product Naturalis-L). This strategy is mainly used in organic production. Another biocontrol strategy could be the use of parasitoids. However, the use of larval parasitoids is hampered by the steadily increasing fruit size of cherries for fresh consumption: parasitoids are no longer able to reach the larvae in the center of the cherry fruit. The use of crop netting to protect trees is the currently most widely used method of cherry fruit fly control. With the increasing number of dwarf tree cherry orchards covered against rain to avoid fruit splitting, it has become a viable, cost-effective method of cherry fruit fly control. However, for high standard trees this method is not suitable. In this situation, the use of nets for soil covering (to avoid hatching of flies from overwintering pupae in the soil) can be used.