Walnut Husk Fly (Rhagoletis completa Cresson), the Main Burden in the Production of Common Walnut (Juglans regia L.)

Abstract

The walnut husk fly (Rhagoletis completa Cresson) is the most important pest of walnuts (Juglans regia L.). It causes economically significant crop losses (up to 80% yield loss) in many growing regions, including the United States and most European walnut-producing countries. This chapter describes the impact of pest infestation on yield quantity and quality along with the current geographic distribution of the pest. Its bionomy and infestation symptoms are described in detail. An overview of monitoring and control methods used is also provided, and new methods that may prove useful for walnut husk fly control are listed. Monitoring the occurrence of the pest is the most important part of controlling the walnut husk fly, as only with an effective monitoring system can insecticides be applied at the appropriate time. Emphasis is placed on biotic protection and the possible role of phenolic compounds in cultivar resistance to walnut husk fly. Other control methods (non-chemical, mechanical, and biological control) are also gaining importance in pest management as more and more active substances in pesticides are regulated or phased out each year. Mechanical control methods are more or less only suitable for walnuts grown in the protected areas.