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Abstract :
[en] Most European walnut producers have to deal with the recent introduction of the Walnut Husk Fly, Rhagoletis completa (Diptera, Tephritidae), that causes severe economic losses, especially in biological productions. In orchards where R. completa is present and uncontrolled, losses in walnut yields can reach up to 80%. As a consequence, there is a need for developing environment-friendly methods of control.
In this research, we evaluated the efficiency of two different semiochemical blends to trap R. completa in walnut orchards. The first semiochemical blend consisted in walnut fruit volatiles, previously collected and identified from two walnut varieties. The second semiochemical blend was made of the putative male sex pheromone, made of two lactones, and previously collected from R. completa males. In field both semiochemical blends were associated with yellow sticky traps. The assays were conducted in France, in a total of 53 orchards, in 2015, 2016 and 2017.
The first blend (made of fruit kairomones) was highly attractive for both male and female R. completa in a laboratory assay, but did not enhance the number of fly captures in the field. On the other hand, sticky traps associated with the putative sex pheromone captured up to 10 times more fruit flies each week during the entire season. The total number of captured flies was also more important than with a mass trapping system baited with food attractant. These field results are promising for R. completa monitoring and mass trapping.
