Résumé
Cacopsylla pruni is the vector of ‘Candidatus Phytoplasma prunorum’, responsible for the disease called European stone fruit yellows. In this work we obtained new data on the overwintering of C. pruni and we measured the evolution of the quantity of phytoplasma in the insects after acquisition. The life cycle of C. pruni was completed for the first time, demonstrating directly that it is a univoltine species. From the data obtained on the overwintering places, we assume that the overwintering takes place through long distance migrations from Prunus to conifers. We demonstrated that when C. pruni are grown on an infected Prunus, they accumulate the phytoplasma and then multiply it so that after the overwintering period the phytoplasma concentration is at its uppermost value. The young adults of the new generation, although frequently infected, had low transmission efficiency. Despite multiplying the phytoplasma, the healthy reimmigrant vectors fed on ESFY-infected Prunus appeared to die before they could transmit it to other plants. Thus, it seems that the overwintering reimmigrants infected the previous year are the most efficient vectors of the phytoplasma and that the dissemination of the disease should be understood at a regional scale.