Analysis of the acquisition and multiplication efficiency of different strains of Ca. <i>Phytoplasma mali</i> by the vector <i>Cacopsylla picta</i>

Abstract

Based on previous observations during long-term acquisition and transmission trials, studies were carried out under standardized conditions in order to analyse the acquisition and multiplication efficiencies of different strains of Candidatus Phytoplasma mali by different developmental stages of Cacopsylla picta. The acquisition of Ca. P. mali from micropropagated plants infected with different strains was tested for nymphs, larval stages and new adults of C. picta. When born on infected plants a nearly 100% acquisition was achieved for all strains of Ca. P. mali by C. picta. Differences in acquisition efficiency were observed for new generation adults which acquired the phytoplasma as imagines. The multiplication efficiency of the different Ca. P. mali strains inside the insects was analysed by quantitative real-time PCR. Significant differences in the capacity of the different strains to colonise the insect were found. Despite high acquisition rates only few subsequent transmission events to healthy test plants could be recorded.