Cacopsylla picta as most important vector for 'Candidatus Phytoplasma mali' in Germany and neighbouring regions

A survey of the distribution of Cacopsylla picta and Cacopsylla melanoneura, the putative vectors of ‘Candidatus Phytoplasma mali’, and their natural infection with the agent has been conducted between 2002 and 2007 in Germany, northern France (Alsace) and northern Switzerland (Aargau, Solothurn). It could be demonstrated that both psyllid species are present in all investigated regions but only individuals of C. picta carried the phytoplasma. Except for northern Germany, phytoplasma-infected C. picta were found in all geographic areas. During transmission trials under controlled conditions it was proven that only C. picta was able to transmit the pathogen while C. melanoneura had no importance as vector for ‘Ca. P. mali’ in the studied regions.