Cacopsylla pyri is a vector of pear decline in Spain
Studies were carried out in Northern Spain to determine the ability of Cacopsylla pyri (Homoptera: Psyllidae) to transmit the phytosplasma associated with pear decline (‘Candidatus Phytoplasma pyri’ – EPPO A2 list). Studies were done in a commercial plot (400 non-certified Pyrus communis cv. Williams) with many trees known to be infected by pear decline (incidence was estimated at 80%). Over a period of 1 year, approximately 100 psyllids were collected monthly from pear trees, using the beating tray method, and tested for the presence of ‘Ca. P. pyri’. Psyllids were then used for experiments on phytoplasma transmission both to healthy P. communis trees and to an artificial feeding medium. Results showed that C. pyri can transmit ‘Ca. P. pyri’. These results confirmed other studies done in Italy and France. It was also found that the frequency of psyllids carrying the phytoplasma varied according to the season, with the highest percentages in September and October and lowest in February, which coincided with the seasonal detection of ‘Ca. P. pyri’ in pear trees. Differences between males and females in phytoplasma transmission were observed, and females were found to be significantly more efficient than males. In addition, studies of the sex ratio indicated that there was a higher proportion of females than males throughout most of the year. It is felt that more detailed investigations are needed to better understand how females are involved in disease spread. Finally, since C. pyri is the most important pear psyllid species in Spain and other Mediterranean countries, it is likely to be the main vector of pear decline in these countries.
Garcia-Chapa M, Sabaté J, Laviña A, Batlle A (2005) Role of Cacopsylla pyri in the epidemiology of pear decline in Spain. European Journal of Plant Pathology 111(1), 9-17.