Cacopsylla pyri is a vector of pear decline phytoplasma
In Italy, studies were done on Cacopsylla pyri which is the most commonly found psyllid in pear orchards and a suspected vector of pear decline phytoplasma (EPPO A2 quarantine pest). This insect has 4-5 generations per year and overwinters as the adult stage in pear orchards. In 1997/1998, groups of adult C. pyri were caught every month from March to October in orchards showing a high incidence of pear decline (70-80 %). Insects were tested by PCR/RFLP and used to inoculate young pear seedlings. Results showed that C. pyri can transmit pear decline phytoplasma throughout the vegetation period. Similar experiments were carried out to determine whether the phytoplasma was retained in the vector during the winter period. Results showed that insects caught during winter 1998/1999 carried the pathogen, but plants exposed to insects during the winter period (November to March) were not infected. However, these insects were able to transmit the pathogen in April, as soon as the growing season starts. The authors concluded that C. pyri is indeed a vector of pear decline phytoplasma. The pathogen is not transmitted by C. pyri during winter to dormant plants but can be retained in the vector, keeping its infectivity.
Sources
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Carraro, L.; Osler, R.; Loi, N.; Ermacora, P.; Refatti, E. (1999) Problemas relacionados con las infermedades de los frutales producidas por fitoplasmas y transmitidas por psílidos. Situación actual del pear decline, european stone fruit yellows y el apple proliferation, en Italia.
Phytoma-España, no. 114, 159-162.
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