The alien planthopper Ricania speculum acquires Flavescence dorée phytoplasma, but is unable to transmit it.

"Ricania speculum is an alien planthopper accidentally imported from Far East, detected for the first time in the province of Genoa (Liguria, Italy) and spread out in Liguria and Tuscany regions. The species is univoltine in Italy, its overwintering eggs are inserted in linear rows inside thin plant structures (e.g. twigs, leaf ribs, stems). The nymphs have a huge wax tail used like a parasol for covering their bodies when disturbed. Ricania speculum is polyphagous on wild and cultivated plants, herbaceous and woody crops. This phloem feeder colonizes, among others, grapevine and Clematis vitalba plants, well-known hosts of Flavescence dorée phytoplasma (FDp), a quarantine phloem-limited pathogen, transmitted by the Nearctic leafhopper Scaphoideus titanus, which is one of the main constraint to viticulture in several areas of Europe. Moreover, two Ricaniidae specimens tested positive for the Banana Wilt Associated Phytoplasma (BWAP) in Papua New Guinea. Therefore, the aim of this work was to ascertain if R. speculum could act as a vector of FDp. To this purpose, nymphs reared from eggs were allowed to feed on FDp-infected broad beans and, after the completion of the latent period, transferred onto grapevine, broad bean and C. vitalba test plants for inoculation. At the same time, a number of adults fed on infected source plants were analyzed by PCR for the presence of FDp to check if the planthopper was able to acquire the pathogen. Transmission experiments to about 50 test plants and PCR analysis of more than 60 adults showed that R. speculum is unable to transmit FDp, although some individuals can acquire the phytoplasma and support a low level of its multiplication, as shown by qPCR. In conclusion, although R. speculum can damage plants by feeding and egg laying, it should not be regarded as a threat for FDp spread "