PAPAYA MELEIRA VIRUS IS NEITHER TRANSMITTED BY INFECTION AT WOUND SITES NOR BY THE WHITEFLY TRIALEURODES VARIABILIS

摘要

Papaya meleira virus (PMeV), a double-stranded RNA (dsRNA) virus present in the latex of papaya (Carica papaya L.), is the causal agent of 'meleira' or 'sticky disease', which prevails in eastern Brazil. Disease management strategies in the orchards are impaired by the lack of knowledge on PMeV transmission. We have therefore evaluated inoculation methods (five mechanical and one biological) for virus transmission to different papaya cultivars using crude latex collected from symptomatic plants. Inoculated plants were kept under observation for symptom development and checked for the presence of viral dsRNA for over three months. Test plants wounded by cutting or abrasion, which resulted in latex exudation, were not infected, whereas PMeV dsRNA was detected 15 days after inoculation by latex injection into the stem apex. The whitefly Trialeurodes variabilis was unable to transmit PMeV from diseased to healthy papayas, even though the presence of the virus was ascertained in adults and nymphs. These data confirm previous field observations that faded to associate sticky disease with this whitefly species.