Prevalence of mealybug wilt-associated viruses in pineapple 'Queen Victoria' cultivars in Reunion Island and the potential of virus-free vitroplants for disease management

Mealybug wilt disease of pineapple (MWP) poses a significant threat to global pineapple production, yet its etiology remains poorly understood. The disease is believed to involve mealybugs, multiple pineapple mealybug wilt-associated viruses (PMWaVs, genus Ampelovirus), and possibly other viruses from the Badnavirus, Secovirus, and Vitivirus genera. This study examines the distribution and prevalence of three ampeloviruses (PMWaV1, PMWaV2, PMWaV3) and two badnaviruses (PBERV, PBCOV), previously associated to MWP symptoms, across 15 pineapple plots of the ‘Queen Victoria’ cultivar in Reunion Island. A total of 450 symptomatic and asymptomatic leaf samples were analyzed using PCR and RT-PCR-based diagnostics. Globally, 93 % of samples were infected with at least one virus, and 76 % were co-infected with two to four viruses. PMWaV1 (78 %) and PBCOV (87 %) were the most prevalent, while PBERV was not detected. Virus presence was associated with leaf dieback, wilting, and curling. Leaf reddening and yellowing, commonly associated with MWP, were not associated with viral infection, suggesting that other biotic or abiotic factors may be responsible for these symptoms. Viral infections and MWP symptoms were significantly lower in plots planted with vitroplants (VPs) compared to those using suckers, highlighting the potential of VPs in reducing viral infections. These findings highlight the complexity of MWP and underscore the potential benefits of using virus-free VPs to manage the disease.