Aetiology and control of mealybug wilt disease of pineapple in Reunion Island
Massé, Delphine | Cassam, Nathalie | Hostachy, Bruno | Teycheney, Pierre-Yves | Lefeuvre, Pierre | Lett, Jean-Michel | Chiroleu, Frédéric
Pineapple production is hampered by mealybug wilt disease of pineapple (MWP) worldwide. The aetiology of MWP is thought to involve mealybugs, several species of pineapple mealybug wilt-associated virus (PMWaV, genus Ampelovirus) and potentially other viruses of genera Badnavirus, Secovirus and Vitivirusbut is not entirely elucidated yet. We addressed this issue through a study of the distribution and prevalence of five viruses previously described as associated with MWP, in 15 plots of cultivar 'Queen Victoria' cultivated across Reunion Island, and a statistical analysis of the association of some of these viruses with MWP symptoms. We collected 450 symptomatic and asymptomatic leaf samples and indexed them by PCR analysis for the presence of three ampeloviruses (PMWaV1, PMWaV2 and PMWaV3) and two badnaviruses (PBERV and PBCOV). We found that 93% of the analyzed samples were infected with at least one of these viruses and 76% were co-infected by two to four viruses. The most prevalent viruses were PMWaV1 (78%) and PBCOV (87%), whereas PBERV was not detected. The presence of viruses was significantly associated with symptoms of leaf dieback, wilting and curling, but not with leaf reddening or yellowing, which are nonetheless described as typical MWP symptoms, but which also correspond to leaf reactions to other biotic and abiotic stresses. Additionally, viral infections and MWP symptoms were significantly less prevalent in plots using vitroplants (VPs) as planting material than in plots using suckers, suggesting that VPs could help limit the impact of MWP in Reunion Island.
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