Piper Yellow Mottle Virus in Black Pepper: A Critical Synthesis of Biology, Epidemiology, Diagnosis and Integrated Management

Abstract

Piper yellow mottle virus (PYMoV) is a major viral constraint of black pepper (Piper nigrum L.) and a persistent challenge for germplasm exchange, nursery certification and plantation health in tropical pepper-growing regions. The disease problem is unusually difficult because infection biology intersects with an endogenous viral sequence problem: black pepper can contain PYMoV-derived DNA integrated into its genome, so a positive DNA-based assay does not necessarily demonstrate an active episomal infection. This critical narrative review integrates evidence on PYMoV biology, host and viral diversity, transmission, environmental modulation of symptoms, diagnostic development and management. Literature published from the first formal description of PYMoV in 1997 to 19 June 2026 was appraised for methodological adequacy, biological plausibility, reproducibility and relevance to field management. The evidence supports a bacilliform pararetrovirus with a circular double-stranded DNA genome, substantial but structured sequence diversity, a host range extending beyond black pepper to other Piper species, and efficient persistence through vegetative propagation. Mealybugs are established vectors, with the clearest transmission kinetics available for Ferrisia virgata, whereas evidence for seed and mechanical transmission is inconsistent across studies and locations. Symptoms are unreliable indicators because they vary with cultivar, environment, infection complex and apparently latent or masked states. Diagnostic progress has moved from microscopy and serology to conventional and real-time polymerase chain reaction, loop-mediated isothermal amplification, recombinase polymerase amplification and lateral-flow formats. Yet analytical sensitivity alone is insufficient: the central diagnostic requirement is discrimination of active infection from endogenous PYMoV sequences. Integrated management therefore depends most strongly on correctly indexed propagation material, protected mother-stock systems, sanitation, vector- and ant-aware nursery hygiene, and validated virus-elimination procedures. Major priorities are an internationally harmonised active-infection reference standard, geographically representative transmission experiments, prospective field epidemiology and controlled trials that quantify the disease and economic effects of integrated management packages.