Hot-water immersion against Paracoccus marginatus: disinfestation efficacy on sprouting potato and effects on papaya fruit quality.

BACKGROUND: Paracoccus marginatus is a regulated, highly invasive pest that poses a significant risk to papaya production and international trade, necessitating effective phytosanitary disinfestation measures. Hot-water treatment (HWT) is widely recognized as a residue-free alternative to chemical fumigation; however, its operational schedules require alignment between pest thermal tolerance and fruit quality. In this study, the thermal tolerance of developmental stages of P. marginatus was quantified, and candidate HWT regimes were evaluated based on thermal tolerance determined on a surrogate host (sprouting potato), while papaya physiological and sensory responses were assessed separately.

RESULTS: Eggs exhibited the highest heat tolerance among developmental stages and were therefore used as the conservative biological endpoint for treatment optimization. Time-mortality analysis and large-scale confirmatory trials conducted on sprouting potato demonstrated that immersion at 49 °C for 22 min, or 47 °C for 81 min, achieved complete mortality of P. marginatus. Fruit quality assessments indicated that optimized HWT regimes delayed ripening, reduced decay incidence, and maintained firmness, color, and sensory acceptability during storage, whereas prolonged exposure at lower temperatures induced cumulative physiological stress.

CONCLUSION: By combining pest mortality data from sprouting potato with papaya fruit tolerance limits, this study identifies candidate temperature-time parameters that may achieve phytosanitary security while preserving papaya fruit quality. The results provide a practical basis for developing heat treatment schedules consistent with the International Standards for Phytosanitary Measures. © 2026 Society of Chemical Industry.