A Study on the Optimal Temperature-Control Mechanism for Eradicating Bradysia odoriphaga in Protected Horticulture Using Soil Flame Disinfection (SFD)

This study developed a heat transfer model and systematically simulated heat conduction behavior during flame disinfection to optimize surface flame disinfection (SFD) technology targeting Bradysia odoriphaga larvae. By determining pest mortality rates at various temperatures, we identified 40 °C as the critical threshold. When temperature increased from 30 °C to 65 °C, the time required to achieve 50% (LT50, median lethal time, represents the baseline threshold for control efficacy) mortality dropped sharply from 131 s to merely 6 s, while the time to reach 95% mortality (LT95, i.e., 95% lethal time, represents the standard for complete control in the field) decreased from 279 s to 12 s. The model demonstrated that higher surface temperatures enabled heat to penetrate deeper into the soil. For every 20 °C increase in temperature, lethal depth increased by 2.1 cm, and heat conduction depth increased by 1.2 cm. Soil thickness exhibited a dual effect; although deeper soil could increase lethal depth, it also created thermal resistance that slowed heat penetration. In practical applications, heating a 20 cm thick soil layer to 163 °C could achieve effective pest control at a depth of 32.5 cm. This framework provides support for achieving precise flame disinfection and promotes sustainable pest management with reduced chemical pesticide use.