Ozone gas treatment against three main pests of stored products by combination of different application parameters

In the present study, the application of ozone, already reported as effective in controlling several insects and microorganisms of stored-products, was evaluated to sanitize dried herbs from main insect storage pests. Since its effectiveness is influenced by parameters of treatment application (i.e., C = concentration, T = exposure time), four categories of C × T (14,400, 28,800, 72,000, 144,000 ppm × min) were compared by combining different ozone doses per time with the untreated control (0 ppm × min), on eggs of Plodia interpunctella, and on adults of Tribolium castaneum and Lasioderma serricorne. Treatments were found to be effective with C × T of 72,000 ppm × min on the three tested species, causing mortalities higher than 80%. Slight differences were observed in percent mortality per dose × time combination within each tested C × T category. Ozone treatments with C × T values of 144,000 ppm × min seemed to be adequate to sanitize dried aromatic herbs from main noxious storage species, reaching mortality of 95–99%. The concentration of 50 ppm, recommended for the fumigation of empty facilities and grain storage, demonstrated to be effective against the three testes species after 48 h of application. Higher ozone concentrations, on the other hand, could affect the organoleptic properties of dried herbs. Therefore, to preserve them, lower C × T doses of ozone, such as those obtained to kill 50% of insect populations (LDT50, ppm × min, P. interpunctella: 16,962; T. castaneum: 54,217; L. serricorne: 58,636), should be considered in association with other treatments (e.g., ultrasound, ultraviolet irradiation, controlled atmosphere, etc.). Further studies are needed to investigate the feasibility of actual ozone application for sanitization of aromatic herbs at producer level.