Primary Efficacy of Co-Fumigation with Methyl Bromide and Phosphine Against and in Wood Pellets as a Quarantine Treatment.

Pests in wood pellets are treated using methyl bromide (MB) fumigation, which has low efficacy against pests because of its high adsorption to wood pellets. In this study, we assessed the feasibility of combined MB and phosphine (PH) fumigation of adults and pupae of and . The LC of MB for pupae were 31.49, 39.21, and 53.48 mg/L for 24 h treatment at 20, 10, and 5 °C, respectively. For , the LC were 24.32, 36.06, and 51.49 mg/L under the same conditions. The addition of PH (0.04 mg/L) to MB against pupae significantly decreased the LC of MB to 4.05 mg/L at 20 °C. MB was strongly adsorbed to wood pellets, which prevented complete extermination of at loading ratios between 20 and 60%. However, at the highest filling ratio (60%), the addition of 0.7 mg/L PH with 70 mg/L MB achieved 100% mortality for . When pupae of were targeted, MB + PH effectively disinfected both stages of both pests after 24 h at 5, 15, and 20 °C. Combined MB + PH treatment is an alternative to the currently approved MB treatment for controlling exotic beetles in imported wood pellets in Korea.