The effect of fumigation on the phosphine-susceptible and -resistant strains in the T. castaneum was evaluated using phosphine, ethyl formate, and combination with phosphine and ethyl formate (phosphine+ethyl formate). The Lethal Concentration Time (LCT)50 analysis of susceptible strains, late larva showed that phosphine (0.13 mg·h / L), ethyl formate (80.91 mg·h / L), and phosphine + ethyl formate (19.36 mg·h / L). The LCT50 of adult was 0.05 mg·h / L, 68.58 mg·h / L and 17.84 mg·h / L when treated with phosphine, ethyl formate, and phosphine + ethyl formate. The LCT50 of resistant strains, late larva was found to 33.32 mg·h / L of phosphine, 113.46 mg·h / L of ethyl formate and 129.85 mg·h / L of phosphine + ethyl formate, and the LCT50 of adult was 55.71 mg·h / L of phosphine, 85.39 mg·h / L, phosphine + ethyl formate 85.83 mg·h / L. The treatment of three fumigants (phosphine, ehtyl formate, and phosphine+ethyl formate) showed the possibility of controlling against T. castaneum of phosphine-susceptible and –resistant strains.

Stored grain pests can cause reduction of grain quantity, quality, commercial value and germination rate. Susceptibility of three fumigants, methyl bromide, ethyl formate and phosphine, were assessed on Tribolium castaneum, which is an important stored grain pest. On susceptible insects, LCT50 of phosphine was 0.654mg h/L for egg, 0.127mg h/L for late larvae, 0.105mg h/L for pupae and 0.048mg h/L for adult stage, respectively. LCT50 of methyl bromide was 33.193mg h/L for egg, 14.585mg h/L for late larvae, 8.616mg h/L for pupae and 11.967mg h/L for adult stage, respectively. LCT50 of ethyl formate were 25.165mg h/L for egg, 80.912mg h/L for late larvae, 176.326mg h/L for pupae and 68.578mg h/L for adult stage, respectively. On resistant insects, LCT50 of phosphine were 82.325mg h/L for egg, 33.315mg h/L for late larvae, 73.546mg h/L for pupae and 55.707mg h/L for adult stage, respectively. LCT50 of methyl bromide were 19.250mg h/L for egg, 43.413mg h/L for late larvae, 76.842mg h/L for pupae and 19.387mg h/L for adult stage, respectively. LCT50 of ethyl formate were 87.552mg h/L for egg, 113.457mg h/L for late larvae, 200.122mg h/L for pupae and 85.394mg h/L for adult stage, respectively.

We assessed the susceptibility of three fumigants on Phthorimaea operculella, which is an important pest of stored potato worldwide. 5 to 6 initial dosage of each fumigants were treated on every growth stages of P. operculella. Methyl bromide showed 100% mortality at CT 33.40mg h/ L on egg, CT 14.41mg h/L on late larvae, CT 31.89mg h/L on pupae and CT 16.01mg h/L on adult, respectively. The LCT50 of methyl bromide was 19.115mg h/L on egg, 3.934mg h/L on late larvae, 13.810mg h/L on pupae and 6.260mg h/L on adult, respectively. In case of phosphine, 98% mortality was achieved at CT 16.77mg h/L on egg, and 100% mortality was achieved at CT 16.58mg h/L on late larvae, CT 18.54mg h/L on pupae and CT 12.28mg h/L on adult, respectively. The LCT50 of phosphine was 1.457mg h/L on egg, 2.236mg h/L on late larvae, 1.282 mg h/L on pupae and 0.253mg h/L on adult, respectively. In case of ethyl formate, 100% mortality was achieved at CT 96.21mg h/L on egg, CT 101.30mg h/L on late larvae, CT 120.66mg h/L on pupae and CT 148.30mg h/L on adult, respectively. The LCT50 of ethyl formate was 23.730mg h/L on egg, 13.706 mg h/L on late larvae, 29.578mg h/L on pupae and 19.235mg h/L on adult, respectively.

Carbonyl sulfide(COS) is a naturally generated gas from fermentation process of microbes and from plant root and stem. COS was firstly registered as a fumigant at 1993 to control stored product pests. To supplement environmental problems and toxicity of commercial fumigants and develop new fumigant, we have processed the susceptibility assessment of carbonyl sulfide on important agricultural pests, Myzus persicae and Tetranychus urticae. Every growth stages of two insect species were tested, and five dosages of carbonyl sulfide were treated for 4 hours, and the mortality was investigated after 24 hours of treatment. Nymphal stage of M. persicae was completely controlled at more than 20 mg/L dosage, and adult stage showed 95.8% mortality at 80 mg/L dosage. The LC50 of M. persicae was 7.314mg/L for nymph and 26.117mg/L for adult stage. Egg stage of T. urticae showed 91.2% mortality when treated with 100mg/L carbonyl sulfide, and nymph and adult stage showed 100% and 94.1% mortality at 8mg/L and 80mg/L, respectively. The LC50 of T. urticae was 73.110mg/L for egg, 2.818mg/L for nymph and 12.054mg/L for adult stage.

The susceptibility of three fumigants, methyl bromide, ethyl formate and phosphine, and concurrent treatment of ethyl formate and phosphine were tested on Lasioderma serricorne. Susceptibility assessment were performed by treating 5 to 6 initial dosage on every growth stages of L. serricorne. The LCT50 of methyl bromide was 13.896mg h/L for egg, 36.038mg h/L for late larvae, 25.172mg h/L for pupae and 21.758mg h/ L for adult, respectively. The LCT50 of phosphine was 0.317mg h/L for egg, 0.649mg h/L for late larvae, 3.748mg h/L for pupae and 0.703mg h/L for adult, respectively. In case of ethyl formate, the LCT50 was 43.657mg h/L for egg, 137.606mg h/L for late larvae, 72.676mg h/L for pupae and 52.951mg h/L for adult, respectively. Concurrent treatment of ethyl formate and phosphine was performed by treating 5 to 6 initial dosage of ethyl formate with 0.5 mg/L phosphine for 4 hours on every growth stages of L. serricorne. The LCT50 of ethyl formate concurrent treatment was 13.746mg h/L for egg, 8.156mg h/L for late larvae, 27.087mg h/L for pupae and 11.353mg h/L for adult, respectively, and these results indicate that concurrent treatment can control pest with lower dosage and shorter period. Sorption rates and ventilation periods of each fumigants were also calculated for efficacy and safety

Recently, phosphine resistance of Sitophilus oryzae has been reported from China, India, Brazil and Australia. In this study, susceptibility of three fumigants were assesses on phosphine resistant and susceptible S. oryzae to investigate domestic phosphine resistance level and to use base data for resistance control. On susceptible insects, LCT50 of phosphine was 0.440mg h/L for egg, 0.602mg h/L for early larvae, 3.901mg h/L for late larvae, 6.171mg h/L for pupae and 0.295mg h/L for adult stage, respectively. LCT50 of methyl bromide was 9.997mg h/ L for egg, 12.113mg h/L for early larvae, 18.952mg h/L for late larvae, 21.104mg h/L for pupae and 17.824mg h/L for adult stage, respectively. LCT50 of ethyl formate was 75.795mg h/L for egg, 60.110mg h/L for early larvae, 160.491mg h/L for late larvae, 255.797mg h/L for pupae and 77.711mg h/L for adult stage, respectively. On resistant insects, LCT50 of phosphine was 6.959mg h/L for egg, 28.456mg h/L for early larvae, 48.170mg h/L for late larvae, 29.106mg h/L for pupae and 16.550mg h/L for adult stage, respectively. LCT50 product of methyl bromide was 17.842mg h/L for egg, 14.900mg h/L for early larvae, 25.840mg h/L for late larvae, 43.520mg h/L for pupae and 16.397mg h/ L for adult stage, respectively. LCT50 of ethyl formate was 60.034mg h/L for egg, 64.450mg h/L for early larvae, 149.028mg h/L for late larvae, 140.408mg h/L for pupae and 66.043mg h/L for adult stage, respectively. Domestic resistant S. oryzae showed 4 to 56 times higher resistance rate than susceptible insects.

Carbonyl sulfide is a chemical that is registered as a crop protection product in Australia due to microorganisms such as soil, plant roots, branches, fertilizers and compost. In order to develop new fumigants for domestic use, the susceptibility of Carbonyl sulfide fumigants to two agricultural pests was evaluated. The susceptibility of peach aphid and spotted mite, which is an agricultural pest, was evaluated. After 5 hours of treatment (10, 20, 40, 60, and 80 mg / L) . As a result, peach aphid larvae showed a high mortality rate of 97.6% at 10 mg / L and 100% at 20 mg / L or more. Larvae were found to have a rate of 95.8% at 80 mg / L. The insect mortality rate was 91.8% at 60 mg / L and 94.1% at 80 mg / L.

The susceptibility of the Cigarette beetle, which are pests in tobacco, to methyl bromide and phosphine fumigants was evaluated. Five concentrations of each methyl bromide were selected for all stages and treated for 4 hours. As a result, 100% larvae were observed in eggs CT 51.20, late larva CT 73.61, pupa CT 71.87 and adult 52.87 mg h / L, respectively. The LCT50 values for methyl bromide were 13.896 for eggs, 36.038 for late larvae, 25.172 and 21.758 mg / l, respectively. The phosphine treatment was carried out for 5 to 6 concentrations (0.025, 0.051, 0.099, 0.501, 0.999 and 1.500 mg / L) for 20 hours. As a result, egg and late larvae showed 100% larvae at CT 5.137 and 6.435 mg h / L, respectively, and 61.9% and 98.9% of larvae and adult larvae were similar to each other. Pupae showed 86.4% larvae at CT 10.520 and 100% larvae at over 13.777 mg / h of CT. The LCT50 values for phosphine were 0.317 for eggs, 0.649 for late larvae, 3.748 for pupa and 0.703 mg / l for adults.