The fumigation toxicity of carbonyl sulfide to T. castaneum as a storage grain pest was evaluated. Carbonyl sulfide (COS) is registered in Australia for microorganism present in soil, root and fertilizer. the fumigation activity of carbonyl sulfide was investigated in 12 L desiccator for 24 h exposure to eggs, larvae, pupae, adults of T. castaneum. Eggs and pupae were showed 87.3% and 95.6% mortality for 25 mg/L of COS, respectively. Larvae and adults were investigated with 80.0% and 100.0% mortality at 15 mg/L treatment, respectively. Therefore, the eggs of T. castaneum showed the highest tolerance to COS.

The fumigation activity of phosphine (PH3) to T. castaneum as a storage grain pest was evaluated. The lethal concentration time (LCT) value of each developmental stage (egg, early larva, late larva, pupa and adult) of T. castaneum was analyzed in 12 L desiccator. At the T. castaneum larva stages, exposure for 4 h showed low LCT value, especially in early stage larvae (LCT99 = 0.32 mg·h/L) which is very high susceptibility to PH3. However, T. castaneum eggs were observed very high tolerance to PH3 at LCT99 77.47 mg·h/L. Therefore, the fumigant activity of PH3 against T. castaneum can be found to be significantly different depending on developmental stage.

This study investigated the fumigant activity of phosphine (PH3) on 2 kinds of mealybug (Pseudococcus longispinus and P. orchidicola (Hemiptera: Pseudococcidae)) adults and nymphs. All of the two mealybugs adults showed higher LCT99 values than nymphs, and P. longispinus showed higher tolerance than P. orchidicola in a 12 L desiccator. The absorption of phosphine on 13 nursery plants showed 12.2~41.5% difference depending on the plant. All of the mealybugs treated with phosphine 2 mg/L in 0.5 m3 fumigation chamber for 4 h showed 100% fumigant activity, except P. longispinus adult (approximately 90% at bottom part). However, when the exposure time was increased to 24 h, all of them showed 100% mortality. In the treatment of 10 m3 container, the 24 h treatment of phosphine showed 100% mortality to P. longispinus and P. orchidicola adults and nymphs. In all the experiments, no phytotoxicity of phosphine observed on 13 plants until 1 month after treatment.

A combination using phosphine (PH3) and ethyl formate (EF) was performed to compensate for the disadventages (long exposure time and phytotoxicity) of a single substance. P. longisipinus was more susceptible to mixed phosphine and ethyl formate than P. orchidicola in 12 L dessicator. Mortality of mixed treatment was higher than aggregated mortalities that treated individually, so it indicated to have a synergic effect on each other. Ethyl formate was showed higher adsorption rate than phosphine on imported nursery plants and showed differences depending on the plant. P. longispinus and P. orchidicola was showed 100% mortality when phosphine and ethyl formate was treated as 1 g/m3 and 30 g/m3 for 4 hour in 0.5 m3 fumigation chamber and in 10 m3 container. Phytotoxicity was evaluated to mixture of phosphine and ethyl formate at 1 month after treatment.

Fumigation activity of Frankliniella occidentalis, western flower thrips, and phytotoxicity were evaluated with phosphine(PH3) and ethyl formate (EF) in the asparagus. Fumigation activity of PH3 and EF showed in the order of egg (64.7 mg·h/Land 132.9 mg·h/L), nymph (5.5 mg·h/L and 14.8 mg·h/L), and adult (3.8 mg·h/L and 14.7 mg·h/L) respectively at 5˚C in12 L desiccator. The adsorption of PH3 was 24% at 5˚C. However, the adsorption of EF increased sharply to 98% at 5˚C.PH3 showed 100% control for all development stage of F. occidentalis with 4g/m3 in 0.65m3 at 2˚C for 48h exposure. Thephytotoxicity was not found. The results revealed that the EF is highly absorbable in asparagus, so it is not suitable as afumigant, but PH3 is considered to be suitable as an alternative MB fumigant for control of the F. occidentalis in asparagus.

Ethyl formate (EF) and phosphine (PH3) is an alternative fumigant to methyl bromide (MB). For applying import sweet pumpkins in Korea, the efficacy of EF and PH3 was evaluated on Tetranychus urticae adult and egg stage which is pest in sweet pumpkins. The eggs of T. urticae were more tolerance than adults in both EF and PH3. When T. urticae eggs were treated with EF for 4 hrs, LCT99=107.63 mg/L and LCT99=45.37 mg/L at 5°C and 20°C, respectively. PH3 treatment at 5°C and 20°C for 24 hrs, eggs were controlled LCT99=49.44 mg/L and LCT99=17.23 mg/L, respectively. The mixed treatment of EF and PH3 showed no significant synergistic effect on T. urticae. However, EF (80 mg/L) and PH3 (4 mg/L) treatment did not cause any external phytotoxicity damages in sweet pumpkin even when treated with the maximum amount of fumigant at 5℃ and 20℃ for 24hrs.

Ethyl formate (EF) and phosphine (PH3) is an alternative fumigant to methyl bromide (MB). The egg, nymph, and adult stages of Frankliniella occidentalis in asparagus were examined for the fumigation activity of EF and PH3. The eggs of F. occidentalis were more tolerance than other stages (adults and nymphs) in both EF and PH3. When the EF was treated for 4 hrs at 5℃ and 20℃, the eggs of F. occidentalis were LCT99=98.70 mg/L and LCT99=61.13 mg/L, and adults were LCT99=11.50 mg/L and LCT99=3.18 mg/L, respectively. However, at 5℃ and 20℃, the eggs were LCT99=83.76 mg/L and LCT99=53.6 mg/L, and adults were LCT99=4.58 mg/L and LCT99=3.44 mg/L, respectively for 4 hrs treatment of PH3. The PH3 was not any external phytotoxic damages at the maximum dose (4 mg/L), but the EF caused significant phytotoxicity in asparagus.