Fumigation of fruits and vegetables during quarantine and pre-shipment (QPS) treatment should be effective with a shorter fumigation time to minimize phytotoxicity. In this research study, a shorter fumigation time, 2 hours exposure which is shorter than that of the current commercial fumigation procedures using a lower dose of ethyl formate (EF) mixed with phosphine (PH3) on strawberry was investigated. The reciprocal effect between EF and PH3 against nymphs and adult Myzus persicae (Sulzer) and Tetranychus urticae (Koch) was evaluated. In addition, L(Ct)50 and L(Ct)99 of EF only and EF mixed with PH3 were analyzed at 5°C and 20°C. The synergistic ratio (SR) of L(Ct)50 and L(Ct)99 for the nymph and adult stages of M. persicae were >1.0, which indicated a synergistic effect between EF and PH3. However, the SR values of L(Ct)50 and L(Ct)99 of the nymph and adult stages of T. urticae were ≤1.0 indicating that there was no synergistic effect between the two fumigants against T. urticae. Our results showed that the reciprocal effect between EF and PH3 has different effects on M. persicae and T. urticae. This could be attributed to the biological and physical differences between the class Arachnida and Insecta. The synergistic effect between EF and PH3 against M. persicae within a shorter exposure period and without phytotoxicity on fruits and vegetables will significantly benefit the horticultural industry.

Abstract
INTRODUCTION
MATERIALS AND METHODS
    1. Insects and chemicals
    2. Fumigation
    3. Measurement of fumigant concentration
    4. Determination of concentration time (Ct)product of fumigant in a fumigationdesiccator
    5. Statistical analysis
    6. Determination of the combined toxicity ofethyl formate and phosphine mixtures
RESULTS AND DISCUSSION
    1. Efficacy on green peach aphids
    2. Efficacy on two-spotted spider mite
REFERENCES

• Bong-Su Kim(Animal and Plant Quarantine Agency (APQA)/School of Veterinary and Life Science, Murdoch University)
• Jeong-Oh Yang(Yeongnam Regional Office, Animal and Plant Quarantine Agency)
• Gwang Hyun Roh(USDA-ARS, US Pacific Basin Agricultural Research Center)
• Yonglin Ren(School of Veterinary and Life Science, Murdoch University)
• Byung-Ho Lee(Institute of Life Science, Gyeongsang National University)
• Sung-Eun Lee(Department of Applied Biosciences, Kyungpook National University)