The study investigated the efficacy of four different essential oils on the repellent responses of large black chafer (Holotrichia parallela) Motschulsky (Coleoptera: Scarabaeidae) in organic pear (Pyrus pyrifolia) orchards. Cinnamon, pine, peppermint, and eucalyptus oils were used, and the behavioral responses and repellent effects against H. parallela were investigated under laboratory and field conditions. Adult beetle responses to different oils were examined using a Y-tube olfactometer in the laboratory and four absorbent blocks with each oil in the field. The repellent responses rates of H. parallela were 100% for cinnamon oil; however, only 67% of adult beetles avoided peppermint and eucalyptus oil in the Y-tube olfactometer bioassay. In the field tests, the least damage to leaves was observed on trees treated with cinnamon oil, whereas the most damage was observed in the control (non-treated) trees and those treated with peppermint oil, followed by eucalyptus and pine oil. Therefore, cinnamon oil can be used as a repellent to avoid damage form large black chafers in organic pear orchards.

Ⅰ. Introduction
 Ⅱ. Materials and Methods
  1. Insects
  2. Y-tube olfactometer bioassay
  3. Field experiments
  4. Statistical analyses
 Ⅲ. Results and Discussion
  1. Repellent responses in the Y-tube olfactometer bioassay
  2. Repellency rates in an organic pear orchard
 Ⅳ. Conclusions
 References

• Song, Jang-Hoon(Pear Research Institute, National Institute of Horticultural & Herbal Science) | 송장훈
• Choi, Eu-Ddeum(Pear Research Institute, National Institute of Horticultural & Herbal Science) | 최으뜸
• Md, Abdul Alim(Department of Entomology, Hajee Mohammad Danesh Science and Technology University) | 압둘알림
• Choi, Duck-Soo(Jeonnam Agricultural Research and Extension Services) | 최덕수
• Seo, Ho-Jin(Pear Research Institute, National Institute of Horticultural & Herbal Science) | 서호진 Corresponding author