Fumigant Toxicity and the Repellent Effect of Essential Oils against Sitophilus zeamais Motschulsky

Stored grain insects appear frequently as grains are harvested, stored, and distributed on the market. Producers mostly depend on chemical fumigants to control and repel insect pests, but this application of chemicals may cause side effects for humans and the environment. Safer control approaches, including the use of natural products are required, and in this study, we assessed the control effect of essential oils on stored grain insects. The essential oils of 8 plant species from 6 families were tested for their fumigant toxicity and repellent effects using a Y-tube Olfactometer against Sitophilus zeamais adults. Pennyroyal and tea tree oil respectively exhibited 97% and 63% mortality at $10{\mu}{\ell}L^{-1}$ air concentration in tested fumigant toxicity. Of particular note, pennyroyal oil ($LT_{50}$, hour=3.87) showed higher adulticidal activities than tea tree oil ($LT_{50}$, hour=4.09). When assessing repellent effects, using a Y-tube Olfactometer at $10{\mu}{\ell}$/filter paper concentration, the cedarwood, cinnamon, cypress, patchouli and pennyroyal essential oils showed potent repellent activities against Sitophilus zeamais adults. Cinnamon, cypress and pennyroyal essential oils showed notably high repellent activities of 82.4%, 80.0% and 86.7%, respectively, at $1{\mu}{\ell}$/filter paper concentration.

어리쌀바구미에 대한 식물정유의 훈증독성과 기피효과

본 연구는 쌀을 비롯한 저장곡물을 가해하는 어리쌀바구미(Sitophilus zeamais) 성충에 대해서 8종의 식물정유의 훈증독성과 Y-tube를 이용한 후각반응으로 기피효과를 조사하였다. $10{\mu}{\ell}/L$ air의 농도에서 훈증독성시험 결과 pennyroyal과 tea tree 오일에서 각각 97%, 63%의 높은 살충효과를 보였다. 특히, pennyroyal oil($LT_{50}$, hour=3.87)은 tea tree oil($LT_{50}$, hour=4.09)보다 높고 빠른 살충력을 보였다. $10{\mu}{\ell}$/filter paper의 농도에서 후각계를 이용한 기피효과는 Cedarwood(80%), Cinnamon(83.3%), Cypress(81.1%), pennyroyal(97.1%) oil이 높은 기피활성을 보였으며, 이보다 낮은 $1{\mu}{\ell}$/filter paper의 농도에서도 Cinnamon(82.4%), Cypress(80.0%), pennyroyal(86.7%) 오일은 높은 기피활성을 나타냈다.