Insecticidal Activity of Cinnamon Essential Oils, Constituents, and (E)-Cinnamaldehyde Analogues against Metcalfa pruinosa Say (Hemiptera: Flatidae) Nymphs and Adults

미국선녀벌레(Metcalfa pruinosa Say)에 대한 계피 정유 유래 물질의 살충 활성

The insecticidal activity of the constituents of cinnamon essential oils and structurally related compounds against both the nymphs and adults of the citrus flatid planthopper Metcalfa pruinosa was examined using a direct-contact application. The toxicity of the cinnamon oil constituents and 21 (E)-cinnamaldehyde related compounds regarding the nymphs of M. pruinosa was evaluated using a leaf-dipping bioassay. Based on 24 h $LC_{50}$ values, hydro-cinnamic acid ($1.55mg/cm^2$) is the most toxic compound, followed by geranic acid ($1.59mg/cm^2$). The $LC_{50}$ values of 11 of the compounds including cinnamaldehyde are between $1.60mg/cm^2$ and $4.94mg/cm^2$. Low toxicities and no toxicity were observed with the other 15 ($5.24mg/cm^2$ to $13.47mg/cm^2$) and two compounds, respectively. Also, the toxicities of the cinnamon oil constituents and 21 cinnamaldehyde related compounds regarding the M. pruinosa adults were evaluated using a direct-spray method. The toxicity of eugenol (10.81 mg) is the most toxic compound for the adults of M. pruinosa, followed by geranic acid (30.68 mg). The $LC_{50}$ values of nine of the compounds including cinnamaldehyde are between 59.16 mg and 96.70 mg. Low toxicities and no toxicity were observed with the other 15 (105.44 mg to 255.76 mg) and three compounds, respectively. The spray formulations that comprise cinnamon bark and cinnamon green leaf oils resulted in 82.3% and 82.9% mortalities, respectively, toward the M. pruinosa adults in a ginseng field. Global efforts to reduce the level of highly toxic synthetic insecticides in agricultural environments justify further studies on cinnamon oils to ascertain whether the corresponding active principles can act as insecticides, when they are applied as a direct spray with contact action, for the control of M. pruinosa populations.

본 연구에서는 계피 정유 3종의 구성성분을 분석하였고, 미국선녀벌레에 대한 살충활성을 검정하였다. (E)-Cinnamaldehyde을 포함한 9종의 계피 정유 구성성분과 21종의 유사 물질을 미국선녀벌레 약충에 대해 살충활성을 검정한 결과, hydro-cinnamic acid가 반수치사농도 $1.55mg/cm^2$로 가장 좋은 살충활성을 보였으며, geranic acid도 $1.59mg/cm^2$로 높은 살충 활성을 보였다. Cinnamaldehyde를 포함한 hydro-cinnamaldehyde, (E)-cinnamaldehyde, cinnamdyl alcohol, cinnamyl acetate, dibutyl phtalate, anethole, a-cyano cinnamic acid, (s)-perillyl alcohol, methyl cinnamaldehyde, bonyl acetate 12종이 중간정도의 활성($1.60-4.94mg/cm^2$)을 보였으며, 다른 물질들은 살충활성이 낮거나 없었다. 미국선녀벌레 성충에 대해서는 eugenol 이 반수치사 농도 10.81 mg로 가장 높은 살충활성을 보였으며, geranic acid (30.68 mg)도 높은 살충력을 보였다. Cinnamaldehyde 등 9종이 반수 치사 농도 105.44~255.76 mg의 살충활성을 보였다. 다른 18종의 물질은 활성이 낮거나 없었다. 실제 포장인 인삼포장에 발생하는 미국선녀벌레에 대한 적용시험에서 cinnamon bark 정유와 cinnamon green leaf 정유가 각각 82.3%와 82.9%의 높은 살충활성을 보였다. 농업환경에서 고독성 합성살충제의 사용을 줄일 수 있는 방안으로 본 논문에서 선발한 계피정유가 미국선녀벌레의 약충 및 성충 방제에 유용한 수단으로 이용될 수 있을 것으로 사료된다.