To mitigate the intrusion of insect pests, behavioral modifications using repellents are commonly employed. Among their active ingredients, plant essential oils have gained prominence as safer alternatives to synthetic repellents. However, the absence of rigorous scientific efficacy testing have been undermined the reliability of these essential oil based repellent products. Previous studies have highlighted that the observed repellency in bioassays are strongly influenced by the testing environment. Our research introduces three distinct laboratory-scaled repellency test methods – spatial repellency, choice repellency in a closed and opened environment – to evaluate prevalent insect repellent products. Notably, we observed significant variations in repellency percentages among products. The most effective product from each method was identified, and its active ingredients were analyzed both quantitatively and qualitatively, by GC-MS analyses. To determine the applicability of these methods in selecting active ingredient concentrations, individual active ingredient components underwent dose-response testing. Our findings suggest that, when selected appropriately, these three methods can be applied for the development and evaluation of potent essential oil based repellent products.

갈색날개매미충의 방제전략을 확대하기 위하여 박하유에 대한 기피 효과를 살펴보았다. 23종의 방향유를 Y-tube olfactometer를 이용하여 후각 검정을 실시한 결과, 박하유(peppermint oil)와 lemongrass oil을 제외한 21종의 방향유는 갈색날개매미충에 대하여 기피반응이 나타나지 않았다. 단지 박하유만이 80% 이상의 기피효과가 관찰되었다. 박하유의 처리량에 따른 기피반응을 조사한 결과, 갈색날개매미충은 0.1, 0.5, 1 ㎕ 처리시 기피율이 점차 높아졌으며, 10 ㎕(76.47%) 처리량에서 높은 기피효과를 보였다. 박하유에는 1,8-cineole(4.7%), menthone(23.9%), iso-menthyl acetate(8.0%), menthol(53.7%) 등이 함유되어 있었다. 이들의 주요 성분함량을 혼합하여 Y-tube olfactometer를 이용하여 후각 검정한 결과, 5 ㎕ 처리시 76.2%의 높은 기피율을 보였다. 박하유는 야외에서 갈색날개매미충의 기피 및 산란 기피효과를 보였으나 단시간에만 활성이 강한 점과 약해의 가능성을 보아 제형 개발의 필요성이 대두된다.

Insecticidal and repellent activity of sandalwood oil (Santalum austrocaledonium) and its components was tested against cotton aphid , Aphis gossypii in laboratory and field. The activity was estimated by calculating survival rate of aphid after application of sandalwood oil and its components. Analysis by gas chromatography-mass spectrometry led to identification of 5 compounds, alpha-santatol, bergamotol, epi-beta-santalol, and beta-satalol. The components of sandalwood oil was isolated by column chromatography for testing insecticidal and repellent activity. Santalol showed strong insecticidal and repellent activity as a commercial insecticide, imidachloprid. Sandalwood oil and isolated alpha-santatol and beta-santatol also showed strong insecticidal and repellent activity, however there was no significant difference among them.

Thirteen plant essential oils were tested for their repellent activity against the bean bug Riptortus clavatus. Among the tested oils, caraway (100%) and clove bud oil (92%) significantly repelled the bean bugs at a dose of 0.142㎕/cm2 by using a Y-tube olfactometer. GC and GC-MS analyses revealed that the active components responsible for the effective repellency of caraway and clove bud oil were carvone (75%) and limonene (76.9%); eugenol (100%), isoeugenol (54.3%) and β-caryophyllene (60.0%), respectively. Of the different active fractions, eugenol was the most significant one than the other components with reference to repellent activity against the bean bugs. In the GC-EAD, limonene and carvone of caraway oil were responded to the antenna of Riptortus clavatus.

Repellent and acaricidal activities of eucalyptus oil, permethrin, and DEET against Leptotrombidium pallidum larvae, which are a vector transmitting tsutsugamushi disease, were evaluated under laboratory conditions using a filter paper impregnated method. The LD₅₀ values of eucalyptus oil and DEET were 0.025 and 0.018 ㎎/㎠, respectively while that of permethrin was higher than 0.2 ㎎/㎠. In the repellency test of these materials at 6.14 ㎎/㎠, eucalyptus oil gave complete repellency, and the larvae crossed the treated zone killed. But permethrin showed 60% repellency at 9.20 ㎎/㎠ and the mites croosed the zone were not killed. The percent repellency of DEET at 0.53 ㎎/㎠ was 8.3 and 2.8 times higher than that of permethrin and eucalyptus oil, respectively. The acaricidal activities of emulsifiable concentrates-pump sprayers containing the eucalyptus oil as an active ingredient were assayed. The emulsifiable concentrates containing 1% and 3% eucalyptus oil showed weak mortality at 1 hour after treatment, while all ones containing more than 6% oil produced 100% activity against L. pallidum larvae. The mortality also increased as exposure time to the concentrates increase. These results suggest that the potential of eucalyptus oil highly expected to be used as a control or repellent agent against L. pallidum larvae may be very high.

Purpose : We will develop the distribution method of wide oil extract technology to develop repellent using this technology and study mosquito repellent persistence. Research design, data and methodology : A positive control group containing purified water, ethanol and picaridin was prepared, and the experimental control group was prepared in the same proportion as the positive control group, and 0.6% of broad oil was added. The results were summarized using the calculation method according to the avoidance effect and statistically tested by t-test using the excel statistics program. Results : Experiments on skin surface area and voice control of participants showed that men had 8.9% wider skin surface area than women, and voice control tests showed that women were bitten by mosquitoes five times more than men. Both the positive and the experimental control groups had a valid duration of up to three hours, but from the time of five hours, the positive control group had 77% and the experimental control had 90%, indicating a difference of 14.4% over the positive control group. Conclusions : The mosquito repellents developed in this study on the basis of safety and continuity are cost-effective in terms of mosquito repellent, and in addition fragrance, odor removal, perfume, ink, skin care and massage effect.