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.

Due to the concerns over their environmental and health impacts, there have been attempts for shift towards biorational pesticides from synthetic pesticides. Among them, plant essential oils have emerged as promising active ingredients. Due to the complex interactions among their constituents, the bioactivities of essential oils can vary depending on the compositions, which often undermine their stability in efficacy. Here, we present a model-based optimization approach to develop reliable rosemary oil-based biorational pesticide, against two-spotted spider mites, Tetranychus urticae Koch. The ecotoxicity against Daphnia magna and foliar phytotoxicity against Phaseolus vulgaris were also evaluated. Our quadratic models accurately predicted miticidal activity, ecotoxicity, and phytotoxicity. We aimed to maximize, minimize, and minimize these parameters, respectively. We employed seven multi-objective evolutionary algorithms in Matlab. Among them, the nondominated sorting genetic algorithm II with adaptive rotation based simulated binary crossover (NSGA-II-ARSBX) performed best. We experimentally determined the thresholds for miticidal activity and phytotoxicity, based on the current approval process for agricultural pesticide products in Korea. After applying the thresholds, we validated the obtained viable solutions. Our study offers a novel framework to enhance the reliable and responsible use of essential oils as biorational pesticides.

Aerosol-type insecticides are one of the most widely used household insecticides to control mosquitoes. Not only the structural difference such as the size and shape of orifice, but also the difference in formulation including solvent system and proportion of propellent can affect the efficacy of those aerosol products. Orifice structure can be represented by nozzle diameter while solvent systems are divided into water-based and oil-based types in wide view. In the present study using Asian Tiger Mosquito, Aedes albopictus, we found that the orifice nozzle size made a significant difference in shoot-out range, followed by heterogeneous mortality by distance. Additionally, oil-based spray affected farther space than water-based one. Oil-based solvent system was also responsible for lowering the LT50 and KT50(knock-down time 50) values. Therefore, they are one of the definitive parts in insecticides formulation that determine the way of insecticide delivery. In terms of insecticide resistance management, we define efficiency of insecticide as the proportion of insecticide treated to environment that is solely acted as toxin to target pest. The higher efficiency of insecticide, the less overused chemicals we face, which may imply lower risk of resistance development. Thus, we argue that formulations, the specific route of insecticide discharge to environment, should be deliberately considered not only for consumer satisfaction, but also for insecticide resistance management.

Miticidal and repellent activity of twenty plant essential oils against the adults of two spotted spider mites, Tetranychus urticae, were examined. Sandalwood oil was the most potent one in mortality, whereas clary sage oil exhibited the greatest repellent activity. On those twenty essential oils tested, no apparent correlation between toxicity and repellency was observed. The chemical compositions of sandalwood and clary sage oils were identified via GC/MS analyses. The major constituents of sandalwood oils were sesquiterpene compounds, whereas the major ones for clary sage oil were monoterpenes. Among the major components in clary sage oil, linalyl acetate was not only the most abundant constituent, but also the most responsible one for its repellent activity against the adults of the two spotted spider mites. Nevertheless, the combination of seven major constituents of clary sage oil showed lesser repellent activity than the original essential oil did, implying the presence of interactions between the major and minor constituents affecting the overall repellent activity of the crude oil.

본 연구에서는, 20종의 식물정유를 이용하여 점박이응애 성충에 대한 살비활성 및 기피활성을 확인하였다. 살비활성 평가에서는 샌달우드 오일이, 기피활성 평가에서는 클라리 세이지 오일이 가장 높은 효과를 나타내었고, 평가에 사용한 20종의 식물정유간에는 살비활성과 기피활성간 의 상관관계가 매우 낮게 나타났다. 높은 활성을 나타낸 정유들의 혼합시험에서는, 거의 대부분의 조합이 서로간에 저해효과를 갖는 것으로 확인되었다. 샌달우드 및 클라리 세이지 오일의 구성성분은 GC/MS 분석을 통해 확인하였으며, 샌달우드는 세스퀴터펜류가, 클라리 세이지 오일은 모노 터펜류가 주종을 이루었다. 클라리세이지 오일의 구성성분 중에서는 linalyl acetate가 가장 높은 함량을 갖고 있을 뿐만 아니라, 해당정유가 기피효과를 갖는 주된 효능물질임을 확인하였다.

Chemical control is the indispensable part of insect pest management. However, due to overuse of pesticides, the emergence of resistance to pests and environmental pollution problems are appeared. In order to solve these problems, the need of integrated pest management (IPM) has emerged. The IPM means that the pest density should be controlled and maintained to avoid any economic loss, also to minimize any side effects to the human beings and environment using appropriate control methods. In order to do successful IPM, sampling plan should be prepared. Sampling plan consists of monitoring, density estimation and decision making of target insect pests in certain crop field including the knowledge of spatial distribution. Tabaco whitefly, Bemisia tabaci, and Western flower thrips, Frankliniella occidentalis, are serious insect pests in paprika greenhouses. We selected two paprika greenhouses with different sizes (12,000 m2 and 4,000 m2). Insect pests monitoring was evaluated from January 24, 2014 to June 27, 2014. Two monitoring methods are used to develop sampling plans, one is visual survey for B. tabaci population, and the other is using sticky trap for F. occidentalis population, respectively. We calculated spatial distribution using Taylor’s Power Law (TPL). In visual survey results, TPL showed that adults and pupae of B. tabaci were aggregated in paprika greenhouses. And in trap survey results, F. occidentalis was also aggregated with different scale of the slope of TPL equation. In density estimation, the more density of insect pests, the less samples were required. Moreover, the more accuracy, the more samples were required for stop sampling in greenhouses. We selected hypothetic action threshold of 0.3 and 5 for decision making. As a result, if the action threshold is increased, the maximum sample number is decreased