During the larval development process of insects, juvenile hormone (JH) is essential for regulating various aspects of larval life, including growth, reproduction, and behavior, throughout their larval stage. The larval stage of Spodoptera frugiperda, when it consumes plant-derived metabolites, develops into pupae, but these pupae are unable to molt successfully. In this way, plant-derived metabolites contain or produce inhibitors of juvenile hormone, thereby disrupting the development of insect larvae and making them vulnerable to harm. Therefore, in this study, we established an in vitro screening system using yeast cells transformed with the Met-SRC juvenile hormone receptor of S. frugiperda. Through this system, we were able to identify juvenile hormone disruptors from plant-derived metabolites and confirm their developmental inhibitory effects on the larvae of S. frugiperda.
Machilus thunbergii (Laurales: Lauraceae, 후박나무) is planted as a street tree in Jeollanamdo and Jeju Island. Orthaga olivacea (Lepidoprate: Pyralidae, 제주집명나방) is known as a major pest of M. thunbergii. For managing O. olivacea by eco-friendly control method, the mating disruption would be expected. The sex pheromone of O. olivacea was identified as a mixture of (Z)-11-hexadecenyl acetate (Z11-16Ac), (Z)-11-hexadecenal (Z11-16Ald), and (Z)-11-hexadecenol (Z11-16OH) at a ratio of 100: 0.1:0.1 by Chinese research group. Before applying mating disruption, confirmation of its attraction in Korea was essential. The pheromone traps composed of Z11-16Ac alone and the blend of three components (100:0.1:0.1) were installed in Haenam, Jeollanamdo in 2021, and Jeju and Seogwipo, Jeju in 2022. In field attraction test, no O. olivacea was attracted to any trap. However, Mamesastra brassicae (Lepidoptera: Noctuidae), which was not intended, was caught in both years in the trap. Total of 19 in Haenam between September 23 and 30, total of 11 in Jeju between September 30 and October 28, and total of 108 in Seogwipo between September 15 and November 11 were caught to the trap lured with Z11-16Ac. While in the trap lured with the blend, total 1 and 6 were captured in Haenam and Seogwipo, respectively.
참깨는 건전 유기 종자생산을 위해서는 Corynespora cassicola 등과 같은 종자전염 병원균의 감염을 최소화해 야 하므로 비가림하우스 내에서의 종자생산이 필수적이다. 그러나 비가림하우스 재배 시 진딧물의 대발생으로 참깨의 생산량 저하 되므로 본 연구에서는 참깨 비가림하우스 내 유기 재배 시, 진딧물에 대한 효과적인 유기농업 자재를 선발하고자 한다. 등록된 유기농업자재 8종 중 4종을 기내에서 선발하였으며 선발된 유기농업자재 4종을 참깨 재배기간 중 주 1회 처리한 결과, 처리 간 유의한 차이가 나타났다. 수확기인 8월 3일 기준 무처리구 대비 데리스추출물 70%와 데리스 20%+시트로넬라 30%+계피추출물 10%은 12.3%, 9.0%만이 고사하여 우수한 방제 효과를 나타냈다. 본 연구 결과는 참깨 재배 시 농림현장에서 발생하는 복숭아혹진딧물에 대한 유기농업자재 효과를 검정함으로써 유기재배 농가의 자재 선택에 대한 정보를 제공하고자 한다
Leaf-spray in vitro bioassays appraise new aphicidal formulations for managing deleterious plant-feeding aphids. The formulation may utilize alternative and integrated strategies. However, leaf spraying even under controlled conditions may affect aphid reproduction and mortality. This study examines leaf spray applications for optimum and reproducible aphicidal results using tobacco leaves overlaid on cotton fabric or water agar surfaces. Infestation of the undersides of tobacco leaves with nymphs of green peach aphids was used in the assays. Spray distance and volume were optimized using water-sensitive paper to ascertain the best surface coverage. Overlays of the leaves on water agar caused less mortality and greater reproduction than the use of cotton fabric. The relative humidity of the insect-rearing chambers changed with the watering regime for the insect - rearing chambers with cotton fabric; 60% relative humidity was optimal. Relative humidity was not affected by the concentration of agar in the water agar chambers. Applications of the chemical aphicidal standard, Sulfoxaflor, under the optimized conditions exhibited similar times for lethality although the rate was faster with leaves on the cotton fabric than on water agar. These studies establish reproducible and sensitive techniques for assessing the lethality and effects on reproduction of potential aphicidal products.
Botanical extracts are employed in management of aphids. Extracts from Tanacetum cineariaiaefolium, Derris elliptica, and Sophora flavescens are widely used to control various insects. In this study, we determined concentrations of active insecticidal compounds (Ais) in commercial botanical extracts of these plants, and we investigated the time and concentration for lethal results with the green peach aphid, Myzus persicae. The concentrations of Ais, pyrethrins from T. cineariaiaefolium, rotenone from D. elliptica, and matrine and oxymatrine from S. flavescens, were determined after their fractionation by liquid chromatography followed by mass analysis and comparison with standard compounds. The extracts were tested for lethality in a bioassay with green peach aphids. Sprays at defined doses were applied to tobacco leaves infested with aphid nymphs. The lethal concentrations (LC50) were 20.4 ppm for pyrethrins, 34.1 ppm for rotenone, and 29.6 ppm for matrine at 48 h after treatments. At 100 ppm application levels, the lethal time LT50 was 13.4 h for pyrethrin, 15.1 h for rotenone, and 14.4 h for matrine. Kaplan - Meier analysis indicated the lethal times for the three botanical extracts at 100 ppm were significantly faster than application of a chemical insecticide, Sulfoxaflor, applied at the recommended level. These results provide baselines to develop and formulate single or mixed preparations containing botanical extracts to control green peach aphids on commercial crops.
Although ethylformate and phosphine fumigants are widely used for pest quarantine, studies related to their mechanism of action and metabolic physiological changes in Drosophila models are still unclear. In this study, we investigated how key metabolites altered by fumigants and cold treatment are associated with and affect insect physiology by comparative metabolome analysis. Fumigant treatment significantly altered cytochrome P450 and glutathione metabolites involved in the detoxification mechanism and showed lower expression of PGF2α involved in the immune response compared to the control. Additionally, most of the metabolites functioned in metabolic pathways related to the biosynthesis of amino acids, nucleotides and cofactors.
배에 피해를 주는 해충 중 하나인 주경배나무이는 2~3월 경 배나무의 거친껍질 밑에서 겨울을 난 후 나무 위로 올라가 산란하는데, 이 때를 월동 후 방제적기로 한다. 월동 후 방제에는 주로 기계유유제를 사용하고 있으나 저온피해가 자주 발생하거나 나무의 세력이 약한 농가는 방제 후에 언피해 발생을 우려하여 살충제를 살포하거 나 방제를 하지 않는다. 월동 후 발생밀도를 조절하지 못할 경우 생육기에 피해가 커지기 때문에 기계유유제를 대체할 수 있는 약제를 확인하고자 하였다. 또한 2023년 2월 EU 수출 대상 농가에는 아바멕틴 성분의 살충제 사용을 제한하는 규제가 발표되어 생육기에 발생하는 주경배나무이 여름형 성충에도 아바멕틴 성분을 대신하 여 적용 가능한 약제를 선정하고자 하였다. 주경배나무이 대상 등록 약제 중 아바멕틴, 아세타미프리드, 이미다 클로프리드, 설폭사플로르를 시험약제로 선정하였으며, 약제검정 결과 겨울형 성충에는 아세타미프리드 > 아 바멕틴 > 이미다클로프리드 > 설폭사플로르, 여름형 성충에는 아바멕틴 > 설폭사플로르 > 이미다클로프리드 > 아세타미프리드 순으로 살충률이 확인되었다. 살충력 추가 검정 및 여름형과 겨울형 성충의 충체 특성을 비교 한 후 기계유유제 및 아바멕틴 성분 대신 사용이 가능한 약제 성분을 권장할 수 있을 것으로 사료 된다.
강원특별자치도 18개 시군을 대상으로 감나무와 콩에 발생하는 미국선녀벌레, 썩덩나무노린재, 담배거세미 나방의 발생을 조사하였다. 돌발해충인 미국선녀벌레는 약충기인 6월과 성충기인 10월에 발생조사를 진행하고 남방계해충인 담배거세미나방과 썩덩나무노린재는 7월과 9월 콩 재배기에 발생조사를 진행하였다. 미국선녀 벌레는 강원지역에 있는 감나무에서 발생을 확인할 수 없었고. 감나무 주변 기타 수목에서 가지당 평균 6.7마리 발생하였다. 담배거세미나방은 7월, 속초를 제외한 모든 시군에서 발생이 되었으며, 춘천, 횡성에서 트랩당 60마 리가 넘는 발생밀도를 보였으며, 원주, 강릉, 화천 등 에서는 트랩당 1마리로 낮은 발생밀도를 나타냈다. 썩덩나무 노린재는 7월 춘천, 속초, 홍천 등 7개 시군을 제외한 11개 시군에서 트랩에 포획되는 것을 확인하였으며, 화천에 서 트랩당 26마리로 최고발생밀도를 보였다.
The occurrence status of eggs and adults of Pochazia shantungensis, Lycorma delicatula, and Lymantria dispar was investigated in the Chungcheongbuk-do region. The results showed that the overwintering eggs of P. shantungensis occurred in 24.2% of the region in 2021 and 22.1% in 2022, while adults occurred in 25.2% in 2021 and 24.3% in 2022, indicating the highest occurrence among the pests studies in this research. The occurrence of overwintering eggs of L. delicatula was relatively low, with 2.6% of the region affected in 2021 and 1.9% in 2022. Adults of L.delicatula occurred in 3.2% of the region in 2021 and 3.6% in 2022, while they were not undiscovered in Jeungpyeong, Jincheon, Goesan, and Danyang areas. Their area of occurrence was less than 3% of the region, and the volume of occurrence was not very large. Overwintering eggs of L.dispar occurred in 4.1% of the area in 2021 and 1.7% in 2022, showing a decreasing tendency compared to the previous year, and their occurrence was only low to middle in terms of the degree of occurrence.
Because Scotinophara lurida has the habit of living under the rice plant, an introduction of a method for efficient control when spraying eco-friendly organic materials is needed. In this study, we investigated the density of S. lurida in drained- and irrigated-paddy field after spraying an organic material containing garlic bulb extracts, which has high insecticidal activity in S. lurida in direct spraying test in glass tube. As a result, an irrigated rice paddy showed a control effect of 66.4% after 3 days of spraying and 86.2% after 7 days, while a drained rice paddy showed a control effect of 33.9% after spraying and 61.9% after 7 days. These results suggest that effective control can be achieved in irrigated rice fields if organic farming materials are evenly sprayed and reach to the body of S. lurida. It is remained to study how irrigated water do contribute to increase the insecticidal effect in the future.
Scotinophara lurida is one of major sap-sucking pests in an organic rice farming paddy fields in Korea. Several Poaceae grasses (e.g, rice, barley etc) have been known as a host plant. To find out a true host plant of S. lurida, the developmental characteristics such as weight gain and developmental duration were checked on total eight grasses species including rice and corn. In the results, weight of the fifth nymphal stage was the highest value in the barnyard millet and rice plant. In addition, nymphal duration was the shortest value in the barnyard millet and rice plant. But, in corn and common millet plant, S. lurida nymphs could not complete the development to the adult stage. These results suggest that six Poaceae grasses including rice and barnyard millet out of eight test grasses are close related to true host plants of S. lurida.
A machine learning-based algorithms have used for constructing species distribution models (SDMs), but their performances depend on the selection of backgrounds. This study attempted to develop a noble method for selecting backgrounds in machine-learning SDMs. Two machine-learning based SDMs (MaxEnt, and Random Forest) were employed with an example species (Spodoptera litura), and different background selection methods (random sampling, biased sampling, and ensemble sampling by using CLIMEX) were tested with multiple performance metrics (TSS, Kappa, F1-score). As a result, the model with ensemble sampling predicted the widest occurrence areas with the highest performance, suggesting the potential application of the developed method for enhancing a machine-learning SDM.
The development of biochemical pesticides to replace existing chemical pesticides and the search for new substances with potential insecticidal ability are continuously required. The purpose of this study is to control myzus persicae with pyrethrum biochemical pesticide containing of high concentration of pyrethrin as an active ingredient. Pyrethrum dried powder was extracted with 95% ethanol for different periods of time and it was confirmed that the pyrethrin content increased as the extraction period increased and the extraction conditions for 20 days had the highest yield with 0.2% pyrethrin. We produced a prototype containing 0.13% pyrethrin content (pyrethrin II: 0.06%, pyrethrin I: 0.06%). and in 200 fold dilute spray condition. It showed a 77.2% corrected mortality against myzus persicae which is comparable to chemical pesticide. We are continuously researching to reduce the decomposition of active ingredients and look for additives to increase the insecticidal activity.
We investigated the behavioral attractive responses of a lepidopteran larva parasite, Exorista japonica to 10 synthetic herbivore-induced plant volatiles (HIPVs). These synthetic HIPVs have been revealed the attractive effect on several parasites. For each of the HIPVs, we asked the following two questions : (1) Which volatiles show the attractiveness to this parasitoid, (2) Whether the attractant directly or indirectly affects the host settlement and parasitism of the parasitoid. To experimentally address these questions, we performed 2 and 4 choice indoor cage tests. E. japonica adults were significantly attracted to benzaldehyde and (Z)-3-hexen-1-ol showing higher settlement and parasitic rates on Spodoptera litura of treatments. Compared to the untreated plots, the average parasitism of E. japonica on S. litura larvae in the benzaldehyde treatments increased by approximately 20%.
This study aimed to develop a new eco-friendly control method of B. tabaci using a trap plant treated with systemic insecticide. Due to high preference, tobacco plant was selected as a trap plant among solanaceous plants. Out of all 6 systemic insecticides, dinotefuran WG showed the highest mortality (> 97.3 %) against B. tabaci. The concentrations of dinotefuran in tobacco leaves after systemic treatment showed the sharp increase in the pesticide from 2 hrs until 48 hrs (2 d) and steady increase over 35 d. The mortality of B. tabaci in tobacco leaves was about 80% at 9 hrs after treatment and over 90% at 1, 2, 3, 6, 9, and 35 d after treatment. The number of B. tabaci was counted every week after dinotefuran-treated tobacco pots were placed in the tomato greenhouse cultivation. The density of the insects with 3 tobacco plants was app. 75% lower than the control (w/o tobacco plant).
농가 현장에서는 미소 해충의 약제저항성 발달로 인하여 방제에 어려움을 겪고 있다. 본 연구는 약제저항성 수준을 효율적으로 진단하고, 화학적 방제 의사결정을 지원할 수 있는 약제저항성 관리 플랫폼을 구축하고자 수행하였다. 플랫폼은 크게 ⅰ) 농가 맞춤형 약제 추천, ⅱ) 지역별 약제저항성 지도로 구성되어 있다. 이용자는 잔류접촉법 기반의 생물검정법 RCVpW(Residual Contact Vial plus Water) 결과를 현장에서 입력하면 PLS에 부합 한 약제 정보를 제공받을 수 있다. 또한 생물검정 결과는 DB화를 통해 지역별 약제 저항성 정보 지도를 보여줌으 로써 해충별, 작물별, 연도별 저항성 패턴 결과를 확인할 수 있다. 본 플랫폼을 활용한다면 약제의 오남용을 줄임 은 물론 해충의 약제저항성 발달 지연 및 약제저항성 발달 양상을 확인할 수 있어 향후 방제전략 수립에 활용할 수 있을 것으로 생각된다.
2022년 10월부터 2023년 5월까지 친환경 딸기재배 농가에서 점박이응애는 칠레이리애응애와 사막이리응애, 진딧물은 콜레마니진디벌을 대상으로 하는 천적처리구와 유기농자재를 사용하는 관행방제구에서 천적의 해 충 밀도억제 효과를 조사하였다. 천적처리구에서 점박이응애 성충 밀도는 잎당 1.5마리 이하, 알은 4개 이하로 관리되었고, 사막이리응애는 잎당 최대 0.4마리까지 증가하여 점박이응애 밀도억제에 많은 영향을 미친것으로 보인다. 반면, 관행방제구에서 점박이응애 밀도는 천적 방사구에 비하여 오히려 많은 발생량을 보였지만, 3월 9일부터는 사막이리응애의 증가와 유기농자재의 효과로 점박이응애 밀도는 급격하게 감소하였다. 진딧물 천적 처리구에서 진딧물 밀도는 1월부터 발생하였으며 3월 상순에 잎당 0.3마리까지 증가하였으나 이후 감소하였고, 콜레마니진디벌은 진딧물 발생이 많지 않아 3.9마리/㎡(2회) 방사하는 데 그쳤다. 한편, 관행방제구 포장의 진딧 물은 유기농자재의 영향으로 거의 발생하지 않았다.
2022년 국내 노지 마늘, 대파, 양파, 부추 작물재배지에서 채집한 파총채벌레 지역집단들에 대하여 살충제 저항성을 조사하였다. 제조사 추천약량에서의 살충력은 acrinathrin SC를 제외한 6종 약제들이 안성 등 8개 집단 에서 모두 90%이상을 보였으며, Spinetoram SC와 fluxametamide EC는 추천농도의 100배 희석농도에서도 전 지역 집단에 걸쳐 높은 살충력을 보여주었다. 미리 저항성 진단농도로 코팅한 바이알을 이용한 지역집단의 저항성 검정을 실시한 결과, emamectin benzoate의 저항성이 신안 등 9개 지역집단에서 매우 높았으며, chrantraniliprole은 부산 등 4개 , spinetoram은 의성 등 3개, actamiprid와 chlorfenapyr는 각각 1개의 지역집단에서 저항성이 높게 발달 하고 있는 것을 확인할 수 있었으며, 지역별로는 주요 대파 및 양파 재배지인 안성, 서산, 진도, 신안 지역의 저항성 이 모든 약제에 대하여 전반적으로 높게 나타났다.
Recently, the occurrence of the fall webworm, one of the foreign invasive pests, is rapidly increasing due to the increase in average annual temperature due to global climate changes. In this study, we are presenting diverse eco-friendly technologies to control the fall webworm. (Grant No. PJ014845032023).
As global warming and consumer’s preference for tropical/subtropical fruits increase, the number of orchards cultivating tropical/subtropical fruits in Korea is increasing. Accordingly, concerns about the introduction of exotic invasive pests that host tropical fruits. In this study, efficacy of ethyl formate(EF), as alternative to methyl bromide(MB), was evaluated. Commercial trial of EF was conducted in mango post-harvest storage conditions for controlling Scirtothrips dorsalis. Application of 10 g/m3 of EF for 4 hours at 10 ℃ showed proven efficacy on S. dorsalis without any phytotoxic damage on mango fruits in that condition.