점박이응애(Tetranychus urticae)는 250과 1400여종의 식물에 피해를 주고 있는 해충으로 높은 번식력, 근친 교배, 무성생식, 짧은 수명주기 로 년간 발생회수가 많기 때문에 약제에 대한 저항성이 빠르게 발달하는 종이다. 저항성 기작은 AChE 저해, sodium channel modulator, glutamate gated chloride channels allosteric, mite growth inhibitors, inhibitors of acetyl CoA carboxylase, mitochondrial ATP synthase 저 해, mitochondrial complex I, II, III, 그리고 electron transport 저해 등이 있으며 약제에 따라 작용기작이 다르므로 약제살포 시 확인이 필요하 다. 약제저항성 발달을 평가하는 독성시험방법으로 slide dip, leaf dip, leaf disc, topical application, vial leaf dip, spray potter tower, leaf vial dipping 등이 있으며 최근에는 분자학적 진단법 등도 개발되어 있으나 이들 방법은 해충 종이나 발육상태에 약제에 따라 정확도가 달라지므로 현장 에 가장 맞는 방법을 찾아야 할 것이다. 저항성 점박이응애를 효과적으로 관리하기 위한 방법으로 저항성 위험이 낮은 살응애제(chemical acaricide) 약제 선발, 천적인 칠레이리응애, 사막이리응애를 이용한 생물적 방제, 님, 제충국, 등 식물추출물이나 정유를 활용한 친환경적인 방법 등이 제시되 고 있으며 종합관리를 위한 다양한 요인을 찾아 약제 사용을 줄여 나가야 할 것이다.

The two-spotted spider mite, Tetranychus urticae Koch, is one of the economically important agricultural pests globally, as it attacks a wide range of vegetable and horticultural crops. In this study, we evaluated spatial repellent and oviposition deterrent activities of T.urticae in response to fifteen compounds derived from ester-containing natural products. To evaluate the tests, we used bridge two-choice test and host two-choice test in laboratory conditions. Among the eight compounds showed spatial repellent and oviposition deterrent activities against T. urticae at the 20 mg dose and some compounds had the activities at lower dose. We also conducted two-choice test with a blend and single compounds to determine which showed stronger spatial repellent and oviposition deterrent activities. In host two-choice test, we evaluate repellence between distance of compounds. This study concluded that series compounds from ester-containing natural products have the potential to be used managing T. urticae in the field.

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most important agricultural pests. Therefore, we screened fifteen compounds from natural products for their spatial repellent and oviposition deterrent activities against T. urticae in the laboratory by using two-choice and no-choice tests. In the bridge two-choice test, nine compounds showed the spatial repellent effects on T. urticae at 20 mg dose, resulting in reduced numbers of eggs. Among the nine compounds, at 2 mg dose, two compounds were selected as having more spatial repellent activity than the others. The two compounds also showed spatial repellent and oviposition deterrent effects in the two-choice test from hosts. In the no-choice test from a host, the spatial repellent effects of the two compounds to T. urticae were significantly stronger than that of controls. These results suggest that the findings can be used as potential agents for the prevention and population control of T. urticae in the field.

점박이응애는 광식성 초식자로서, 사과의 주요 해충 중 하나이다. 사과 품종에 따라 점박이응애의 밀도 형성이나 피해 규모가 다르게 나타난다. 세 가지 품종, 쓰가루, 홍로, 후지의 잎에 대한 점박이응애의 이동 선호성, 발육속도, 그리고 산란능력이 다른지를 시험하였다. 잎 절편을 이용한 실험 결과, 이동 선호성은 쓰가루나 홍로보다 후지 잎에서 높았다. 알에서 성충까지 발육기간은 후지 잎에서 가장 짧았고 홍로에서 가장 길었다. 암컷 성충 수명은 후지에서 가장 짧았다. 암컷의 총산란수는 사과 품종에 따라 다르지 않았지만, 일 평균 산란수는 후지에서 높았다. 생명표 분석 결과 홍로 잎에서 점박이응애의 적합도가 가장 낮게 나타났다. 이상의 결과는 사과원에서 품종에 따른 점박이응애 발생 양상의 차이를 설명 해주고 있으며, 향후 다양한 사과 품종에 대한 평가를 통해, 품종별 응애류 관리 전략 개발에 기초 자료가 될 것이다.

해충의 예찰 없이 작물 정식 초기에 천적을 먼저 적용할 수 있는 천적-서식처 혼합적용(Natural Enemy in First; NEF)기법의 방제효과를 확인하였다. 시설 딸기에서 조사 12주차에 NEF처리구와 천적 단독 처리구에서 친환경자재 처리구 대비 각 83%, 70%의 점박이응애 밀도 억제효과를 확인할 수 있었다. 또한 예찰 없이 작물 정식 초기에 NEF를 적용한 처리구에서 천적 단독 처리구보다 3배 이상의 높은 천적 밀도를 확인하였다.

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.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pest species devastating many horticultural and ornamental crops and fruit trees. In the present study, a field strain was collected in January 2001 and has been selected for sixteen years with acequinocyl. The resistance ratio calculated from the LC50 of eggs and adults was 191- and 4,237-fold, respectively. The laboratory-selected acequinocyl resistance (LSAR16) strain was screened with 11 acaricides for cross-resistance. The detoxifying enzyme activities and quantitative real-time PCR analysis were performed in the LSAR16 strain. Crossing experiments revealed that LSAR16 strain was inherited maternally, incompletely dominant and monogenic. Most importantly, we identified two new point-mutations at mitochondrial cytb from acequinocyl resistant T. urticae.

Orius minutus (L.) (Hemiptera: Anthocoridae) is a native predators of soft body insects such as mites, thrips, and aphids.We compared 24 h consumption rate of O. minutus with that of a commercialized O. laevigatus (Fieber) on egg andadult stage of Tetranychus urticae Koch (Acari: Tetranychidae). Orius minutus predated 1.4 times more adult T. urticae(58 mites) in 24 h than O. laevigatus. Similarly, O. minutus consumed 128 eggs while O. laevigatus consumed 98 eggsin 24 h without statistical difference. These results suggest that native O. minutus can be applied for the augmentativebiological control after the development of mass-rearing method.

The two-spotted spider (Tetranychus urticae) is an important pest of many agricultural crops. Laboratory bioassayswere conducted to determine the toxicity of Pyflubumide and Cyenopyrafen against three populations of T. urticae collectedfrom apple orchards. The adults and eggs of three populations all showed susceptibility to Pyflubumide and Cyenopyrafen,as the 50% lethal concentration (LC50) values were all lower than each of the recommended concentrations. There wereconsiderable differences in susceptibility of the acaricides between eggs and adults in different populations. Pyflubumideshowed highest toxicity to adults of Yeongju population (LC50 = 1.40 mg/l) and eggs of Andong population (LC50 =0.54 mg/l). Cyenopyrafen showed lowest toxicity to adults of Andong population (LC50 = 20.29 mg/l) while displayedhighest toxicity to their eggs (LC50 = 2.64 mg/l). These results suggested that T. urticae had not developed resistancein these three regions, Pyflubumide and Cyenopyrafen can serve as alternative chemical candidate for integrated mite managementin apple orchards.

Amblyseius eharai is a native predatory mite in Korea and a candidate of biological control agent to control spidermites. To evaluate the predation ability of A. eharai, its functional response was tested at 10, 30, 50, 70 and 130 larvaeof Tetranychus urticae. A. eharai showed the Type 2 functional response. The attack rate of female and male A. eharaiwas 0.109 and 0.019, respectively. The handling time of female and male was 0.164 h and 0.234 h, respectively. Theattack rate was significantly different between male and females at 95% confidence interval. However, handling time wasnot statistically different. In comparison with Neoseiulus californicus, attack rate and handling time of A. eharai werebetter than N. californicus. These result should be helpful for evaluation of A. eharai for a biological agent against T.urticae.

This study was conducted from November 2016 to March 2017 for the development and evaluation of the biologicalcontrol of the two spotted mite (Tetranychus urticae; TSSM) in the strawberry greenhouses. Natural enemy plot and conventionalplot were selected to compare the mean density of T. urticae. T. urticae was sampled by taking three leaflets (1 stalk)from each plant (3 three-leaflet) leaves from each sampling position. Natural enemy plot was released with Phytoseiuluspersimilis and conventional plot was sprayed with pesticides(abamectin, cyenopyafen, etc). Each stage of TSSM densitywas higher in conventional pesticides than natural enemy. Spatial Analysis by Distance IndicEs (SADIE) was used toanalyze spatial distribution and index of aggregation   , index of clustering  ,   were used to investigate the spatialdistribution. Also, the clustering indices were mapped as red-blue plot. As a result, The spatial distribution of T. urticaewas varied, particularly, feeding ability and density of P. persimilis caused regular spatial distribution of T. urticae.

본 실험은 유기농 신선초(Angelica utilis)포장에서 점박이응애(Tetranychus urticae)의 발생지점 및 확산 양상을 확인하고자 수행하였다. 실험은 17주 동안 강원도 원주시 신림면 용암리에 위치한 유기작목반 비닐온실(625㎡/동)에서 진행되었다. 온실 입구부터 5m 간격으로 확대경을 이용해 해충 밀도를 조사한 결과 A농가에서는 1주차에 입구에서 95m 지점의 해충밀도가 가장 높았으며, 시간이 경과함에 따라 앞쪽으로 확산되었다. 이는 A농가 뒤쪽 우거진 수풀에서 점박이응애가 유입되어 도로변이 있는 앞쪽으로 확산된 것으로 보인다. B농가의 경우 1주차에 입구에서 50m 지점의 해충밀도가 가장 높았으며 시간이 경과함에 따라 뒤쪽으로 확산되었다. 이는 B농가 앞쪽에 있는 신선초온실에서 해충이 유입되어 확산된 것으로 보인다. 또한 점박이응애의 천적을 1주일간격으로 3회 방사한 결과 A농가는 방사 6주차에, B농가는 방사 3주차에 100% 해충방제효과를 보였다. 신선초는 1년 상시 재배되는 작형인 만큼 계절별, 지리적 특성에 따라 해충 양상이 달라질 수 있으므로 추후 체계적인 모니터링을 통해 효과적인 천적방사시기 및 방사지점을 확인한다면 해충발생초기에 소량의 천적투 입으로 방제효과 극대화, 노동력과 방제비용의 절감을 기대할 수 있을 것으로 기대된다.

Due to its rapid development of resistance to nearly all arrays of acaricide, Tetranychus urticae is extremely hard to control using conventional acaricides. As an alternative control measure of acaricide-resistant mites, RNA interference (RNAi)-based methods have recently been suggested. A double-stranded RNA (dsRNA) delivery method using multi-unit chambers was established and employed to screen the RNAi toxicity of 42 T. urticae genes. Among them, the dsRNA treatment of coatomer I (COPI) genes, such as coatomer subunit epsilon (COPE) and beta 2 (COPB2), resulted in high mortality [median lethal time (LT50) = 89.7 and 120.3h, respectively]. The transcript level of the COPE gene was significantly (F3,9 = 16.2, P =0.001) reduced by up to 24% following dsRNA treatment, suggesting that the toxicity was likely mediated by the RNAi of the target gene. As a toxicity enhancement strategy, the recombinant dsRNA was generated by reciprocally recombining half-divided fragments of COPE and COPB2. The two recombinant dsRNAs exhibited higher toxicity than the respective single dsRNA treatments as determined using LT50 values (79.2 and 81.5h, respectively). This finding indicates that the recombination of different genes can enhance RNAi toxicity and be utilized to generate synthetic dsRNA with improved RNAi efficacy.

The two spotted mite, Tetranychus urticae Koch, is a global pest, and has developed severe resistance to several types of acaricides. Acequinocyl-resistant strain and bifenazate-resistant strain of T. urticae showed higher relative activity level of glutathion-S-transferases (GSTs) than susceptible strain. Studies of resistance in T. urticae have focused on classical detoxifying enzyme system, such as GSTs. We examined the expression of six GSTs genes in T. urticae belong to five different cytosolic classes, including two in delta, one in omega, one in mu, one in zeta, and one mitochondrial GSTs class, kappa. RT-qPCR results showed that, among these six GSTs genes, the relative expression level of delta 1 was significantly higher in bifenazate-resistant strain than in other strains (susceptible, abamectin, acequinocyl, etoxazole and pyridaben strain). Expression level of the delta 2 was also higher in acequinocyl-resistant strain than in other strains. The elevated GSTs gene transcripts following exposure to acequinocyl, bifenazate might be one of the mechanisms involved in detoxification of these acaricide. These results may be caused by different mechanisms in the resistance development of T. urticae to these two different types of acaricides.

The detoxification enzymes activities were investigated to Tetranychus urticae Koch using five acaricide-resistant strains. Activities of detoxification enzymes which are glutathione S-transferase (GST), general esterases (α-naphthyl acetate and β-naphthyl acetate), and cytochrome C oxidase were determined to each resistant strain mite. Acequinocyl-resistant strain and bifenazate-resistant strain of T. urticae were showed 2.1 folds and 1.6 folds higher relative activity (RA) level of GST than susceptible strain. Other three resistant strain mites were not significant different to susceptible strain mite. General esterases and cytochrome C oxidase were not significant to all the strain of T. urticae. Acaricidal activities of acequinocylresistant strain and bifenazate-resistant strain of T. urticae showed cross-resistant both acequinocyl and bifenazate. However, other strain mites were showed susceptible acaricidal activities to two acaricides. In this result suggests that resistance of two acaricides (acequinocyl and bifenazate) might be influenced by glutathione S-tansferase activity.

국립수목원 열대식물자원연구센터내 유리온실에서 관리중인 열대 관상수 2종 (Phyllanthus acidus, Erythrina caffra)에 발생한 가루깍지벌레(Pseudococcus comstocki)과 점박이응애(Tetranychus urticae)에 대한 천적 적용 가능성을 실험하 였다. Phyllanthus acidus에 발생한 가루깍지벌레의 방제를 위해서 Chrysoperla nipponensis를 사용하였으며 Erythrina caffra에 발생한 점박이응애의 방제를 위해 서 칠레이리응애(Phytoseiulus persimilis)를 사용하였다. Phyllanthus acidus에 발 생한 가루깍지벌레의 방제를 위해서 Chrysoperla nipponensis 유충 30개체를 방사 했으며, Erythrina caffra에 발생한 점박이응애의 방제를 위해서 칠레이리응애 약 200개체를 방사하였다. 방사 후 24주 동안 2주일 간격으로 엽당 해충의 밀도를 조 사하였다. 조사결과 가루깍지벌레는 방사 직후부터 급격히 밀도가 줄기 시작하여 4주차 경과시 최초 밀도대비 22% 수준으로, 점박이응애는 2주차 이후 급격히 밀도 가 줄기 시작하여 4주차에는 최초밀도 대비 10%수준으로 밀도가 낮아지는 것을 확인할 수 있었다.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pest species devastating many horticultural, ornamental crops and fruit trees. Difficulty in managing this mite is largely attributed to its ability to develop resistance to many acaricides. Development of 3,700 folds resistance to etoxazole was found in the population of T. urticae collected from rose greenhouses in Buyeo, Chungnam Province in August 2000. This population has been selected for eleven years with etoxazole (over 500 times), and increased over 5,000,000 fold in resistance as compared with susceptible strain (S). Etoxazole-resistant strain was shown to be maternally inherited. The objective of this study was to determine whether resistance of T. urticae to etoxazole was linked with point mutations in the mitochondrial gene. DNA sequencing of cytochrome c oxidase subunit I (COX1), COX2, COX3, cytochrome b (CYTB), NADH dehydrogenase subunit 1 (ND1), ND2, ND3, ND4, ND5, and ND6 were analyzed by comparing two isogenic etoxazole-susceptible (EtoS) and etoxazole-resistant (EtoR) strains. As a result, all genes revealed no point mutations between the two strains.