국립수목원 열대식물자원연구센터내에서 생육중인 열대관상 식물인 Acalypha wilkesiana에 발생하여 피해를 주고 있는 점박이응애(Tetranychus urticae)의 생물학적 방제를 위해서 칠레이리응애(Phytoseiulus persimilis)를 방사한 후 8주간 매 1주일 간격으로 점박이응애의 밀도변화를 조사하였다. 칠레이리응애는 점박이응애 발생 지점에 300개체/m2의 밀도로 방사하였다. 방사 후 1주차에는 점박이응애의 상대밀도가 다소 증가하였으나 2주차에는 최초 밀도대비 64%수준으로 4주차에는 16%수준으로 5주차 이후에는 2%수준으로 줄어들었다. 식물원의 특성상 해충 발생지점이 구획화 되어있기 때문에 점박이응애의 조기발견 후 천적 투입량의 밀도를 조절할 경우 2주차 정도의 시간이면 방제효과의 가시적인 관찰이 가능한 것으로 나타났다.

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.

Establishment of rapid resistance level detection system is essential step to adopt the adaptive management for the control of various kinds of resistant pest population. Here, we established acaricides resistance detection methods based on residual contact vial bioassay (RCV) and quantitative sequencing methods (QS), and applied to determine the resistance levels from several populations in two-spotted spider mite, Tetranychus urticae, which has been considered as major notorious pest in rose cultivation area in worldwide. 12 acaricides were applicable to the RCV among 19 representative acaricides by showing the dose-dependent mortality within 8 hr, suggesting the acaricide suitability for the RCV might be varied by toxicity mechanism in each acaricides. The QS regression was established for 10 point mutations associated with five number of acaricides resistance such as organophosphate, pyrethroid, abamectin, bifenazate and etoxazol. The 95% prediction level was ranged from 10.8±5.4∼92.2±3.2%. The resistance levels were determined by above two detection methods from a total 12 strains. The laboratory-reared populations were revealed high susceptibility with low resistance allele frequencies to some acaricides, suggesting the several acaricides would be chosen for the control of those populations. However, the field-collected populations were exhibited a severe cross resistance with low susceptibility and high resistance allele frequency to almost tested acaricides, suggesting the current acaricides resistance levels are serious in rose cultivation area in Korea. The RCV and QS methods would be useful for the rapid and accurate collection of valuable information associated with acaricide resistance.

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.

A major concern in exporting agricultural commodities is the introduction or spread of exotic quarantine pests to the new area. To prevent spread of insect pests, various phytosanitary measures are used. In this study, we compared the effect of electron beam and X-ray irradiation on development and reproduction of the two-spotted spider mite, Tetranychus urticae. Eggs, nymphs, and adults were irradiated at target doses of 50, 70, 100, 150, 200, 250, and 300 Gy with electron beam and 10, 20, 30, 50, 70, 100, 150, and 200 with X-ray irradiation. When eggs were irradiated, egg hatching was completely inhibited at 150 Gy of electron beam and 50 Gy of X-ray irradiation. When irradiated to the nymphs, emergence was not affected at all target dose in both electron beam and X-ray irradiation. Hatchability of F1 generation was significantly decreased at 100 Gy of electron beam and 70 Gy of X-ray irradiation. When irradiated to the adults, longevity did not show any differences at all target dose in both electron beam and X-ray irradiation. These results suggest that the effect of X-ray irradiation was more potential than electron beam irradiation.

Abamectin, soil-born bacterial acaricides, has been intensively used to control Tetranychus urticae. Target site insensitivity and enhanced activity of detoxification enzymes have been considered as major resistance mechanisms. Here, we identified the differentially expressed genes after feeding sublethal dose of abamectin for 36 h by RNA-seq analysis. About 4.9 million reads (± 2,630,543 reads) were assembled into T. urticae. Among a total of 75 genes showing differential transcription, 18 and 14 genes were up- and down-regulated over two fold ratio, respectively. In the validation analysis, the calculated fold change of each genes between RNA-seq and qPCR were moderately correlated (r 2 = 0.661). A cuticular protein was shown as the highest up-regulated gene (192.3-fold) and a chitinase was revealed to be the highest down-regulated (-16.4-fold). Further study would be necessary to validate their roles in T. urticae adaptation to acaricides.

Emergence of resistant two-spotted spider mite (TSSM) can induce the over usage of standard amount of acaricides and result in various side effects. Rapid resistance monitoring is essential step for the efficient management of resistant populations by enabling the selection of appropriate acaricides. Here, we evaluated the 10 acaricides to determine its suitability on residual contact vial bioassay (RCV) by using PyriF strain as standard. Five acaricides (Abamectin, monocrotophos, tebufenpyrad, bifenazate and cyflumetofen) revealed the dose-dependent mortality within 8 h, whereas other remaining acaricides (Fenbutatin oxide, fenpyroxymate, flufenoxuron, spiromesifen and etoxazole) did not. This finding suggests that the application of RCV method is limited depending on the mode of action and physicochemical properties of each acaricide. Resistance levels to five acaricides (Abamectin, monocrotophos, tebufenpyrad, bifenazate and cyflumetofen) were determined for four field populations of TSSM by using RCV diagnostic kit. All TSSM populations showed the highest sensitivity to cyflumetofen, indicating that it would be most effective in controling field populations. RCV diagnostic kit would enable to provide crucial information for choosing the most appropriate acaricides in the field.

심비디움(Cymbidium spp.)의 시설 재배 시 가장 피해가 큰 해충은 점박이응애 (Tetranychus urticae)이다. 양란 재배 농가에서 응애의 방제에 주로 사용되고 있는 약제 중 사이에노피라펜액상수화제, 사이프로루메토펜액상수화제, 스피로디클로펜수화제, 에톡사졸액상수화제 등 4종의 약제에 대한 점박이응애 방제효과를 검토하였다. 3년생 심비디움에 약제를 처리한 후 살충효과를 7일, 14일 후에 조사하였다. 처리 후 7일차에 에톡시액상수화제를 제외하고 3종에서 7.1% 이하의 생충율을 보였고, 14일차에서도 에톡시액상수화제를 제외한 모든 약제에서 3.4% 이하의 생충율을 보였다. 점박이응애에 대한 방제효과는 에톡시액상수화제를 제외한 3종의 약제에서 96.5%이상의 방제효율을 보였다

The two-spotted spider mite Tetranychus urticae is a worldwide crop pest with a high insecticide resistance and an extensive host range. The aim of the present study was to evaluate the effect of PaeciPora®, which was formulated from the aerial conidia of an entomopathogenic fungus Paecilomyces lilacinus strain HY-4, to control T. urticae in cucumber field. In the field study, conidia of P. lilacinus HY-4 and a chemical acaricide azocyclotin were investigated for their control of the adult females of T. urticae. The strain produced a mortality of 56.0% on day 3 and 63.6% on day 7 post-treatment respectively at 1×107 conidia/mL, and no evidence of a mortality benefit was seen in the control group. Additionally, in the pesticide injury test, no agrochemical damage was found in hot pepper, watermelon, Chinese cabbage, oriental melon or strawberry by spraying PaeciPora® on them. The results indicated the possibility of the use of P. lilacinus HY-4 as a microbiological control agent against T. urticae in the Integrated Pest Management program.

A project has been launched and aims to introduce Amblyseius swirskii for the control of Tetranychuns urticae in rose cultivating greenhouse. This study was intended to use selective acaricide, sensibly, to reduce risk for the natural enemy agent of A. swirskii in controlling T. urticae. T. urticae was susceptible strain UD from Entomology laboratory of SNU and A. swirskii was purchased from commercially available source. When LC50s were compared with A. swirskii and T. urticae of abamectin 1.8EC and 7 other acaricides, chlorfenapyr+cyenopyrafen (4+20)SC, abamectin 1.8EC, and chlorfenapyr 10SC for A. swirskii showed 148, 74, and 14 times, respectively, higher dose than T. urticae, as selective acaricides. However, fenpropathrin 5EC and fenpyroximate 5SC for T. urticae showed 22, and 25 times, respectively, higher dose than A. swirskii. For T. urticae bifenazate 23.5SC and cyflumetofen 20SC showed more than 97% mortality at less than the recommended dose, but the acricides did not kill A. swirskii 16 and 4 times as much dose as the recommended dose. The results suggested that several acaricides have inherent lower toxicity to A. swirskii. For practical application, it might be recommended to use acaricides in a way to strengthen inherent selectivity.

The screening of effective lethal genes was conducted via the systemic delivery of dsRNA for the RNA interference (RNAi)-based management of Tetranychus urticae. Four candidate genes (coatomer protein complex, T-COP; M1 metalloprotease, T-M1MP; Ribosomal protein S4, T-RPS4; A subunit of V-ATPase, T-VATPase) with a reference genes (EGFP) were tested for the experiment. Translocated dsRNA to the leaf disc (ca. 30 mm diameter) was detected at 12 h post-treatment, indicating that dsRNA could move through leaf veins. In the evaluation of mortality, the T-COP, T-RPS4 and T-VATPase exerted moderate levels of toxicity at 72 h post-treatment among four dsRNA tested. Knockdown of the target genes were confirmed by quantitative PCR, suggesting that RNAi of target genes was accomplished by feeding dsRNA. In summary, the dsRNA delivery via leaf disc was effective in screening lethal genes, and some genes, such as T-COP, T-M1MP, T-RPS4 and T-VATPase, can be applicable for establishing a RNAi-based control system against T. urticae.

점박이응애(Tetranychus urticae)에 대한 살비활성을 가지는 물질을 알아보기 위하여 약용식물 25과 35 종의 메탄올 또는 헥산 추출물을 이용하여 잎 침지법과 살포법으로 실내와 pot, 야외에서 실험을 수행하였 다. 살비활성은 약용식물 종류별로 차이를 보였다. 강남콩(Phaseolus vulgaris var. humilis) 잎을 1,000 ppm 농도의 추출물에 1분간 침지한 후 점박이응애에 대한 치사율을 조사한 결과, 비자나무(Torreya nucifera) 열매 추출물과 팥꽃나무(Daphne genkwa)와 도꼬마리(Xanthium strumarium), 나팔꽃 (Pharbitis nil) 씨앗 추출물이 각각 56.8%와 47.8, 47.7, 47.7%의 살비활성을 나타내었다. 잎 침지시간을 30초로 단축시켜 점박이응애에 대한 살비효과검정 시는 1분 침지에 비하여 효과가 감소하였고, 나팔꽃과 도꼬마리의 살비 활성이 가장 높았다. 도꼬마리와 나팔꽃 씨앗 헥산 추출물의 반수치사농도는 각각 1,824 ppm과 1,899 ppm이었다. 두 식물의 1,000 ppm 온수 및 냉수 추출물은 점박이응애에 대한 살비효과가 20% 이하로 낮았다. Pot의 강낭콩에 점박이응애를 접종한 후 분무법으로 추출물을 1,000 ppm 농도로 살포한 결과 도꼬마리와 나팔꽃 씨앗 헥산추출물은 각각 76.3과 71.3%의 높은 살비활성을 나타내었다. 그리고 온실에서 국화의 점박이응애를 대상으로 나팔꽃 씨앗 헥산 추출물을 2,000 ppm과 1,000 ppm으로 처리 시에 는 50.8%와 35.1%의 방제가를 보였다.

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.

The screening of effective lethal genes was conducted via the systemic delivery of dsRNA for the RNAi-based management of Tetranychus urticae. Six candidate genes (COPI coatmer, T_COPI; ESCRT III_Snf7, T_SNF7; Ribosomal protein S4, T_RPS4; v-ATPase A subunit 2, T_V-ATPase; Aminopeptidase N, T_APN3; Acetylcholinesterase, T_AChE) and two reference genes (EGFP and T_AChEintron) were tested for the experiment. The permeated dsRNA to the leaf disc (ca. 30 mm diameter) was detected at 6 h after treatment, indicating that dsRNA could move through veins on the leaf. In the reference gene selection, the T_AChEintron was chosen for its low mortality compared with EGFP gene. In the evaluation of mortality, the T_COPI, T_V-ATPase and T_RPS4 exerted higher toxicities at 24 hour after treatment among six genes tested. Interestingly, T_APN3 showed toxicity after 72 hour. In summary, the dsRNA delivery via leaf disc was effective in screening lethal genes and some genes, such as COPI, V-ATPase and RPS4, can be applicable for establishing a RNAi-based control system against T. urticae.

This study was conducted to examine the potential of surface enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) to screen Tetranychus urticae resistance to pyridaben and dicofol. T. urticae is one of the most important pests in greenhouse and orchard, and huge expense is needed to control because of its strong resistance to acaricides. Consequently speedy and accurate monitoring of acaricidal resistance is the key factor of IPM for T. urticae. SELDI-TOF MS is a novel approach to biomarker discovery that combines two powerful techniques: chromatography and mass spectrometry. It can provide a rapid protein expression profile of acaricidal sensitive and resistant T. urticae. In this study we had different protein and peptide patterns between sensitive and resistant strains to pyridaben and dicofol. In the future this results could be a useful data to develop a good monitoring tool of site and host specific mite resistance to various acaricides.

Two-spotted spider mite, Tetranychus urticae (Koch) is one of the serious pests in economically important crops such as strawberry and cucumber and so on. Acaricides have been used as the main control agents. This study was conducted to test the synergistic effects of the Beauveria bassiana GHA, which has been registered for whitefly and thrips, and five pesticides (abamectin, acrinathrin, bifenthrin imidacloprid, dinotefuran, and indoxacarb, which are commonly used pesticides in strawberry in Korea), on the two-spotted spider mite T. urticae. Five tested pesticides did not inhibit spore germination and mycelial growth of B. bassiana. Pesticides were applied to potted strawberry plants at four different treatments (recommended concentration, 1/5 recommended concentration, 1/5 recommended concentration + GHA(108 conidia/ml), and only GHA(108 conidia/ml). Mortality in larvae of two-spotted spider mite was 12% in GHA 5 day after treatment. Mortality in abamectin treated T. urticae was 98.5% and 100% at 1/5 recommended concentration and recommended concentration, respectively, 3 days after treatment. Acrinathrin, indoxacarbe, dinotefuran and difenthrin imidacloprid caused 60%, 14%, 16% and 91% mortality at recommended concentration 5 day after treatment. The tested five pesticides and B. bassiana GHA had no synergistic effect.

The two-spotted spider mite, Tetranychus urticae Koch, is an economically important pest of crops of plant grown in the field or greenhouse worldwide. It has recently become a serious problem because of the continuous use of acaricides resulting in resistance among spider mite population. Thus, there is a need to find alternative control measures to suppress spider mite populations. In this study, we report the screening result of pathogenic fungi for the control of spider mite. Initial screenings were performed using 352 isolates of putative pathogenic fungi from Korea soils. As results, 11 strains of acaropathogenic fungi were isolated from 8 cadavers of spider mite supporting fungal conidiation. These isolated were identified as four isolates of Beauveria bassiana (6, 2R-3-3-1, 2R-4-5, 2R-4-7), two isolates of Metarhizium anisopliae (4-2, 2-2), one isolate of Clonostachys rosea 5-2, one isolate of Lecanicillium attenuatum 4-1, one isolate of Pochonia suchlasporia 2R-3-1, one isolate of Aspergillus flavus 7 and one isolate of Isaria lilacinus 2R-4-6 by microscopic examination and genetic sequencing of the ITS region. Based on the screening results, eleven isolates were tested for their virulence against adult spider mites. All fungal isolates were pathogenic to spider mite but mortality varied with isolates. These acaropathogenic fungi may be useful to develop eco-friendly acaricide to control two-spotted spider mite.

Daily predation of femlae/male O. sauteri during nymphal development were 4.2/3.9, 11.4/9.5, 14.3/10.8, and 14.7/12.5 at 17, 22, 27, and 32℃, respectively, and consumed 14.3/10.8 thrips, 7.5/7.2 aphids, 45.9/38.8 mites at 27℃, respectively. Adult females ate 42.8 thrips daily during preoviposition period and 63.2 thrips during oviposition period at 27℃. Predation by O. sauteri on F. occidentalis increased as the density of F. occidentalis increased. However, the rate of increase gradually lessened, resembling a Holling’s type II functional response. The attack rate of adult female is higher than that of the 5th nymph. Adult female and 5th nymph of O. sauteri appeared to prefer 2nd larva of F. occidentalis.

Vapormate™, a new gas formulation of ethyl formate (EF) with carbon dioxide, is an alternative fumigant to methyl bromide (MB). The efficacy of the vapormate fumigation was evaluated on an acaricide susceptible and resistant Tetranychus urticae strains. A resistant strain showed resistance ratio (RR) of 21.9 and 379.6 to acrinathrin and chlorfenapyr, respectively. Fumigation was done in desiccators (6.8 L) which were empty or filled 30% in space with paprika for 6 h at 15℃ in the laboratory. The concentration adopted were 9.6, 17.2, 24.5, 36.4 mg/L in empty desiccator and 10.2, 17.9, 24.9, 35.2 mg/L in paprika-filled desiccator. In empty desiccator, susceptible and resistance T. urticae showed 100% mortality at higher concentration than 17.2 and 24.5 mg/L, respectively. In paprika-filled desiccator, susceptible and resistance T. urticae showed 100% mortality at higher concentration than 24.9 and 35.2 mg/L, respectively. Hatchability was greatly reduced by the fumigation. Hatchability was 3.7% in the empty desiccator at 9.6 mg/L and 37.2% in the paprika-filled desiccator at 10.2 mg/L.

This study was conducted to examine the ability of the predacious mite G. occidentalis to limit population density of T. urticae infesting roses in the greenhouse, Washington state university, Pullman, U.S.A. Population fluctuations of T. urticae, G. occidentalis, and Macrosiphum euphorbiae were assessed for over two years on greenhouse roses through time series data. During the first half of experiment a stratified random sampling was performed (from May 2000 to May 2001) and the presence/absence and randomized sampling method was utilized during second half (from June 2001 to September 2002). Populations of T. urticae and G. occidentalis were estimated by R-functions or discrete prey-predator equations. During 121 weeks there were six population fluctuations of T. urticae, G. occidentalis and M. euphorbiae. The variation of G .occidentalis was closely associated with that of T. urticae but G. occidentalis did not overexploit T.urticae. The predicted populations of both mites were explained by above equations. M. euphorbiae and T. urticae might be compete for limited resource in the greenhouse rose and the movement of G. occidentalis was inhibited by the honeydew of M. euphorbiae. Therefore, M. euphorbiae showed negative relationship with T. urticae and G. occidentalis from the results of non-linear regression analysis. Although the relationship between T. urticae and G. occidentalis was negative it was unlikely to present complete biological control of T. urticae on greenhouse roses. It might be necessary an integrated management strategy to control T. urticae in bent-cane greenhouse roses.