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.

본 연구에서는 감귤원에서 초생재배 유무(초생재배 W, 제초제 살포 NW)와 합성피레스로이드계 살포유무(살포 P, 무살포 NP)에 따른 귤 응애의 개체군 동태를 구명하고자 수행되었다. 두 가지 기본적인 가설로 1) 초생재배는 천적의 서식처를 제공하여 천적의 정착을 높이므로 귤응 애의 발생을 감소시키는 요인으로 작용하며, 2) 합성피레스로이드계는 천적을 제거하여 귤응애의 밀도를 증가시키는 요인으로 가정하였다. 관측 된 천적 개체군(주로 이리응애류와 마름응애류)의 발생은 가정에 근거한 기대치와 크게 다르지 않았다. 2011년의 경우 NW+NP 처리구와 W+NP 처리구에서 차이가 있었으나, 2012년 실험에서는 기대치와 관측치가 거의 일치하였다. 전체적으로 약제효과가 뚜렷하게 나타나서 합성 피레스로이드계 살포시 천적이 유의하게 감소하였다. 잡초효과는 엇갈리는 결과를 보였는데, 봄-유래 여름 개체군 대비 가을 개체군의 증가 등을 고려할 때 초생재배를 하는 경우 천적의 발생이 증가하였다. 다만, 합성피레스로이드계 살포구에서 귤응애가 감소하는 비이상적인 결과는 귤응 애의 합성피레스로이드계에 대한 강한 기피성을 전제로 해석할 수 있었다.

Fumigation of fruits and vegetables during quarantine and pre-shipment (QPS) treatment should be effective with a shorter fumigation time to minimize phytotoxicity. In this research study, a shorter fumigation time, 2 hours exposure which is shorter than that of the current commercial fumigation procedures using a lower dose of ethyl formate (EF) mixed with phosphine (PH3) on strawberry was investigated. The reciprocal effect between EF and PH3 against nymphs and adult Myzus persicae (Sulzer) and Tetranychus urticae (Koch) was evaluated. In addition, L(Ct)50 and L(Ct)99 of EF only and EF mixed with PH3 were analyzed at 5°C and 20°C. The synergistic ratio (SR) of L(Ct)50 and L(Ct)99 for the nymph and adult stages of M. persicae were >1.0, which indicated a synergistic effect between EF and PH3. However, the SR values of L(Ct)50 and L(Ct)99 of the nymph and adult stages of T. urticae were ≤1.0 indicating that there was no synergistic effect between the two fumigants against T. urticae. Our results showed that the reciprocal effect between EF and PH3 has different effects on M. persicae and T. urticae. This could be attributed to the biological and physical differences between the class Arachnida and Insecta. The synergistic effect between EF and PH3 against M. persicae within a shorter exposure period and without phytotoxicity on fruits and vegetables will significantly benefit the horticultural industry.

차응애(Tetranychus kanzawai Kishida)의 기주식물에 대한 가치를 평가하기 위하여 기주식물로 제주 감귤의 주요 품종인 한라봉, 감귤원 에서 많이 서식하는 잡초인 왜제비꽃과 대조군으로 강낭콩을 선정하였다. 항온조건 20℃, 25℃, 30℃에서 발육실험과 산란실험을 진행하고 생명표 분석을 수행하였다. 차응애는 한라봉 어린잎, 왜제비꽃, 강낭콩에서 발육을 완료했지만 한라봉 구엽에서는 발육을 완료하지 못했다. 한라봉 어린잎을 섭식하는 차응애의 총 발육기간은 각 온도조건에서 17.4, 13.4, 10.2일로 강낭콩에서 조사된 16.1, 9.5, 7.0일보다 길었다. 한라봉 어린 잎에서의 차응애 성충의 수명은 각 온도에서 19.1, 15.0, 12.3일로 강낭콩에서 조사된 22.1, 14.1, 10.9일과 유의한 차이는 없었으며, 산란수는 각 온도에서 18.1, 23.9, 17.8개로 왜제비꽃(93.3, 105.8, 115.0개)과 강낭콩(127.4, 121.0, 117.1개)에서 보다 적었다. 조사된 발육데이터를 기반으로 생명표 통계량을 추정한 결과 서로 간 유의한 차이를 보였으며 내적자연증가율(rm)은 각 온도에서 강낭콩(0.1542, 0.2563, 0.3251), 왜제 비꽃(0.1087, 0.2007, 0.2673), 한라봉(0.0868, 0.1002, 0.1217)순으로 높게 나타났다. 이상의 결과를 종합하여 감귤원(한라봉)의 차응애 관리 전략에 대하여 고찰하였다.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pest species, because it devastates many horticultural and ornamental crops and fruit trees. The resistance ratios calculated for the LC50 value in acequinocyl- and pyridaben-resistant strain was 4,237- and 5,555-fold higher than that of the susceptible strain, respectively. The objective of this study was to evaluate the cross-resistance to several acaricides and to identify the mechanisms associated with acequinocyl- and pyridaben-resistant strain of T. urticae.

Orius minutus (L.) (Hemiptera: Anthocotidae) is a native predator of mites, thrips, and aphids whereas Orius laevigatus (Fieber) is a commercialized predator were assessed against O. metasequiae in laboratory and field. Adult females of both predator predated equally O. metasequiae adult after 3 hours of exposure in the laboratory on no choice assay. Orius minutus and O. laevigatus released with Portulaca oleracea plant in Metasequouia glyptostroboides tree reduced O. metasequiae population equally by 48.3% and 42.7% on first week after exposure. But O. laevigatus released without P. oleracea plant reduced 52.4% on the first week whereas O. minutus reduced only 6.2% of O. metasequiae population. We found only 3 O. minutus eggs on M. glyptostroboides leaves where 22 O. laevigatus eggs were found when treated without P. oleracea plant. Orius laevigatus laid 160.0 eggs on P. oleracea plant where as O. minutus laid only 25.7 eggs per plant. These result demonstrate that O. laevigatus can be applied for conservation biological control to suppress O. metasequiae population.

The two-spotted spider mite, Tetranychus urticae, is a worldwide agricultural pest that invades a wide range of host crops and rapidly develops resistance to pesticides. T. urticae can be resistant to one acaricide or exhibit multiple resistances or cross resistance to various other acaricides. Acequinocyl inhibits respiration in mitochondria at the ubiquinol oxidation site (Q0) of Complex III of the electron transfer chain. Pyridaben is a METI acaricide that inhibits mitochondrial electron transport at complex I. In this study, we investigated the cross resistance to seven acaricides in acequinocyl- and pyridaben-resistant strain. Furthermore, the frequencies of the I256V and N321S mutations in mitochondrial cytochrome b (cytb) of pyridaben-resistant and fieldcollected strain was analyzed.

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.

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.

The two spotted mite, Tetranychus urticae Koch, is a global pest, and has developed severe resistance to several types of acaricides. This study compared the development in susceptible (S) and acequinocyl, bifenazate, pyridaben, abamectin and etoxazole-resistant (AcR, BR, PR, AbR and ER) strains of T. urticae by X-ray irradiation. When eggs were irradiated with 100 Gy, the egg hatching was completely inhibited in all strains. When nymphs were irradiated with 200 Gy, their hatching was completely inhibited in all strains. When adults were irradiated, the fecundity and egg hatching was decreased at 150 Gy and above, and hatchability of F1 generation was completely inhibited at 300 Gy in all strains. Adult longevity was slightly increase at 150 Gy and above. In addition, we performed quantitative real-time PCR on several genes. To examine the difference of all strains on radiation stress-induced gene expression, we performed quantitative RT-PCR (qPCR) of several known stress-induced genes.

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.