The Kanzawa spider mite, Tetranychus kanzawai (Acari: Tetranychidae) constructs webs over leaf surfaces and usually lives under the webs. T. kanzawai produces two types of excreta, black and yellow pellets, and uses its webs as a place for excretion. T. kanzawai also uses its webs as a refuge when the predatory mite, Neoseiulus womersleyi (Acari: Phytoseiidae) is present. To clarify what factors deter N. womersleyi from foraging on T. kanzawai webs, I experimentally examined the effects of T. kanzawai excreta on its own fitness (fecundity) and the foraging behaviour of N. womersleyi. When the excreta of T. kanzawai was put on leaf surfaces, the fecundity of T. kanzawai adult females was reduced by the black but not the yellow faecal pellets. On the other hand, predation by N. womersleyi was reduced by the yellow but not the black pellets. Although this effect of the yellow pellets on N. womersleyi did not last on leaf surfaces, it deterred N. womersleyi from staying on the webs regardless of its freshness. These results suggest that T. kanzawai deposits black pellets on webs to avoid its negative effect on their own fitness, and yellow pellets are deposited on webs to reduce the risk of predation.

Some solitary wasps and bees exhibit peculiar structures, i.e., acarinaria, which are invaginated chambers harbouring certain mite species for transfer to brood cells of hosts. Acarinaria have long been considered morphological adaptations that evolved to securely transfer beneficial mites into nests but there is little compelling evidence to support this hypothesis. The dispersal deutonymphs of the mite Ensliniella parasitica are housed in acarinaria of the host A. delphinalis during phoresy. The mite life cycle has been investigated in detail; the deutonymphal mite using acarinaria invades into a host cell during wasp oviposition, the tritonymph feeds on heamolymph from lepidopteran prey, then adults from the juvenile host, the female begins laying eggs on the host after the host pupates, and larvae and protonymphs acquire nutrition from the pupa, developing into deutonymphs by host eclosion. Although totally parasitic to the juvenile host throughout its life cycle, the mite did not negatively affect on the host. Nests were sometimes infested with other natural enemies, which included a parasitoid wasp (Melittobia acasta), a kleptoparasitic fly, and unknown pathogens. When the parasitoid and adult mites co-existed in a host cell, we found that either all mites or all parasitoids died. A single adult parasitoid (female) and adult mites were placed in transparent acrylic tubes containing a single prepupal host. In some cases, the parasitoids harbouring mites eventually died. However, in other cases, the parasitoid counterattacked mites by possibly biting them on their dorsum. This experiment demonstrated that the probability that the parasitoid was killed depended on the number of mites. Although mutualisms to protect a partner are common, this wasp-mite interaction is exceptional, because the mite is non-predacious and much smaller in body size than the enemy but protects the host wasp.

Gamasid mites are free living predators of soil mites, collembolans, nematodes and other small insects in soil surface. We studied the faunal assemblages of gamasid mites in the severely disturbed mountain sites by fire. Total 12 families 55 species were found from this study. From all sites, species in the family of Parholaspidae were dominant; Holaspina alstoni and H. dentatus. Also, Rhodacarus dentitulatus was also abundant regardless of fire disturbance. In control site, Asca aphidioides was also abundant but not in any of the fire disturbed sites. The abundance was highest in control site followed by IC2, IT3 and lower in IT2 and IT1. Species richness was in the same order of abundance ranging from 2.6 to 12.8 per site. In all sites, species diversities were relatively low ranging from 0.6 to 1.7, but it was higher in control site and lower in IT1. Further discussion will be made on the recovery process of soil inhabiting mites.

Spider mite is the most concerned pest in apple production. This study compared and analyzed the historical changes of two mite pests, Tetranychus urticae koch and Panonychus ulmi (Koch) in 16-30 representative apple orchards in the major apple production area; Gyeongnam, Gyeongbuk, and Jeonbuk province of Korea from 1992 to 2007. Monthly sampling of 100 leaves per orchard provided the basic data of population density of two mite species. Among those orchards, chemical spray history was also analyzed from four orchards, which could be representatives of IPM practitioners. It was found that overall population densities of T. urticae were higher than those of P. ulmi for 16 years. Before 2000, T. urticae was dominant over P. ulmi in most orchards. However since 2000, P. ulmi have occurred more than or as much as T. urticae.. Moreover, although there was large fluctuation of occurrences of two mite species over the years and localities, spider mite pressure appeared to decrease, in general. It seemed to relate the timing of ground cover management with pheromone-based IPM implementation nationwide from late 90s. Panonychus ulmi appeared to rise in April and July in general, fall in August, and go up again in the late season; September-October, while T. urticae appeared to begin to rise in June with July or August peak and sometime with late season second peak in October. Application frequency of acaricide has been dropped from four times in the late 1990s to 2.5 times in the late 2000s.

In Jeju cirtrus orchards, Panonychus citri, citrus red mite is the most important pest requiring 3 times acaricide sprays. In open field conventional orchards, P. citri usually shows three population peaks; from end of Jun to July, from end of Aug. to Sep., from end of Oct. to Nov. However, natural enemy complex and its function regulating P.citri are poorly understood. From the survey of P.citri natural enemy in citrus orchard in Jeju from 2004 to 2006, predatory beetle, Oligota spp. was most abundant. Three predatory mite, N. californicus, Amblyseius eharai, and N. barkeri, were identified. Among them, the predatory mite, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae), was first found in Korea. Even though it was first found, N. californicus was the dominant species occupying 84% of phytoseiid mites. These predatory mites mostly occurred in Jun and peaked at July, which was accorded with the high humidity season of the year. From the survey, the density relationship with P. citri was unclear. From the study conducted in 2005-2007, N. californicus was more abundant in greenhouse citrus (var. Shirahuhi) than in open field orchards; conventional or organic mandarine citrus. In greenhouse citrus, phytoseiid mites showed suppressing P. citri population. As a next step, the inundative biological control study was conducted using commercial strain of N. californicus, which was originated from Jeju, 2005, in greenhouse citrus. One thousand N. californicus per 1a were released 2 times at 10 day interval on citrus leaves when the initial density of P. citri was about 0.2 per leaf. The release effects were variable depending on the field condition. However, N. californicus did successfully reduce P. citri in greenhouse citrus orchards.

Why do two-spotted spider mites (Tetranychus urticae) inhabit on the underside of leaves? Why are diapause females orange? A possible key to answering these questions is ultraviolet (UV) radiation. UV radiation directly damages DNA and produces reactive oxygen species (ROS). ROS also damages DNA, dissociates proteins, and oxidizes lipids. Because mites are small, the UV/ROS-induced damage would be lethal to mites. In non-diapause females, mortalities under UV-C (250 nm) at 0.6 W m–2 and UV-B (300 nm) at 2.4 W m–2 were significantly higher than those under continuous darkness (DD; control). Oviposition rates in such treatments were significantly lower than those under DD. No significant effects for mortality and oviposition rate were observed under UV-A (350 nm) even when the intensity was as high as 2.4 W m–2. In diapause females, the differences in mortalities between all types of UV radiation and DD were not significant. Interestingly, more than half of diapause females escaped from leaf disks under all types of UV radiation, and the escape rates were significantly higher than those under DD and those for non-diapause females. This suggests that diapause females exhibit negative phototaxis. Mites inhabit the underside of leaves in summer with dense vegetation. Most of UV radiation is absorbed and reflected by leaves. Therefore, the underside of leaves is considered a suitable environment for mites to avoid UV radiation, particularly UV-B (UV-C is completely absorbed by the ozone layer). In autumn, leaves start turning yellow and red as winter approaches and finally, fall. During this phenological event, the UV-B level in the plant canopy would increases dramatically while female mites enter diapause with a change in their body color from yellow-green to orange. It is known that the orange color is mainly due to the accumulation of β-carotene, which plays a role as a scavenger of ROS. Therefore, low mortalities observed in diapause females under UV-C and UV-B may be a result of β-carotene accumulation or merely due to the increase in the escape rate. Therefore, whether the escaped diapause females are resistant to UV-C and UV-B damage needs to be confirmed. Our findings suggest that UV radiation is utilized as an effective non-chemical measure to reduce the mite population and that the selection of habitat and change in body color is the mite’s strategy to reduce the deleterious effects of UV-B.

Molecular mechanisms of monocrotophos resistance in the two-spotted spider mite (TSSM), Tetranychus urticae Koch, were investigated. The resistant (AD) strain showed ca. 3,565-fold resistance compared to a susceptible (UD) strain. No significant differences in the esterase and gluthathion-S-transferase activities were found between two strains whereas AD showed a 1.9-fold higher mixed function oxidase activity. Acetylcholinesterase (AChE) inhibition assay revealed that the AChE from AD strain is 91-fold less sensitive to monocrotophos, suggestive of the target site insensitivity mechanism. Three point mutations (G228S, A391T and F439W/Y) in the AChE gene (tssmace) appeared to primarily contribute to the reduced sensitivity of AChE as judged by the correlation study of mutation frequency versus resistance levels (LC50) of several field populations. The resulting correlation coefficients of the G228S and F439W mutations were 0.711 and 0.300, respectively, suggesting that G228S mutation may play a more significant role in resistance. The A391T mutation, saturated in all field populations examined, appears to provide a base line resistance.

Six kinds of insecticides, fenpropathrin, dicofol, milbemectin, tebufenpyrad, monocrotophos and propargite, were selected for investigating LC50s to local two spotted spider mite(TSSM) strains. The TSSMs were collected from peach (Cheongdo area) and apple orchards (Chungju, Kunwi and Sobo areas) in 2005, from strawberry plastic house (Nonsan and Damyang areas) in 2006 for experiment and some insecticides selected TSSM strains for more than 20 generations were also used. Each strain was clustered by LC50 value got from six selected insecticides treatment. Every insecticide showed about three-fourfold LC50 difference among TSSMs caught in same area. There are no specific differences in LC50 patterns of TSSM to insecticides within peach orchard and among apple orchards. But TSSMs of apple orchard and peach orchard were clustered into different group each other. Grouping of selected TSSM strains with insecticides in lab artificially showed good relationship between action mechanisms of insecticides. In strawberry strains TSSM showed regional differences between Damyan and Nonsan. The TSSMs of Nonsan showed more resistance to Tebyfenpyrad and Propargite, but TSSM of Damyang was more resistant to fenpropathrin than that of Nonsan. The TSSMs selected with monocrotophos and bifenazate, known as acetylcholinesterase inhibitors, and also pyridaben and chlorfenapyr, known as inhibitors of mitochondrial electron transportation, were grouped close respectively.

In Korea, the backgrounds of predatory mite introduction are increase of the higher income level and the consumer interested in environmental-friendly agricultural products. So, the studies on pest control with natural enemy instead of pesticide have been increased. In early days of natural enemy research in Korea, domestic natural enemies as like Amblyseius womersleyi Evans were attempted for control of spider mites in orchard and greenhouse. As the number of crops and the cultivation area in greenhouse were rapidly increased till now, it is preferred not to find and mass-rear dominant species but introduce the natural enemy species from other countries which are suitable under greenhouse environment (high temperature, low humidity). Chilean predatory mite (Phytoseiulus persimilis Athias-Henriot) was a first natural enemy mite imported from other country and utilized for control of two-spotted spider mite in strawberry greenhouse. The attempt was successful and use of Chilean predatory mite was expanded national widely. After then, pest control by natural enemy has been increased and several companies which produce and sell natural enemies commercially were established. The government recommends the policy, the environmental-friendly agriculture without pesticide for safe and high-quality agricultural product, and gives financial support to farmers. The predatory mites to allow import into Korea in present are 4 species : Phytoseiulus persimilis Athias-Henriot, Amblyseius cucumeris (Oudemans), Hypoaspis aculeifer (Canestrini), and Amblyseius swirskii Athias-Henriot. These predatory mite natural enemies are mainly included in Phytoseiidae (Acari) and introduced and sold to control small animal pest as like spider mites and thrips.

Recognition and discrimination ability of organisms is assumed in numerous biological and ecological contexts. Recognition systems research has originally focused on intraspecific interactions and social recognition but is similarly applicable to interspecific interactions and recognition of environmental features. Common features of recognition systems are at least two participants, called cue bearer (sender) and evaluator (recipient), and three components, expression, perception, and action (Sherman et al. 1997, Liebert & Starks 2004, Mateo 2004, Starks 2004). The recognition systems concept provides a unified framework for studying and understanding recognition processes across biological and ecological contexts. In general, recognition may be indirect, mediated by third organisms or environmental features of the cue-bearer, and direct. I here focus on the latter type of recognition and emphasize how direct recognition processes govern intraand inter-specific interactions within and between plant-inhabiting arthropod species and the plant they inhabit. All species dealt with have relevance in agriculture as either herbivorous pests or natural enemies. Each studied system represents a subset of a multi-trophic community that may occur in natural settings and may be artificially created in greenhouse crops in the course of biological control (Figure 1). The interacting organisms in this community are the predatory mites Phytoseiulus persimilis and Neoseiulus californicus, their prey, the herbivorous two-spotted spider mite Tetranychus urticae and western flower thrips, Frankliniella occidentalis, the host plant of the herbivores, common bean, Phaseolus vulgaris, and a below-ground symbiont of bean, the mycorrhizal fungus, Glomus mosseae. Highlighted topics include mycorrhiza-induced host plant quality recognition by T. urticae (Hoffmann et al. 2008), recognition of and preference towards T. urticae life stages by P. persimilis (Blackwood et al. 2001, 2007), predator recognition and within plant dispersion of T. urticae (Walzer et al. 2008), predator recognition by F. occidentalis and trait-mediated predator effects (Walzer & Schausberger 2008), early learning and recognition of F. occidentalis by N. californicus (Schausberger et al., 2008), intraguild predator recognition with emphasis on P. persimilis and N. californicus (Schausberger & Croft 2000ab, Schausberger & Walzer 2001, Walzer & Schausberger 1999, Walzer et al. 2006), and kin recognition and cannibalism by P. persimilis (Schausberger & Croft 2001; Schausberger 2005, 2007; Schausberger & Hoffmann 2008). The organizational level worked with in the aforementioned studies primarily was the individual level but also included populations and communities; the experimental scale ranged from artificial cages, to detached leaf cultures and whole plants. For each recognition system and ecological context I emphasize the adaptive significance of recognition and indicate, if applicable, the potential population consequences of a given recognition process. In conclusion, I argue that recognition systems are ubiquitous in the studied multi-trophic community and point at the relevance of recognition systems research to biological control.

This study was conducted to investigate the regional difference in the degree of resistance development of the spirodiclofen 36% WP, an acaricide of tetronic acid class, against two-spotted spider mite, Tetranychus urticae occurred in apple orchard. Two-spotted spider mite was collected from every three regions in the Chungbuk and Gyeongbuk. To compare with the degree of resistance development, this pest was focused on the ovicidal activity (when treated acaricide). The managed orchard in Sancheok-myeon, Myeongseo-ri, Chungju was controlled by several different acaricides from 2001 to 2007, and spirodiclofen WP was used for the last six years. In case of managed orchard, LC50 of spirodiclofen WP was 14.0 ppm, it showed 1.6 fold (resistance ratio) that was estimated as considerably low level resistance ratio comparing to the those of susceptible strain showed in 8.7 ppm. LC50 of spirodiclofen WP against etoxazole-resistant two-spotted spider mite, gained from Chungbuk National University, was investigated in 7.5 ppm. This observation indicates that spirodiclofen WP did not occurred in cross resistance with etoxazole SC. At other regions in Chungju, the resistance ratio against spirodiclofen WP showed as 1.0 and 1.4 fold, respectively. In Gyeongbuk, one region of Yecheon and two regions of Yeongju, it showed as 0.7, 0.8 and 0.9 fold, respectively.

The study was conducted to investigate dispersal of T.urticae and its predatory mite on connected strawberry leaves. The experiments were run on laboratory conditions, 24±1℃, 50-65% RH, and a photoperiod of 16:8 (L:D). The excised leaf disk (diameter 3cm) of two strawberry varieties- Maehyang, Seolhyang- were placed upside down on a water-saturated cotton pad in an aluminum pan (width x length 17.4 x 21.5cm). Twenty leaf disks were placed on each experimental set and the disks (width x length 4 x 5 ca) were connected with each other for dispersing of T. urticae and its predatory mite. There were six different experiment sets - two strawberry varieties and three treatments (no predatory mite, releasing Neoseiulus californicus, and releasing Phytoseiulus persimilis). The experiment sets were covered with plastic cage to protect from invading other insects and mites. The investigation was conducted by examining two or three times per week and all life stages of T. urticae and predatory mite were reported until all leaves were occupied by mites. Repeated-measures data were analyzed by MANOVA. The average number of T.urticae per cm2 was no significant difference between two strawberry varieties in no predatory mite system (F=0.65, p>0.4195). Although the external structure of two strawberry varieties is very similar the dispersal rate of T. urticae was different between two strawberry varieties in all experiment sets. However, the number of T. urticae per cm2 was no significant different (df=1, F=1.28, p>0.2628). Within the same strawberry variety T.urticae populations among experiment sets were significant different (df=2, F=14.95, p<0.0001 Seolhyang, df=2, F=15.03, p<0.0001 Maehyang).

House dust mite of the indoor environment is one of the most important causes of allergic asthma and rhinitis. It has been known that more than 70% of Korean children and about 50% of adult with the respiratory allergy are sensitive to house dust mite. The purpose of our study is to find out the relationship between the concentration of formaldehyde (HCHO)/PM10 and the number of house dust mite in the indoor environment. In this study, sampling sites were education, social and dwelling facilities. We inquire the questionnaire of the resident on the indoor air quality in all sampling sites. At the same time, we measured the concentration of formaldeh yde(HCHO)/PM10 as well as house dust mites. it was complained by 20% respondents that the indoor air quality was bad and by 10% that the atopy symptom was evident. When a certain amount of house dust mites were detected, the contents of PM10 were observed high and that of HCHO low. However when the house dust mites were not detected, the concentration of PM10 was low and that of HCHO high. From our results, it is concluded that the indoor air quality (i.e. conc. of PM10/HCHO) is quite related to the contents of house dust mites supporting the fact that the symptom of atopy and asthma is due to these small organisms.

The insecticidal potency of some essential oils have been suggested that they may find an application in the control of house dust mites. We compared the repellent effect of four essential oils ; lemon grass (Cymbopogon nardus), lavender(Lavandula vera), rosemary(Rosmarinus officinalis) and ylang ylang(Cananga odorata). The oils were exposed at different doses(0.1, 0.05, 0.025, 0.0125, and 0.00652 ㎕/㎠) and different times(1, 2, 3, 4, 5 hours) on house dust mites(Dermatophagoides farinae and D. pteronyssinus). The repellent effects(%) of essential oils that were exposed at 0.1 ㎕/㎠ and for 1 hours against house dust mites were lemon grass(63.3%) and rosemary(61%), lavender(40%), ylang ylang(40%) in the order named.

본 연구는 훼손되지 않은 천연보호림인 점봉산의 고도 1,000미터 지점의 이웃한 남북사면의 서식처 환경차이에 따른 날개응애의 군집구조를 분석을 통한 생태계 구조를 이해함을 목적으로 1994년 5월부터 1996년 8월까지 매월 조사를 수행하였다. 두 조사지에서 채집, 동정한 날개응애의 종수및 개체수 비교에서는 유의성 있는 차이를 보였는데(t-test, p〈0.05), 북사면의 평균 밀도와 종수는 99.2±17.6, 24.7±3.0이고 남사면에서는 234.2±62.6, 40.8±5.8였다. 종다양도는 남사면이 3.09±0.11로 북사면 2.71±0.13보다 높게 나타났다. 날개응애의 개체군 크기를 전체 밀도에 대한각종의 밀도 백분율로 구하여 우점종, 중세종 그리고 약세종으로 나누어 나타내었고, O. nova와 Suctobelbella naginata가 조사지 모두에서 우점종으로 나타났고, Trichogalumna nipponica는 남사면에서는 우점종이었으나, 북사면에서는 채집이 되지 않는 종이다. 두 조사지의 우점종의 먹이 습성은 토양미생물을 섭식하는 식균성(microphytophagous) 이었다. 고도 1,000미터 지점으로 서로 이웃한 남/북사면 조사지에서 종수 및 개체수, 우점종 구성이 뚜렷한 차이를 보였고, 조사지별 유사도가 낮게 나타나 미소환경의 이질성이 날개응애 군집의 특성에 큰 영향을 미침을 알 수 있었다

2000년 12월 경북 칠곡의 장미재배지에서 채집한 점박이응애를 실험실에서 4년 동안 bifenizate로 150회 이상 도태하여 248.8배의 저항성계통을 얻었다. 이 저항성 계통의 유전과 9종 살비제에 대한 성충과 알의 교차저항성 유무를 조사하였다. 감수성계통 수컷과 저항성계통 암컷을 상호교배하여 얻은 우성도는 성충과 알에 대해서 각각 0.48, 0.94로 불완전우성이었으며, 으로 상호 교배하여 얻은 우성도는 성충과 알에 대해서 각각 -0.85, -0.17로 불완전열성이었다. 이 저항성 점박이응애의 성충은 acequinocyl, fenpyroximate에 대해 각각 9.9, 5.0배의 교차저항성을 나타내었으며, emamectin benzoate, milbemectin에 대해서는 각각 0.14, 0.04배의 역상관교차저항성을 나타내었다. 알은 amitraz, emamectin benzoate, fenpyroximate, milbemectin, pyridaben, spirodiclofen에 대해 각각 22.0, 11.7, 32.3, 16.3, 394.8, 19.5배의 교차저항성을 나타내었으며, abamectin에 대해서는 0.01배의 역상관교차저항성을 나타내었다.