Predation, development, and ovipostion experiments were conducted to evaluate Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae) as a potential biological control agent for tomato russet mite, Aculops lycopersici (Massee) (Acari: Eriophyidae) which is a periodic pest of greenhouse tomatoes. Results show that A. swirskii attacked all developmental stages of A. lycopersici, and had a type II functional response on the prey densities given. The predation rates of A. swirskii on A. lycopersici in the presense of alternative food sources such as pollen, thrips first instar, or whitefly eggs were recorded as 74%, 56%, and 76%, respectively of the predation rate on A. lycopersici alone. Amblyseius swirskii successfully completed their life-cycle on either A. lycopersici or cattail pollen. At 25oC, 70% RH, development time of female A. swirskii fed on A. lycopersici or on cattail pollen took 5.0 and 6.2 days, respectively. For the first 10 days after moulting to the adult stage, A. swirskii fed on A. lycopersici had higher daily oviposition rate (2.0 eggs per day) than on pollen (1.5 eggs per day). From this laboratory study, it can be concluded that A. swirskii has promising traits as a predator against A. lycopersici and that their populations can be stably maintained using alternative food such as cattail pollen. We suggest that the effectiveness of A. swirskii against A. lycopersici under field conditions deserves to be investigated.

Biological Characteristics of Lycorma delicatula and insecticidal activity of some insecticides against nymphs of L. delicatula was investigated. Nymph of L. delicatula had 4 instars, and color of body was black. There were white spots on the body of 1st-3rd nymph. Upper body became red at 4th nymph. Adult forewings were brownish, and had black spots. Color of hind wing were red. The egg mass was covered with a yellowish brown secretion. The adult of L. delicatula emerged once a year. Among test insecticides, deltamethrin 1% EC and fenitrothion 50% EC showed very quick and strong insecticidal activity against the 2nd-3rd nymphs of L. delicatula. Imidacloprid 4% SL and clothianidin 8% SC showed 100% insecticidal activity at 24h after treatment. Thiacoprid 10% SC revealed the weakest insecticidal activity among the insecticides tested.

Five effective strains against tobacco cutworm, Spodoptera litura (Lepidoptera: Noctuidae), Steinernema carpocapsae (GSN1), Steinernema sp. (GSNUS-10), Steinernema sp. (GSNUS-14), Heterorhabditis bacteriophora Hamyang (HbH), and Heterorhabditis sp. (GSNUH-1) were selected among 14 isolates of Korean entomopathogenic nematode in laboratory tests. LC₅₀ values of above five strains against tobacco cutworm were various by different nematode strains and developmental stages of tobacco cutworm. LC₅₀ value of S. carpocapsae (GSN1) was the lowest by 4.0~8.3 infective juveniles (Ijs) and 2nd instars of tobacco cutworm was most susceptible. Pathogenicity of five effective strains against tobacco cutworm depends on nematode strain, concentration, and application times. The most effective strain was determined as S. carpocapsae (GSN1). Two or three times of applications were effective regardless of nematode strain, or concentration. Efficacy of S. carpocapsae (GSN1), Steinernema (GSNUS-10), Steinernema (GSNUS-14), and Heterorhabditis (GSNUH-1) was variable depending on nematode strain, concentration, application times, and host variety. S. carpocapsae (GSN1) was the most effective and inoculation of 100,000 infective juveniles per ㎡ (720,000 Ijs/7.2 ㎡=1×10⁹ Ijs/㏊) resulted in higher efficacy. Three times of application of nematodes led to higher control efficacy than one or two applications. Efficacy of nematodes was higher on Chinese cabbage than cabbage or kale.

Due to internal feeding behavior, the oriental tobacco budworm, Helicoverpa assulta (Guenée), infesting hot pepper has been regarded to be effectively controlled by targeting egg and neonate larval stages just before entering the fruits. This study aimed to develop an efficient biological control method focusing on these susceptible stages of H. assulta. An egg parasitoid wasp, Trichogramma evanescens Westwood, was confirmed to parasitize the eggs of H. assulta. A mixture of Gram-positive soil bacterium, Bacillus thuringiensis subsp. kurstaki, and Gram-negative entomopathogenic bacterium, Xenorhabdus nematophila ANU101, could effectively kill neonate larvae of H. assulta. A sex pheromone trap monitored the occurrence of field H. assulta adults. The microbial insecticide mixture was proved to give no detrimental effects on immature development and adult survival of the wasp by both feeding and contact toxicity tests. A combined treatment of egg parasitoid and microbial pesticide was applied to hot pepper fields infested by H. assulta. The mixture treatment of both biological control agents significantly decreased the fruit damage, which was comparable to the chemical insecticide treatment, though either single biological control agent did not show any significant control efficacy. This study also provides morphological and genetic characters of T. evanescens.

In 2005, the invasion of Bemisia tabaci Q-type was detected at first in the southern part of Korea. And then the pest has been spread rapidly over the nation, and it has attacked various fruit vegetables including yellow melon, tomato, sweet pepper, and so on. During three years since 2005, many kinds of predators and parasitoids have been applied to establish the biological control program to solve the Bemisia tabaci problem. Parasitoids were regarded as promising natural enemies, at first. However, Encarsia formosa famous for the parasitoid of greenhouse whitefly is not so effective to control Bemisia tabaci. Although other parasitoids, Eretmocerus eremicus and Eretmocerus mundus, were introduced successively, application results of them were not satisfactory. Owing to the difficulties in settling the parasitoids on crops, total cost of biological control program tends to be increased by the iterative periodic release. On the other hand, it was great that the application result of predatory mite, Amblyseius swirskii. Laboratory experiments show that the mite can consume large amount of Bemisia tabaci eggs. In addition, the mite can survive and reproduce without prey. Plant-associated materials such as pollens are sufficient for the development and reproduction of the mite. Field observations reveal that just onetime release after the first blossom is enough for the preventive treatment. The mite is especially so effective on the pollen-rich crops such as sweet pepper. Flowers and leaves are infested by the mite in a brief instant. While flower-dwelling mites take a role of natural enemy of thrips, leaf-dwelling mites effectively suppress the density of Bemisia tabaci. Anyway, curative treatment of the mite is not desirable, for it usually do not feed on other stage of Bemisia tabaci except fresh eggs within one or two days. It is also unfortunate that the mite seldom moves on tomato. It is even reluctant to go out from distribution box. When we put some mites on a leaf of tomato, they usually aggregated in a point. Sticky trichomes and semiochemicals might be engaged in such phenomena. In addition, the mite seems to be suffered by high temperature. So the density of Bemisia tabaci could be increased continuously in summer season, regardless of the presence of the predatory mite. In recent, we keep an eye on another predatory bug, Nesidiocoris tenuis, as a biological control agent against whiteflies on tomato. Nesidiocoris tenuis is an active and aggressive natural enemy. It likes to eat whitefly eggs, larvae and pupae. It can also feeds on aphids and mites. Once established in tomato greenhouse, whiteflies were overwhelmed by the predator. In our observation, Bemisia tabaci could be successfully controlled by the predator without any pesticide application, during about a half year from early spring to mid summer. However, we should take precaution against the side effects of Nesidiocoris tenuis, which is ironically known as a serious pest on tomato. From time to time, growing points of tomato could be disappeared by the damage of Nesidiocoris tenuis. So we need to control the density of the bug under the economic threshold. Owing to the bug, the production of sesame could be decreased remarkably. To avoid side effects, Nesidiocoris tenuis should be handled by the experts who know well about the ecological characteristics of it. In the case of yellow melon, biological control of any pest is not easy task. Without pesticide, yellow melon is frequently damaged destructively by aphids, mites and whiteflies. However, the temperature in greenhouse is too high to release and augment ordinary natural enemies. We just regard Nesidiocoris tenuis as a promising natural enemy of whiteflies on yellow melon, because it is resistant to high temperature. Many trials and errors might be required to establish reliable strategy to solve the problem caused by Bemisia tabaci. And it should be continued that the efforts for the integrated pest management based on biological control.

Environmental tolerance of three important spider mite predators; Neoseiulus womersleyi, Neoseiulus californicus and Phytoseiulus persimilis (Phytoseiidae) was experimented by treating combination of temperature and relative humidity for egg hatching and immature survival. Egg hatching rate increased at the relative humidity incrased for three species. Temperature effects were only significant to N. californicus and P. persimilis. The lethal humidities for three species were in the range of 56-77, 82.0, 66-94% RH, respectively. Larva does not need to feed for larval development into protonymph in three tested species. No larvae survived at lower than 75% RH for N. womersleyi, but around 80% at 95% RH. N. californicus larvae survived around 50% and 100% at 75 and 95% RH. P. persimilis larve survival was decreased as the temperature increased at 75% RH, but platued around 100% at 95% RH. Cannibalism was higher in N. californicus and lower in P. persimilis. Implementation of the results was discussed relative to biological control of spider mites in open field and greenhouse crops.

As indigenous aphid parasitoid, Aphelinus varipes kill aphids for feeding in addition to parasitization. Because of this characteristic of A. varipes, this parasitoid may have the possibility of biological control agent against aphids. So we have evaluated traits such as daily paratization, total parasization, number of aphids killed by host feeding, sex ratio, development time, pupal mortality of A. varipes parasitizing green peach aphid, Myzus persicae. At 25°C and 16L:8D, longevity, total paratization and host feeding of A. varipes female was 11.0, 25.3, and 63.3 days, respectively. And development time of male and female, sex ratio (M:F), pupa mortality of offspring of A. varipes were 12.0 days, 12.5 days, 0.88, and 11.6%, respectively. However, because these results are not enough to estimate potential of A. varipes as biological control agents/factors, other factors such as host suitability (Macrosiphum euphorbiae, Aulacorthum solani), effect of temperature, and host seeking behavior of A. varipes continually will be investigated.

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.

Models are useful tools for understanding and improving biological control of arthropod pests by means of natural enemies. Thus, models can be applied to simulate various scenarios in order to identify optimal control strategies. Although simulations can never replace real experiments, they can often serve as guidelines for choosing relevant field experiments and thereby save a lot of laborious and costly field work. Whereas the processes underlying population dynamics (e.g. dispersal, functional response, mutual interference) can be studied under laboratory conditions, large-scaled experiments in the field or in greenhouses are unsuited for this purpose. Instead such experiments may provide information about the patterns (e.g. spatial distributions of prey and predators) generated by the underlying processes. A major purpose of modeling is to link the patterns to the processes that generate these patterns. Petri-dish and single plant experiments have clearly demonstrated the capacity of predacious mite Phytoseiulus persimilis to feed effectively on the two-spotted spider mite Tetranychus urticae. This quickly leads to reductions in the abundance of prey, followed by a decline in predator abundance and eventual extinction. However, when larger systems, consisting of many hundred plants, are infested with the two mite species, extinction of one or both species seems less likely at the system level, although it may still occur at the individual plant level. The qualitative difference between small and large systems with respect to persistence and extinction risks is attributed to the fact that mites move among plants, but to prove that dispersal per se plays a role for the overall dynamics is hard to demonstrate experimentally. To circumvent this problem, I developed a stochastic simulation model of a greenhouse system that explicitly incorporates within and between plant dynamics. The model is used for analyzing a series of experiments with biological control of spider mites in multi-plant systems. In these experiments, the number of plants as well as their connectivity and the numbers of introduced mites were varied in order to examine whether these factors affect e.g. the predator-prey ratio or the time to extinction of one or both species. In my presentation I will also demonstrate an interactive version of the model (called DynaMite). It allows the user to interfere in the system during a simulation so as to mimic the options a grower has in order to prevent losses and to maximize his profit. Such options include spraying with acaricides, releasing predators, and replanting in substitute of damaged plants. By choosing different control strategies, the user may gradually improve his skills according to the principle of learning by experience. The model can be freely downloaded from http://www1.bio.ku.dk/ansatte/beskrivelse/?id=43077

Occurrence of Liriomyza trifolii and its biological control efficacy using Neochrysocharis formosa were evaluated in two eggplant cropping systems of spring and autumn cultivation. L. trifolii adults began to be attracted on a yellow sticky traps from late April and they increased from early June. A high density of L. trifolii adults was maintained from middle June to middle July. The releases of two N. formosa per plant with 3 times as weekly intervals from May 25, 2004 for spring culture resulted control effect of 90.1% in parasitism to L. trifolii in late July. The releases of two N. formosa per plant with 4 times as weekly intervals from Auguest 31, 2004 for autumn culture resulted control effect of 81.3% in population of L. trifolii with 64.4-69.9% in parasitism.

Biological control of Liriomyza trifolii (Burgess) using Diglyphus isaea (Walker) has been evaluated in tomato greenhouse, for three seasonal culture types: spring type (March-July), summer type (June-October) and autumn type (July-December). For spring type, totally 5.8 individuals/㎡ of D. isaea has been released at six times from late April, when the density of L. trifolii was about 1.0 individuals/plant. Corrected mortality of Liriomyza trifolii caused by parasitoids was 97.6% at early July, and the proportion of D. isaea was 88.9% of all parasitoids collected in the greenhouse. In the case of summer type, totally 1.8 individuals/㎡ of D. isaea has been released at five times from early July, when the density of L. trifolii was about 0.4 individuals/plant. Corrected mortality of L. trifolii caused by parasitoids was 84.4% during the whole season, but the proportion of D. isaea was very low (only 13.8%). Immigrating parasitoids such as Chrysocharis penthus were synchronized to control the leafminer in the greenhouse. For autumn type, totally 2.7 individuals/㎡ of D. isaea has been released at four times from mid September, when the density of L. trifolii was about 0.7 individuals/plant. Corrected mortality of L. trifolii caused by parasitoids was 85.7% at mid December, and the proportion of the D. isaea was 83.4%.

Five strains of Korean entomopathogenic nematodes (EPN), steinernematids and heter-orhabditids were evaluated and tried in laboratory, pot, and vegetable greenhouses for environmentally friendly control of diamondback moth (DBM), Plutella xylostella, from 2002 to 2005. LC₅₀ values of five EPN strains against DBM were different depending on nematode strain and DBM instar. LC₅₀ value of Steinernema carpocapsae GSN1 (GSN1) was the lowest representing 2.6~3.9 infective juveniles (Ijs, 3rd stage) to 2nd to 4th instars of DBM. Pathogenicity of five effective strains against DBM was different depending on nematode strain, concentration, application times, and vegetable in pot. The most effective nematode was GSN1. Steinernema spp. was more effective than Heterorhabditis spp. against DBM. Two or three times of applications of EPN were effective regardless of nematode strain and concentration in pot. Efficacy of EPN was different depending on vegetable species. Efficacy was higher on Chinese cabbage, red mustard, and Ssamchoo than that on cabbage, kale, and leaf broccoli. Efficacy of GSN1, Steinernema GSNUS-10, Steinernema GSNUS-14, and Heterorhabditis GSNUH-l was variable depending on nematode strain, concentration, application times, and vegetable in greenhouse experiments. GSN1 was the most effective and 100,000 infective juveniles per ㎡ (=1 × 10⁹ Ijs/ha) resulted in higher efficacy. Three times of application of nematodes led to higher control efficacy than one or two applications. Efficacy of nematodes was higher on Chinese cabbage than cabbage or kale in greenhouse.

This study was carried out to clarify the biologies and morphological characteristics of Rhynchaenus sanguinipes. Also some chemicals were tested to screen the effective insecticide for the control of the species. Up to date, Zelkova serrata has been known as host plant of Rhynchaenus sanguinipes, which shows serious damage in this country. In the present study, Ulmus pumila was first found as host plant in this study. Body lengths of larvae, pupa and adult were 4.53±0.30 ㎜, 3.30±0.42 ㎜ and 2.96±0.12 ㎜, respectively. The overwintered adult of the species emerged on early April to late April, and adult of next generation emerged on early May to late May. Pupal periods were 10, 7.2, 5.1 and 4 days on 16, 20, 24 and 28℃, respectively. The lower developmental threshold temperature was 5.8℃. Four braconid parasitoids were found as natural enemies, which emerged mainly on late April to early June. Insecticidal activities with treatments of fenitrothion 50% EC, indoxacarb 30% WG, ethofenprox 20% EC and thiacloprid 10% SC was investigated against adult of R. sanguinpes, and they showed ＞90% mortality.

Biological control of Tetranychus urticae by Phytoseiulus persimilis was observed in eggplant greenhouse for spring and autumn season culture. Tetranychus urticae was controlled to low density of less than 1 mite from June 24 after P. persimilis were released 3 times at rate of 10 per plant on June 1, 11, and 18, 2004 in spring season experiment. The population of Tetranychus urticae was also less than 1 mite per eggplant leaf from September 1 to October 22 after three times releases of 10 P. persimilis in autumn season experiment. In Phytoseiulus persimilis released plot, the percentage of leaves with T. urticae adults and nymphs were 8.6~13.3% and 5% or less in spring and autumn season experiment. The density of T. urticae was from 1 to 2 on leaves with T. urticae adults and nymphs.

Effectiveness of Orius strigicollis (Poppius) and Amblyseius cucumeris (Oudemans) as natural enemies against thrips were evaluated on greenhouse green pepper, sweet pepper and cucumber respectively. Control efficacy was calculated by the formula, (D<SUB>control</SUB> - D<SUB>treatment</SUB>)/D<SUB>control</SUB> × 100, where D<SUB>control</SUB> is the average density of thrips on the plots in which any natural enemy was not released and D<SUB>treatment</SUB> is the average density of thrips on the plots in which natural enemies were released respectively. As a result, control efficacies of O. strigicollis against Frankliniella occidentalis (Pergande) on green pepper and sweet pepper were 14.3~99.5% and 21.6~98.3%, respectively. In addition, control efficacy of it against Thrips palmi Kany on cucumber was 61.2-74.4%. Control efficacies of A. cucumeris against F. occidentalis on green pepper and sweet pepper were 12.9~38.3% and 17.1~87.0%, respectively. Control efficacy of it against T. palmi on cucumber was 90.4~97.4%. Field evaluation showed that the prompt applications of natural enemies were effective to reduce the density of thrips. In detail, to control F. occidentalis effectively on green pepper and sweet pepper in spring season, five to six individuals of O. strigicollis per crops should be released three to six times continuously. To control T. palmi effectively on cucumber in autumn, more than 100 individuals of A. cucumeris per crop should be released four times repeatedly.