Do-Ik Kim

Screening of Some Crude Plant Extracts for Their Acaricidal and Insecticidal Efficacies

Abstract Methanol extracts from 28 samples of 22 plant species in 17 different plant families were tested at 10, 000 ppm for evaluating their insecticidal and acaricidal activities against Tetranychus urticae Koch, Aphis gossypii Glover, Myzus persicae Sulzer, Trialeurodes vaporariorum (Westwood), and Panonychus citri (McGregor). In a test with T. urticae, extracts from Albizzia coreana twig and Pyracantha angustifolia leaf possessed potent acaricidal activities. Reproduction of T. urticae for three days significantly decreased in the extract treatments of Gardenia jasminoides, Ficus carica, and Albizzia coreana twigs. Though slight repellent activities against T. urticae were obtained from extracts of Camellia japonica seed, G. jasminoides peel and fruits, Ligustrum japonicum leaves, A. coreana twig, and Machilus thunbergii leaves in 24 h after treatment, but tended to decrease in 72 h. Extracts of F. carica leaves and G. jasminoides fruits had potent insecticidal activities against M persicae and A. gossypii. Methanol extracts of F. carica leaves possessed insecticidal activity against T. vaporariorum. In a field test with P. citri, extracts from C. japonica seeds, A. coreana leaves, Ranunculus japonicus leaves and roots, an Houttuynia cordata leaves exhibited acaricidal activities.

Occurrence Ecology of Ricania sp. (Hemiptera: Ricaniidae) and Selection of Environmental Friendly Agricultural Materials for Control

An outbreak of Ricania sp. occurred in the Kurye, Jeonnam area in 2011. This outbreak damaged many kinds of fruit trees such as Cornus, Persimmon and Chestnut. This experiment was conducted to survey the occurrence ecology of Ricania sp. such as host plants, oviposition characters, morphological characters and life cycle, as well as to select environmental friendly control agents. Ricaina sp. host plants included 51 species such as 32 xylophytes, and 19 herbaceous plants. Ricaina sp. preferred Cornus officinalis, Diospyros kaki, Castanea crenata, Eucommia ulmoides, Styrax japonicus for oviposition. Adults laid eggs on new inner twigs with 28.8 eggs per egg-mass. Egg size was 1.24 mm(length), 0.55 mm(width) in an oval shape. Nymphs molted four times. Every nymph stage had an x shape of yellow or white beeswax around the anus. Overwintered eggs of Ricania sp. hatched from the mid May to early June. Nymphal periods were from mid May to mid August and adults appeared from mid July but spawning began in mid August. Ricania sp. damaged new twigs by oviposition and retarded growth by sucking nutrients and producing a sooty mold. Sophora and natural plant extracts were effective environmentally friendly agricultural materials used to control the nymph and adult Ricania sp. Mortality was > 80%.

Evaluation of Toxicity of Plant Extract Made by Neem and Matrine against Main Pests and Natural Enemies

KNI3126 which is the eco-friendly material made by plant extracts - neem and matrine - have been evaluated for efficacies against 6 main pests and toxicity on natural enemies. Insecticidal efficacies of KNI3126 against plant hopper were above 95% at 5 days after treatment (DAT), whereas pesticidal effects against the cotton aphid were above 95% at 3 DAT and slightly decreased at 5 DAT. Insecticidal efficacy against the palm thrips resulted in lower control value as 68.1% than that of chemical insecticides. KNI3126 showed more than 95% control value against diamond back moth, suggesting that it could suppress the population of pest hard to control as eco-friendly material. Mortalities against two-spotted spider mite were about 80% at 1 DAT and over 90% at 5 DAT, respectively. For evaluation of the toxicity on natural enemies, effect against predatory natural enemy was classified as moderate selective toxicity based on the criterion of International Organization of Bio-Control (IOBC), whereas against parasitic natural enemies was found to be relatively safe. Repellent effect was weak against plant hopper, but strong against two-spotted spider mite. In the toxicity test for safety, KNI3126 was classified as the lowest level at acute oral, acute dermal and fish toxicity test and did not induce the irritancy at skin irritation test and eye irritation test.

Biological Control of Thrips palmi (Thysanoptera: Thripidae) with Orius strigicollis (Hemiptera: Anthocoridae) on Cucumber in Plastic Houses in the Southern Region of Korea

Abstract Field evaluations were conducted to determine the efficacy of Orius strigicollis for biological control of Thrips palmi with different initial density in plastic houses. O. strigicollis released three times after 0, 5, 30, 100 thrips were inoculated per 30 cucumber plants. Three hundred and sixty predators were released in each plot. After inoculation of 5 T. palmi per 30 plants in each plot in plastic houses, T. palmi population increased rapidly with 16.3 individuals per plant in the fourth week, and O. strigicollis could not suppress T. palmi population because O. strigicollis population did not build up quickly. In the plot of 30 thrips inoculation, the density of O. strigicollis increased to 2.1 individuals per plant in the third week and 9.8 individuals per plant in the sixth week. The density of T. palmi increased to 33.8 individuals per plant in the sixth week. In the 100 thrips inoculation plot, the density of O. strigicollis increased to 9 individuals per plant in sixth week, which was similar to that in the 30 thrips inoculation plot. But the density of T. palmi increased rapidly from 2.9 to 384.7 individuals per plant in the sixth week. So, control of T. palmi by O. strigicollis did not appear. In autumn culture, in the 5 thrips inoculation plot, the density of O. strigicollis was so low that it could not suppress thrips density. In the 100 thrips inoculation plot, the density of T. palmi was so high that O. strigicollis could not suppress T. palmi density. In the 30 thrips inoculation plot, the density of O. strigicollis was 4.8 individuals per plant in the sixth week and the thrips population was suppressed. But O. strigicollis could not suppress the thrips population after sixth week because of low temperature and short photoperiod. These results indicate that control of T. palmi using O. strigicollis may be possible on cucumber in the spring culture.

Determination of Economic Injury Levels and Control Thresholds for Spodoptera exigua on Chinese Cabbage

Economic injury level and control thresholds for the management of beet army worm, Spodoptera exigua (Lepidoptera: Noctuidae) were evaluated on chinese cabbage of two different planting time. Two inoculation times were tested for each planting and the number of inoculated larva was 10, 20, 40, 80, respectively. Damages of leaves by first inoculation were 63.2% after eight days planting on 80 larva inoculation plot. By the second inoculation, those were below 50% after 20 days planting on the end of September. The linear relationships between population density and yield reduction were as following; Y

Temperature-dependent Development Model of Larvae of Mealworm beetle, Tenebrio molitor L. (Coleoptera: Tenebrionidae)

The developmental times of mealworm beetle larvae, Tenebrio molitor were studied at six temperatures ranging from 15 to with 60~70% RH, and a photoperiod of 14L:10D. Mortality of larval period was very low at 17 and but did not die over . Developmental time of larva was decreased with increasing temperature. The total developmental time of T. molitor larvae was longest at (244.3 days) and shortest at (110.8 days). Egg and larvae were not developed at . The lower developmental threshold and effective accumulative temperatures for the total larval stages were and 2564.1 degree-days, respectively. The relationship between developmental rate and temperature was fitted by a linear model and nonlinear model of Logan-6(

Environmentally-friendly Control Methods and Forecasting the Hatching Time Lycorma delicatula (Hemiptera: Fulgoridae) in Jeonnam Province

This study was conducted to predict the hatching time of eggs of Lycorma delicatula, to select an effective environmentally-friendly agriculture material (EFAM) and to evaluate the attraction effect of brown sticky traps for controling of Lycorma delicatula nymph and adults. Eggs hatched 55.9, 26.8, 21.6 days after incubation at 15, 20, with 14L:10D condition and the hatching rates of egg were 61.9, 57.8, 30.4%, respectively. At high temperature conditions, egg development periods were shorter and the hatching rate was lower. The relationship between temperature and developmental rate was expressed by the linear equation Y

Comparison of Development times of Myzus persicae (Hemiptera:Aphididae) between the Constant and Variable Temperatures and its Temperature-dependent Development Models

The developmental time of the nymphs of Myzus persicae was studied in the laboratory (six constant temperatures from 15 to 30℃ with 50~60% RH, and a photoperiod of 14L:10D) and in a green-pepper plastic house. Mortality of M. persicae in laboratory was high in the first(6.7~13.3%) and second instar nymphs(6.7%) at low temperatures and high in the third (17.8%) and fourth instar nymphs(17.8%) at high temperatures. Mortality was 66.7% at 33℃ in laboratory and 26.7℃ in plastic house. The total developmental time was the longest at 14.6℃ (14.4 days) and shortest at 26.7℃ (6.0 days) in plastic house. The lower threshold temperature of the total nymphal stage was 3.0℃ in laboratory. The thermal constant required for nymphal stage was 111.1DD. The relationship between developmental rate and temperature was fitted nonlinear model by Logan-6 which has the lowest value on Akaike information criterion (AIC) and Bayesian information criterion (BIC). The distribution of completion of each developmental stage was well described by the 3-parameter Weibull function (r 2 =0.95~0.97). This model accurately described the predicted and observed occurrences. Thus the model is considered to be good for use in predicting the optimal spray time for Myzus persicae.

Control Thresholds for the Management of Beet Army Worm, Spodoptera exigua (Lepidoptera : Noctuidae) on Welsh Onion (Allium fistulosum L.)

Control thresholds for the management of beet army worm, Spodoptera exigua (Lepidoptera : Noctuidae) were evaluated on welsh onion of two different planting time. Two inoculation times were tested for each planting and the number of inoculated larva was 5, 10, 20, 40 per twenty plants. The injured rate of leaves was 33.5% to 10.9% at 7th September at 40 to 5 larva inoculation plot on the five days planting. That of leaves was 20.5% at 40 larva on the twenty days planting. The yields of welsh onion on non-inoculation plot were 4,395 kg per 10a. The rate of reduced yields was 49.2%(1,774.2 kg) and 36.5%(2,220.5 kg) at 40 larva inoculation on the 5 and 20 days planting, respectively. The linear relationships between population density and yield reduction were as following; it was Y

Pattern of the Occurrence of Tomato yellow leaf curl virus on Cultivation

Tomato yellow leaf curl virus (TYLCV) disease survey of tomato plants cultivated at Youngam, Changseong and Hwasun in Jeonnam Province was conducted in 2012 to 2013. To detect TYLCV in the field, PCR assay was performed using genomic DNAs extracted from tomato samples. According to cropping pattern, 23 and 59.4% of TYLCV infections were shown in semi-forcing and retarding cropping systems, respectively, and the frequencies of diseased plants were 0.4 and and 13.1% in the two cropping systems, respectively. Especially, TYLCV incidences in the susceptible varieties were 24.3 and 83.0% in semi-forcing and retarding cropping systems, respectively. Resistant varieties showed 9.1% infection in retarding cropping system but did not in semi-forcing cropping system. Also, TYLCV was occurred on early June after transplanting on April and at approximate 20 days after transplanting on August or September.