Myoung Rae Cho

Biological control of Meloidogyne arenaria by Pasteuria penetrans.

Abstract An obligate parasitic bacterium of nematode, Pasteuria penetrans 98–35 (PP), isolated from oriental melon greenhouse soil in Korea, was evaluated against root-knot nematode, Meloidogyne arenaria (MA), in tomato ( Lycopersicon esculentum Mill. var. Youngkwang) and oriental melon ( Cucumis melo L. var. Eunchun). Pot experiments were conducted by planting the tomato seedlings in a medium inoculated with 5,000 MA juveniles/pot (J2), J2+100,000 PP endospores/1 g medium, and J2+200,000 PP endospores/1 g medium. After 10 weeks from planting, root gall percentage in J2+100,000 and J2+200,000 PP endospores/1 g medium were significantly lower with 37.5% and 6.7%, respectively, compared with the J2 of 85%. In the second planting of tomatoes in the same pots, root gall numbers were significantly lower in PP treated pots representing 68.8 and 31.4/root in J2+100,000 and J2+200,000 PP endospores/1 g medium, respectively, compared with the J2 of 460.6/plant. In oriental melon experiment, numbers of root galls after 10 weeks from planting were significantly lower in J2+100,000 endospores/1 g medium with 32.5 compared with 64.1 and 87.5 in J2+100,000 endospores/1 g medium and the J2, respectively. However, there were no significant differences in plant growth characteristics among the treatments in the both crops.

PCR-RFLP Identification of Three Major Meloidogyne Species in Korea

Abstract Partial mitochondrial DNA from single female or second stage juvenile (J2) of root-knot nematodes was amplified by PCR (polymerase chain reaction), and the further analysis by RFLP (restriction fragment length polymorphism) provided discriminatory profiles useful for three major Meloidogyne species, M. arenaria, M. incognita , and M. hapla , in Korea. The nematode DNA was extracted individually in nuclease-free water. The sizes of PCR product (1.7 kb and 500 bp) and restriction patterns obtained from single female nematodes were consistent with the results from single J2 within the same species. M. hapla was easily differentiated from the two other root-knot nematode species by the size of the PCR products. A fragment of 500 bp was generated from M. hapla , while M. arenaria , and M incognita produced an 1.7 kb fragment in PCR amplification. M. arenaria could be distinguished from M. incognita by analysis of restriction enzyme digestion with Hinf I or Alu I. Hinf I had no digestion site in mitochondrial DNA of M. arenaria; however, it generated 1.3 kb and 400 bp fragments in M. incognita. Alu I digestion resulted in 1 kb, 460 bp, and 250 bp fragments in M. arenaria , but showed different digestion patterns in M. incognita by generating 800 bp, 460 bp, 250 bp, and 150 bp fragments.

On New Representatives of the Helminth Fauna of Reptiles (Testudines and Sauria) in Uzbekistan

Abstract In a survey on parasitic helminthes of reptiles comprising 8 species under the orders of Testudines and Sauria in different areas of the plain land and foothill zones of the Ferghana Valley of Uzbekistan from 1993 through 2001, 14 species of parasitic helminthes comprising 2 cestode and 12 nematode species new to the fauna of Uzbekistan were found. List of hosts by parasitic helminthes, extensiveness and intensity of the infection, the time and sites of findings of the helminthes are reported with brief descriptions and drawings of the female nematodes of Parapharhyngodon szczerbaki Radchenko et Shapiro, 1975, Mehdiella hamosa Forstner, 1960 and the male of Abbreviata schulzi Markov et Bogdanov, 1961.

Molecular Diagnosis of Grapholita molesta and Grapholita dimorpha and Their Different Occurrence in Peach and Plum

The plume fruit moth, Grapholita dimorpha Komai, a fruit tree pest occurring in the northeast Asia, was firstly reported to infest apple in Korea in 2009, but its direct damage to other fruit trees has been poorly studied. In this study, we investigated shoots and fruits of both peach and plum trees and compared their damage rates by G. dimorpha to those by G. molesta, a congeneric species. In order to discriminate the two moth species, we developed a molecular diagnosis method using species-specific primer sets on different PCR conditions and distinguished the two species collected from the damaged shoots or fruits. The shoots and fruits of peach were infested mostly by G. molesta. However, in plums, the shoots were damaged by G. molesta and the fruits mostly by G. dimorpha. In addition, these two species showed a clear difference in host preference in fruit damage, where 92.5% of the Grapholita moths collected in peach fruits were identified as G. molesta, but 97.0% of the moths in plum fruits were G. dimorpha. The difference of the damage between the two fruit trees may give important information for monitoring of the two moth species in these orchards.

Identification and field evaluation of the sex pheromone components of a Korean population of Glossosphecia romanovi

Glossosphecia romanovi (Leech) (Lepidoptera: Sesiidae) is a pest of grape in northeast Asia. We analyzed pheromone gland extracts of female moths and compared attractiveness of various pheromone blends to male moths in the field. Two major components from pheromone gland extracts were identified as (Z,Z)‐3,13‐octadecadien‐1‐ol (Z3,Z13‐18:OH) and (Z,Z)‐3,13‐octadecadienyl acetate (Z3,Z13‐18:OAc) in a ratio of approximately 9:1. Field tests showed that male G. romanovi were attracted to Z3,Z13‐18:OH alone, but the maximum number of males was attracted to the binary blend of Z3,Z13‐18:OH and Z3,Z13‐18:OAc mimicking the blend found in female extracts. In addition to these components, small amounts of (E,Z)‐3,13‐octadecadien‐1‐ol (E3,Z13‐18:OH) were detected in the pheromone gland of females, but addition of this component inhibited attraction to the primary binary blend. The blend of Z3,Z13‐18:OH and Z3,Z13‐18:OAc at the natural ratio should provide a sensitive and effective lure for monitoring populations of this pest.

Molecular identification of fungus gnats from shiitake mushroom in Korea

Fungus gnats are usually found in mushroom farm and have recently become important pest because they can cause severe damage and reduce the production on shiitake mushroom. Usually shiitake mushrooms are cultivated on both oak bed logs and in the artificial sawdust beds in greenhouses. Using yellow sticky trap, the dipteran species in shiitake mushroom farm were collected from May to September in Kyonggi-do and Chungcheong-do in 2013. To identify the main species of fungus gnat on the shiitake farm in Korea, the collected samples were determined the sequence of cytochrome c oxidase subunit I (COI) by DNA barcoding. The phylogeny based on maximum likelihood analyses from COI sequence showed that Bradysia difformis and B. alpicola were main species of shiitake bed log and Scatopsidae sp. and B. difformis were dominant species of sawdust beds.

Pests occurring on Cymbidium

A survey of pest occurrence and status of farmer`s pest management was conducted at 45 cymbidium farms in 10 major cultivation areas in Korea. The pest species collected from the cymbidium farms were identified as follows: Tetranychus urticae Koch, Frankliniella intonsa Trybom, Pinnaspis aspidistrae Signoret, Incilaria confusa Cockarel, Halyomorpha brevis Walker, Myzus persicae Slzer, and Aphis gossypii Glover, Coccus hesperidum Linnaeus, Thrips flavus Schrank, and Thrips tabaci Lindeman. The two-spotted spider mite, T. urticae, was the key pest in cymbidium production, occurring on 45 farms, followed by scales (20 farms), slugs (6), thrips (8), aphids (5), and stinkbug (1). PCR-RFLP of the rDNA ITS2 region revealed that two thrips species, Thrips flavus Schrank and Thrips tabaci Lindeman, occur on cymbidium farms. Therefore, it is necessary for the cymbidium farmers to establish an integrated pest management system to meet quarantine standards.

Survey on Nematodes in Cymbidium and Chemical Control of Ditylenchus sp.

Surveys were conducted on the occurrence of nematodes in the root systems of 1-3-year old Cymbidium hybida Swartz cultivated for export in Korea. The most frequently detected plant-parasitic nematode was Ditylenchus sp. with 4.7, 43.7, and 49.7/200 cc growth medium in 1, 2, and 3 year-old cymbidiums, respectively. And the densities of non-parasitic nematodes, dorylaimids, were 35.3, 70.5, and 155.8/200 cc growth medium in 1, 2, and 3-year-old cymbidiums, respectively. Three-year-old cymbidiums collected from Siheung, Ansan, and Gimpo had low densities of Aphelenchus sp. and Aphelenchoides sp. with under 40 individuals/pot, and the dorylaimid densities were 56-824/pot. To evaluate the effects of nematicides on Ditylenchus sp. in cymbidium, Emamectin benzoate EC, Fosthiazate SL, and Cadusafos CS were tested at two farms in Ansan and Gimpo. Emamectin benzoate EC showed control effects of 75.7 and 89.5%, whereas Fosthiazate SL and Cadusafos CS showed 27.2 and 65.3% and 30.1 and 90.5% control effects in the tests.

Infectivity of entomopathogenic nematode Steinernema carpocapsae Pocheon strain (Nematoda: Steinernematidae) on the green peach aphid Myzus persicae (Hemiptera: Aphididae) and its parasitoids

Abstract Infectivity of entomopathogenic nematode (EPN) Steinernema carpocapsae Pocheon strain on the green peach aphid Myzus persicae and its parasitic wasps (e.g., Aphidius colemani, Aphidius gifuensis and Diaeretiella rapae) was evaluated under laboratory conditions. Infective juveniles (IJs) of S. carpocapsae Pocheon strain had low infectivity against nymph and adult stages of M. persicae, showing 2% and 6.7% of mortality, respectively. Application of the EPNs had little effect on mummies caused by the three parasitoid species, allowing them to remain intact. No IJ invaded the host, regardless of EPN application rate. The parasitoid emergence from mummies ranged from 80% to 85% in the presence of EPN while 79–86% was recorded in the absence of EPN. However, the presence of the IJs reduced oviposition by the three parasitoid species, decreasing the rate up to 59% when the nematodes were applied before parasitoid release, while little difference in oviposition was observed when nematodes were applied after parasitoid release.

Economic Injury Level of Thrips tabaci (Thysanoptera: Thripidae) on Welsh onions (Allium fistulosum L. var) in the Early Transplanting Stage

This study was conducted to develop economic injury level (EIL) of onion thrips, Thrips tabaci, on welsh onion (Allium fistulosum L. var) in the early transplanting stage. The changes of welsh onion biomass, yield loss, and T. tabaci density were investigated according to the inoculation periods of T. tabaci. In the early transplanting stage of welsh onion, the yield loss (%) increased with increasing inoculation periods: 17.0, 53.3, 38.4, and 80.8% yield loss in 5, 10, 15, and 20 d inoculation periods, respectively. The relationship between Cumulative Insect Days (CID) of T. tabaci and yield loss (%) of welsh onion was well described by a nonlinear logistic equation. Using the estimated equation, EIL of T. tabaci on welsh onion was estimated to 30 CID per plant based on the yield loss 12% (an empirical gain threshold 5% + marketable rate 93% of welsh onion). ET was calculated to 24 CID, which corresponds to 80% of EIL. Until a more defined EIL-model is developed, the present results should be useful for T. tabaci management in early growth stage of welsh onion. The effect of T. tabaci attack on the yield of welsh onion in late growing season (120 days after transplanting) was also examined. The yield of welsh onion increased at a low population density of T. tabaci and decreased at higher densities, showing a typical over-compensatory response.