Chung-Gyoo Park

Comparison of open pulled straw (ops) vs glass micropipette (gmp) vitrification in mouse blastocysts

The purpose of this study was to investigate the use of a glass micropipette (GMP) as a vessel for vitrification of mouse blastocysts, and to compare the post-thaw survival of these blastocysts with those cooled in open pulled straws (OPS). The GMP vessel permits higher freezing and warming rates than OPS due to the higher heat conductivity of glass and lower mass of the solution containing the embryos. Groups of 6 mouse blastocysts were sequentially placed into 2 vitrification solutions before being loaded into either the OPS or GMP vessels and immersed into LN2 within 20 to 25 sec. Post-thaw blastocysts were serially washed in 0.25 and 0.15 M sucrose in holding medium (HM) and modified human tubal fluid medium (mHTF), each for 5 min, and then cultured in mHTF supplemented with 10% FCS for 24 h. The rate of blastocyst re-expansion did not differ significantly for OPS (93.5%) and GMP (95.0%) methods (P<0.05). The hatching rate in OPS (88.7%) was similar to that in GMP (90.0%) but was lower than for the unvitrified control embryos (98.3%, P<0.05). To determine the optimal embryo population per GMP vessel, the pipettes were loaded with 2 to 10 embryos. The rate of blastocyst re-expansion after vitrification was significant for 2 to 4 embryos than for 6 to 10 embryos per vessel. In addition, the rate of blastocyst re-expansion was significantly lower if blastocysts were vitrified in the wide rather than the narrow portion of the micropipette (100 vs 87.5%; P<0.05) even when only 4 blastocysts were loaded per vessel. These results indicate that both vitrification vessels can provide high rates of embryo survival. However, the GMP vessel does not need a cap to protect the vessel from floating after immersion in LN2. The number and location of the embryos (narrow versus wide portion of capillary) were considered to be limiting factors to the viability of mouse embryos.

Report on Two Egg Parasitoid Species of Riptortus clavatus (Thunberg) (Heteroptera: Alydidae) on Soybean

Two hymenopteran egg parasitoid species, Gryon japonicum (Ashmead) (Scelionidae) and Ooencyrtus nezarae Ishii (Encyrtidae), were emerged from eggs of bean bug, Riptortus clavatus Thunberg (Heteroptera: Alydidae). The former parasitoid is first recorded in Korea. Brief morphological and biological characteristics, and parasitism on R. clavatus eggs are described.

Composition of the Aggregation Pheromone Components of Korean Bean Bug and Attractiveness of Different Blends

Male adults of bean bug, Riptortus clavatus Thunberg (Heteroptera: Alydidae), release aggregation pheromone (AP) attracting both sexes of adult and nymphs, which its egg parasite, Ooencyrtus nezarae (Hymenoptera: Encyrtidae) exploits the pheromone to find host. The AP consists of three components; (E)-2-hexenyl (Z)-3-hexenoate (E2HZ3H), (E)-2-hexenyl (E)-2-hexenoate (E2HE2H), and tetradecyl isobutyrate (TI). We analyzed composition of the pheromone components of bean bugs from different geo graphical locations of Korea and Japan. The attractiveness of different blends of AP components to R. clavatus was also tested in the fields in Jinju, Korea and in Kumamoto, Japan. Composition ratios (E2HZ3H: E2HE2H:TI) of the AP of Jinju and Iksan populations were 1:1.4:0.2 and 1:0.8:0.2, and those of Tsukuba and Kumamoto populations were 1:2.8:0.2 and 1:1.5:0.1, respectively. In field tests, traps baited with ratio of 1:1:1 (E2HZ3H:E2HE2H:TI

Pheromone trap type and height for attracting of Riptortus clavatus (Thunberg) (Hemiptera: Alydidae) in soybean field.

This study was conducted to determine pheromone trap type and height in forecasting populations of R. clavatus in soybean fields using pheromone. The most effective pheromone trap type and height in forecasting populations of R. clavatus were fish trap and 60 cm above ground. Ratio of R. clavatus adults female and male in soybean field was 1.5 to 1 and Piezodorus hybneri was also attracted to the aggregation pheromone trap of R. clavatus. Attractiveness of two stink bug species caught on synthesis pheromone of R. clavatus was surveyed with imported production and synthesized production. Imported pheromone attracted only adult of R. clavatus, but synthesized pheromone attracted both adult of R. clavatus and P. hybneri. Change of population of R. clavatus was observed using pheromone trap and sweeping method in soybean field. Adults of R. clavatus occurred from early August and the population reached its peak in early September when pheromone trap was used. In case of sweeping method, its fluctuation pattern was similar to that of pheromone trap.

Variation in aggregation pheromone secretion of bean bug, Riptortus clavatus.

Male adults of bean bug, Riptortus clavatus Thunberg (Heteroptera: Alydidae), release aggregation pheromone (AP) which consists of (E)-2-hexenyl (Z)-3-hexenoate (E2HZ3H), (E)-2-hexenyl (E)-2-hexenoate (E2HE2H), and tetradecyl isobutyrate (TI). Variation in the pheromonal secretion were checked by the factors of age, mating status, seasons, body weight and time in a day. There were no significant differences in the amounts of AP secretion by mating, body weight, and time in a day. Higher amount of AP was detected from older males than younger ones. The amount of AP detected was higher in the males collected from April to September than in those collected during October. No AP was detected in the males of November and December. These phenomena in the AP secretion were discussed in relation to food exploitation and reproductive diapause of the bean bug.

Movement of Monochamus alternatus Hope (Coleoptera: Cerambycidae) Adults among Young Black Pine Trees in a Screen Cage

Movement of adult Monochamus alternatus was investigated on young black pine, Pinus thunbergii, trees for about one month in a screen cage. Number of pine trees to which M. alternatus females and males moved during the experimental period was and out of 15 trees, respectively. Adult females and males moved to and tree per day, respectively. A 74.6 and 80.7% of adult females and males moved at night (17:00-08:00) to other trees. After moving, most beetles (72.6% of females and 76.0% of males) stayed on the tree to which they moved for one to two days. Some beetles stayed for up to seven days.

Effect of Day Length and Temperature on the Diapause Termination of Riptortus pedestris (Hemiptera: Alydidae) Male Adults

The bean bug, Riptortus clavatus Thunberg (Hemiptera: Alydidae), is a pest of soybeans and tree fruits. It enters reproductive diapause during winter. We studied the effect of different combinations of temperature, day length, and treatment period on the termination of diapause in R. clavatus using adult females collected in October and November 2006. Ovarian development was used to determine diapause termination. The treatments were: (1) HTLD; , 14L:10D treatment for 1, 2, 3 weeks and 30 days, (2) HTSD; , 10L:14D treatment for 1, 2, and 3 weeks, (3) LTLD; , 14L:10D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks, and (4) LTSD; , 10L:14D treatment for 1, 2, and 3 weeks followed by HTLD for 3 weeks. The HTSD treatments did not affect ovarian development, and resulted in no significant difference in the number of mature eggs in ovaries or the percentage of diapause-terminated females compared to the control females before treatment. The percentage of females that terminated diapause was significantly higher in the HTLD treatment than in the HTSD treatment. The HTLD treatment for more than 14 days increased the percentage of diapause-terminated females, accelerated the development of the ovaries, and increased the number of mature eggs in ovaries. Compared with the HTLD or HTSD treatments, the LTLD or LTSD treatments followed by the HTLD treatment accelerated ovarian development and increased the number of ovipositing females. The pre-LTSD treatment for 1 week was enough to increase the number of eggs oviposited.

Effects of Temperature on the Development and Longevity of the Gray Field Slug, Deroceras reticulatum Müller (Stylommatophora: Limacidae)

The egg size and weight of the gray field slug, Deroceras reticulatum Muller, was mm and 3.3 mg at , respectively. Its weight increased from newly laid eggs to adults for 17 weeks at four temperature regimes and was heaviest at , followed by 24, 16 and . Likewise, hatching rate of the egg batches was highest with 95% at , followed by 24, 16 and with significant differences. The number of eggs in the batches was increased with 20 at while it was only 10 at . The average accumulated egg-laying days was longest with 15 days at while shortest with 9 days at . The range of egg-laying period was shortest with 84-134 days at and longest at . Thus, the total number of eggs laid by adult D. reticulatum was highest with 217 at and lowest with 105 at . The egg period was 12-19 days while the juvenile period and adult longevity were 51-68 days and 85-134 days, respectively. The life span of D. reticulatum from egg to adult was longest with 216 days at , followed by 193 days at , 170 days at and 151 days at . Accordingly, the most favorable temperature for the oviposition, development and longevity of D. reticulatum is .

Concurrent application of ethyl formate and 1-methylcyclopropene to control Tetranychus urticae on exported sweet persimmons (Diospyros kaki Thunb. ‘Fuyu’): Application of ethyl formate on persimons

Extending the shelf life of fruits during post‐harvest storage and eradicating pests associated with quarantine issues could together comprise the key steps toward expanding the exportation of sweet persimmon in South Korea. Here we firstly investigated the concurrent application of ethyl formate (EF), a methyl bromide alternative fumigant, which is currently considered a beneficial and safe fumigant in quarantine use, and 1‐methylcyclopropene (1‐MCP), an anti‐ethylene compound that is broadly used in post‐harvest systems, on sweet persimmon. We also suggest the proper fumigation methods to be follow when using these compounds. Tetranychus urticae, an important quarantine pest, was inoculated under the calyx of sweet persimmon, and the fruits were then fumigated using 35.0 mg L−1 of EF for 6 h before and after treating with 1.0 μL L−1 of 1‐methylcyclopropene for 24 h under storage conditions of 5°C. Our results showed that concurrent treatments with 1‐MCP and EF could be suitable for commercial purposes by extending shelf life, delaying color changes and softening, and offering complete control of the target pest, Tetranychus urticae.

Evaluation of Different Applications of Ethanedinitrile (C2N2) in Various Fumigation Chambers for Control of Monochamus alternatus (Coleoptera: Cerambycidae) in Naturally Infested Logs

Abstract Monochamus alternatus Hopeis is an important vector of nematode pests of timber in Korea, particularly Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle. Previously, we reported that ethanedinitrile (C2N2) has the potential to replace methyl bromide and metam sodium to control M. alternatus larvae and B. xylophilus under low-temperature (<5 °C) conditions. Herein, we report on fumigation trials of C2N2 over a 3-yr period (February 2013–October 2015) conducted at higher temperatures. The trials were conducted under 24 different conditions that incorporated varying fumigation chamber types (plastic sheeting-enclosed chambers of differing construction or an ISO shipping container, interior size: 5.90 m length by 2.35 m width by 2.40 m height), log water content (24.1–43.5%), filling ratios (5, 20, and 40%), and temperatures (10.5–17.3 °C). Highest concentration × time (Ct) product values were obtained with the ISO shipping container followed (in order of decreasing Ct values) by a 0.1-mm-thick, low-density polyethylene tarpaulin enclosure, a 0.1-mm-thick polyvinyl chloride (PVC) tarpaulin enclosure, and a 0.05-mm-thick PVC tarpaulin enclosure. The correlation between Ct product value and mortality of M. alternatus larvae was calculated with all treatment combinations. From this, the L(Ct)50 and L(Ct)99 values for C2N2 were determined to be 73.19 and 194.90 g h m–3, respectively. Ethanedinitrile showed promise as a practical alternative fumigant for use on fresh pine logs infested by M. alternatus larvae.