The cotton bollworm, Helicoverpa armigera, is an economically important pest, which harms various kinds of important agricultural crops, such as tomato. The purpose of the present study was to investigate the effect of ionizing radiations (electron beam, X-ray, gamma-ray) on the development and reproduction of H. armigera and to determine the optimal dose of three ionizing radiations for the construction of quarantine technology applicable to tomato export.

Whitefly (Hemiptera: Aleyrodidae) pests, including the sweetpotato whitefly, Bemisia tabaci, and the greenhouse whitefly, Trialeurodes vaporariorum, are economically important in agriculture. With the annual growth of the domestic fresh fruit export market, various quarantine treatment methods are being used to export strawberries of better quality. The purpose of the present study was to investigate the effect of ionizing radiations (electron beam, X-ray, gamma-ray) on the development and reproduction of two species of whitefly and to determine the optimal dose of three ionizing radiations for the construction of quarantine technology applicable to strawberry export.

Whitefly (Hemiptera: Aleyrodidae) pests, including the tobacco whitefly, Bemisia tabaci, and the greenhouse whitefly, Trialeurodes vaporariorum, are economically important in agriculture. With the annual growth of the domestic fresh fruit export market, various quarantine treatment methods are being used to export strawberries of better quality. The objective of the present study was to evaluate the effects of gamma rays on the development and reproductive sterility of B. tabaci and T. vaporariorum. In both species, the eggs were completely inhibited from hatching at 50 Gy, and the emergence of 3rd instar nymphs was completely suppressed at 150 Gy. Some adult B. tabaci and T. vaporariorum spawning occurred at 100 Gy and 70 Gy, respectively; however, at these irradiation levels, F1 hatchability was completely inhibited. Dosimetry results showed that the penetrating power of gamma ray in the strawberry-filled box was the lowest at the mid-box position. Therefore, B. tabaci and T. vaporariorum were placed in the middle of the strawberry-filled box and irradiated. A gamma-ray irradiation of 100 Gy suppressed the development and reproduction of eggs and adults in both B. tabaci and T. vaporariorum. However, the development of 3rd instar nymphs was inhibited at 300 Gy for B. tabaci and 200 Gy for T. vaporariorum. Our data suggest that at least 300 Gy should be used for the control of these two types of whitefly for strawberry export.

The green peach aphid, Myzus persicae Sülzer, is an important sap-sucking pest of many plants, including Chinese cabbage. The objective of this study was therefore (1) to determine the effects of sublethal concentrations of afidopyropen, sulfoxaflor, and spirotetramat on adult longevity and the fecundity of M. persicae, and (2) to study the feeding behavior of M. persicae on Chinese cabbage leaves treated with various concentrations of these three insecticides. Longevity and total fecundity of M. persicae adults were decreased at concentrations higher than LC30. Feeding behavior analyses using an electrical penetration graph showed that sublethal concentrations of afidopyropen, sulfoxaflor, and spirotetramat had significant effects on the duration of phloem ingestion.

Background : The causative organism of Astragalus membranaceus (Hwanggi) root rot disease was known as Pythophthora drechsleri. In this study, a new species of root rot causative organism has been identified and reported. Methods and Results : Hwanggi, which has root rot disease, was collected in Jungsun-gun, Gangwon-do. The diseased root was cut into 1 ㎝ size and disinfected with 1% sodium hypochlorite solution for 1 minute and washed with sterile distilled water. The dried samples were dipped in the PDA medium and cultured in at 25℃ incubator. The 21 isolates were cultured under the same conditions and genomic DNA was extracted. The genomic DNA of isolated strains was extracted using a kit of Biofact. The isolated strains were identified using internal transcribed spacer (ITS) region sequencing. The ITS region was amplied using the primer pair ITS1 (5’-TCCGTAGGTGAACCTGCGG-3’) and ITS4 (5’-TCCTCCGCTTATTGATATGC-3’). The PCR was performed in a final volume of 50 ㎕ containing 10 mM Tris-HCl (pH 8.3), 50 mM KCl, 1.5 mM MgCl2, each dNTP at a concentration of 0.2 mM, 1.25 IU of Taq polymerase, each primer at a concentration of 10 pmol, and 2ul of the DNA template. Sequencing was performed by asking Macrogen. The analyzed sequences were compared using the Blast program provided by NCBI. As a result of identification of 21 strains, 13 Fusarium spp., 1 Peronospora sp. (causative organism of downy mildew), 3 Acremonium spp., 3 Uncultured fungus, 1 Phyrtophthora sp.. The main pathogen of wilt disease was known as Fusarium sp., a soil-borne pathogen. After analyzing the systematic taxonomic relationships, the systematic diagram was created using the neighbor-joining method. Conclusion : We have finally identified Phytophthora cryptogea as a causative organism of Hwanggi root rot disease and will check whether the disease has occurred on the inoculation through pot test.