Paratlanticus ussuriensis enter prolonged diapause at an egg stage. Environmental conditions, such as temperature, can modify the diapause duration at initial diapause. Eggs enter initial diapause at 20℃, but continued early embryonic development at 30℃. Final diapause at a fully developed embryonic stage is obligatory regardless of temperature conditions. To determine temperature effects on diapause mechanism of P. ussuriensis eggs, we compared weights, DNA and RNA amounts of eggs incubated at either 20℃ or 30℃ for 50 days after oviposition. Both egg weight and total amount of DNA were constant at 20℃ but gradually increased at 30℃. However, total RNA level was rapidly increased at 15 days-old eggs at 30℃ and maintained high levels during further period whereas its level was constant at 20℃. In addition, we identified three heat shock protein 70 (hsp70a, hap70b, hsp70c) genes of P. ussuriensis and determined those expression levels at different temperature conditions. The levels of hsp70a and hsp70b was not detectable until 20 days after oviposition at both temperature conditions, but highly increased at 50 and 60 days when incubated at 30℃. In contrast, hsp70c level was rapidly peaked at 20 days after oviposition, which is the time of initial diapause entrance. Our results suggest that high temperature breakdown initial diapause and a certain hsp gene, such as hsp70c, may involve in the initial diapause mechanism of P. ussuriensis eggs.

The sweetpotato whitefly, Bemisia tabaci, acts as a vector of more than 100 plant viruses. B. tabaci is known to harbor a primary endosymbiont (Portiera) and 6 secondary endosymbionts (Arsenophonus, Cardinium, Fritschea, Hamiltonella, Rickettsia and Wolbachia). These endosymbionts play important roles in the acquisition and transmission of plant viruses. Using PCR analysis, we identified endosymbiotic bacteria in various B. tabaci populations collected from different places of Korea. Distribution of endosymbionts was different according to the biotype of B. tabaci. Subsequently, their relative densities of endosymbionts were compared between TYLCV-viruliferous and non-viruliferous populations of the Q biotype using quantitative realtime PCR. We found that the densities of Portiera, Cardinium and Hamiltonella are higher in viruliferous than non-viruliferous whiteflies. Our results suggest the role of endosymbiont for the TYLCV transmission of whiteflies.

The diapause duration P. ussuriensis eggs is known to either one year or prolonged to additional years. This complex life cycle is mainly caused by the interruption at two embryonic stages: early stage (initial diapause) and fully developed late stage (final diapause). The environmental cues, such as temperature, is critical to determine the diapause duration but the precise diapause mechanism of P. ussuriensis eggs is unclear. We demonstrated temperature effects on the entrance of initial diapause. Newly oviposited eggs were incubated at two temperature conditions (20℃and 30℃) for 60 days. When eggs were incubated at 20℃, egg weights were not significantly changed, but at 30℃ those were gradually increased to 1.5 times for 50 days. Genomic DNA contents of eggs were similarly increased at 30℃. Total RNA contents at 30℃ were highly increased from the 15-days-old but not at 20℃. In addition, we further analysed expression levels of two heat shock protein 70 (hsp70a, hap70b) genes during embryonic development. Our results suggest that initial diapause occurred between 10 and 15 days after oviposition and its entrance was blocked by high temperature incubation.

Spider mites are one of major pests in cultivations of various ornamental plants and also important in plant quarantine service. Due to the very small body size and high similarity within the Genus the identification of species is difficult even at the microscopic observation. To identify 5 major species (Tetranychus cinnabarinus, T. urticae, T. phaselus, T. kanzawai and T. truncatus) in the Genus Tetranychus at the molecular level, we designed 4 species-specific primer sets using nucleotide sequences of the internal transcribed spacer (ITS2) region in the nuclear ribosomal repeat unit. At the PCR diagnosis of extracted genomic DNAs of 5 species using each primer set, specific primers of both T. phaselus and T. truncates were species-specific to their own species samples. However, specific primer set of T. urticae detected T. cinnabarinus as well as T. urticae. Specific primer set of T. kanzawai detected T. truncates as well as T. kanzawai, even though detection intensities were lower in non-target species.

Due to the very small body size of spider mite, it is difficult to prepare DNA extraction simultaneously with slide samples from a single individual. Here we developed non-mashed DNA extraction method from a single spider mite to apply for molecular as well as morphological identification. Total genomic DNA was isolated from a single female adult using Genomic DNA extraction kit without the sample homogenization. DNA content of a single spider mite was 60-90 ng, which is sufficient for the PCR analysis. However, the quantity of extracted DNA and quality of the cuticle sample were dependent on the incubation time into the lysis buffer. Our results suggest that non-mashed DNA extraction method would be useful for the identification of very small mites as well as insects at the levels of DNA and morphology.

During the last several years, the population of the ussur brown katydid, Paratlanticus ussuriensis has been highly increased at mountain-side orchards in Youngdong province in Korea. Nymphs and adults emerged one time per year from early May to August and cause a serious demage on the crop production. Adults oviposit eggs from July to September under the ground and eggs overwinter at diapause stage. However, the diapause duration P. ussuriensis is known to either one year or prolonged to additional years. The environmental cues, such as temperature, could be a critical to determine the diapause duration but the precise diapause mechanism of P. ussuriensis eggs is unclear. We demonstrated to determine the stage of diapause initiation during embryogenesis. Newly oviposited eggs were incubated for 60 days at two temperature conditions (20℃and 30℃). When the eggs were incubated at 20℃ those weights were not changed, but when they incubated at 30℃ those were increased from 15-days-old. Total RNA contents of eggs incubated at 30℃ were highly increased from the 15-days-old when they compared with those of eggs incubated at 20℃. In addition, total DNA contents of eggs were greatly higher when they incubated at 30℃. Our results suggest that early embryonic development was sensitive to high temperature and it was stimulated at 15-days-old. To determine the temperature response of embryonic development at molecular level we identified heat shock protein 70 (hsp70) gene of P. ussuriensis. Further analysis would conduct the gene expression rate of diapausing eggs on different temperature conditions by using real time RT-PCR technique and determine the molecular characteristics of P. ussuriensis egg diapause.