The sweetpotato whitefly, Bemisia tabaci, is a vector insect of more than 100 plant-diseased viruses as well as a serious pest of various horticultural crops. B. tabaci is a species-complex that consists of at least 24 biotypes, which show different biological characteristics including host range, fecundity, insecticide resistance and virus transmission. Here we identified biotype, endosymbiotic bacteria, and tomato yellow leaf curl virus (TYLCV) acquisition of various B. tabaci populations collected in Korea. In addition, we compared those profiles with B. tabaci collected from Bangladesh and Myanmar, and the greenhouse whitefly, Trialeurodes vaporariorum. PCR diagnosis of cytochrome oxidase I (COI) showed that all B. tabaci populations of Korea were Q-biotype and closely related with a subgroup I (MedBasin 1), which is indigenous to the Western Mediterranean area. Ribosomal DNA analysis of 5 endosymbionts showed that both Cardinium and Hamiltonella were detected in most tested populations while the presence of Arsenophonus, Fritschea and Wolbachia dependent on populations. Our results suggest that the acquisition of TYLCV do not related with the endosymbiont profile of B. tabaci.

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.

Sweet potato whitefly Bemisia tabaci is a serious pest of various economically important crops. For the control of B. tabaci in an environment-friendly way, we demonstrated the effect of azadirachtin, which is an active conpound of neem oil as an botanical insecticide, on the development of B. tabaci by using an assay of single tomato leaf. Egg hatch rates were 53.6, 50.3% at 5 and 10 ppm, respectively. Adult eclosion rates were 30.0, 22.9% at these doses. We determined the whitefly control efficacies of two application methods of neem-based products by comparing between a direct spray of liquid-type into leaves and a soil treatment of pellet-type. Soil treatment of neem was greatly inhibited adult colonization by 75%. Those plants also inhibited the rates of oviposition and larval development. However, single treatment of foliar spray of neem (5-10 ppm) did not significantly inhibit the initial colonization of adult whiteflies. Furthermore, adult colonization was gradually increased regardless of neem spray.

The use of electron beam irradiation has been emerged as one of alternative ways of the restriction of methyl bromide usage for the disinfestation of stored-products and quarantine pests. Here we demonstrated effects of electron beam irradiation on development and gene expression of P. interpunctella, which is a serious pest of various stored-products. P. interpunctella at various developmental stages were irradiated at 0, 0.25, 0.5, 0.75 and 1 kGy. Eggs failed to hatch at all treated doses of electron beam. Fifth instar larvae pupated only 6.7% by 0.25 kGy irradiation but failed pupation at above doses. Interestingly, survived larvae by low-dose irradiation did not pupated until 40 days. Pupae eclosed to adults only 12.1% by 0.25 kGy irradiation but failed at above doses. In addition, 5-day-old pupae eclosed 94.4, 91.6, 100 and 49.9% at 0.25, 0.5, 0.75 and 1.0 kGy, respectively. However, most of those emerged adults were malformed, especially in wings, and showed very low oviposition rate. We demonstrated whether the electron beam irradiation induces gene expression. Upregulated genes at any doses were hsp70, which is a stress-responsive protein, at fifth instar larval stage and hemolin, which is an immune-responsive protein, at pupal stage. Some genes of pupae, such as β-1,3 glucan recognition protein, hsp70 and acp25 (small hsp) were upregulated only at high doses. However, other genes, such as prophenoloxidase, ultraspiracle , ecdysone receptor and heat shock proteins (hsp90, hsc70) were downregulated by irradiation of electron beam

The sweet potato whitefly Bemisia tabasi is one of the most important pests of various horticultural crops. In addition, B. tabaci is a vector of many plant-pathogenic viruses and cause a serious secondary damage to crop plants. Association of plant-pathogenic virus with vector insects is known to be effective on the transmission capacity, fecundity, longevity of vectors including whiteflies. However, the interactive mechanisms between virus and vector insects are still poorly understood. Recently, a serious damage caused by virus disease together with B. tabasi emergence was identified at tomato glasshouse in Tongyoung. We detected the signals of Tomato Yellow Leaf Curl Virus (TYLCV) in tomato leaves and vector whiteflies using PCR amplification and confirmed its presence by those sequence comparison. To determine the effects of TYLCV acquisition on physiological status of vector whiteflies, transcript levels of genes that associated with metamorphosis, metabolism, stress and immune processes were compared between TYLCVinfected whiteflies and non-infected ones. Generally, the transcript levels of virus-infected whiteflies were lower than those of non-infected ones. In addition, the associations of endosymbiont levels within whiteflies were discussed in aspect of the acquisition and transmission of TYLCV.