Diapause duration of Paratlanticus ussuriensis is prolonged as an egg that enter both initial and final diapause stgaes. Environmental conditions, such as temperature, can modify the duration of 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 initial 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. We identified small heat shock protein (shsp), heat shock protein 90 (hsp90) and three heat shock protein 70 (hsp70a, hap70b, hsp70c) genes of P. ussuriensis and determined those expression levels at different temperature conditions. The levels of shsp, hsp70a, hsp70b and hsp90 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. We analysis of temperature sensitivity of P. ussuriensis eggs. Hsp70a is expressed after the first cold treatment of mature eggs. Hsp70b is highly expressed just before hatching. Both shsp and hsp70c was highly expressed at the heat shock condition into immature egg stage. Our results suggest that high temperature breakdown initial diapause and one hsp gene, such as hsp70c, may be involved into the mechanism of initial diapause of P. ussuriensis eggs.

Root knot nematodes were extracted from five different plants (indian spinach, papaya, sweet gourd, okra and jute) collected from kurigram, gazipur, jessore and patuakhali districts of Bangladesh. Firstly, Meloidogyne spp. were identified morphologically mainly based on perineal pattern of adult female. Secondly, female were collected from plant roots and used directly in PCR for amplification of mitochondrial DNA (mtDNA) region between COII and lrRNA genes followed by hinfI digestion and sequencing. The root knot nematodes in indian spinach, jute and sweet gourd were identified as M. incognita whereas in okra and papaya were M. javanica.

The sweetpotato whitefly, Bemisia tabaci, is a vector of more than 100 plantdiseased viruses as well as a serious pest to various horticultural crops. Virus acquisition affects the vector’s development and reproduction, but its mechanism is largely unknown. Here we compared the temperature responses between non-viruliferous and TYLCV-viruliferous Q biotype of B. tabaci. When both non-viruliferous and viruliferous whiteflies were exposed for 1 and 3 h at 4, 25, and 35°C, the mortality rate of viruliferous whiteflies is higher than nonviruliferous after exposure at 4°C and 35°C, but no differences at 25°C between them. Analysis of the expression levels of heat shock protein (hsp) genes using the quantitative realtime PCR showed that viruliferous whiteflies has higher expression in hsp70, and hsp90 at both 4°C and 35°C, but no differences at 25°C. The results suggest that vector insects may not be durable to unfavorable temperature conditions when they acquisite plant viruses.

Tetranychid mites are one of the most diverse group including at least 1,200 species in the world. Species identification is difficult due to the small size and similar morphology within the group. We collected 17 species of spider mites from various host plants in different regions of Korea and determined species identity by the comparison of morphological characters and nucleotide sequences of internal transcribed spacer 2 (ITS2) and the cytochrome oxidase subunit I (COI). In addition, we report three new species that were firstly identified in Korea. Amphitetranychus quercivorus (Ehara and Gotoh) was collected from Mongolian oak plant in Daegu, Schizotetranychus miscanthi Saito was from the common reed plant in Ulleungdo, and S. cercidiphylli Ehara was from Bamboo plant in Jeju. Morphological identification of three species were similar with those of Japanese samples, but the ITS2 and COI sequences of A. quercivorus and the COI sequence of S. miscanthi were different with Japanese species at the rates of 1/419, 2/331 and 3/332 nucleotides, repsectively. S. cercidiphylli can be identified by the aedeagus shape of males but we firstly sequenced ITS2 and COI of this species. Our results can be used for the identification of spider mites which are important in plant quarantine.

Species of root knot nematodes, Meloidogyne spp. were identified through the PCR amplification and sequence analysis of mitochondrial DNA (mtDNA) region between COII and lrRNA genes. Root knot nematodes were extracted from 5 plant samples [kiwi (Japan), rhododendron (Japan), cornus (Japan), ficus (China) and jasmine (Vietnam)] that were collected from Plant Quarantine Station in Korea. At first, species was identified using morphological characters, such as the length and shape of stylet, the tail length and the perineal patterns. Secondary, single individuals of either female and juvenile collected from plant tissues were used for PCR and further sequencing analysis. The results showed that cornus, jasmine and ficus plants were infected by M. incognita, and kiwi and rhododendron plants were infected by M. interolobii.

The oral toxicities of symbiotic bacteria Photorhabdus temperata ssp temperata (Ptt), mutually associated with entomopathogenic nematode Heterorhabditis megidis, and P. luminescens ssp. laumondii (TT01) with H. bacteriophora, were demonstrated to adults of the sweetpotato whitefly Bemisia tabaci. Sucrose solution (25%) containing bacteria-free supernatant of culture media of symbiotic bacteria was ingested into adult whiteflies within the glass tube. Whitefly mortalities were shown similar patterns against two bacterial media. Mortalities were significantly increased to 60-64% at 36 hours and almost 100% at 60 hours after treatments. In addition, We demonstrated the effect of oral ingestion of symbiont culture media on the gene expression of B. tabaci. Several genes fluctuated those expression levels. Our results suggest that oral ingestion of symbiont culture media of entomopathogenic nematodes significantly changed metabolic rates and highly lethal to whiteflies. The use of symbiotic bacteria of entomopathogenic nematodes provides a great potential as an alternative genetic resource of Bacillus thuringiensis, a major resource of microbial insecticide.

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.

Recently, several significant plant virus diseases have devastated various crops in agricultural fields of Korea, These virus disease are mostly transmitted and spread by vector insects, such as rice stripe virus (RSV) transmitted by planthopper Laodelphax striatellus, tomato spotted wilted virus (TSWV) by thrips Frankliniella occidentalis and tomato yellow leaf curl virus (TYLCV) by whitefly Bemisia tabaci. Insects as vectors are significantly important for the control of plant disease as well as insect themselves. Here, on the view of insects, interactive mechanisms of vector insect and plant pathogens were discussed on the system of TYLCV and B. tabaci. When insects acquisited virus they would be beneficial, neutral or detrimental. Generally, plant virus are ingested into the mouse and move from the gut to hemolymph and back to salivary gland. During this movement there would be numerous molecular interactions at a vector-virus specific mode. In addition, virus acquisition change vector's physiological and developmental states including longevity, fecundity and dispersal behavior. However, these interactive mechanisms of vector insects with plant virus are largely under investigated. B. tabaci is genetically diverse and transmit many begomoviruses including TYLCV. I demonstrated effects of TYLCV acquisition on fecundity, thermal response, endosymbiont profile and gene expression of B. tabaci.

Oral toxicities of 5 Photorhabdus temperata ssp. temperata (Ptt) strains collected in different regions of Korea were determined against the larvae of Plodia interpunctella, Galleria mellonella, Lucilia caesar, Culex pipiens pallens and Paratlanticus ussuriensis. When a diet or water containing culture media of 5 different Ptt strains were ingested to immature insects, mortalities of the first instar larvae of G. mellonella, L. caesar, P. ussuriensis and young nymphs of C. pipiens pallens were rapidly increased and 100% within 3-5 days after treatments. However, mortality of P. interpunctella neonate larvae was slightly slower and 94.4-100% within 7 days after treatments. As controls, a diet containing either water, the medium without culturing bacteria, or E. coli culture medium did not effective on their mortalities. As another control group, the culture medium of P. temperata ssp. laumondii (KACC) were variously effective to mortalities of 4 species, namely, 100, 45.3, 2.8 and 0% to Galleria, Lucilia, Plodia and Culex, respectively. Culture media of Ptt strains inhibited developmental late of late larvae of P. interpunctella. Our results suggest that the oral administration of the culture medium of Ptt symbiotic bacteria was highly effective to control various immature insects.

An outbreak of Ussur Brown Katydid, Paratlanticus ussuriensis, occurred in the orchard areas of central Korea during 2006 and 2007. These crickets occur widely in Korea but before 2000 they were not regarded as an agricultural pest and were mainly confined to wooded hillsides. In an attempt to understand this katydid ecology, firstly, we have conducted a life cycle study of the Ussur brown katydid. This katydid spends one or two years as an egg stage. Most of eggs enter the initial diapause, which take place in stage 4. Less than 10% eggs didn't occur the initial diapause and developed until in stage 23 before beginning winter season. In the laboratory experiment, diapause depends on the initial temperature after eggs laid. They had an initial and final diapause around less 25℃. Therefore, it takes two years to hatch at low temperature. On the other hand, eggs are kept at temperatures around over 27℃, entry into the first diapause stage was circumvented and eggs emerged the following spring. That is, the high temperature seems to affect on the life cycle of Katydid. Thus, if they are exposed to high temperature on early egg stage, they emerge next year just after spending a winter.

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

A glucose-regulated protein 78 (grp78) gene, which is belongs to a heat shock cognate 70 (hsc70) subfamily, was cloned from Indian meal moth, Plodia interpunctella. Its full length cDNA was 2679 bp and contains a 1980 bp open reading frame. The translated amino acid sequence consists of 660 residues with a calculated molecular mass of 72,975 Da and an isoelectronic point (pI) of 5.27. It contains several highly conserved functional motifs of the Hsp70 family and, particularly, C-terminal motif of KDEL that is characteristic for endoplasmic reticulum (ER) hsc70. Its deduced amino acid sequence shows a high identity (83-94%) with Hsc70s of other insects and grouped with Hsc70-3 among 5 Hsc70 members of Drosophila melanogaster. During development the grp78 transcript level was high in egg, feeding larval and adult stages but low in molting and wandering larval and pupal stages. Particularly its level was higher in the gut than integument and fat body of fifth instars. Furthermore its level was greatly decreased when fifth instar larvae were starved for 48 hrs but recovered at 3-6 hrs after re-fed diet. Our data suggests that grp78 is a member of hsc70 gene that belongs to ER and may have a role for energy metabolism at cellular level.

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.