• Korean journal of applied entomology
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• v.53 no.4
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• pp.497-501
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• 2014

The small brown planthopper, Laodelphax striatellus (Fall$\acute{e}$n) (SBPH) is one of the important rice pests in Korea, which transmits rice stripe virus (RSV) to rice. This pest is an indigenous species in Korea and has also known to migrate from China to the western coastal areas of Korea. This study was conducted to investigate the wing morphs of SBPH and its parasitism rate of Haplogonatopus atratus Esaki et Hashimoto in Korea. In 2014, SBPH were collected in April and July from 16 sites throughout South Korea and their wing morphs and parasitism rates were measured under the microscope. Percentage of brachypterous male in July was significantly declined compared to that in April, while that of brachypterous female did not change. A positive relationship was found between latitude and percentage of brachypterous adults in April. Parasitism rate of both nymphs and adults were higher in April than July. In addition, nymphal parasitism rate was generally higher in western coastal areas.

• The Plant Pathology Journal
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• v.36 no.3
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• pp.280-288
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• 2020

RNA interference (RNAi) has attracted attention as a promising approach to control plant viruses in their insect vectors. In the present study, to suppress replication of the rice stripe virus (RSV) in its vector, Laodelphax striatellus, using RNAi, dsRNAs against L. striatellus genes that are strongly upregulated upon RSV infection were delivered through a rice leaf-mediated method. RNAi-based silencing of peroxiredoxin, cathepsin B, and cytochrome P450 resulted in significant down regulation of the NS3 gene of RSV, achieving a transcriptional reduction greater than 73.6% at a concentration of 100 ng/μl and, possibly compromising viral replication. L. striatellus genes might play crucial roles in the transmission of RSV; transcriptional silencing of these genes could suppress viral replication in L. striatellus. These results suggest effective RNAi-based approaches for controlling RSV and provide insight into RSV-L. striatellus interactions.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.347-354
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• 2019

Temperature-dependent traits of Laodelphax striatellus, rice stripe virus vector, were investigated at 10 constant temperatures (12.5, 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, 32.5, and 35.0 ± 1℃) under a fixed photoperiod (14/10-hr light/dark cycle). Unit functions for the oviposition model were estimated and implemented into a population dynamics model using DYMEX. The longevity of L. striatellus adults decreased with increasing temperature (56.0 days at 15.0℃ and 17.7 days at 35.0℃). The highest total fecundity (515.9 eggs/female) was observed at 22.5℃, while the lowest (18.6 eggs/female) was observed at 35.0℃. Adult developmental rates, temperature-dependent fecundity, age-specific mortality rates, and age-specific cumulative oviposition rates were estimated. All unit equations described adult performances of L. striatellus accurately (r² =0.94~0.97). After inoculating adults, the constructed model was tested under pot and field conditions using the rice-plant hopper system. The model output and observed data were similar up to 30 days after inoculation; however, there were large discrepancies between observed and estimated population density after 30 days, especially for 1^st and 2^nd instar nymph densities. Model estimates were one or two nymphal stages faster than was observed. Further refinement of the model created in this study could provide realistic forecasting of this important rice pest.

• Korean journal of applied entomology
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• v.34 no.4
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• pp.321-327
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• 1995

This study was conducted to determine the winter ecology of the small brown planthopper (SBPH), laodelphax striatellus Fallen, in Milyang, east Kyungsangnamdo province. The age distribution in the overwintering SBPH population varied according to collection dates. In early December, the population distribution was 60% 4th instar, 30% 3rd instar, 6% 5th instar, 3.4% 2nd instar with very few adults and 1st instar. In early March 5th instars had the highest propotion (47-50%) with 4th instar 44-46%. In early April the adult population was 75-81% of the population. The averaged nymphal instar converted the age distribution of he overwintering SBPH in to the into the numerical values tended to increase continuously. However, there were some differences in the averaged nymphal instar of overwintering SBPH annually and these differences resulted from different age distribution of the overwintering SBPH due to different annual temperature fluctuations during overwitering periods. The weight of the overwintering SBPH increased continuously during overwintering periods. The collection density of the overwintering SBPH population was significantly higher on the levee than in the barley field. Percent nymphal parasitism by haplogonatopus atratus in the overwintering SBPH population averaged about 21% regardless of overwintering years.

• Animal cells and systems
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• v.12 no.1
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• pp.47-52
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• 2008

Effects of wood vinegar on the activity of various insecticides were determined by measuring the mortality of two species of rice planthoppers, Nilaparvata lugens and Laodelphax striatellus. Wood vinegar itself did not show insecticidal activity on planthoppers. When the planthoppers were treated with wood vinegar mixed with one of insecticides such as BPMC, dinotefuran, imidacloprid, carbosulfan or insect growth regulators, the planthopper mortality induced by carbosulfan was greatly increased by the wood vinegar in comparison with a single carbosulfan treatment. Wood vinegar showed no effect on other insecticides. In addition, the wood vinegar-carbosulfan mixture significantly reduced AChE activity of planthoppers, which is a target molecule of carbosulfan. This result suggests that wood vinegar has a synergistic effect on the insecticidal activity of carbosulfan. Our study provides information on a potential role of wood vinegar in facilitation of activity of specific insecticides.

• Research in Plant Disease
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• v.10 no.1
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• pp.30-33
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• 2004

Until now, occurrence of rice stripe virus (RSV) is limitted in southern part of Korea. However, recently the occurrence of RSV is increased and spreaded in central part of Korea including Chungcheong and Kyonggi province. It is very difficult to distinguish RSV symptoms on virus symptom physiological damage of rice. We detected RSV viral RNA from infected rice and its insect vector Laodelphax striatellus using specific primer of RSV-polymerase and coat protein gene with reverse transcription (RT)-PCR. The result of RT-PCR, we observed specific band including RSV-polymerase (1,,023 bp) and CP (969 bp) in both host of rice and insect vector.

• The Plant Pathology Journal
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• v.29 no.3
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• pp.330-337
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• 2013

Rice stripe virus (RSV), the type member of the genus Tenuivirus, transmits by the feeding behavior of small brown planthopper (SBPH), Laodelphax striatellus. To investigate the interactions between the virus and vector insect, total RNA was extracted from RSV-viruliferous SBPH (RVLS) and non-viruliferous SBPH (NVLS) adults to construct expressed sequence tag databases for comparative transcriptome analysis. Over 30 million bases were sequenced by 454 pyrosequencing to construct 1,538 and 953 of isotigs from the mRNA of RVLS and NVLS, respectively. The gene ontology (GO) analysis demonstrated that both libraries have similar GO structures, however, the gene expression pattern analysis revealed that 17.8% and 16.8% of isotigs were up- and down-regulated significantly in the RVLS, respectively. These RSV-dependently regulated genes possibly have important roles in the physiology of SBPH, transmission of RSV, and RSV and SBPH interaction.

• Korean journal of applied entomology
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• v.16 no.2 s.31
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• pp.121-125
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• 1977

This is the first report on. rice black-streaked dwarf virus in Korea. The occurrence of this virus in Korea was confirmed by symptoms On rice Plants, Vector transmission and microscopic Observation in 1975. The smaller brown planthopper, Laodelphax striatellus FALLEN, transmits this virus which is spherical with a diameter of about 60 nm. Higher infection was observed in earlier transplanted rice with higher levels of fertilizer than in normal and standard cultivation fields.

• Korean Journal Plant Pathology
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• v.1 no.3
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• pp.190-194
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• 1985

The insect vector (Laodelphax striatellus) of rice black-streaked dwarf virus prefered rice plant to maize in feeding both in the cage and in the field, whereas the percent of infectious plants was much higher in maize than rice plants. The causal virus reduced the adult longevity, total number of hatching nymphs and maturity rate from nymphs of the insect vector. The percent of dry weight over fresh weight in rice from early to late growth stages was lower in diseased plants than in healthy plants but it was reversed on maize plant in early growth stage. In agarose gel-diffusion and microprecipitin serological tests, the intensities of antigen with antisera were in orders the preparation partially purified from infected maize leaves> rice stems> rice leaves> maize stems. The pholem galls in diseased plants developed well in the low temperature.

• Korean journal of applied entomology
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• v.55 no.4
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• pp.351-358
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• 2016

Consistent with a previous study on the brown planthopper Nilaparvata lugens (BPH) (Seo et al., 2009), we identified seven distinct EPG waveforms (np, L1, L2, L3, L4-a, L4-b, and L5) in adult female Laodelphax striatellus (SBPH) that fed on rice plants, by using the direct current electrical penetration graph (DC-EPG) system. The shape of waveforms and the pattern of occurrence of each waveform of SBPH were very similar to those of BPH. L3 and L4-a always occurred prior to L4-b. Periodical honeydew excretion was observed in L4-b only. Microsection observation following laser stylectomy revealed that the tips of SBPH stylets severed in L3, L4-a, and L4-b were commonly located in or near the phloem region of rice plants, but were located in the xylem in L5. Plant sap flowed from the stylets severed in L4-b only, and its main carbohydrate component was detected as sucrose by HPLC analysis. These results and the patterns of EPG waveform progress in SBPH suggested that feeding activities on rice plant tissue were relevant to each EPG waveform. L1 and L2 corresponded to the initiation of stylet penetration and stylet movement with salivation on the outside of the vascular bundle. L3 and L4-a were related to feeding activities within the phloem region in preparation for phloem sap ingestion. L4-b was closely associated with phloem sap ingestion, and L5 corresponded to xylem feeding behavior.