Development, survival, and reproduction of brown planthopper (BPH) Nilaparvata lugens Stål (Hemiptera: Delphacidae), were studied in laboratory at 25±2°C, 65±5% RH and a 16L : 8D hours photoperiodism on five rice cultivars of: Dongjin 1ho, Chungchungbyeo, Jangseongbyeo, Chinnongbyeo and Jungmo 1045. BPH nymphs successfully survived on all rice cultivars, although survival rate was lowest on Jangseongbyeo (36.0%). Developmental time of immature stages ranged from 11.7±0.59 d on Jungmo 1045 to 12.8±0.59 d on Chinnongbyeo. Reproductive period and female longevity were longest on Dongjin 1ho, Chinnongbyeo and Jungmo 1045 while highest fecundity of N. lugens being observed on these three rice cultivars. Highest and lowest net reproductive rates were calculated on rice cultivars, Jungmo 1045 and Jangseongbyeo, respectively. Mean generation time was the longest on rice cultivar Dongjin 1ho. Respective descending order of intrinsic rates of population increase were on Jungmo 1045, Chinnongbyeo, Dongjin 1ho, Chungchungbyeo and Jangseongbyeo. These population parameters showed that N. lugens can successfully survive and reproduce on Chinnongbyeo and Jungmo 1045.
애멸구(Laodelphax striatellus)는 rice stripe virus (RSV)의 매개충으로 벼에 큰 피해를 주는 해충이다. 본 연구에서는 애멸구의 장·단시형, 암·수, 약·성충에 대한 RSV 보독률과 이병률을 비교하였다. 애멸구의 장·단시형의 RSV 보독률은 각각 60.7%, 63.1%로 크게 차이는 없었다. 암·수에 대한 RSV 보독률은 각각 61.9%, 52.2%로 암컷의 보독률이 더 높았으나 유의성은 없었다. 약·성충의 보독률을 비교한 결과 각각 51.2%, 58.7%로 역시 크게 차이가 나지는 않았다. RSV에 감염된 애멸구에 노출된 건전한 벼의 이병률은 장시형은 53.3%, 단시형은 48.2%를 보였으며, 약·성충의 이병률은 각각 38.2%, 42.6%를 보여 유의성은 없었다. 반면 암컷은 50.5%의 이병률을 보이고 수컷은 22.3%의 이병률을 보여 암컷이 수컷에 비해 22.3% 이병률이 높아 유의성이 있었다. 또한 벼와 애멸구의 RSV 감염여부에 의한 애멸구의 발육기간은 건전한 벼에 RSV 감염 애멸구를 접종 했을 때 가장 긴 것으로 나타났으며, 건전한 벼에 건전한 애멸구를 접종 했을 때 발육기간이 가장 짧은 것으로 나타났다.
In order to understand the relationship between the distribution of epilithic diatoms and the habitual environments, land-use, water qualities, and epilithic diatoms were studied at 141 sampling sites in the midwestern stream of Korean peninsula (Geum river, Mangyeong river, Dongjin river, and Sapgyo river). The total 183 diatom taxa was appeared in the study, while the dominant species were found to be Nitzschia palea (10.9%) and Achnanthes convergens (8.4%). Based on the abundance of epilithic diatoms, a cluster analysis results indicate that the sampling sites divided the sampling sites into 4 groups (G) at the 25% level. In term of geographic and aquatic environments, G-I and -II accounted for the upper and mid streams of the Geum river, and had large forest areas and good in water quality. G-III accounted for farmland and urban, and high concentration nutrient levels (TN and TP) and electric conductivity. G-IV accounted for mostly farmland, and high levels in turbidity, BOD, nutrient and electric conductivity. CCA results showed that the saproxenous taxa Meridion circulare was the indicator species of G-I, which strongly influenced by altitude and forests. In G-II, the indifferent taxa Navicula cryptocephala was influenced by Chl-a, AFDM, and DO. In G-III and -IV, the indifferent taxa Fragilaria elliptica and saprophilous taxa Aulacoseira ambigua were influenced by electric conductivity, turbidity, and nutrient counts. Meanwhile, random forest results showed that the predicting factor of indicator species appearance in G-I, -II, and -III was found to be electric conductivity whereas in G-IV it was found to be turbidity. Collectively, the distribution of diatoms in the midwestern of Korean peninsula was found to depend more on the land-use and its subsequent water qualities than the inherent characteristics of the aquatic environment.
There are relatively few cases of classical biological control in Korea. During 1904 to 1905 the wooly apple aphid, Eriosoma langigerum, had been happen to invade into Korea from Japan together with imported seedling of apple and its damage spread to Jinampo near Pyoung-Yang City and it occurred all across the country by 1934. In 1934 a parasitic wasp, Aphelinus mali, was introduced and released to apple orchards and found established in nature. And it was the first case of classical biological control in Korea. Afterward couple of classical biological control programs against invaded pests were conducted mainly by the RDA with variable results. For example the orange scale, Ceroplastes rubens, and the Eggar which were successfully controlled by introduction Anicetus beneficus and Thecodiplosis pinico, respectively.
Rice stem borer, Chilo suppressalis Walker is a significant rice insect pest. A newly hatched larva bores a hole into the rice stem and feeding inside. The damage results in drying and white heads of rice. Climate change will affect pest and its host population dynamics variously. In this study, the degree of asynchrony between emergence of rice stem borer and rice transplanting was examined by their phenology models. Also, correlation was examined between winter mortalities of the rice stem borer and relative humidity categorized by daily minimum temperature in 12 sites throughout the country from 1992 to 2013. The degree of asynchrony appears to be increased in future climate condition. And we found a negative correlation between winter mortality and the relative humidity. Winter mortality will be decreased in the future because of increasing winter minimum temperature and snowfall. We hypothesize that the stem borer may increasingly harbor in alternative hosts such as reed in its first generation and move to rice in the second generation. Currently the simulation study is being conducted to verify this hypothesis.
Anatatus orientalis (Hymenoptera: Eupelmidae) is aparasitic natural enemy of the lantern-fly Lycorma delicatula (Hemiptera:Fulgoridae) in China. It can complete 6 generations from April to December in a year under laboratory conditions. It takes 18-28 d for development of one generation at about 25℃. Under the room temperatures of 23-25℃, the developmental duration of eggs is 1-2 days, 10 days for larvae, 4 days for prepupae and 7 days for pupa stage. A. orientalisis a mono-parasitic wasp in the eggs of L.delicatula and its female can oviposit 9.18 eggs on average. The oviposition period is 5-20d. The adults can survive 4-7d on average without supplying any nutrition. While feeding with 20% honey solution, the female adult longevity can reach 25 days on average.
Real Time PCR을 이용한 벼 흰잎마름병균의 밀도를 측정할 수 있는 새로운 방법을 개발하였다. Real Time PCR을 이용하여 벼 흰잎마름병을 예찰하기 위하여 TaqMan MGB probe를 이용한 프라이머인 Xan_PahgeF & Xan_PahgeR primer와 Xan_Pahge FAM MGB probe를 제작하였으며, 높은 특이성이 인정되었다. 병원균 배양액, 벼 흰잎마름병원균의 DNA, 병원세균에 오염된 물에서도 효과적으로 검출이 되었다. 농수로물이나 관개수에서 벼 흰잎마름병균의 밀도를 측정할 때 정량 PCR의 저해인자 제거 후 신속하게 벼 흰잎마름병균의 밀도를 측정할 수 있다.
참딱부리긴노린재의 생물학적 특성을 조사하기 위하여, 온도 20±1, 25±1, 30±1, 35±1, 37.5±1, 40±1℃, 습도 80±10%, 광주기 16:8(L:D)에서 발육실험을 실시하였다. 그 결과 알부터 성충우화까지의 발육영점온도는 14.8℃, 유효적산온도는 399.1일도였다. 35℃에서 조사한 결과를 정리하면 다음과 같다. 알 기간은 5.6일, 부화율은 81.1%, 약충 기간은 14.3일(1령 3.2, 2령 2.2, 3령 2.7, 4령 2.7, 5령 3.6일)이었다. 암컷 성충의 수명은 33.8일, 산란기간은 29.2일이었다. 총 산란수는 111.2개, 하루 최대산란수는 14.8개(7일차)였다. 알과 약충은 37.5℃까지만 발육하고 40℃에서는 발육하지 못했으며, 40℃에서 총 산란수는 22.1개였다. 참딱부리긴노린재 1령, 3령, 5령, 성충의 담배가루이 번데기 하루포식량은 각각 1.9, 7,3, 18.7, 29.5마리였다.
This study was carried out to know whether the host plant feeding have an influence to subsequent prey consumption of a zoophytophagous mirid, Nesidiocoris tenuis, with biological control potential. Piece of leave of Paprika, Sesame, and cotton ball soaked with water were respectively provided to the test insects, adult mirid starved about a day, and frozen eggs of Ephestia kuehniella, were presented to them for a day and counted the number of the eggs consumed by them. The mirid fed by Sesame leave took significantly less prey than both the Paprika and the water fed one.
Maize weevil (Sittophilus zeamais) and Indian meal moth (Plodia interpunctella) are the dominant species among the stored grain insect pests of the rice grain and bran. This experiment was conducted to investigate developmental characteristic and damages of S. zeamais and P. interpunctella on the rice. Under five constant temperatures, 15, 20, 25, 30 and 35℃, developmental periods from egg to adult of Sittophilus zeamais were 43.0, 36.4, 29.2, 20.8 and 16.3 days, respectively. With egg periods being 9.6, 7.3, 5.2, 3.2 and 2.6 days, and larval periods being 25.2, 22.6, 19.8, 14.5 and 11.3 days, and adult periods being 129.3, 116.1, 108.6, 89.2 and 73.3 days, respectively. Damages of S. zeamais adult at 15, 20, 25 and 30℃ were 67.2, 96.2, 134.0 and 174.5 for 24hr on the rice. Damages of P. interpunctella larval 15, 20, 25 and 30℃ were 56.2, 78.3, 109.4 and 138.7 for 24hr on the rice. The duration of maximum occurrence were June to August for S. zeamais, late May to early August for P. interpunctella.
The methanol extracts and essential oils from 9 medicinal plants, Ulmus davidiana var. japonica, Cryptomeria japonica, Hedera rhombea, Prunus mume, Taxus cuspidatal, Paulownia coreana, Kalopanax pictus, Paris verticillata, and Ixeris dentata were tested for their insecticidal activity against larvae of P. xylostella by topical application method. And the methanol extracts and essential oils obtained from Paris verticillata and Ixeris dentata were subjected to a screening test for their antifeeding activities, pupation and adult emergence of P. xylostella by a leaf-dipping method at a concentration of LC50 value. The methanol extract from all parts of P. verticillata and the essential oil from all parts of I. dentata exhibited potent activity with LC50 of 6.34 and 6.53(g/L) 5days after treatment. And the essential oil from all parts of P. verticillata and I. dentata have shown strong antifeeding activity compared to those of methanol extracts against larvae of P. xylostella. Also, the methanol extract and essential oil of P. verticillata and I. dentata gained 37.5%, 5.0% of pupation and 22.5%, 2.5% of adult emergence, respectively.
The methanol extracts and essential oils from 9 medicinal plants, Ulmus davidiana var. japonica, Cryptomeria japonica, Hedera rhombea, Prunus mume, Taxus cuspidatal, Paulownia coreana, Kalopanax pictus, Paris verticillata, and Ixeris dentata were tested for their insecticidal activity against larvae of S. exigua by topical application method. And the methanol extracts and essential oils obtained from Paris verticillata and Ixeris dentata were subjected to a screening test for their antifeeding activities and pupation and adult emergence of S. exigua by a leaf-dipping method at a concentration of LC50 value. The methanol extract from the bark of C. japonica, the leaf of H. rhombea and all parts of P. verticillata exhibited potent activity with LC50 of 5.02, 4.21 and 5.46(g/L) 5days after treatment, respectively. But all of the essential oils except for I. dentata with LC50 of 4.92(g/L) had shown high potential insecticidal activity compared to the methanol extracts against S. exigua. And the essential oil from all parts of P. verticillata and I. dentata have shown stronger antifeeding activity than those of methanol extracts against larvae of S. exigua. Also, the methanol extract and essential oil of P. verticillata and I. dentata affected growth pattern showing those of 32.5%, 10.0% of pupation and 27.5%, 10.0% of adult emergence of S. exigua.
In Korea, agricultural environment has been rapidly changed by several factors and the directions of agricultural policy of government have not been maintained by the sudden changes in recent years. The paradigm of agriculture policy is shifted from the maintenance and conservation of agricultural production to the increase of economic, social and ecological value based on agricultural profitability. The agricultural policy and production system are changed by following main social concerns; first the concern of the exhaustion of natural resources, second the quality of life is decreased by the physical and biological change of climate disturbance, third the deterioration of living environment by human activity and finally, the attention of food security by the unbalance and decrease of food production. Furthermore, in spite of low food (23%) and energy (29%) self-sufficiency, it would seem that the importance of the expansion and improvement of food production is not considered by agricultural policy makers. The foundation of agricultural production is collapsed and weakened because the policy makers decide to relegate the importance of food production to lower priority. Our present life style will be changed by the exhaustion of carbon energy. As a result, the production system of agricultural products will be improved and the price of the products will be increased. It is discussed how our agricultural environment will be changed with the surroundings, what factors, specially climate changes, will be considered to research pest management, and how the strategy of green pest management based on sustainable agriculture will be possible.
In many cases over the years, we failed to forecast accurately outbreak of Rice stripe virus (RSV) disease using population density of overwintering small brown planthopper (SBPH), Laodelphax striatellus. What is the source of error in this viral disease assessment? For answering the question, spatial distribution of RSV in paddy fields was investigated in relation to the yield of rice grain, and the population density of overwintering SBPH in ridge of paddy fields. Total 14 paddy fields in 5 regions were surveyed in June, 2008. Disease assessment was carried out with each of 30 rice plants in the one of the borders, 5th, 10th line from ridge, and 90 rice plants in diagonal line for conventional method. The ears of rices from 18 plants in the same surveyed line were collected in the late of August for the weights of 100 rice grains. The infection rate of RSV was decreased by the distance from ridge; on the contrary, the increase tendency was shown in the yield of rice grains in the middle of paddy field. It is suggested that the border effect of viral distribution between ridge and paddy field is caused by the spatial distribution of the vector insect. Thus, in this case, the narrow border effect could represent that the SBPH migrated short distance from the ridge to paddy field. The conventional method, observing the disease in middle area of diagonal line, showed no correlation to the population density of overwintering vector generation in ridge. It might cause underestimation of the regional disease rate. The counting of RSV-diseased plant in border line only overestimated it also. However, the RSV infection rate in the near border had highly positive linear relationship (R2=0.91) to the regional average values by regression analysis. Therefore, the near border sampling method can improve the RSV disease risk assessment.
The functional response and spatial distribution of parasitoid may be useful for understanding host-parasitoid dynamics because information on these will give knowledge of the host-parasitoid interaction, which could lead to the development of strategy for biological control of insect pests. The functional responses of A. asychis on the green peach aphid and potato aphid was investigated in eggplant leaf-disc arena. As a result, among the three types of functional response, type III best described the A. asychis response to the aphid densities, according to the Bayesian Information Criterion (BIC). Functional response and spatial distribution of A. asychis on green peach aphid, Myzus persicae, was investigated on 5x5 eggplants in the net cage. After M. persicae were inoculated uniformly at the densities of 1, 3, 6, 9 and 12 (per plant) on upper, middle and lower leaves of each 25 eggplants, one mated female of A. asychis was introduced on the central eggplant. Each aphid density was duplicated. A. asychis showed a type II functional response different from that estimated on the eggplant leaf-disc arena. Although the initial distribution of the aphids in the 25 eggplants was uniform vertically and horizontally, the aphids became gradually concentrated on the upper leaves of eggplants, so did immature A. asychis.
Global warming is one of the most buzzing words these days, as the average temperature increased up to 6.4℃ before the end of 21st century and the water level to 59cm causing severe draught, heavy snowfall, and monster typhoon all over the world. The capacity of natural ecosystem will not be able to contain such changes. Many of the species will be endangered and some of them are warned to be extinct, and accordingly water and food supply will not meet the demand of human. In 2007, IPCC, Inter Governmental Panel on Climate Change, made fourth report about global warming and estimated that the CO2 content in the atmosphere increased about 1.35 times to 379ppm at 2005 from 280ppm before the industrialization period pulling the average air temperature up by 0.7℃ a year. The water level as well increased by 1.8mm a year as the polar iceberg and permanent snow melt down. Global warming caused by environmental pollution and greenhouse gas may lead to the increase of price of not only agricultural product but also the industrial products as a consequence, a phenomenon so called Ecoflation, Ecology+inflation. IPCC forecasted that if the present phase use of fossil energy continues the air temperature in 2090-2099 will increase by 4℃ and the water level by 26-59cm compared to that of 1980-1999, warning particularly that the average increase of global temperature by 1.5-2.5℃ a year will put the species of 20-30% into danger of extinction.
According to the report by the Korea National Statistical Office about the effect of climate change on the production of agriculture and fishery, the cultivation area of apple which is typical temperate fruit decreased to 29,204ha in 2007 from 52,447ha in 1992. On the other hand the cultivation area of peach increased greatly to 15,014ha(2005) compared to 12,000ha in 1996 as it became possible to grow wherever in Korea. Similar change can also be found for orange and grape, orange can be grown in Jeonnam and Kyuongnam province, and grape in Kangwon province. Jeju island and southern coastal area of Korea worry about the inhabitation of subtropical pests when they invade these area, in fact the pest outbreak as a result of the increase of generation a year is ever more frequent. The typical examples are Paratlanticus ussuriensis (Uvarov), the lantern fly, Lycorma delicatula, and the fruit moths like Carposina sasakii Walsingham.
For the physiological study on environmental impact of genetically modified (GM) pepper plant on non-target but three-trophically related insect species, we investigated behavioral responses of Aphis gossypii and Aphidius colemani in Y-tube olfactometer to the cucumber mosaic virus (CMV)-resistant transgenic pepper plant (H15 GM line) expressing coat protein gene of CMV and its wild type pepper plant (untransformed, susceptible to CMV pathotype II, P2377 inbred line) in relation to CMV infection. CMV-infected plants were prepared with the 30 min of inoculation by the winged A. gossypii viruliferous or mechanical inoculation using CMV-Fny, and with molecular diagnosis using reverse transcriptase-polymerase chain reaction (RT-PCR) over 2 weeks after inoculation. In this study, time for attraction responses (attraction time) of A. gossypii were not significantly different in the pepper strain, and the virus infection of plant. However, the attraction time of A. colemani was significantly different between the GM plant and the non-GM plant. In addition, the attraction time of A. colemani to the GM plant was significantly decreased according to the CMV infection. For further study, the volatile organic compounds (VOCs) emitted by these plants were collected with an entrainment kit and analyzed by Gas Chromatography (GC) on HP-1 column. The specific VOCs related to CMV infection were detected in the GM plant over 4 weeks after inoculation of CMV in this study. Thus, it is suggested that VOCs of the GM plant in this study may be produced more as a signal attracting A. colemani in relation to CMV infection.