꼬마남생이무당벌레(Propylea japonica)는 딱정벌레목(Coleoptera) 무당벌레과(Coccindllidae)에 속하고, 여러 진딧물 에 대한 국내 토착 포식성 천적으로 알려져 있어 진딧물에 대한 생물적 방제 방법에 이용하기 위해 진딧물의 1일 포식량을 조사하였다. 온도 25℃, 습도 60±10, 16L:8D의 조건에서 피망에 접종한 복숭아혹진딧물을 1령, 2령, 3령, 4령 유충이 각각 4.6, 12.3, 18.1, 33.4마리를 포식하였다. 20, 25, 30℃에서 꼬마남생이무당벌레의 복숭아혹진딧물 1일 포식량은 암컷이 각각 65.7, 64.5, 82.0마리이었고, 수컷은 각각 39.0, 52.9, 62.3마리로 온도가 높아질수록 1일 포식량이 증가하는 것으로 나타났다.
Worldwide, increasing numbers insecticide resistant insect is one of the main problem in agriculture not only in the field but also in the storage. The rusty grain beetle, Cryptolestes ferrugineus is one of the cosmopolitan insect that infests a wide range of stored cereals and related commodities. Until quite recently, phosphine (PH3) has been effective in controlling this species in worldwide including Korea. However, strongly resistant populations of RGB have been detected in Australia that could threaten market access of infested commodities. Resistant populations detected in Australia showed extremely high levels of resistance to phosphine, up to 1300 folds higher than that of susceptible strain. So here we tried to identify their phosphine resistance mechanism based on transcriptome analysis using RNaseq in adult stage. Over 10Gb were sequenced in each strains and some of specific P450 were over expressed in resistance strain.
The pea aphid Acyrthosiphom pisum (Harris) (Hemiptera: Aphididae) is a pestiferous species with a worldwide distribution. We investigated the development periods and survivorship of A. pisum nymph, and longevity and fecundity of A. pisum adult. The study was conducted at five constant temperatures of 10, 15, 20, 25, and 30°C. Higher temperature threshold (TH) and lower temperature threshold (TL) were calculated by two nonlinear functions. The temperature range of A. pisum from TL to TH using empirical model (29.29) was wider than that using biophysiological model (21.85). The adult emergence frequency of A. pisum over full range of constant temperatures was simulated using developmental rat
The world’s climate is changing. Aphids are emerging as lookouts of climate change and they are a good model to understand these environmental changes especially through migratory behavior. We monitored of the occurrence of aphid in same place (Pyeongchang) of seed potato field since 1977 in Korea. Dates of the start of spring migration of these aphids’ species were getting earlier. And, the pick of autumn migration were gradually move to winter season. Moreover, annual total numbers of collected aphids were also dramatically increased during 40 years. There is potential threats of distribution expansion of aphid species in Korea where is the hot spot of climate change with average temperature over 1.7 °C increase for 4 decades. Therefore we hypothesized that aphids’ migration pattern could be associated with temperature
Riptortus pedestris is a polyphagous species and an important pest of soybean. We investigated the phenology of R. pedestris at 14 locations - Jeonju, Naju, Goheung, Namhae, Milyang, Gunwi, Andong and 7 areas of Jeju. Commercial pheromone monitoring traps were used. The traps were baited with lures containing a 1:5:1 ratio of myristyl isobutyrate, (E)-2-hexenyl (E)-2 hexenoate and (E)-2-hexenyl (Z)-3-hexenoate. There was difference the first adult catch and nymph emergence among locations. To develop spring emergence distribution pattern, we used the trap data from each location. Spring emergence by sampling date was cumulated and analyzed relative to the Julian date using Weibull distribution function.
The soybean bug, Riptortus pedestris, is a polyphagous species and an important pest of soybean. We investigated the development periods and survivorship of R. pedestris egg and nymph stage. The study was conducted at eleven constant temperatures of 12, 14, 16, 18, 20, 24, 28, 32, 34, 35, and 36℃, respectively. Egg could not hatch under 14℃. Nymph could not develop to adult at 16℃. The lower developmental threshold (LDT) and thermal constant (K) of R. pedestris nymph stage were estimated by linear regression. Higher temperature threshold (TH) and lower temperature threshold (TL) were calculated by two nonlinear functions (Performance and SSI model). The adult emergence frequency of R. pedestris over full range of constant temperatures was simulated using developmental rate functions and Weibull function.
감과원에 돌발적으로 발생하여 경제적 피해를 주고 있는 볼록총채벌레(Scirtothrips dorsalis HOOD)에 대해 경북 상주군, 청도군 감과원에서 피해증상 및 발생상황을 조사하였다. 감과원에 발생되는 총채벌레 종류는 볼록총채벌 레, 대만총채벌레, 꽃노랑총채벌레, 하와이총채벌레, 감관총채벌레 등이었으며 이중 감에 가장 심각한 피해를 일으키 는 종은 볼록총채벌레였다. 볼록총채벌레에 의한 과실의 피해 증상은 개화기 전후로 약충이 꽃안에 들어가 과피를 흡즙하며 개화후 꽃이 떨어지지 않은 마른 꽃속을 돌아다니며 과피에 피해를 주며 꽃받침과 과실의 경계부위 과피도 피해가 발생된다. 흡즙된 과피는 갈색반점이 생기고 점차 코르크화 되고 과실이 자라면서 과실 적도면, 과정부에 콜로니모양을 형성한다. 황색끈끈이트랩을 이용한 볼록총채벌레 밀도 조사 결과, 4월상순부터 9월상순까지 감과원에서 계속 발생하였으며 과실내에는 볼록총채벌레 약충이 5월상순에 최초 발생하였고 5월하순부터 밀도가 급격히 증가하여 6월중순까지 발생되었다.
The two-spotted spider mite, Tetranychus urticae Koch (TSSM)(Acari: Tetranychidae) is the major arthropod pest in strawberry greenhouses. Elevated levels of stress caused by high populations of TSSM can lead to a significant reduction in vegetative growth and flower development, which can decrease the quality and quantity of mature fruits. Currently, TSSM is managed by pesticide, and which makes that is distributed all over the world with various pesticide resistances and environmental side effects. To solve these problems, alternative pest management strategies are being tried. Biological control, one of alternative strategies, is relatively low toxicity and stable to agricultural ecosystems. I compared the density of TSSM in export strawberry greenhouses, those are under conventional pesticides and natural enemy applied, respectively, and also evaluated the cost of management of each control strategy.
The family Coccidae Fallén, 1814, which is named soft scale insect, is recognized from Laos as twenty-two species including nine new records: Ceroplastes cirripediformis (Comstock, 1881), C. stellifer (Westwood, 1871), Coccus formicarii (Green, 1896), C. gymnospori (Green, 1908), C. hesperidum Linnaeus, 1758, C. latioperculatum (Green, 1922), Drepanococcus cajani (Maskell, 1891), Saissetia miranda (Cockerell & Parrott in Cockerell, 1899), and S. oleae (Olivier, 1791). A key to the Lao species of Coccidae is provided with diagnoses, photographs and host information for each species.
Rice stripe virus (RSV) is one of the serious plant pathogenic viruses for rice transmitted by small brown planthopper (SBPH), Laodalphax striatellus. RNA interference (RNAi) was recently suggested as a promising strategy for controlling insect pests, including those that serve as important vectors for plant pathogens. To disturb transmission of the RSV in SBPH using RNAi pathway, we chose nine genes highly expressed in RSV-viruliferous SBPH by transcriptome sequencing. These SBPH-derived dsRNAs were applied to the insects indirectly through xylem of rice leaves by irrigation. qPCR result demonstrated that five out of nine SBPH-derived dsRNAs successfully reduced the replication of RSV in viruliferous SBPH in dose-dependent manner, suggesting that these five dsRNAs could suppress replication of RSV and provide a new tool for RSV control strategy.
Entomopathogenic fungi have been widely studied for their potential as the effective biological control agents. They produce variety of secondary metabolites with insecticidal activities, and it is reasonable to assume that entomopathogenic fungi might produce secondary metabolites modulating juvenile hormone for their survival against defense mechanisms of host insect. In this study, acetone extract of the Lecanicillium spp. cultured on unpolished rice medium showed juvenile hormone antagonist (JHAN) activity in the yeast-two hybrid β-galactosidase assay and high insecticidal activity against Aedes albopictus and Plutella xylostella. In addition, to compare bioactivities of secondary metabolites from solid and liquid culture, the Lecaniciilium spp. strain cultured on unpolished rice medium or PDB medium were serially extracted with acetone and ethyl acetate respectively. Both extracts showed JHAN activity and high insecticidal activity against A.albopictus. Theses results suggested that secondary metabolites of entomopathogenic fungi could be useful for development of novel IGR insecticides.
Insect growth regulators (IGRs) are insecticides that disrupt the normal development of target insects by inducing symptoms such as premature molting or supernumerary larval stages. Juvenile hormone (JH)-based IGRs are of particular interest because they simulate or interfere with the formation of juvenile hormone receptor complex. Insect larvae generally have been poorly susceptible to JH agonists (JHAs) because endogenous JH titer is already high in the larval stage. In contrast, JH antagonists (JHANs) might be more effective for control of target pests in larval stages through interference in the status quo action of JHs. In this study, we tested 2,354 chemical compounds using the yeast-two hybrid system to identify JHANs. Among them, K265674 sample was selected and its insecticidal activity was evaluated against Aedes albopictus larvae. These results may be useful for development of novel IGR insecticide.
RNA interference (RNAi) is an universal gene-knockdown mechanism in eukaryotic organisms including insects. RNAi has been considered as an alternative strategy to control agricultural pests whereby double-stranded RNA triggers a potent and specific inhibition of its homologous mRNA. Bacillus thuringiensis (Bt) is a spore-forming bacterium that produces a copious amount of crystal proteins δ-endotoxins under the control of sporulation-dependent promoter. In order to develop dsRNA mass-production platform utilizing recombinant Bt, the pHT1K-EGFP which expresses dsRNA against EGFP under the control of Cyt1-Aa sporulation-dependent promoter was constructed and the expression level of transgene (EGFP) was confirmed by qPCR analysis. These results suggested that Bt’s potential of becoming a new platform in dsRNA production.
Plant essential oils have been reported to show repellent, insecticidal and growth-reducing effect on many insect herbivores. Recently, it has been reported that plants synthesize secondary metabolites regulating insect juvenile hormone (JH) receptor complex as a part of their defense mechanisms. We tested 180 plant essential oil compounds using a yeast two-hybrid system transformed with the Aedes aegypti JH receptor as a reporter system. Among them, we identified 17 compounds that showing high JH agonist (JHA) or antagonist (JHAN) activities. They were grouped into 4 groups by their structural similarity and their insecticidal activity was tested against larvae of Aedes albopictus, Plutella xylostella, Plodia interpunctella and Laodelphax striatellus. These results could provide insights on the plant-insect coevolution and may be useful for the development of insect specific and safe pesticides.
Secondary metabolites isolated from Actinomycete have been studied to find potent pest control agents as their insecticidal and growth inhibitory activities. In order to investigate novel insecticidal compounds, second metabolites from 363 Actinomycete isolates were evaluated for their insect growth regulatory activities. Among them, ethyl acetate extracts from ten Streptomyces spp. showed high level of Juvenile hormone antagonist activity. In addition, their insecticidal activities were tested against larvae of Aedes albopictus, Plutella xylostella and Laodelphax striatellus. These results suggested that secondary metabolites from Streptomyces spp. could be used for development of novel IGR-based insecticides.
There are two different types of acetylcholinesterase (AChE1 and AChE2) in the western honeybee as in most of insects. It is suggested that soluble AmAChE1 might be related with a stress response as judged from its elevated expression level in honey bee workers when brood rearing was suppressed. In this study, to ensure the nature of AmAChE1 responding to stress factors, the expression patterns of AmAChE1 following heat shock, brood rearing suppression and chemical treatments (Imidacloprid and fluvalinate) were investigated. Also, several heat shock protein (hsp) genes (hsp10, hsp60, hsp70 and hsp90) known as general stress markers were tested as positive references. Heat shock induced expression of every tested hsp along with AmAChE1. In brood rearing-suppressed worker bees, 7 days old bees showed much higher expression level of AmAChE1 and hsp90 compared to control honey bees. However, treatment of imidacloprid and fluvalinate did not induce any apparent overexpression of these genes. These results confirm that both HSP and AmAChE1 genes generally respond to temperature and brood rearing suppression and further suggest that AmAChE1 can serve as a potential biomarker along with hsps for the detection of stress in honey bee colonies.
호리허리노린재는 유숙기의 벼이삭을 가해하여 반점미를 유발하는데, 아직까지는 일본에서만 피해가 보고되고 있다. 한국에서는 제주도와 남부 해안 주변의 강아지풀 군락에서 주로 발견되고 있다. 하지만 기후변화에 의해 분포가 확장되고 밀도가 증가하게 될 경우, 주요 해충이 될 가능성이 있어 호리허리노린재의 월동성충 유입모델과 발육산란모델 자료를 이용하여 계절 발생 모형을 작성하였다. 또한 미래 지구온난화 기후예측모델인 RCP 8.5 시나리오 를 이용하여 년도에 따른 변화를 비교 분석하였다. 2015년의 월동성충 유입이 50%가 되는 시기는 175일(Julian day)이며, 총 3세대가 발생하는 것으로 나타났으나 2세대가 발생 최성기였다. 2090년대에는 159일에 50%의 월동 성충 유입이 완료되며, 년간 4세대가 발생할 것으로 예측되었다. 월동성충 유입과 유사하게 발생 최성기는 2015년 269일에서 2090년대 260일로 점차 앞당겨질 것으로 예측되었다. 발생 최성기의 개체수는 처음 성충 1마리가 유입되었 을 때, 2015년에는 3.41마리, 2090년대에는 268.12마리로 급증할 것으로 예측되었다.
Metabolic resistance mechanisms of Laodelphax striatella to several insecticides, such as neonicotinoids, organophosphates and pyrethroids, have been investigated by evaluating the transcription levels of CYP450 genes. Nevertheless, no study on the CYP450-mediated carbamate resistance in L. striatella has been conducted to date. Here, we determined the transcription levels of six CYP450 genes and one carboxylesterase gene to screen detoxification genes associated with carbamate resistance. The CYP6CW1 exhibited the highest transcription level (18 fold) in a resistance strain. Interestingly, its transcription level increased slightly (3 fold) in a susceptible strain upon the exposure to a sublethal dose (LC30) of carbofuran. These results suggest that CYP6CW1 expression is inducible by carbofuran and its overexpression is likely responsible for carbofuran tolerance and resistance in L. striatella.
It has been proved that agroinfiltration-based temporary expression of coatomer subunit alpha (COPA) gene from Tetranychus urticae hairpin RNA induces RNA interference (RNAi) and lethality to T. urticae. To establish detailed protocols for agroinfiltration, the efficiency of agroinfiltration to the soybean and kidney bean was determined with respect to different Agrobacterium delivery methods (sea sand, carborundum and syringe) and the spacial expression patterns of hairpin RNA was investigated following Agrobacterium delivery. Sea sand and syringe showed the highest expression level in soybean and kidney bean, respectively. Considering the resulting tissue damage, syringe appeared the best choice for agroinfiltration in both soybean and kidney bean. The apical region of a leaf showed more relative expression levels in both soybean and kidney bean compared to the basal region. Following agroinfiltration, adjacent untreated leaves were determined to express hairpin RNA though the expression level was low, suggesting that hairpin RNA can be translocated to other leaves. In conclusion, Agrobacterium delivery by syringe and use of whole leaf were recommended for T. urticae bioassay following agroinfiltration.
Perturbation of normal behaviors (e.g., nursing and foraging) in honey bee colonies by any external factors would immediately reduce the colony’s capacity for brood rearing, which can eventually lead to collapse of entire colony. To investigate the effects of brood rearing suppression in the biology of honey bee workers (nurse and forager), the gene-set enrichment analysis (GSEA) was performed for the transcriptomes of worker bees with or without their brood rearing being suppressed, from which functional profiles of pathways under influences by each condition were identified. Blocking of normal labor (i.e., nursing or foraging) induced the over-representation of pathways related with reshaping of worker bee physiology, suggesting that transition of labor is physiologically reversible. In addition, brood rearing suppression appeared to result in the reduction of neuronal excitability and aggressiveness in both forager and nurse, which would be necessary to manage the in-hive stress under unfavorable conditions