Beauveria bassiana is widely studied for its potential as biopesticide. However, little is known about the factors to influence genetic diversity among isolates. In this work, we aimed to study the gene diversity of 42 isolates to figure out the impact of sequences variability on various biological features. The accumulated data showed no correlation between sequence variability and the fungal geographic localization. Meanwhile, weak to strong correlations have been obtained between the sequence diversity of various genes and the studied biological features. Interestingly, Biotrophy-associated gene 2 gene variability was correlated with all the studied biological features, being an important marker to determine isolates of interest for biological control. Therefore, the obtained data would serve as a database to focus on interesting genes related to improving or screening highly virulent isolates as biological control agents.

A species of Beauveria bassiana is widely used for biological pest management in many countries. Many efforts have been given to figure out the clear fungal mode of action to enhance the insecticidal activity. Homologous recombination (knock-out) or hairpin RNA (knock-down) is popularly used in fungal gene function study, but gene cloning and generation of knock-out or -down mutants takes long time or temporarily knock-downed. Here in this work, we used previously generated egfp-expressing B. bassiana strain (Bb-egfp #3) and integrated dsegfp to the Bb-egfp #3 using a protoplast integration method. This work suggests that protoplast integration with dsRNA possibly generate significantly reduced gene expression in B. bassiana and the reduction is quite stable over generations which provide easy of functional study for fungal mode of action.

The serious emergence of chemical-mediated residual toxicity and insect resistance have been enforced the regulation of synthetic pesticides. Future decisions to select more realistic control options probably depend on the speed of technological development in chemical and biological pesticides. Now, a strategic collaboration between synthetic pesticides and biopesticides has been progressed, such as distribution and R&D in collaboration and M&A for obtaining microbial resources. Recently registered microbial pesticides are entomopathogenic fungi in pest management. A concept of e-biopesticide could be properly combined with digital agriculture and accelerate the use of biological control agents in the future farming.

The longhorned tick, Haemaphysalis longicornis, is one of the vectors of severe fever with thrombocytopenia syndrome virus (SFTSV) in human. The use of pyrethroid insecticides induced pest resistance and environmental residual toxicity. Here in this work, our interest was given to the selection of highly virulent fungi against longhorned tick. A total of 101 fungal pathogens were assayed by dipping the nymph stage of ticks into a conidial suspension. Interestingly of the several species, one species showed high virulence and mycosis were observed in 7-15 days. Highly virulent strains were selected, and semi-field experiments were conducted. As a result, the control efficacy of the isolate was over 80% at 30 days of treatment. This work suggests that entomopathogenic fungi could be used to effectively control longhorend ticks.

Silverleaf whitefly, Bemisia tabaci is a worldwide agricultural pest that cause serious damage to crops. However, since this insect developed resistance to variety of chemicals, alternative control strategy needs to be studied. In this study, we aimed to evaluate the potential of entomopathogenic fungi as biological control tools against this pest. We developed a dipping method in laboratory conditions to screen insecticidal activity of different fungal species and isolates against the nymphal stage of whitefly. The highly virulent isolates were characterized and 2 isolates were further selected based on their high conidial productivity and thermotolerance. Finally, several grain substrates were used to confirm the conidial productivity and thermotolerance of the selected isolates, revealing optimum conidial production when the fungi were cultured on millet grains. Both isolates could be used in further millet grain-based formulations to control the whitefly in fields.

Red mite, Dermanyssus gallinae is one of the serious pests, damaging to the egg production in chickens. Moreover, the overuse of chemical insecticides caused pest resistance and environmental residual toxicity. Therefore, this work provides a screening method to select entomopathogenic fungi as a candidate of environmentally safe control agent, having high miticidal activity against D. Gallinae. The virulence test was conducted using a spraying method. Of the several species, Beauveria species showed high virulence and mycosis were observed. Some isolates were produced on eight cereal grains in Petri dish conditions. Millet, perilla seed and barley showed the high conidia production. Conidia of the isolates produced on millet and rice showed high thermal stability, when exposed to 45℃. Based on these results, this work suggests that entomopathogenic fungi could be used to control the D. Gallinae.

Insect-killing fungi have high potential in pest management. A deeper insight into the fungal genes at the whole genome level is necessary to understand the inter-species or intra-species genetic diversity of fungal genes, and to select excellent isolates. In this work, we conducted a whole genome sequencing of Beauveria bassiana (Bb) JEF-007 and characterized pathogenesis-related features and compared with other isolates including Bb ARSEF2860. A large number of Bb JEF-007 genes showed high identity with Bb ARSEF2860, but some genes showed moderate or low identity. The two Bb isolates showed a significant difference in vegetative growth, antibiotic-susceptibility, and virulence against Tenebrio molitor larvae. When highly identical genes between the two Bb isolates were subjected to real-time PCR, their transcription levels were different, particularly in heat shock protein 30 (hsp30) gene which is related to conidial thermotolerance. In several B. bassiana isolates, chitinases and trypsin-like protease genes involved in pathogenesis were highly conserved, but other genes showed noticeable sequence variation within the same species. Given the transcriptional and genetic diversity in B. bassiana, a selection of virulent isolates with industrial advantages is a pre-requisite, and this genetic approach could support the development of excellent biopesticides with intellectual property protection.

Longhorned tick, Haemaphysalis longicornis (Ixodida: Ixodidae) is one of the vectors of severe fever with thrombocytopenia syndrome virus (SFTSV) in human. The tick occurs in mostly grass fields, and the use of pyrethroid insecticides induced pest resistance and environmental residual toxicity. Particularly the use of chemicals near residential areas where persons live become a big issue, so environmentally safe control agents need to be considered. Here in this work, our interest was given to the selection of highly virulent fungi against H. longicornis. A total of 101 fungal pathogens collected from mountainous areas were assayed by a dipping the nymph stage of ticks into a conidial suspension (1×107conidia/ml). Interestingly among several species, one species showed high virulence and mycosis were observed in 7-15 days. Most of the selected isolates produced a large amount of conidia in Italian millet, rice and millet with thermotolerance at 40-45°C. Based on these results, we selected a couple of isolates with high virulence against H. longicornis and they could be used for the control of the ticks after the set-up of a practical application strategy in fields by optimizing fungal colonization in soil and phyllosphere.

Thrips is one of the serious insect pests in many economic crops, in which general managements rely mainly on chemical insecticides. However, the overuse of chemicals led to the development of insect resistance and environmental residual issues. Therefore, thrips management requires the consideration of alternative strategies which are less harmful to the environment and working on different target points. In this work, we isolated entomopathogenic fungi from soil, and identified them with morphological and molecular biology methods, followed by a preliminary virulence assay against Tenebrio molitor larvae. Selected fungal isolates were adjusted to 1×107 conidia/ml for an indoor virulence assay against thrips adults, and highly virulent isolates were added to a thrip-pathogenic fungal library. Biological characteristics of efficacious isolates were investigated comparing to a previously commercialized fungal isolate. This entomopathogenic fungal library could be used as a valuable resource for developing effective strains to control thrips in agricultural fields.

Entomopathogenic fungi have been known as promising candidates for biological control of insect pests. Recently, researchers consider the fungal thermotolerance in formulations and field applications. In this study, we investigated the production of thermotolerant Isaria javanica and I.fumosorosea conidia through grain-based solid cultures and exposure to light stress. As results, of the ten grain substrates, Italian millet, rice, perilla seed and sesame, rice, sorghum produced highly thermotolerant conidia in the strains. The two strains were exposed to a light stress and showed enhanced thermal stability compared to control, when exposed to 45°C for 2 hours. This work suggests that heatresistant entomopathogenic fungal conidia can be produced by grainbased solid cultures and exposure to light stress.

Whitefly has a broad host range of more than 600 species, and 40 biotypes have been reported worldwide. Among the various ecological types, B and Q are the most problematic. Especially, Biotype Q, which causes serious damage in the green house, mediates more than 40 kinds of viruses, including Tomato yellow leaf cull virus (TYLCV). The development of resistance to whitefly, adverse effects on non-target organisms, and strengthened legal regulations are making chemical control difficult in application. For these reasons, the use of alternative strategies is needed to suppress the Biotype Q whitefly population. Entomopathogenic fungi were investigated and developed to control hard-control insect pest, such as whitefly. These fungi are natural pathogen of their invertebrate host and contribute to the regulation of their host population in the environment. In addition, these agents are typically harmless to humans and non-targeted organisms and do not adversely impact the environment. Therefore, in this study, we screened pathogenic fungi against whitefly using our entomopathogenic fungal library, and virulence tests were conducted with conoidal suspension (1×107conidia/ml) in laboratory conditions. As a result, 10 isolates showed 80-100% mortality at 5 days after treatment. We will analyze the characteristics of these fungal isolates and evaluate their potential as insecticides against whitefly. The selected isolates against the high mortality of whiteflies can be effectively used in integrated pest management programs for whiteflies.

과일이나 농작물의 부패 및 발효 환경에서는 Methanol, Ethanol, Acetic acid을 비롯한 다양한 화학물질들이 생산된다. Drosophila melanogaster는 이러한 발효·부패 환경에 서식하면서 일정 농도 이상의 다양한 화학물질에 지속적으로 노출되어 생존하도록 적응되어온 것으로 생각된다. 다양한 화학물질이 포함한 환경에 안정적으로 서식하기 위해서는 D. melanogaster는 화학물질에 능동적으로 반응하여 해독 유전자나 대사 관련 유전자의 발현량을 변화 시킴으로써 발효·부패 환경에서 생성되는 화학물질에 대한 높은 내성을 가지고 있을 것으로 판단된다. 현재까지 유전자의 발현량 측정을 위해 real-time PCR를 이용하여 reference gene의 발현량을 기준으로 정량화하는 방법이 가장 널리 사용되고 있다. 그러나 조직별, 환경별, 발달단계를 비롯한 다양한 조건에서 안정적으로 발현되는 reference 유전자 선정이 필수적으로 선행되어야 하므로 본 연구에서는 발효·부패 환경에서 생산되는 두 화학물질인 Methanol과 Ethyl Acetate에 노출된 D. melanogaster에서 안정적으로 발현되는 reference gene을 찾는 연구를 실시하였다. 본 연구에서는 다양한 농도의 Methanol과 Ethyl Acetate을 D. melanogaster에 노출시킨 후 RNA 추출과 cDNA 합성을 실시였고, 5가지 후보 reference gene (hsp22, nd, rpL18, tbp and ef-1b)의 안정적 발현 여부를 qRT-PCR을 통해 조사하였으며, 유전자 발현의 안정성을 측정하는 3가지 프로그램(geNorm, NormFinder, BestKeeper)을 이용해 비교·분석하였다. 본 학회에서는 연구의 과정과 그 결과를 발표하고자 한다.

Japanese pine sawyer beetle, Monochamus alternatus Hope (Coleoptera: Cerambycidae) is considered as a serious pest in pine trees. To develop an eco-friendly strategy to manage this forest insect, we collected entomopathogenic fungi from Korean soil and assessed their virulence against the adults of the insect in laboratory conditions. As a result, two isolates with conidial suspension (1.0×107conidia/ml), showed 87% and 90% mortality 12 days after fungal treatment, respectively. We assessed the potential of the fungi-derived destruxin and protease as additives to the fungal isolates, and they showed insecticidal activity via feeding and spraying treatments. Finally, we produced fungal conidia in massive solid cultures and formulated wettable powders, and now studying optimal conditions of oil-based formulation with two isolates. Based on these results, we are evaluating the control efficacy of the fungal agents against M. alternatus in field conditions.

Roller Compacted Concrete Pavement (RCCP) is placed by roller compaction of a mixture of less cement and unit water content and more aggregates and provides excellent early strength development with the help of interlocking of aggregates and hydration. The unit cement content of RCC pavements accounts for 85% of conventional pavements, with low drying shrinkage. As low drying shrinkage leads to smaller crack widths than ordinary concrete, RCC pavements can help elevate reflecting crack resistance if applied to a base layer of a composite pavement system. In a composite pavement with an asphalt surface laid over a concrete base, pavement temperature change is important in predicting pavement performance. As movement of the lower concrete layer is determined by temperature depending on pavement depth, temperature data of the pavement structure serves as an important parameter to prevent and control reflecting crack. Among the causes of reflecting crack, horizontal behavior of the lower concrete layer and curling-caused vertical behavior of joints/cracks are considered closely related to temperature change characteristics of the lower concrete course (Baek, 2010). Previous studies at home and abroad about reflecting crack have focused on pavement behavior depending on daily and yearly in-service temperature changes of a composite pavement (Manuel, 2005). Until now, however, studies have not been conducted on initial temperature characteristics of concrete in composite pavements where asphalt surface is placed over an RCC base. Annual temperature changes of in-service concrete pavements go up to 60 ℃, and those of asphalt overlays become around the twice at 110 ℃. This study evaluated initial crack behavior of composite pavement by investigating pavement temperature by depth of an RCC base and analyzing joint movement depending on change to temperatures of continuously jointed pavements. Findings from the study suggest that in composite pavements and asphalt overlays, time of laying asphalt has an important impact on crack behavior and reflecting crack.

The composition of the deicer sprayed on the highway is spreading over the highway by the scattering or snow removal activity, or car movement and consequently affecting the vegetation environment around the highway. These are the cause of the damage of fruit trees and crops, and also the cause of corrosion of highway structures. The goal of this study is to estimate the detected range of deicer components from a highway. The concentration of the deicer components in gauze and soil were investigated according to the crossing distance from the highway. The data collected were then used to estimate the concentration range of deicer components in a rage of distance up to 100 m from the highway where the deicer was spread. The sample time and weight of gauze were measured before and after installation, and the soil was collected at more than three points in parallel with the highway at the gauze installation point. The components in gauze and soil were investigated in addition to the deicer components (Ca2+, Na+, Cl-) as well as Mg2+ and K+. As Ca2+ and Cl- components of deicer were affected by agricultural use, Na+ component was selected as a tracer and further SAR (Sodium Adsorption Ratio) of soil was analyzed to examine the degree of influence on vegetation indirectly. The gauze concentration was evaluated by the concentration of the deicer ingredient at the background concentration of the blank gauze. The total amount of the deicer sprayed in the study road for 4 months (winter season) was about 93 ton/km. In the gauze test, the spread of the deicer was detected at a distance of 100 m in study area, but the concentration of the deicer in the gauze by distance decreased rapidly within 10 m from the highway. And concentration of the deicer components in gauze and soil came down after rainy season (August ~ Sep.). The results showed that the components of the deicer could be spread widely by the wind. The effective range of the deicer on vegetation based on SAR in soil was estimated to be less than 20 m from the highway. This study examines the concentration changes of the deicer components in gauze and soils and shows that deicer components sprayed on the highway are accumulated and moved over time by wind, snow removal, terrain, water system and land use around the highway.

It is well known fact that the filed asphalt mixture is aged in the truck while hauling and queuing for one to four hours before dumping to the hopper of the paver. This aging, which is called short-term aging (STA), affect the physical and mechanical properties of asphalt mixture. For example, the maximum theoretical density of mixture is changed before and after STA. Therefore, when the asphalt mixture specimen is prepared for testing various physical and mechanical properties in laboratory, the mixture should be STA conditioned by a most-likely STA condition of the field. This is the reason why the STA should be performed properly. This study initiated to investigate STA conditioning protocols, set forth many agencies in the world, and to suggest a proper STA protocol which simulates field HMA condition as most likely as possible. According to this study, it was suggested that the blended loose mix for one specimen poured in a canister should be kept in a drying oven (no forced draft) without cap at 163±2℃ and for 70±15 min for normal HMA mix. This protocol was suggested based on that the absolute viscosity level of the recovered binder after STA should be a similar level of the same binder after a standard RTFO run.

최근 봄철 기온이 높아짐에 따라 마늘 뿌리응애 피해가 늘어나고 있는 실정이다. 이러한 뿌리응애 피해를 최소하 하고자 발생양상과 22종의 약제에 대하여 살비효과를 조사하였다. 마늘 재배시기 중 뿌리응애의 발생은 충북 보은 등 5지역에서 2015년부터 2017년까지 3년간 3월부터 6월까지 뿌리응애 발생밀도를 조사하여 발생양상을 확인하였다. 뿌리응애는 2016년에 가장 많이 발생하였으며, 발생시기는 월동 후 3월 상순부터 발생하여 6월 중순경까지 지속적으로 밀도가 높아지는 양상을 나타내었다. 조사된 5지역 중 가장 높은 밀도로 조사된 보은지역은 6월 상순경 주당 13.3마리가 발생하였다. 뿌리응애에 대하여 우수한 살비효과를 나타낸 약제는 분무처리시 약제처리 10일 후에서 dimethoate, azocyclotin, abamectin, hexythiazox, cabosulfan, spirotetramat, benfuracarb가 90% 이상의 살비효과를 나타내었다