Insects are the dominant animals in the world, with more than one million described species. Insects, not only produce direct damage to plants but also acts as a vector for various pathogens. In recent years, next-generation sequencing (NGS) techniques have provided fascinating opportunities to understand the basic biology, biochemistry, and molecular biology of these intimate and intriguing relationships. The decrease in sequencing costs and extensive sequencing services from NGS providers has brought many scientists to be involved in genome sequencing of insects and their associated entomopathogens. By using high-throughput genomic technologies, scientists can elucidate the virulence, host adaptation and gene function of the particular entomopathogen including virus, fungi, bacteria and nematode.
Entomopathogenic fungi play an important natural role in regulating their insect host populations, and their ecology was also associated with plant and soil. These microorganisms have been living by reacting to insect, plant and environmental factor. The advanced bioinformatics technology such as next-generation sequencing and RNA sequencing has revolutionized in understanding of entomopathogenic fungi. Recently studies provided a lot of information on evolutionary relationships and virulence-related characteristics. We are starting to know where these microorganisms from is, and how they live in nature. The bioinformatics technology will give us further our understanding of the natural roles of these fungi in nature.
The varroa mite, Varroa destructor, is a small ectoparasitic mite which attacks honeybee, Apis mellifera, and also known to harbor small RNA viruses which infect honeybees. To survey the transcriptome of varroa mite, total RNA of female adult mites was subjected to RNA-seq to construct an in silico cDNA library. 2 × 8.3 Gbase of quality filtered paired-end nucleotide sequences were obtained to construct 28,302 of protein-coding contigs by de novo assembly, and subsequent BLAST search revealed the viruses infect honeybee or associated with varroa mites. Six of the contigs showed high sequence identity to Iflavirus, picorna-like virus, rhabdovirus, and macula-like virus were discovered. It implies that the viral flora in varroa mites and honeybees might be more complex than previously studied, and suggests the importance of further virome studies for better understanding of honeybee health.
한반도에서의 기후 변화는 최근까지 해충이 아니던 토착 곤충이나 비례 곤충들이 해충화 될 수 있는 가능성을 높여주고 있다. 가장 중요한 예가 토착 곤충이던 풀무치의 대량 발생에 따른 해충화가 있다. 낮은 밀도에서는 식생에 위험을 주지 않는 단독형으로 존재를 하던 풀무치가 평균온도의 상승과 강우 패턴의 변화로 대량 발생을 하여 강력한 이동성을 가지고 식생을 파괴하는 군집형으로 변화된 예가 있다. 하지만, 아직까지, 단독형에서 군집형으 로의 변화에 대한 기전이해는 완성이 되지 않은 상태이다. 기후의 변화는 겨울철 평균기온의 상승을 가져와서 한반도에서 월동이 불가능했던 해충이나 약제 저항성 계통들이 급속도로 번식할 수 있는 가능성을 열어 놓았다. 그러므로, 이러한 약제 저항성과 기후변화와 관련성에 대한 유전자 수준에서의 변화에 대한 이해가 필요한 실정이다. 위의 목적을 달성하기 위하여 우리는 다중분석학을 이용하여 연구를 진행하여 왔고, 연구 결과를 바탕으로 종 특이적이면 환경 친화적인 방제방법의 개발 연구를 진행하여 와서 이에 대한 연구결과를 발표한다(RDA Grant No. PJ010821032018).
Insect growth regulators (IGRs) are insecticides that disrupt the normal development of target insects. Among the IGR insecticides, juvenile hormone (JH)-related IGRs are of particular interest because they stimulate or interfere with the formation of JH receptor complex. In the precious studies, novel JH-related IGRs with JH agonist (JHA) and antagonist (JHAN) activity were identified by using yeast two-hybrid system transformed with the Aedes aegypti JH receptor complex. In this study, the transcriptomic responses of Aedes albopictus were investigated upon JHA and JHAN, respectively. These results will provide important information about understanding of impact of JH-related IGRs in transcription level.
Symposium ⅡS7: Future Careers of Entomologists: Government, Industry and Academia
농학(농업곤충)과 공중위생학(위생곤충) 뿐만 아니라 최근 기초생명과학 분야에서 중요하게 여겨지는 곤충학 전공은 분류학, 생태학, 생리학, 독성학, 생명공학 등을 아우르는 종합 응용학문이라 판단된다. 이러한 다양한 연구 분야를 포함하는 곤충학 전공 학생들의 장래 직업선택에 있어서도 다양한 선택지가 있을 것이다. 대학원생에게 진로 선택은 크게 수학의 연장과 취업으로 구분될 수 있다. 수학 연장의 경우에는 국내 및 외국으로의 박사과정 혹은 박사후과정으로의 진학이 가능하며, 취업의 경우에는 공공분야(국가 연구소), 기업 및 대학 연구원으로의 지원이 가능할 것이다. 특히 박사학위 취득 후에는 추가로 교수직 지원 또한 가능하게 된다. 성공적인 진학 또는 취업을 위한 정보의 획득과 전략의 수립은 각각의 진로 방향성에 맞게 특화되어야 할 것으로 판단되며, 본 심포지엄에서 는 공공기관, 기업, 해외 및 국내교수직에 종사하고 있는 여러 선배 곤충학자들을 통해 그들의 경험과 정보를 공유하고, 성공적인 취업 준비에 대한 논의를 하고자 한다. 뿐만 아니라 해외 박사과정 및 박사후과정을 마친 선배들을 통해 해외로의 진학을 위한 구체적 정보, 일정 및 전락에 대해서도 논의하고자 한다.
Symposium Ⅱ S8: Insect Chemical Ecology in Korea, 5th: Toward diversity
Herbivorous insects use plant metabolites to inform their host plant selection for oviposition. These host-selection behaviors are often consistent with the preference-performance hypothesis; females oviposit on hosts that maximize the performance of their offspring. However, the metabolites used for these oviposition choices and those responsible for differences in offspring performance remain unknown for ecologically-relevant interactions. In this time, I will talk about the host-selection behaviors of two sympatric weevils, the Datura (Trichobaris compacta) and tobacco (T. mucorea) weevils in field- and glasshouse-experiments with transgenic host plants specifically altered indifferent components of their secondary metabolism. In addition, I will show that adult females are able to choose the best host plant for their offspring and use chemicals different from those that influence larval performance to inform their oviposition decisions.
세계 작물보호제의 개발 흐름은 화학농약보다 친환경제제에 더욱 집중하고 있다. 이는, 수십 년 동안 행해진 화학농약 의존 농업에 대한 경각심의 우회적 표출이며, 개선하려는 국제적 움직임으로 해석할 수 있다. 친환경제제 중 하나인 곤충페로몬 이용 제품은 화학농약을 대체하거나 감소시킬 수 있는 제제로 국내외적으로 평가받고 있다. 이러한 곤충페로몬을 이용한 친환경 제품이 국내농업에 사용된 지 약 16년이 되었다. 그동안 국내 농업시장에서 통용된 곤충페로몬 이용 제품에는 어떠한 것이 있었고, 시기 및 지역별로 제품 사용의 변화 확인을 통해 다양성을 향한 앞으로의 제품 개발과 활용을 토의하고자 한다. 또한, 곤충페로몬 방출기 관련 연구개발 지식 공유를 통해, 제품 및 기술 개발을 위한 논의를 하고자 한다.
The ambrosia beetle, Xyleborinus saxesenii Ratzeburg, infests physiologically stressed apple and peach trees in Korea. Dispersing females utilize the degradation product ethanol and host-related volatiles to locate and colonize new host trees. We examined the extent to which 12 chemicals emitted from fruit trees act synergistically with ethanol to attract X. saxesenii. The addition of benzaldehyde to ethanol significantly increased beetle attraction, although benzaldehyde was not attractive by itself. The addition of α-pinene, ethyl butyrate, ethyl isovalerate, limonene, 3-methyl-1-butanol, ethyl tiglate, aromadendrene, vanillin, 2-butanol, styrene, or ethyl 3,3-dimethylacrylate to ethanol had no effect on beetle attraction. In a dose-response test, the addition of 5–50% benzaldehyde doses synergistically increased the number of beetle captures; however, trap catches did not increase as the benzaldehyde dosage increased. The synergistic influence of benzaldehyde on beetle response to ethanol was lower in early spring than in late summer to early fall, probably because synthetic benzaldehyde emissions from field lures were overwhelmed by background levels of natural benzaldehyde emitted from peach twigs in the flowering stage.
Conventional chemical ecology approach for identification of semiochemicals from natural sources is based on isolation of active ingredients after fraction and bioassay. Instead, we identify potential semiochemicals using reverse chemical ecology approach. In this way, we discovered an odorant receptor (CquiOR136) for DEET, which was not know how and why it work. Additionally, we identified a link between this synthetic repellent and methyl jasmonate, thus suggesting that DEET might work by mimicking defensive methyl jasmoante from plant. Moreover, we serendipitously found that a receptor, CquiOR36, responded to an old sample of nonanal in ethanol. Careful investigation led us to identify the active ligand as acetaldehyde (derived from ethanol) from “contaminants” in the old nonanal sample. We explored that acetaldehyde in a wide range of dose both attracts gravid mosquito and stimulate them to lay eggs in oviposition trays.
최근 기후변화로 인하여 다양한 산림곤충들이 대면적으로 발생하여 산림수목에 큰 피해를 주고 있다. 그러나 산림해충의 정확한 발생모니터링이 이루어지고 있지 않으며 대부분의 방제 또한 유기합성농약에 의존하고 있다. 페로몬은 해충의 정확한 발생 모니터링뿐 아니라 대량포획 및 교미교란에 의한 친환경 방제방법으로 널리 활용 될 수 있다. 특히 산림은 다양한 생태계로 구성되어 있기 때문에 유기합성농약을 줄이거나 대체 할 수 있는 방제방법이 시급한 실정이다. 본 발표에서는 주요 산림해충인 천공성 해충류, 곰솔의 주요 해충인 솔껍질깍지벌레, 나비목 해충류에 대한 근래 연구동향에 대해 소개하고 미래의 산림해충 화학생태학의 연구 방향에 대한 제언을 하고자 한다.
Bacterial cells communicate with each other through their specific chemical languages, by which bacteria regulate a set of genes in a multicellular behavior, including antibiotics, biofilm, motility, and virulence. The twitter communication in Gram positive bacteria is mediated by diffusible signal molecules, N-acyl homoserine lactones (HSLs), that differ with respect to the length, saturation and substitutions of the side-chain. In Gram negative bacteria, diffusible peptides control the physiological phenotypes. In this presentation, some general examples of bacterial twitter communication, such as Vibrio fischeri, Burkholderia glumae, Agrobacterium tumefaciens, and Serratia marcescens will be presented. The contribution of bacterial communication to pathogenicity of Pantoea ananatis, our model bacterium causing bacterial rice sheath rot and onion center rot diseases, will mainly be discussed.
Global Symposium GS1: Frontiers in Crop Protection
Both a fluorescent marking system (FMS) and a portable harmonic radar system (PHRS) are effective insect tracking methods. Prior to comparing their efficacies, we tested the viability of FMS in detection of an agricultural pest, Riptortus pedestris (Hemiptera: Alydidae); previous studies showed the harmlessness of PHRS on R. pedestris and its detection distance. Fluorescent marking allowed the detection of marked R. pedestris from > 25 m, when illuminated with a laser in the dark, while affecting only the vertical walking distance of the insect. Then, we assessed the efficacy of the FMS and PHRS as well as combining both methods (BOTH) in detection of R. pedestris in a grass field and a bean field during day and night. PHRS and BOTH showed higher detection rates than FMS in all settings, except for in the bean field at night. Also, although BOTH did not enhance total detection time, it facilitated the retrieval of the sample at night compared to only using PHRS.
The Subspecies of lucanid beetle Cyclommatus metallifer (Boisduval, 1835) from Indonesia are revised here. Six subspecies were known from Indonesia. Among them, Cyclommatus metallifer otanii Mizunuma and Nagai, 1991 was confirmed to be a synonym of Cyclommatus metallifer aenomicans Parry, 1863. Moreover, a new subspecies, Cyclommatus metallifer butonensis ssp. nov., is described from Buton Island of Indonesia. The identification key, distributional data, photos of adult habitus, male genitalia, and figures for each species are provided.
Modern technique development provides a new opportunity to expand entomological researches. Aerial insect sampling has been conducted with fixed-wing unmanned aerial vehicles (UAVs). With improved maneuverability, rotary-wing UAVs can serve as more convenient and feasible tools with lower cost. A rotary-wing UAV with remotely controlled insect nets was developed to collect insects at designated altitudes above the rice field (ca. 80 × 240 meter (width × length)) in Boryeong, South Korea. From 21 flights in June, July, and August 2017, 235, 7, 6, and 3 insects were caught at 5, 10, 50, and 100 meters above the rice field, respectively. The collected insects were identified to family level. Diptera (Phoridae and Chironomidae), Hemiptera (Aphididae and Delphacidae), and Thysanoptera were found from the sample, some of which may contain possible insect pests on rice. Therefore, UAVs have potential as an alternative aerial insect sampling method.
Melon thrips, Thrips palmi Karny (Thysanoptera: Thripidae) is a serious insect pest of various crops in the world. The management of this pest mainly have relied on chemical agents. However, the overuse of chemical agents for long times causes insect resistance, and negative effects on environment. Therefore, alternative control methods, such as biological control, that are less harmful to the environment and have different mode of action are needed to control this pest. In this study, we isolated entomopathogenic fungi from Korean soil, and characterized them via morphological and molecular identifications and pathogenicity check against Tenebrio molitor larvae. The isolated fungi were subjected to virulence assay against T. Palmi with a conidial suspension of 1×107 conidia/ml in laboratory conditions. This entomopathogenic fungi library would be a good resource to select effective strains for the control of T. palmi in fields.
The potato tuber moth (PTM) is a cosmopolitan insect pest and hosts various solanaceous crops including tomato. We tested olfactory behavior and larval development of PTM on different varieties of tomato fruit namely, Money maker, Campari, Ailsa craig, LA 3475 (M82) and E-6203, and one wild species, S. pimpinellifolium. We also analyzed essential oil of the tomato fruits through GC/MS. There were significance differences in immature developmental period and head capsule size among the tested varieties. PTM larvae showed highest survival on Ailsa craig (66.0±6.0) and E-6203 (64.0±4.0) and lowest on S. pimpinellifolium (14.0±6.0). The major compounds found in the tomato fruit’s essential oils include n-hexadecanoic acid (14.2%) and 2-octylcyclopropaneoctanal (8.7%) in Money makers; hexadecanoic acid, 2-hydroxy -1-(hydroxymethyl) ethyl ester (13.1%) in Campari; tert-hexadecanethiol (6.8%) and 1,4-benzenedicarboxylic acid, bis (2-ethylhexyl) ester (6.2%) in Ailsa craig; (Z)-13-docosenamide (13.39) in S. pimpinellifolium; Eicosane (4.4%,), (Z)-9 -octadecenamide (4.2%), and n-hexadecanoic acid (4.1%) in E-6208. The larval development result on tomato fruit could support its suitable nutritional contents to PTM, posing pest potential in the future where higher exposure is expected.
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 a heat stress. And they showed enhanced thermal stability compared to control, when exposed to 45°C for 2 hours. This work suggests that heat-resistant entomopathogenic fungal conidia can be produced by grain-based solid cultures and exposure to light stress.
The potato tuber moth Phthorimaea operculella (Zeller) is an important pest for solanaceous crops mainly potatoes. There is an increasing concern on host expansion to tomato which is higher cash crop. We monitored PTM population dynamics in potato dominated area and tomato greenhouse area in Andon, South Korea for 2 years using delta sticky trap with sex pheromone lure. PTM population was higher in potato growing area and low in tomato area; 19.82 PTM/trap/week and 0.8 PTM/trap/week, respectively. Peak occurrence time was related to the crop phenologies; August in potato field and November in tomato field. Land scape analysis showed that there was significant positive correlation between habitat potato field itself and green house with the number of moth catch during the monitoring period.
The potato tuber moth (PTM) is an oligophagous insect pest on solanaceous crops. Potato tuber is regarded as the main host of PTM but it can also feed, develop and reproduce on other solanaceous crops such as tomato. We tested adult olfactory behavior and larval development on 5 cultivated tomato varieties namely Money maker, Campari, Ailsa craig, LA 3475 (M82) and E-6203, and one wild species, S. pimpinellifolium. Tomato leaf hydro-distilled oils of Money maker, Campari, Ailsa craig, S. pimpinellifolium and E-6203 leaves showed strong attractiveness for mated adult PTM of both sexes (> 70%) in two-armed bioassay. LA 3475 (M82) oil showed repulsive response (83.7% for males and 87.3% for females). GC-MS analysis of the hydro-distilled oils of all tomato leaves contain the fatty acid n-hexadecanoic acid (Palmitic acid) as a major compound with relative percentage as S. pimpinelifollium (32.1%) > E-6203 (26.5%) > money maker (26.1%) > LA-3475 (16.3%) > Campari (15.0%) > Ailsa craig (10.4%). LA 3475 consists of (1-hexyltetraecyl)cyclohexane (10.5%) as the second major compound which was absent in all other tomato varieties. In no choice test, PTM larvae showed highest developmental performances such as number of mines, headcapsule size, pupal weight and survival in Ailsa craig, and lowest in LA 3475. In choice test, similar results were observed. This study indicates the leaf volatile of n-hexadecanoic acid might be responsible for PTM attractiveness and (1-hexyltetraecyl)cyclohexane for repulsiveness. And varieties of tomato leaves could support suitable nutritional contents to PTM, posing pest potential in the future where higher exposure is expected.