This research explores the complex interdependencies and dynamic interactions governing the adaptation of species co-evolving within the framework of Eco-Evo-Neuro-Devo, using the fascinating fig-wasp mutualism as a model system. Figs, which have many flowers blooming inside the fruit, are completely dependent on fig wasps as pollinators. The fig-wasp mutualism is a symbiotic relationship where fig trees provide a habitat and food source for specific wasp species, while the wasps, in turn, facilitate pollination and seed dispersal for the fig tree. The fig wasp is born and grows inside the fig fruit and becomes an adult. After mating, the female fig wasp is covered with pollen and enters another fruit, pollinates it and lays eggs there. In addition to the fig-wasp mutualism, additional interactions among hyperparasitic wasps, called non-pollinating fig wasp (NPFW), and flies, nematodes are frequently observed, shaping the co-evolution of the symbionts in the fig community. This study aims to identify the symbionts that make up the symbiotic system, their ecological interactions and genome evolution, and build a model to explore the mechanisms of symbiotic evolution at the molecular level. Sampling and identifying figs and fig-related insects through fieldwork in Korea, various techniques including GC-MS, in situ staining, electrophysiology, and diverse omics tools including WGS, RNA-seq will be implemented to investigate how chemical ecologies of the fig community shape the chemosensory systems of species. Additionally, we will build a cross-platform with Drosophila to narrow the distance between model species and non-model species, facilitating comparative studies across different model organism systems.
Yellow flower thrips (WFT), Frankliniella occidentalis is mainly controlled using chemical control methods. But the continuous use of chemical pesticides in greenhouse may contribute to development of insecticide resistance. Therefore, in this study, we evaluated the insecticidal activity of eleven insecticides against the WFT occurring in greenhouse pepper cultivation in the Gyeonggi province. The results showed no resistance in treatments with emamectin benzoate, fluxametamide, and flometoquin while high levels of resistance were recorded in treatments with acrinathrin, acetamiprid, and dinotefuran. The Anseong and Yeoju population was more resistant against spinetoram and chlorfluazuron, respectively, than populations from other regions.
The box tree moth (BTM, Cydalima perspectalis Walker) is a pest that infests various plants within the Buxus genus. Although a specific parasitoid wasp species associated with the BTM has been observed in the Republic of Korea, no research on this species has been published. Here we describe the fundamental biological and morphological characteristics of this parasitoid. We placed the wasp under the genus Eriborus (Hymenoptera: Ichneumonidae: Campopleginae). Eriborus sp. parasitizes within the living host body, with one wasp emerging from each host. The parasitism rate in collected BTM populations was 33.1%. The emergence rate was 87.1%, with all emerging adults being females, resulting in a sex ratio of 0. The pupal period averaged 9.5 days, and the adult lifespan averaged 10.5 days. Eriborus sp. parasitized BTM larvae from the first to the fourth instar and reproduced by parthenogenesis. Eriborus sp. exhibited morphological differences compared with previously reported Eriborus species in Korea, particularly in the length of the ovipositor sheath. In addition, the proportion of the highest similarity in nucleotide sequences of mitochondrial cytochrome oxidase I DNA was only 94.53%, rendering species identification using GenBank’s mt cytochrome c oxidase 1 DNA sequences unfeasible. These data suggest Eriborus sp. could be used as a biological control agent for managing BTM infestations.
Five insecticides (Acrinathrin, Dinotefuran, Emamectin benzoate, Chlorfenapyr and fluxametamide) approved for tomato cultivation were evaluated in Frankliniella occidentalis populations collected from Chungcheong province (Cheongyang, Chungju and Gongju). Leaf dip bioassay was used to evaluate resistance levels (LC50). Bioassays on Acrinathrin demonstrated higher LC50 concentration in evaluated populations. In particular, the Chungju population was 745.61 times the recommended concentration of the insecticide. Other remarkable resistance levels were recorded for the Dinotefuran with 435.06 times and 196.29 times the recommended concentrations for the populations from Chungju and Gongju, respectively. Bioassays for Emamectin benzoate, Chlorfenapyr and Fluxametamide showed low resistance to insecticides in the evaluated populations.
Spodoptera eridania and S. ornithogalli (Lepidoptera: Noctuidae), which are polyphagous pests that damage various crops such as tomatoes and beans are regulated quarantine species that are highly likely to invade South Korea. Therefore, it is crucial to promptly and accurately identify the presence of S. eridania and S. ornithogalli in crop fields to effectively eradicate as a regulated quarantine species. In this study, we developed a loop-mediated isothermal amplification (LAMP) assay, which allows for rapid in-field identification. To develop the LAMP assay, we selected target species-specific genomic regions from the whole-genome sequences of one target and 13 other lepidopteran species. We validated each five and six primer sets that consistently produced positive reactions in S. eridania and S. ornithogalli, respectively. To test the sensitivity of the each locus, LAMP reactions were performed using various reaction times using crude DNA, which was extracted from various types of adult tissues. All sensitivity tests were also successful.
Two-spotted spider mite (Tetranychus urticae Koch; TSSM) is an agriculturally serious pest tat has acquired strong resistance against acaricide. Alternatively, mite-pathogenic fungi could be used to control the mites. The spider mite has symbiotic microorganisms which could be involved in the physiological and ecological adaption to biotic stress. In this study, mite-pathogenic fungi were used to control female adults, and the change of microbiome in the fungus-infected mites was analyzed. The acaricidal activity of fungal isolates was tested, and Akanthomyces attenuatus JEF-147 with the highest acaricidal activity was determined, followed by semi-field assay. Microbiome in the female adults which was infected by A. attenuatus JEF-147 was analyzed, and composition of microorganism was changed by fungal treatment. In bacteria abundance, the arthropod defense-related Rickettsia increased, but reproduction-associated Wolbachia decreased. The change in major bacterial abundance in the infected mites could be explained by the trade-off between reproduction and immunity. This work describes that a possible trade-off in arthropods against fungal pathogens could be predicted by the microbiome analysis.
Harlequin ladybird (Harmonia axyridis (Pallas, 1773)) is an invasive species originating from Asia, posing a potential threat to the ecosystem and the wine industry in New Zealand due to wine taint, although it can also be a useful biocontrol agent. In this study, the response profiles of antennal olfactory receptor neurons (ORNs) to 32 plant volatiles were examined in male and female H. axyridis, using the single sensillum recording technique. Various types of ORNs were identified from four types of olfactory sensilla in both male and female H. axyridis, with no sexual dimorphism. The most abundant type of sensilla contained two ORNs exhibiting highly specialized responses to methyl benzoate and β-caryophyllene, respectively. Another type of sensilla also contained two specialized ORNs, one responsive to geranyl acetate and the other to some aromatic compounds such as 2-phenylethanol, benzyl acetate, methyl benzoate, and methyl phenylacetate. In contrast, two other types of sensilla contained broadly tuned ORNs, one containing ORN(s) responsive to six-carbon alcohols such as (Z)-3-hexen-1-ol, 1-hexanol, and isomers of 2-hexen-1-ol as well as some other non-alcohol green leaf volatiles, and the other containing ORN(s) exhibiting responses to β-myrcene, geraniol, linalool, nerol, benzyl acetate, and methyl phenylacetate. This study suggests that H. axyridis possesses a set of ORNs specialized for specific plant volatiles, providing insights into the olfactory communication system of this species and potential volatiles to be used for trapping this insect.
As climate changes and global trade volume increases, the spread of invasive alien species accelerates. Early prevention before occurrence is crucial for invasive pest control. Therefore, this study modeled the current and future potential distribution of the tomato leafminer(Tuta absoluta) (Meyrick) (Lepidoptera: Gelechiidae), the most significant pest affecting tomatoes, in Korea. This pest primarily feeds on Solanaceae crops and can cause extensive damage, resulting in 50-100% loss of crops in greenhouses or fields. While previously unreported in Korea, it invaded China in 2017, indicating a potential threat to Korea. The potential distribution of the tomato leafminer in Korea under current and three future climate scenarios (SSP1-26, SSP3-70, SSP5-85) was predicted using the MaxEnt model. Additionally, elevation and land cover were incorporated as abiotic factors considering the ecological characteristics of the pest.
In agricultural ecosystems, the relationship between insect pests and hosts is important, as insect pests can invade hosts, increasing insect pest density that threatens the hosts’ health. Insect pests and hosts are negatively correlated and affect the environment around them. i.e., host health, environment, and insect pest density are causally related, and the environment affects insect pest density. Deep learning is method of machine learning based on neural network theory. This approach enables handling uncertain environmental factors that simultaneously impact the density of F. occidentalis. Environmental factors affecting the density fluctuation of F. occidentalis selected atmosphere factors, soil factors, and host factors. This study aims to F. occidentalis monitoring using deep learning models inputting environmental factors.
Riptortus pedestris is known to acquire their symbiotic bacteria, Caballeronia insecticola, from soil environments in every generation. The symbionts have been demonstrated to affect behavioral and physiological traits of the host insect such as the enhancement of development. In particular, symbiotic effects on female adults could directly entail changes in their population growth. Therefore, we investigated a suite of symbiotic effects of C. insecticola on behaviors and fitness-related parameters of female R. pedestris. Overall, symbiotic females showed an behavioral enhancement in both feeding efficacy and movement capacity including walking and flight. In addition, the survival rates under exposure to overwintering conditions and insecticide resistance level were significantly higher in symbiotic females than the aposymbiotic. Finally, although symbiotic females exhibited shorter longevity, their fecundity was found higher compared to the apo-symbiotic.
To overcome the challenges in tracking insects underground, a detection method consisting of a metal detector and aluminum tag was developed for tracking a dung beetle, Copris ochus (Coleoptera: Scarabaeidae). First, detection rate was evaluated for varying volumes of aluminum tags varying orientations of the tags under soil. Then, the detection efficacy was evaluated in the field at varying depths of hidden tags in two types of vegetation. Finally, the effect of aluminum-tagging on the survivorship, burrowing depth, and horizontal movement of C. ochus adults were assessed. Generally, an increase in tag volume resulted in a greater detection depth with maximum depth of 17 cm. Orientation, however, did not affect detection rate except when tag was placed perpendicular to the soil surface. In the field, metal detectors could detect aluminum-tagged models with success rates ≥85% up to 10 cm and 45−60% at 20 cm under soil. Finally, no significant effect of tagging on survivorship and behaviors of C. ochus was observed.
The small brown planthopper (SBPH), Laodelphax striatellus, is a major insect pest for the rice plants. SBPH is also a known vector of rice stripe virus (RSV), which causes severe yield losses in rice crops throughout the East Asia. RSV is persistently transmitted by SBPH and can also be transmitted to offspring through transovarial transmission. SBPH is known to migrate from China to the west coast of the Republic of Korea (ROK). The study investigated the impact of temperature on the acquisition and transmission of RSV by SBPH in ROK, which is expected to experience increased migration and emergence of SBPH due to climate change. The results revealed that the acquisition and transmission rates of RSV were higher at 27°C compared to 24°C, with rates of 100% and 78.3%, respectively. However, at 30°C, the acquisition and transmission rates of RSV was decreased. The results suggests that temperature can impact the transmission of RSV by SBPH. To investigate this further, SBPH adults were fed on RSV-infected plants and infection rates were compared across various tissues, including the head, salivary glands, midgut, Malpighian tubules, ovary, and hindgut. Results showed that at 36 hours post-infection, RSV was highly detected in the Malpighian tubules, ovary, and hindgut. At 48 hours post-infection, RSV was also detected in the thorax. These results suggest that the transmission rates of RSV in SBPH increase with temperature between 24-27°C, but decrease at 30°C, indicating that the vectorial capacity of SBPH for RSV decreases above a certain threshold.
담배가루이는 전세계의 온대 및 아열대 지방에 넓게 분포하고 있으며, 한국에서는 시설재배작물의 주요 해충 이다. 1998년 충북 친천군 장미재배지에서 처음 확인되었으며, 이후 전국적으로 확산된 것으로 추정된다. 담배가 루이는 고추, 토마토, 오이 등 300종이 넘는 넓은 기주범위를 가지며, 식물체를 흡즙하여 작물의 생산성을 저하시 키고 토마토황화잎말림바이러스(tomato yellow leaf curl virus, TYLCV) 등 100여종이 넘는 바이러스를 매개한다. 담배가루이는 주로 살충제를 이용한 방제가 이루어진다. 하지만 살충제를 이용한 방제법은 살충제 저항성 개체 를 발생시킨다. 살충제 저항성 개체가 발생하게 되면 방제 효율이 급감하여 농가에 추가적인 경제적 피해를 야기 한다. 본 연구는 국내 지역별 담배가루이를 대상으로 약제별 살충제 저항성의 발생 현황을 조사하여, 지역별 효과적인 약제를 탐색하고 향후 방제 전략 수립에 기여하고자 한다. 담배가루이는 전국 15지역(파주, 양평, 화성, 양구, 횡성, 평창, 당진, 천안, 공주, 예천, 구미, 사천, 남원, 나주, 고흥)에서 채집되었다. 살충제는 작용기작 별 사용량이 많은 8종을 선정하였으며, 엽침지법을 사용하여 살충률을 확인하였다. 곤충생장조절제(insect growth regulators, IGR) 피리프록시펜계 약제는 알을 대상으로, 그 외 7개 약제는 2령약충을 대상으로 살충률을 확인하였 다. 모든 지역에서 높은 살충력을 보인 약제는 아버멕틴과 밀베마이신계, 스피노신계, METI살충제, 디아마이드 계 약제이다. 특히 아버멕틴과 밀베마이신계 약제는 살충제 권장사용농도(10ppm)보다 낮은 8.9ppm이하의 LC90 값을 보여 감수성으로 추정되며, 예외적으로 천안 지역의 25.6ppm으로 상대적으로 높은 LC90값을 보였다. 낮은 살충력을 보인 약제는 네오니코티노이드계, 설폭시민계, 피리프록시펜계, 테트론산 및 테트람산 유도체 약제이 다 특히 네오니코티노이드계 약제는 모든 지역에서 살충제 권장사용농도(50ppm)보다 높은 715ppm이상의 LC90 값을 보여, 모든 지역에서 살충제 저항성이 발생한 것으로 추정된다. 실험결과를 통해 살충제 별 살충력의 차이와 지역별 살충제 저항성을 검정하였다. 연구결과를 통해 지역별/약제별 저항성관리 및 대응전략을 수립하여 농업 생산성을 향상시키는 것에 도움이 되고자 한다.
The continuous use of pesticides with the same mode of action has lead to the development of insecticide resistance in the target pests. Establishing pesticide resistance management methods and effective control strategies for these pests has become an important target. Bemisia tabaci, a representative pest of greenhouse, directly affects the growth of crops at all stages of its development except eggs. It also causes indirect damage by secreting honeydew that eventually promotes sooty mold in leaves and fruits. In this study, eight insecticides with different mechanisms of action (Flonicamid, Fluxametamide, Spinetoram, Cyantraniliprole, Dinotefuran, Pyridaben, Milbemectin and Pyriproxyfen), and registered for use against cucumber B. tabaci were selected and tested for insecticide resistance. The tested populations of B. tabaci were collected from greenhouse cucumber cultivations in 12 domestic regions. The results were presented as RR (Resistance ratios), and CEI (Control efficacy index) values.
Hindwings of many lycaenid butterflies have a unique tail-like wing structure referred to as a false head, which actually mimics the antennae. False heads increase butterfly survival by directing predatory attacks towards the false heads thereby enhancing the chance of escape. In this study, using discrete character evolution models of European and American butterflies, we examined the co-evolutionary patterns between false head structures and two associated traits: a highly contrasting color patch neighboring the false head, and hindwing rubbing behaviors. The former is considered a eye-mimicking structure that enhances the effectiveness of false head, and latter generates the movement of false heads which likely increases the success of false head deception. Our findings demonstrate that false heads are ancestral states for both European and American lycaenids. Both contrasting colors and hindwing rubbing behaviors follow correlated evolution models, suggesting that these traits co-evolved in lycanid butterflies. However, specific evolutionray patterns differed between the two continents.
Major pests of greenhouse strawberry include Tetranychus kanzawai (Acari: Tetranychidae) and Bemisia tabaci (Hemiptera: Aleyrodidae) causing significant damage in both yield and quality. We compared control efficacy of two entomopathogenic fungus strains of Beauveria bassiana, AAD16 and GHA, against T. kanzawai and B. tabaci. Both fungus were applied as a foliar spray targeting the undersides of leaves. In preliminary studies in the laboratory, adult T. kanzawai and B. tabaci showed lower LT50 values when treated with AAD16 strain compared to GHA. In the greenhouse, the densities of the both mites (adult and nymph) and whiteflies (adult) were significantly reduced with the application of the two fungus strains compared to the control. The mycosis rate was 88-94% in T. kanzawai and 48-59% in B. tabaci on collected leaves. These findings suggest that Beauveria bassiana AAD16 can be an effective mycoinsecticide against both T. kanzawai and B. tabaci.
식물에 전기장을 처리하면 식물의 생장속도가 빨라지거나 영양학적으로 긍정적인 변화가 생긴다고 알려져 있다. 최근 음이온 처리 시 식물에 전기장을 처리한 것과 유사한 효과가 나타난다고 보고되었고 본 연구에서는 이러한 음이온을 온실해충인 점박이응애와 목화진딧물에 처리하여 방제효과 여부를 확인하였다. 그 결과 음이 온 처리 시 점박이응애와 목화진딧물에서 살충효과와 기피효과가 나타났다. 또한, 점박이응애 알에서도 음이온 처리가 부화율에 영향을 주는 것을 확인할 수 있었다. 이러한 시험 결과를 바탕으로 온실에서 밀도실험 결과, 700,000 ion/cm3 농도에서 무처리구에 비해 밀도가 감소함을 확인할 수 있었다. 따라서, 본 연구는 음이온 처리 시, 부가적인 효과로 온실해충(점박이응애, 목화진딧물)에 대해 친환경적 방제 가능성을 보여준다.
Salt is crucial for survival, yet excessive intake of sodium chloride can have adverse effects. In the fruit fly, Drosophila melanogaster, internal taste organs located in the pharynx play a pivotal role in determining whether to accept or reject food. However, our understanding of how pharyngeal gustatory receptor neurons (GRNs) perceive high salt levels is still limited. In this study, we discovered that a specific member of the ionotropic receptor family, Ir60b, is selectively expressed in a pair of GRNs that respond to high salt concentrations. Through a two-way choice assay (DrosoX) to measure ingestion volume, we established that IR60b, along with two coreceptors, IR25a and IR76b, is necessary to deter excessive salt consumption. Interestingly, mutants lacking external taste organs but retaining internal taste organs in the pharynx showed significantly higher salt avoidance compared to flies missing all three IRs while still possessing all taste organs. These findings underscore the crucial role of IRs in pharyngeal GRNs in regulating the intake of high salt levels.
Acetylcholinesterase (AChE) is a key enzyme that terminates impulse transmission by rapidly hydrolyzing the neurotransmitter acetylcholine at cholinergic synapses. Previous studies have discovered a transiently opening channel referred to as the “back door” in Torpedo californica AChE. Previously, we observed that substituting the Tyr391 residue with a Phe residue significantly decreased the catalytic efficiency of recombinant Apis mellifera AChE1 (AmAChE1), while the reverse substitution restored it. Interestingly, substitution of the Tyr391 residue with a Phe residue in AmAChE1 disrupted the formation of the backdoor, while the reverse substitution restored it. This finding suggests that the Tyr-to-Phe substitution impairs backdoor formation, thereby leading to a significant reduction in the catalytic activity of AmAChE1. This serves as one of the driving forces for the functional transition from AmAChE1 to AmAChE2. In this experiment, we also confirmed the gradual restoration and increase in AChE activity by substituting Phe391 in AmAChE1 with Ser, Trp, Thr, Ile, Asn, and Tyr residues through kinetic assay and molecular dynamics simulation.
Pyrethroid resistance in cockroach populations has been a public health challenge since the 1950s. The pyrethroid resistance in the German cockroach, Blattella germanica, is primarily attributed to knockdown resistance (kdr) mutations (E434K, C764R, and L993F) in the voltage-sensitive sodium channel gene (vssc). In this study, the pyrethroid resistance state of the German cockroach in the Republic of Korea (ROK) was assessed by analyzing the frequencies of kdr mutations using one-step PCR with total RNA. The results revealed that among the 25 populations examined, 14 populations exhibited the L993F kdr mutation, while no other mutations were detected. Since other cockroach species are also commonly found in human dwellings in ROK, the vssc genes were cloned from four other species, including Blattella nipponica, Periplaneta americana, Periplaneta japonica, and Periplaneta fuliginosa. Based on the genomic DNA (gDNA) sequences obtained from the vssc cloning, primer sets were designed to amplify the vssc fragment spanning the L993F mutation for each species and used to monitor the development of pyrethroid resistance in cockroach populations in the ROK. The study will facilitate the implementation of a nationwide monitoring program to assess cockroach resistance and select suitable alternatives.