Publications by authors named "Seungjoon Ahn"

Diuretic hormones (DHs) activate corresponding G protein-coupled receptors (GPCRs), mediating the water and ion homeostasis in arthropods. There are two different DHs known to be expressed in insects, calcitonin (CT)-like DH31 and corticotropin-releasing factor (CRF)-like DH44. In this study, we identified and characterized a DH44 and five GPCR variants, DH44-R1 and DH44-R2a/b/c/d, in Drosophila suzukii (spotted-wing drosophila), causing detrimental damage to fresh and soft-skinned fruits.

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Background: The Oriental tobacco budworm, Helicoverpa assulta, a specialist herbivorous insect that exclusively feeds on plants of the Solanaceae family, causes considerable damage to crops, such as tobacco and hot pepper. The absence of a genome sequence for this species hinders further research on its pest management and ecological adaptation.

Results: Here, we present a high-quality chromosome-level genome of a Korean strain of H.

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Glycoside hydrolases are enzymes that break down complex carbohydrates into simple sugars by catalyzing the hydrolysis of glycosidic bonds. There have been multiple instances of adaptive horizontal gene transfer of genes belonging to various glycoside hydrolase families from microbes to insects, as glycoside hydrolases can metabolize constituents of the carbohydrate-rich plant cell wall. In this study, we characterize the horizontal transfer of a gene from the glycoside hydrolase family 26 (GH26) from bacteria to insects of the order Hemiptera.

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The redbanded stink bug, Piezodorus guildinii (Westwood) (Hemiptera: Pentatomidae), is a significant soybean pest in the Americas, which inflicts more physical damage on soybean than other native stink bugs. Studies suggest that its heightened impact is attributed to the aggressive digestive properties of its saliva. Despite its agricultural importance, the factors driving its greater ability to degrade plant tissues have remained unexplored in a genomic evolutionary context.

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The CRISPR/Cas9 technology has greatly progressed research on non-model organisms, demonstrating successful applications in genome editing for various insects. However, its utilization in the case of the soybean looper, Chrysodeixis includens, a notable pest affecting soybean crops, has not been explored due to constraints such as limited genomic information and the embryonic microinjection technique. This study presents successful outcomes in generating heritable knockout mutants for a pigment transporter gene, scarlet, in C.

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Article Synopsis
  • UDP-glycosyltransferases (UGTs) play a crucial role in insecticide resistance by converting hydrophobic substances into hydrophilic forms, aiding in the elimination of harmful compounds.
  • This study is the first detailed examination of UGT genes in Anopheles funestus, focusing on their evolution and their link to resistance against pyrethroids through a genome-wide association study (GWAS-PoolSeq) and transcriptomics.
  • Key findings include widespread overexpression of UGT310B2 and significant genetic differences in UGT genes among resistant and susceptible populations in Africa, providing valuable insights for improving insecticide resistance management strategies.
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Flea beetles of the genus Psylliodes have evolved specialized interactions with plant species belonging to several distantly related families, mainly Brassicaceae, Solanaceae, and Fagaceae. This diverse host use indicates that Psylliodes flea beetles are able to cope with different chemical defense metabolites, including glucosinolates, the characteristic defense metabolites of Brassicaceae. Here we investigated the evolution of host use and the emergence of a glucosinolate-specific detoxification mechanism in Psylliodes flea beetles.

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  • Diuretic hormones (DHs) help regulate water and ion balance in animals and are crucial for homeostasis; in insects, two types have been identified: DH31 and DH44.
  • This study focused on DH31 and its two receptor variants, DH31-Ra and DH31-Rb, in the spotted-wing drosophila, highlighting that DH31-Ra is more dominant due to higher gene expression and peptide binding.
  • The research revealed differences in the receptor structures and signaling pathways of DH31-Ra and DH31-Rb, with DH31-Ra using both cAMP and calcium as second messengers, whereas DH31-Rb only uses cAMP, which is significant for understanding fluid secretion in these flies
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Diamide insecticides, such as chlorantraniliprole, have been widely used to control insect pests by targeting the insect ryanodine receptor (RyR). Due to the efficacious insecticidal activity of diamides, as well as an increasing number of resistance cases, the molecular structure of RyR has been studied in many economically important insects. However, no research has been conducted on diamide resistance and RyR in the soybean looper, Chrysodeixis includens, a significant crop pest.

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Article Synopsis
  • The tomato leafminer (Tuta absoluta) has developed resistance to many insecticides, prompting researchers to analyze its genome for underlying resistance mechanisms.
  • A study focused on Spanish T. absoluta strains resistant to the diamide insecticide chlorantraniliprole found that resistance is linked to a major overexpression of a gene encoding a UDP-glycosyltransferase (UGT) rather than known target-site mutations.
  • The research provides valuable genomic resources and insights into resistance mechanisms, aiding the development of sustainable pest management strategies.
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Insect CAPA-PVK (periviscerokinin) and pyrokinin (PK) neuropeptides belong to the PRX family peptides and are produced from capa and pyrokinin genes. We identified and characterised the two genes from the western flower thrips, Frankliniella occidentalis. The capa gene transcribes three splice variants, capa-a, -b, and -c, encoding two CAPA-PVKs (EVQGLFPFPRVamide; QGLIPFPRVamide) and two PKs (ASWMPSSSPRLamide; DSASFTPRLamide).

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  • Spotted-wing drosophila (SWD) is a harmful pest that damages small fruits and cherries, currently managed using conventional insecticides.
  • Researchers are exploring RNA interference (RNAi) as a biologically-based control method by targeting specific midgut genes and improving delivery mechanisms for double-stranded RNA (dsRNA).
  • The study identified 1921 genes that are upregulated and 1834 that are downregulated in the midgut, focusing on ten specific genes, especially G protein-coupled receptors (GPCRs), which show potential for developing advanced pest management strategies.
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RNAi efficiency in insects is different from species to species; some species in Coleoptera are relatively more amenable to RNA interference (RNAi) than other species. One of the major factors is the presence of dsRNA-degrading enzymes, called dsRNases, in saliva, gut, or hemolymph in insects, which degrade the double-stranded RNA (dsRNA) introduced, resulting in the low efficacy of RNAi. In this study, we report a dsRNA-degrading activity in the gut homogenates from the spotted-wing drosophila, Drosophila suzukii, by ex vivo assay.

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UDP-glycosyltransferases (UGTs) are important conjugation enzymes found in all kingdoms of life, catalyzing a sugar conjugation with small lipophilic compounds and playing a crucial role in detoxification and homeostasis. The UGT gene family is defined by a signature motif in the C-terminal domain where the uridine diphosphate (UDP)-sugar donor binds. UGTs have been identified in a number of insect genomes over the last decade and much progress has been achieved in characterizing their expression patterns and molecular functions.

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Medical devices, which enhance the quality of life, have experienced a gradual increase in demand. Various research groups have attempted to incorporate soft materials such as skin into wearable devices. We developed a stretchable substrate with high elasticity by forming a porous structure on polydimethylsiloxane (PDMS).

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The relationship between plants and insects is continuously evolving, and many insects rely on biochemical strategies to mitigate the effects of toxic chemicals in their food plants, allowing them to feed on well-defended plants. , the fall armyworm (FAW), accepts a number of plants as hosts, and has particular success on plants of the Poaceae family such as maize, despite their benzoxazinoid (BXD) defenses. BXDs stored as inert glucosides are converted into toxic aglucones by plant glucosidases upon herbivory.

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Neuromedin U (NmU) is a neuropeptide regulating diverse physiological processes. The insect homologs of vertebrate NmU are categorized as PRXamide family peptides due to their conserved C-terminal end. However, NmU homologs have been elusive in Mollusca, the second largest phylum in the animal kingdom.

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Article Synopsis
  • Carabid beetles may help control pests in US annual ryegrass crops, especially during autumn and winter when pests like slugs and lepidopteran larvae are active.
  • The study found that only certain carabid species actively feed on these pests, with one species showing a significant amount of gut DNA from lepidopteran and cranefly larvae.
  • None of the carabid species studied were negatively impacted by disk tilling, but one species showed a preference for vegetated field margins, highlighting considerations for ecosystem management.
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The brown marmorated stink bug, , is an invasive hemipteran that causes significant economic losses to various agricultural products around the world. Recently, the and genes that express multiple neuropeptides were described in this species. Here we report six and GPCRs including two splice variants, and evaluate their (a) ability to respond to neuropeptides in cell-based assays, and (b) expression levels by RT-PCR.

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  • Drosophila suzukii (spotted wing drosophila) is unique among its genus due to its attraction to ripening fruits and specialized ovipositor that allows females to lay eggs inside the fruit.
  • A study examined the antennal transcriptomes of male and female flies, revealing that out of over 13,000 genes, a small number were exclusively expressed in the antennae, with a significant number showing sex-biased expression.
  • The findings suggest that specific genes related to chemosensation and immune response are critical for mating and host-finding behaviors, which could help in developing better pest management strategies for this economically impactful insect.
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Glucosinolates, a characteristic group of specialized metabolites found in Brassicales plants, are converted to toxic isothiocyanates upon herbivory. Several insect herbivores, including the cabbage stem flea beetle (Psylliodes chrysocephala), prevent glucosinolate activation by forming desulfo-glucosinolates. Here we investigated the molecular basis of glucosinolate desulfation in P.

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  • The corn earworm uses a specific compound for sex pheromones, with notable amounts of hexadecanal found in male and female tarsi.
  • Researchers compared the gene activity (transcriptome) in female pheromone glands and male/female tarsi to understand differences in pheromone production and detection.
  • They identified several key genes related to pheromone biosynthesis and sensory functions, noting significant variations in gene expression across the different tissues.
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  • The codling moth is a significant pest for pome fruits, and researchers are exploring neuropeptides as new targets for pest control agents.
  • In an analysis of codling moth head transcriptomes, 50 transcripts were identified, predicting a total of 120 prepropeptides related to neuropeptides and peptide hormones.
  • A key discovery indicated that diapause hormones in the codling moth lack a conserved sequence commonly found in other insects, suggesting unique properties that could inform future research and pest management strategies.
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  • * The study focuses on developing a cost-effective system for producing large quantities of double-stranded RNA (dsRNA) using a microbial approach, specifically the L4440 vector and HT115 (DE3) cells.
  • * Results showed that ultrasonic disruption can efficiently isolate dsRNA from bacterial cultures, offering a quicker and more cost-effective method, although the impact of injected dsRNA on insect mortality was not statistically significant.
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