Spodoptera frugiperda, commonly known as the fall armyworm (FAW), is a major pest across the globe due to its broad host range and distribution worldwide. We investigated the function of microRNAs (miRNAs) in the detoxification of insecticides, with a specific focus on its susceptibility to chlorantraniliprole which is widely utilized insecticide for its management. miRNAs are small non-coding RNA molecules, crucial for post-transcriptional regulation of gene expression. This study aims to elucidate the impact of these miRNAs on the expression of cytochrome P450 genes, which play a significant role in conferring insecticide resistance. We identified notable changes in the abundance of two specific miRNAs, sfr-miR-10465-5p and sfr-miR- 10476-5p through RNA sequencing, after chlorantraniliprole exposure. These miRNAs exhibited significantly high expression in the fat body tissue, while showing relatively lower expression in the head, midgut, and malpighian tubules. Further analysis suggested that these miRNAs might target specific cytochrome P450 genes, like CYP4C1 and CYP4C21, which are known to play a role in insecticide resistance development. Experimentation with miRNA mimics through microinjection revealed a notable increase in the survival rates of S. frugiperda larvae when subjected to chlorantraniliprole exposure, with a significant reduction in CYP4C1 and CYP4C21 gene expression levels. This suggests a direct connection between the miRNAs and the increased tolerance of Spodoptera larvae to the insecticide. Our research presents the complex function of miRNAs in gene expression regulation related to insecticide resistance, offering valuable insights into the molecular mechanisms of chlorantraniliprole resistance in S. frugiperda. These findings pave the way for further investigations into miRNA roles and their potential in managing pesticide resistance in agricultural pests.

겨울과 같은 환경에서 곤충은 생존과 번성을 위해 생리학적, 생화학적 및 행동적 메커니즘을 이용하고 있다. 대부분의 곤충은 생리학적 적응가운데 급속내한성(Rapid cold hardiness, RCH) 유기를 통해 기온이 급격히 낮아 지는 외부 환경에 대해 빠르게 적응하고 저온조건에서 생존율을 높인다. 열대거세미나방의 경우 행동적 메커니 즘을 통해 따뜻한 곳을 찾아 장거리 비행을 하며, 생존에 유리한 환경으로 이동한다. 본 연구에서는 열대거세미나 방의 생리적 월동능력과 RCH 능력에 관해 조사하였다. 그 결과, RCH에 의해 혈중 글리세롤의 농도가 증가와 체내빙결점이 하강하는 것을 확인할 수 있었다. 또한, RCH(-10℃, 1h)에 노출된 2령 유충기를 대상으로 4령과 5령 유충기에 단기저온(5℃, 30min)에 노출 시 글리세롤 생합성에 관여하는 유전자(glycerol kinase 1, 2)의 발현이 RCH에 노출되지 않은 대조구와 비교하여 빠르게 발현되었다. 이는, 열대거세미나방의 유전자 수준에서 저온에 대한 단기기억이 존재하는 것을 제시한다.

The fall armyworm, Spodoptera frugiperda, has developed extremely high levels of resistance to chlorantraniliprole and other classes of insecticides in the field. As microRNAs (miRNAs) play important roles in various biological processes through gene regulation. we examined the miRNA profile of S. frugiperda in response to Chlorantraniliprole, Indoxacarb and Thiamethoxam. Transcriptome analysis showed significant changes in the abundance of some miRNAs after treatment of S. frugiperda larvae with LC20 concentrations of three insecticides. A total of 197 miRNAs were systematically identified from S. frugiperda, and 16, 9, 2 miRNAs were differentially expressed after treatments of three insecticides. Importantly, three miRNAs were significantly downregulated and three were upregulated by RT-qPCR after treatment the LC50 of three insecticides with S. frugiperda larvae. Microinjection of agomirs of these six miRNAs into S. frugiperda larvae resulted in significant changes in mortality rates when exposed to three insecticides. Additionally, we also screened potential target genes for some of differentially expressed miRNAs, which may play important roles in insecticide resistance development. These findings provide valuable insights into the molecular mechanisms of insecticide resistance and underscore the potential of miRNAs as targets for the development of novel pest control strategies in S. frugiperda.

Fall armyworm (FAW, Spodoptera frugiperda) is a major pest worldwide, and since its first domestic invasion was confirmed in 2019, its damage has been steadily increasing in crops such as corn until recently. In order to provide basic data for the management of FAW, we conducted a comparison of host preference and nutritional composition analysis of corn varieties. A total of 12 varieties of corn were selected for the experiment. To investigate the preference among the varieties, we examined the host preferences at the population level and the individual level, and found no statistically significant differences. In the population-level experiment, the highest damage rate was observed for Saekso 4 and the lowest for Heukgeom 2. In the individual-level experiment, the highest damage rate was found for Kangilok and the lowest for Oryun 2 when using leaves, and the highest for Saekso 1 and the lowest for Dreamok when using stems. As a result, the population-level and individual-level results were not consistent, suggesting that FAW's corn variety preference is not clear and may vary depending on various conditions such as corn tissue. Composition analysis of the 12 varieties showed no correlation between composition and FAW preference among the varieties, and considering the feeding behavior of FAW, which are highly polyphagous, it is recommended to control FAW as early as possible to improve control effectiveness.

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.

Spodoptera 속의 담배거세미나방, 열대거세미나방 및 파밤나방은 여러 나라에 분포하는 광식성 해충으로, 본 연구에서는 이들의 페로몬 및 식물냄새물질과 관련한 화학통신시스템에 대해 이해하기 위해 냄새감각기의 종류와 분포, 냄새활성물질 동정 및 야외행동 반응에 대한 연구를 진행하였다. 주사전자현미경 관찰을 통해, 세 종 나방의 암, 수컷 촉각에 여러 종류의 냄새감각기가 존재하며, 형태적으로 구분되는 종특이적 또는 성특이적 냄새감각기들이 존재한다는 것을 확인하였다. GC-EAD 실험을 통해 세 종 나방에 냄새활성을 나타내는 식물 냄새물질과 페로몬 관련 물질들을 동정하고, 이들을 개별 또는 조합하여 야외 트랩실험을 통해 행동활성을 검정 한 결과, 이 중 여러 물질이 담배거세미나방과 파밤나방의 성페로몬에 대한 유인행동 반응을 저해하는 것을 알 수 있었다. 열대거세미나방은 발생이 저조하여 야외에서의 행동반응을 확인할 수 없었다.

대파(Allium fistulosum L.)는 동양에서 옛날부터 중요한 식재료로 재배되어온 중국 원산지의 향신 채소이다. 적어도 통일신라시대부터 재배되어 온 기록이 있으며 현재에도 식재료로 수요가 많아 전국적으로 재배면적이 넓어지고 있고, 종자의 유통량 또한 많다. 대파에는 파굴파리(Liriomyza chinensis), 파좀나방(Acrolepiopsis sapporensis), 파밤나방(Spodoptera exigua) 등이 주요 해충으로 알려져 있다. 전남 진도군은 국내 대파 주산단지로 파밤나방의 발생이 많고 다이아마이드 계통 농약의 저항성이 발현되고 있어 계대사육에 따른 저항성 감소를 실험하고자 한다. 실험은 진도군의 대파밭에서 파밤나방 개체를 채집하여 실내에서 약제처리를 통해 살충률과 섭식률을 검정, 몇세대에 걸쳐 저항성이 감소되는지 알고자 한다.

Spodoptera litura is an omnivorous pest that damages more than 120 types of crops. It is widely distributed throughout the tropics, subtropics, and temperate zones. It is a major pest that causes damage by explosively increasing in density in a short period of time due to its excellent mobility and reproductive ability. S. litura was studied at five constant temperatures (15.0, 20.0, 25.0, 30.0, and 35.0℃), 65±5% relative humidity (RH), and 14L:10D photoperiods. The development period for eggs and larvae tended to become shorter as temperature increased. The growth period of egg, larva, and pupa by 25℃ temperature was 4.0, 32.3, and 12.6 days, respectively.

Spodoptera species (S. exigua and S. litura) are important pests of several crops and vegetables in Korea. We investigated development processes of Spodoptera species under constant temperatures (20, 25 and 30 oC) regimes and relative humidity (RH) (30-35, 50-55, 70-75, and 90-95%) conditions. We collected eggs of Spodoptera species by releasing them into a rectangular box inner walls covered with a sheet of white paper. Temperature and RH significantly impacted on oviposition, immature survival, adult emergence and longevity of Spodoptera species. Maximum number of eggs, shorter developmental time, higher adult emergence with longer longevity were reported in 70-75% at 30 oC. Minimal eggs and larval survival were recorded in 30-35% and 90-95% RH, respectively. This results suggest that temperature and RH had individual apparent effect on the developmental processes of Spodoptera species instead interactive effect. Therefore, there is chance to cause a significant damage to field crops and vegetables in 70-75% at 30 oC.

열대거세미나방이 2019년 국내에 첫 비래한 이후 매년 비래하고 있으며 옥수수 등에서 피해를 주고 있음에 따라 전북지역 주요 옥수수 재배지역에서의 열대거세미나방 발생양상과 약제방제 효과를 조사하였다. 2022년 도에 성페로몬트랩을 이용하여 성충유인량을 조사한 결과 7월 1일 첫 채집되었으며 8월 중순이후 채집량이 증가 하여 9월 중순과 10월 중순에 발생최성기를 보였으며 11월 상순까지 유인되었다. 2022년과 2023년에 식용 옥수 수 재배지역에서 열대거세미나방 유충 피해 조사 결과 6월 수확하는 옥수수에서는 열매피해가 없었으나 9월에 수확하는 옥수수에서는 피해열매율이 30% 이상인 포장들이 관찰되어 재배시기에 따라 피해 정도 차이가 매우 큰 경향이었다. 옥수수 포장에서 열대거세미나방 유충 방제를 위해 2~3령기에 인독사카브 액상수화제를 7일 간격으로 2회 살포한 결과 처리 7일 후 방제효과는 91.7%로 높았다.

During the larval development process of insects, juvenile hormone (JH) is essential for regulating various aspects of larval life, including growth, reproduction, and behavior, throughout their larval stage. The larval stage of Spodoptera frugiperda, when it consumes plant-derived metabolites, develops into pupae, but these pupae are unable to molt successfully. In this way, plant-derived metabolites contain or produce inhibitors of juvenile hormone, thereby disrupting the development of insect larvae and making them vulnerable to harm. Therefore, in this study, we established an in vitro screening system using yeast cells transformed with the Met-SRC juvenile hormone receptor of S. frugiperda. Through this system, we were able to identify juvenile hormone disruptors from plant-derived metabolites and confirm their developmental inhibitory effects on the larvae of S. frugiperda.

Fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is a polyphagous agricultural pest that damages about 80 species of plants. It mainly damages Poaceae and plants used as food resources for humans. Its original habitat is the American continent, but it unintentionally settled in tropical and subtropical Asia, including Africa, India, and Sri Lanka. It occurs every year even in southern China, which is geographically adjacent to the Korean Peninsula, causing damage to crops. In Korea, it was first discovered on Jeju Island in June 2019 and is being discovered every year in Jeju and some inland areas. In 2023, there were a total of 13 discoveries, including those in the Jeju and Jeonbuk regions. Quarantine agency identified the maternal genotypes of all currently discovered individuals using COI and identified differences in genetic traits between individuals using the sex-related Z-chromosome. For comparison with the information on the individuals that invaded the country, 15 individuals from Guangxi and Guangdong provinces in China were collected and secured. Through the analysis of overseas samples, a database has been added to compare genetic information with domestic invasive species, and the reliability of the analysis is expected to increase.