쌍별귀뚜라미는 국내에서 식용 및 파충류의 먹이로 사용되는 중요한 산업곤충으로 알려져있다. 2023년 국내 쌍별귀뚜라미 농가에서 쌍별귀뚜라미 덴소바이러스 감염이 확인되었으며 바이러스 억제제가 요구되는 실정 이다. RNA 간섭(RNAi)은 dsRNA를 이용해 목적 유전자의 발현을 억제할 수 있는 작용기작을 가지며, 바이러스 특이적 시퀀스를 이용한다면 효과적으로 타겟 바이러스의 증식을 저해할 수 있다. 본 연구에서는 덴소바이러스 에 감염된 귀뚜라미에 덴소바이러스 특이적 dsRNA를 제작하여 주입(injection)하고, 바이러스 발현 저해 효과를 관찰했다. 바이러스 감염 수준은 qPCR로 평가하였으며 dsRNA를 접종한 결과 체내 바이러스양이 감소함을 확인 했다. 이 연구는 향후 RNAi를 이용한 쌍별귀뚜라미 덴소바이러스 억제제 개발에 도움이 될 것으로 기대된다.

귀뚜라미는 단백질 함량이 높고 필수아미노산이 풍부하여 세계적으로 식용과 사료용 곤충으로서 가치가 높 다. 국내에서 쌍별귀뚜라미(Gryllus bimaculatus)는 사육이 용이하다는 장점이 있고 주로 파충류, 물고기 등의 사료로 대량 소비되고 있기 때문에 매우 중요한 산업곤충으로 자리매김하고 있다. 그러나 최근 쌍별귀뚜라미의 활동성이 저하되고 다리가 마비되는 등 이상 증상이 발생하여 대량 폐사된 농가가 급증하였다. 이에 대한 원인을 규명하기 위해 질병 발생 농가로부터 귀뚜라미 시료를 수집하여 RNA를 추출하고 metatranscriptomic analysis 를 수행하였다. 그 결과, 신규한 덴소바이러스(Densovirus)가 대량 폐사의 원인임을 밝혀내었고, 이 바이러스를 Gryllus bimaculatus densovirus (GbDV)로 명명하였다. 또한, GbDV의 유전체 분석 결과, genome size는 5,643 bp로 5개의 ORFs(Open Reading Frames)을 포함하며, 왼쪽에는 세 개의 Non-structural proteins을 포함하는 유전자(NS1, NS2, NS3)가 존재했고 오른쪽에는 두 개의 Structural proteins을 포함하는 유전자(VP1, VP2)가 존재했다. 본 연구 는 알 수 없는 곤충 질병의 원인을 밝혀내어 해당 질병에 대한 모니터링을 가능케 함으로써 산업곤충 질병의 예찰하고 확산을 방지하는 데 기여할 것으로 사료된다.

Many insects have gained increasing attention as an alternative protein for humans. Among those, the two-spotted cricket, Gryllus bimaculatus (Orthoptera: Gryllidae), was recently approved as a general food ingredient by the Korean Ministry of Food and Drug Safety. For industrial utilization of G. bimaculatus, mass rearing techniques and production system should be standardized first. In this study, we investigated the effects of five different feeds on the growth and development of G. bimaculatus. Feed is the one of the key factors that has considerable effects on rearing insects. With five different kinds of feed on 1st, 3rd, and 5th instar nymphs, the change of survival rate, body weight were monitored up to eight weeks after hatching. We concluded that 50% of soybean flour, 20% of corn powder, 10% of rice bran, 9% of milk serum, 10% of rice flour, 0.5% of microorganisms, and 0.5% of multivitamins and minerals (diet C) was the best mix for promoting growth and development of 3rd instar nymphs compared to the control diet.

A full-length lysozyme cDNA from Gryllotalpa orientalis was cloned and sequenced. The deduced amino acid sequence of the lysozyme protein was 143 amino acids in length, with a calculated molecular mass of 15.84 kDa and an isoelectric point of 4.74. Sequence motifs, together with alignment and phylogenetic results, confirmed that G. orientalis lysozyme belongs to the C (chicken)-type lysozyme family of proteins. The protein sequence of lysozyme from G. orientalis showed high identity to that of Drosophila melanogaster (51.7%); however, in contrast to D. melanogaster lysozyme, G. orientalis lysozyme was immune inducible and expressed in a wide range of tissues. Expression of G. orientalis lysozyme mRNA was highest at 8 h post-infection and subsequently decreased with time after bacterial infection. We also expressed G. orientalis lysozyme protein in vitro using the pET expression system. Compared with the negative control, over-expressed G. orientalis lysozyme showed antimicrobial activity against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Bacillus subtilis by radial diffusion assay, with MIC values of 30.3 μM and 7.55 μM respectively. These results indicate that G. orientalis lysozyme may have stronger antimicrobial activity than other lysozymes against a broad range of microorganisms.

Male crickets (Order Orthoptera), producing sound for courting females and threatening other males, were chosen to perform researches for the better understanding of the microstructures of sound producing organs. It is known that cricket only makes sound for mating-related events. In this research, two patterns out chirping patterns were observed and analyzed. Each chirp was made of several nodes of waves, each node indicates a movement of wings – friction caused by file and plectrum located on wings. Although both wings possess file and plectrum, only the file on right wing and plectrum on left wing are used to produce sound. Each file consists of 126 teeth, where plectrum gets hooked. The teeth located on file have consistent gap between each other, proportional to the wave nodes acquired – except that the gap in the second region among equally divided six regions were shorter. In case of the usage of file, a cricket mostly uses second region to fifth region, since the teeth in first and sixth region are smaller. Since most of the researches made are mainly focused on the correlation between sound production and behavioral pattern, the current research project aims to reveal and provide thorough understanding on the sound producing organs of cricket, to suggest possible biomimetic applications in our daily lives.

A xylanolytic microorganism, strain DY-7, was isolated from the gut of the mole cricket, Gryllotalpa orientalis. The result of phylogenetic analysis based on its 16S rDNA sequence revealed that the isolate was a Gram-positive bacterium belonging to the genus Streptomyces. The cloned gene (1350-bp) encoding a GH family 10 β -1,4-xylanase (XylA) from Streptomyces sp. strain DY-7 was overexpressed in Escherichia coli BL21 and its gene products were characterized. The hydrolysis activities of rXylA and rXylAΔCBD II against xylosidic materials were maximum at pH 5.5 and 65oC. However, deletion of CBD II in the C-terminus region of XylA significantly increased the thermal stability of the enzyme at high temperatures above 50oC. The xylanolytic activity of rXylA was slightly enhanced in the presence of 1 mM Mn2+ and 5 mM sodium azide but it was completely inactivated by 1 mM Hg2+ and 5 mM N-bromosuccinimide. rXylA was capable of efficiently decomposing various xylosidic compounds, PNP-cellobioside, and PNP-xylopyranoside, whereas other hexose-based compounds were insensitive to the enzyme. The specific activities of rXylA toward oat spelts xylan and PNP-cellobioside were 649.8 U/mg and 328.1 U/mg, respectively. Enzymatic degradation of birchwood xylan and xylooligosaccharides (xylotriose to xylohexaose) resulted in the production of xylobiose (>75%) as the main hydrolysis product together with a small amount (4%<) of xylose as the final hydrolysis product.

본 연구는 외래종 쌍별귀뚜라미 (Gryllus bimaculatus, GB)의 도입에 따른 토착종 왕귀뚜라미 (Teleogryllus emma, TE)의 개체군 크기 감소 위협이 예상됨에 따라, 왕귀뚜라미 (TE)와 쌍별귀뚜라미 (GB)의 체장과 개체수 비율에 따른 생존 경쟁을 조사한 실험이다. 실험에 사용된 쌍별귀뚜라미 (GB)와 왕귀뚜라미 (TE) 공시충은 경북대학교 농업생명과학대학 곤충생태학연구 실 내의 온실에서 대량 사육한 개체들을 사용하였다. 사육온도는 28􀆆C~30􀆆C이며, 장일 조건 (16L : 8D), 상 대습도는 50%~60%로 유지하였다. 매일 두 종의 개체수 를 계측하여 개체수 변화를 조사하였다. 본 실험에서는 더듬이를 제외한 체장 0.5 cm, 1 cm의 왕귀뚜라미 (TE)와 쌍별귀뚜라미 (GB)를 이용하여 왕귀 뚜라미 (TE) : 쌍별귀뚜라미 (GB)의 개체수 비율을 1 : 2, 1 : 1, 2 : 1로 나눈 총 3가지의 조건으로 실험하였다. 그 결 과, 개체가 작을 때에는 쌍별귀뚜라미 (GB)의 세력이 약 하고, 시간이 지날수록 쌍별귀뚜라미(GB)의 세력이 왕귀 뚜라미(TE)보다 강해지는 것을 알 수 있었다. 최종 생존 종은 대부분 쌍별귀뚜라미 (GB)였으며, 쌍별귀뚜라미 (GB)의 노화가 예상됨에도 불구하고 생존력이 강한 경향 을 보였다. 쌍별귀뚜라미 (GB)의 생존율은 큰 차이를 보 이지 않았던 반면, 왕귀뚜라미 (TE)의 생존율이 큰 폭으 로 감소하는 현상이 나타났다.

To understand the evolution and speciation of closely related species, a multiple approach encompassing morphological, behavioral, and genetic analyses is necessary. In Korea, three species of Loxoblemmus crickets occur widely. L. campestris and L. equestris are morphologically indistinguishable, whereas males of L. doenitzi are different from the other two species in head morphology. The genetic analyses using the partial mitochondrial COI sequences showed that L. doenitzi diverged off earlier than L. campestris and L. equestris. The analyses of laboratory recordings revealed that distributions of calling song characters generally overlapped among three cricket species. However, the number of pulses in a chirp was two in L. doenitzi and four in L. campestris, but it was greater than or equal to six in L. equestris. Provided that females make mate choice based on this calling song character, the differentiation in this character may lead to premating reproductive isolation and may have evolved during the speciation proccess in these closely related species.

Cryptic species are hardly distinguished by their morphology but reproductively isolated. To understand the evolution and speciation of cryptic species, differentiations between cryptic species should be studied using multiple approaches including morphological analysis. Two of three species under the genus Loxoblemmus in Korea are morphologically similar and may constitute the cryptic species. We studied the differentiations in morphology, calling songs, and genetic sequences to understand patterns of speciation in these three species. Although L.doenitzi was easily distinguished from the other two species based on morphology, the distributions of the number of file teeth and wing morphology overlapped in L. campestris and L. equestris. However, there were clear differentiations in some calling song characters among three cricket species. The number of pulses in a chirp was two in L.doenitzi and four in L. campestris, but that was greater than or equal to six in L. equestris. The genetic sequence analyses using 16S rRNA and COI barcode revealed that L. doenitzi diverged off earlier from the other two species. Calling songs of L. campestris and L. equestris largely differed in spite of their short divergence time. Our results suggest that the speciation processes may involve differentiation in calling songs in the Loxoblemmus complex.

Sexual dimorphism, the difference between sexes in secondary sexual characters, is in general driven by processes of sexual selection. The horn-headed cricket, Loxoblemmus doenitzi, exhibits sexual dimorphism in head shape, in which males have flat heads and triangular horns on both sides of their heads, whereas females have rounded heads and no horns. We hypothesized that male horns have been evolved due to intra-sexual selection in which males use these horns as weapons in aggressive interactions. To test this hypothesis, we conducted agonistic trials of field-caught males in L.doenitzi. Horn length was significantly correlated with thorax length and hind femur length. During agonistic males aggressively used their horns by beating the opponent’s horns with their horns or by poking the opponent’s body with their horns. However, the result of logistic regression analysis revealed that horn length or horn point frequency were not significant factors for contest outcome. Instead, body size was significant for determining contest outcome

We analyzed the chirp sound and behavior of Teleogryllus emma with observation system, which was consisted of computer, ccd-camera and microphone. Computational methods of wavelet transformation and Self-Organizing Maps (SOM) were utilized to characterized the chirp sound of insect species for automatic counting in this study. Wavelets were initially applied to feature extraction of the chirp sound. Wavelet coefficients were accordingly calculated based on the basis function (e.g., Morlet). The obtained coefficients were subsequently provided to count number of chirps in each song. Sound structure of insect specimens consisted with long chirp and short chirp and the patterns of song were grouped by frequency of long chirp and short chirp. The song patterns of insect specimens were divided by Self-Organizing Map (SOM) that was used number of chirp as input data. Application of computational methods to automatic detection of chirp sound was further discussed for obtaining objective assessment in behavior science.

The genus Loxoblemmus has three speices in Korea: L. doenitzi, L. campestris and L. equestris. Males of L. doenitzi have flat heads and triangular horns on both sides of their frons, whereas males of L. campestris and L. equestris have flat heads and no horns. The latter two species are not clearly distinguished based on morphology and thus may constitute cryptic species. We studied the divergence in morphology, calling songs, and genetic sequences to understand patterns of differentiation of these three species. Distributions of the number of file teeth and wing morphology overlapped in L. campestris and L. equestris. In calling songs, the number of pulses in a chirp was four in L. campestris, but that was greater than or equal to six in L. equestris. The genetic sequence analyses using 16S rRNA and COI barcode revealed that L. doenitzi diverged off earlier from the other two species. Thus, the genetic data were congruent with the calling song data in three Loxoblemmus species. Our results suggest that the speciation processes may be closely related to differentiation in calling songs in the Loxoblemmus complex.

We describe here the cloning and characterization of a cDNA encoding the ferritin heavy chain homologue (TeFerHCH) from the cricket Teleogryllus emma. The TeFerHCH gene spans 1,009 bp and consisted of four introns and five exons coding for 217 amino acids residues. The TeFerHCH subunit contained the conserved motifs for the ferroxidase center typical of vertebrate ferritin heavy chains and the iron-responsive element (IRE) sequence with a predicted stem-loop structure was present in the 5'-untranslated region (UTR) of TeFerHCH mRNA. TeFerHCH was grouped with the S type (HCH) in a phylogenetic tree. The TeFerHCH cDNA was expressed as approximately 27 kDa polypeptide in baculovirus-infected insect Sf9 cells. Northern blot analysis revealed that TeFerHCH exhibited ubiquitous expression and was upregulated by wounding and iron overload in the fatbody, suggesting a functional role for TeFerHCH in iron metabolism.

Males of many cricket species produce calling songs to attract receptive, conspecific females. Calling songs which affected by calling pattern are critical for male mating success, since male with no or limited calling songs are unable to attract female crickets. Investigating among- and within-individual variation in calling pattern may reveal the presence of alternative mating tactics such as attracting females by producing calling songs or being satellites in which males intercept females who are attracted to calling males. In this study, I investigated patterns of calling song production during the entire adulthood of 32 laboratory-reared and 24 field-captured individuals of Teleogryllu emma. Using recording system which can record acoustic signals from up to 32 individuals simultaneously, I measured daily calling output (DCO) and total calling output (TCO) in addition to acoustic parameters of calling songs and classified T.emma males into consistent and inconsistent singers based on the consistency of singing. Consistent singers lived longer, sang longer both in a day and during the lifetime than the inconsistent singers. These results suggest that the consistent singers in this study may be considered to employ the calling tactic. In lab-reared individuals, there seemed to be a trade-off between increasing pulse duration and length of phrases and ling chirp although older males produced calling songs with longer ling chirps and more multiple phrases.