Bombyx Research Articles

Monitoring and Prediction of Siberian Silk Moth Dendrolimus sibiricus Tschetv. (Lepidoptera: Lasiocampidae) Outbreaks Using Remote Sensing Techniques.

The feasibility of risk assessment of a Siberian silk moth (Dendrolimus sibiricus Tschetv.) outbreak was analyzed by means of landscape and weather characteristics and tree condition parameters. Difficulties in detecting forest pest outbreaks (especially in Siberian conditions) are associated with the inability to conduct regular ground surveillance in taiga territories, which generally occupy more than 2 million km2. Our analysis of characteristics of Siberian silk moth outbreak zones under mountainous taiga conditions showed that it is possible to distinguish an altitudinal belt between 400 and 800 m above sea level where an outbreak develops and trees are damaged. It was found that to assess the resistance of forest stands to pest attacks, researchers can employ new parameters: namely, characteristics of a response of remote sensing variables to changes in land surface temperature. Using these parameters, it is possible to identify in advance (2-3 years before an outbreak) forest stands that are not resistant to the pest. Thus, field studies in difficult-to-access taiga forests are not needed to determine these parameters, and hence the task of monitoring outbreaks of forest insects is simplified substantially.

Biomolecular characterization of Antheraea mylitta cocoonase: A secreted protease

Cocoonase is a protease secreted during the emergence of silk moths. In the present study cocoonase of Antheraea mylitta was collected, purified and secondary structure was determined using circular dichroism (CD) spectroscopy which revealed the presence of α-helix 4.3%, β-sheet 55%, turn 8% and random coil 32.7%. The thermal stability of cocoonase was studied using CD spectroscopy while the thermal property was observed using Differential Scanning Calorimetry (DSC). Furthermore, MALDI-TOF peptide mass fingerprinting (PMF) was performed for similar protein identification using the MASCOT server. Using casein as the substrate, the kinetic constants Km and Vmax were 13 × 103 mg/ml and 15.09 × 10−2 μg/mg.s1 respectively. The specific activity of cocoonase was observed to be maximum at temperature 40 °C, pH-8.0. The effect of heavy metals Hg2+, Cd2+, Co2+, Pb2+ showed inhibitory activity at higher concentrations, while few metals like Mn2+, Fe3+ enhanced the activity while the effect of Ca2+ was not much on the activity. Soybean trypsin inhibitor and PMSF showed an inhibitory effect on the activity of cocoonase. Additionally, antioxidant scavenging and fibrinolytic properties were also observed. Furthermore, the imperative information generated through the present study will serve to explore cocoonase for its prospective pharmaceutical applications.

Description of a new species and a new group of Salassa Moore, 1859 (Lepidoptera: Saturniidae) with a molecular study based on partial COI.

Salassa is a genus of the family Saturniidae. It comprises over 30 species that are widely distributed in Asia. This study describes a new species, Salassa sunwukongi sp. nov., found in Chinese Yunnan province. The first molecular study of Salassa was conducted using COI fragments. Molecular and morphological analyses revealed the presence of a monophyletic group, royi-group, distributed in the Himalayas. A key to members of the royi-group, along with species lists and distinguishing characteristics of all three groups of Salassa, is provided.

Critical re-examination of known purported fossil Bombycoidea (Lepidoptera)

We critically re-examine 17 records of fossils currently assigned to the lepidopteran superfamily Bombycoidea, which includes the silk moths, emperor moths and hawk moths. These records include subfossils, compression and impression fossils, permineralizations and ichnofossils. We assess whether observable morphological features warrant their confident assignment to the superfamily. None of the examined fossils displays characters that allow unequivocal identification as Sphingidae, but three fossils and a subfossil (Mioclanis shanwangiana Zhang, Sun and Zhang, 1994, two fossil larvae, and a proboscis in asphaltum) have combinations of diagnostic features that support placement in the family. The identification of a fossil pupa as Bunaeini (Saturniidae) is well supported. The other fossils that we evaluate lack definitive bombycoid and, in several cases, even lepidopteran characters. Some of these dubious fossils have been used as calibration points in earlier studies casting doubt on the resulting age estimates. All fossil specimens reliably assigned to Bombycoidea are relatively young, the earliest fossil evidence of the superfamily dating to the middle Miocene.

Patterns of speciation in a parapatric pair of Saturnia moths as revealed by target capture.

The focus of this study has been to understand the evolutionary relationships and taxonomy of a widely distributed parapatric species pair of wild silk moths in Europe: Saturnia pavonia and Saturnia pavoniella (Lepidoptera: Saturniidae). To address species delimitation in these parapatric taxa, target enrichment and mtDNA sequencing was employed alongside phylogenetic, admixture, introgression, and species delimitation analyses. The dataset included individuals from both species close to and farther away from the contact zone as well as two hybrids generated in the lab. Nuclear markers strongly supported both S. pavonia and S. pavoniella as two distinct species, with hybrids forming a sister group to S. pavoniella. However, the Maximum Likelihood (ML) tree generated from mtDNA sequencing data presented a different picture, showing both taxa to be phylogenetically intermixed. This inconsistency is likely attributable to mitonuclear discordance, which can arise from biological factors (e.g., introgressive hybridization and/or incomplete lineage sorting). Our analyses indicate that past introgressions have taken place, but that there is no evidence to suggest an ongoing admixture between the two species, demonstrating that the taxa have reached full postzygotic reproductive isolation and hence represent two distinct biological species. Finally, we discuss our results from an evolutionary point of view taking into consideration the past climatic oscillations that have likely shaped the present dynamics between the two species. Overall, our study demonstrates the effectiveness of the target enrichment approach in resolving shallow phylogenetic relationships under complex evolutionary circumstances and that this approach is useful in establishing robust and well-informed taxonomic delimitations involving parapatric taxa.

Antimicrobial Peptides: Principal Defense Constituents of Silk Worms - A Review

Insect has a highly developed innate immune system consisting of cellular and humoral responses. Antimicrobial peptides (AMPs) are the important components of the insect’s humoral defense system and were first purified from the giant silk moth, Hyalophora cecropia L (Boman et al., 1980). For a variety of infections, they serve as the initial line of defense. AMPS are low molecular weight peptides and generally cationic in nature. Off late, the resistance of the pathogenic microbes towards established antibiotics have become a serious threat to global health. Over the years, an array of AMPs from natural sources has served as potent candidate against various infective agents viz. bacteria, fungi and viruses. These insect peptides not only exhibit antibacterial action by rupturing the microbial membrane but also prevent the development of drug resistance by microbes. Studies have shown AMPS to have synergistic effects with traditional antibiotics, providing an opportunity for combined therapy. Defensin, cecropins, drosocin, attacins, diptericins, ponericins, metchnikowins and melittin are a few classes of AMPs from insects that are currently isolated. However, the possibility of discovering new AMPs cannot be fully ruled out. Currently, 33 peptides are undergoing clinical trials, and 43% of the 77 AMPs are still in the preclinical stage (Makwana et al., 2023). Daptomycin and ovitavancin are two antibacterial lipopeptides that Food and Drug Administration has recently approved that are used for skin infection caused by bacteria. The present paper is an attempt to provide a comprehensive insight on antimicrobial peptides isolated from silk worm with reference to their structures, functions and possible mechanism of action.

Reproductive Biology of Muga Silk Moth <i>Antheraea assamensis</i> Helfer

Results of morphological and morphometric study of male and female reproductive systems of Antheraea assamensis Helfer (Saturniidae: Lepidoptera), a silk moth cultivated exclusively in the North Eastern Region of India are reported herein along with some observations on its reproductive performance in four seasons. The male reproductive system consists of a pair of testes, paired vasa deferentia, seminal vesicle, ductus ejaculatorius duplex, ductus ejaculatorius simplex, an aedeagus and a pair of male accessory glands. The female reproductive system consists of a pair of ovaries, each with four ovarioles, paired lateral oviducts, a common oviduct which has a dorsal protrusion, the vestibulum, a bursa copulatrix, a spermatheca and a pair of female accessory glands with their reservoirs. Fecundity has been found to be positively correlated with female pupal weight in each season. Hatching % of eggs has been found lowest and significantly different (p<0.001) in summer as compared to autumn, winter and spring seasons. Morphology of eupyrene and apyrene sperm bundles and sperm has also been reported.

Possible Regulation of Larval Juvenile Hormone Titers in Bombyx mori by BmFAMeT6.

Juvenile hormone (JH) plays a vital role in the growth, development, and reproduction of insects and other arthropods. Previous experiments have suggested that BmFAMeT6 could affect the duration of the silk moth's larval stage. In this study, we established the BmFAMeT6 overexpression strain and BmFAMeT6 knockout strain using the GAL4/UAS binary hybrid system and CRISPR/Cas 9 system, respectively, and found that the larval stage of the overexpression strain was shorter, while the knockout strain was longer. Our results exhibited that both the JH titers and BmKr-h1 levels in the larvae of the third instar were reduced significantly by BmFAMeT6 overexpression, but were increased obviously by BmFAMeT6 knockout. In addition, injection of farnesoic acid induced changes in the JH I and JH II levels in the hemolymphs of larvae. This study is the first to directly reveal the role of BmFAMeT6 in the regulation of insect JH titers and the relationship between farnesoic acid and JH (JH I and JH II). This provides a new perspective on regulating the growth and development of insects such as Bombyx mori.

3D reconstruction of larval and adult brain neuropils of two giant silk moth species: Hyalophora cecropia and Antheraea pernyi

We present a detailed analysis of the brain anatomy of two saturniid species, the cecropia silk moth, Hyalophora cecropia, and the Chinese oak silk moth, Antheraea pernyi, including 3D reconstructions of the major brain neuropils in the larva and in male and female adults. The 3D reconstructions, prepared from high-resolution optical sections, showed that the corresponding neuropils of these saturniid species are virtually identical. Similarities between the two species include a pronounced sexual dimorphism in the adults in the form of a male-specific assembly of markedly enlarged glomeruli forming the so-called macroglomerular complex. From the reports published to date, it can be concluded that the neuropil architecture of saturniids resembles that of other nocturnal moths, including the sibling family Sphingidae. In addition, compared with previous anatomical data on diurnal lepidopteran species, significant differences were observed in the two saturniid species, which include the thickness of the Y-tract of the mushroom body, the size of the main neuropils of the optic lobes, and the sexual dimorphisms of the antennal lobes.

Differentiation of Forest Stands by Susceptibility to Folivores: A Retrospective Analysis of Time Series of Annual Tree Rings with Application of the Fluctuation-Dissipation Theorem

This study analyzed the relationship between characteristics of annual tree ring time series and the intensity of attacks on forest stands by forest insects. Using tenets of the fluctuation–dissipation theorem (which is widely used in physics), time series parameters are proposed that can help to assess the susceptibility of a forest stand to insect pests. The proposed approach was applied to evaluate differences in parameters of tree ring widths among outbreaks of the pine looper, Siberian silk moth, and spongy moth. A comparison of trees characteristics between outbreak locations and undamaged forest stands (control) showed that the tested parameters statistically significantly differed between the outbreak locations and control stands and can be used to assess the risk of pest outbreaks in forest stands.

Moth Luna (Actias luna)

The Luna moth (Actias luna) is American Moon Moth also known as the Nearctic moth of the family Saturniidae, subfamily Saturniinae, a group recognized as the giant silk moth. The Luna moth is found east of the Great Plains in the United States from Florida to Maine, North America, and Saskatchewan east through central Quebec to Nova Scotia, Canada. Luna moths are rarely found as vagrants in Western Europe. In June 1987, Luna moth appeared on a United States First Class postage stamp. Within two dozen butterflies have been honored in postage stamps, this was the only moth. This remarkable critter is recognizable by its wings. But, the most interesting thing about Luna Moth is that this insect doesn’t have a digestive system or a mouth. It lives only for about a week after leaving the cocoon and never eats.

Analysis of Odor-Tracking Performance of Silk Moth Using a Sensory-Motor Intervention System.

Animals can adaptively behave in different environmental conditions by converting environmental information obtained from their sensory organs into actions. This sensory-motor integration enables the accomplishment of various tasks and is essential for animal survival. This sensory-motor integration also plays an important role in localization to females, relying on sex pheromones floating in space. In this study, we focused on the localization behavior of the adult male silk moth, Bombyx mori. We investigated sensory-motor integration against time delay using odor plume tracking performance as an index when we set a certain time delay for the sensory and motor responses. Given that it is difficult to directly intervene in the sensory and motor functions of the silk moth, we constructed an intervention system based on a mobile behavior measurement system controlled by them. Using this intervention system, not only can timing the detection of the odor in the environment and timing the presentation of the odor to the silk moth be manipulated, but timing the reflection of the movement of the silk moth can also be manipulated. We analyzed the extent to which the localization strategy of the silk moth could tolerate sensory delays by setting a delay to the odor presentation. We also evaluated behavioral compensation by odor sensory feedback by setting a delay to the motor. The results of the localization experiment have shown that the localization success rate did not decrease when there was a motor delay. However, when there was a sensory delay, the success rate decreased depending on the time delay. Analysis of the change in behavior after detection of the odor stimulus has shown that the movement was more linear when we set a motor delay. However, the movement was accompanied by a large rotational movement when there was a delay in the sensory input. This result has suggested that behavior is compensated for the delay in motor function by feedback control of odor sensation, but not when accompanied by sensory delay. To compensate for this, the silk moth may acquire appropriate information from the environment by making large body movements.

The Role of Forest Stands Characteristics on Formation of Exterior Migratory Outbreak Spots by the Siberian Silk Moth Dendrolimus sibiricus (Tschetv.) during Population Collapse

The characteristics of Abies sibirica Ledeb.- and Pinus sibirica Du Tour dominated forests stands in outbreak spots formed during a Dendrolimus sibiricus outbreak in 2014–2017 were studied at the stage of population collapse (east of the West Siberian Plain and western foothills of the Yenisei Range). The research was based on the data obtained during ground surveys conducted in 2016 when stands characteristics, the Siberian silk moth population density, and defoliation level were recorded. We classified the studied stands using decision trees and random forest algorithms to identify the key characteristics that determine the formation of outbreak spots. The classification results showed that the characteristics of the detected outbreak spots differ significantly from those previously described for dark coniferous stands of the southern taiga in Siberia. The highest probability of the outbreak spot occurrence in the study area was revealed for stands with the following characteristics: moderately moist site; Siberian stone pine and Siberian fir take 40% or more of stem volume; age of less than 105 years. Another group of forest stands under threat are those sharing the following characteristics: large area (more than 60 ha); stand homogeneity; ground vegetation is dominated by feather mosses; age of more than 120 years; Picea obovata Ledeb. takes a significant share in a stem volume. Such characteristics indicate that during the population collapse, the Siberian silk moth forms outbreak spots in stands that either undergo an early successional stage after previous outbreak or have been slightly damaged during the previous outbreaks due to unfavorable habitat conditions.

The Complete Genome Sequence of Actias luna (Saturniidae, Lepidoptera), the luna moth.

Actias luna, the luna moth, is a Nearctic species in the family Saturniidae, the giant silk moths. Known for its large size, bright green wings and elongated tails, it is found in Eastern North America, from east of the Great Plains in the United States, and from Saskatchewan eastward through central Quebec to Nova Scotia in Canada. We present the complete genome sequence of this species. Raw read data and the assembled genome are available in Genbank.

Morphological Variation of Antheraea assamensis Helfer upon Semi-domestication: A Study on Rearing, Disease Incidence and Seed Production Performance

Muga silkworm is multivoltine and primarily feeds on two primary food plants Som (Persea bombycina King. syn. Machilus bombycina) and Soalu (Litsea polyantha Kost. syn. Litsea monopetala). Muga silkworm Antheraea assamensis (n=15) is a semi-domesticated silk moth mentioned in literature as early 1662 BC. In its annual life cycle there are six crops of cultivated muga silk worm whose nomenclature is based on the local Assamese names of month. By virtue of the narrow ecological distribution of host food plant Antheraea assamensis is confined to only Assam and North East state of India. Empirical observations show that the population is declining due to depletion of natural habitat and lack of genetic variability among population. The wild muga silkworm which is tri or tetra voltine in nature is also found nearby forest area of human habitat in different host plant in N E state of India. A stock of wild muga silkworm collected from the nearby area of Nongpoh and Mendipathar Meghalaya. reared and maintained in muga farm and grainage activities of both wild and cultivated muga were conducted for comparative study. Details of morphology, economic characters and disease occurrence of wild and cultivated muga was studied for future improvement and breed development and also for future strategy of muga silkworm. The morphology of wild muga silkworm are little variant than cultivated muga and economic characters i.e. fecundity of wild muga was recorded 220 - 227 nos. in against the fecundity of cultivated muga observed 120-170 nos. and one gram total numbers of egg contain 120 -135 nos in wild muga in against 134 -145 nos.in cultivated muga. Average cocoon weight wild muga cocoon is ♂= 5.80 g & ♀= 6.60 g in against average cocoon weight ♂= 5.10 g & ♀= 5.54 g in cultivated muga silkworm. Average shell weight ♂= 0.51 g & ♀= 0.60 g in wild muga silkworm and average shell weight ♂= 0.43 g & ♀= 0.51 g in cultivated muga silkworm were recorded. Study revealed that the fecundity, weight of eggs, cocoon weight and shell weight are higher in wild muga silkworm than cultivated muga silkworm. Thereafter it is found that only protozoon disease was reported in wild muga silkworm and other disease i.e. Flacherie, Grasserie, Muscardine was not reported in wild muga silkworm. The mono race muga have no high yielding breed or hybrid and hence breeding programme between wild and cultivated muga may be carried out to get more heterosis, vigourity and yield enhancement.

Natural parasitoid species of silk moth in Cameroon Afromontane ecosystem

Natural parasitoid species of silk moth in Cameroon Afromontane ecosystem

The Development of Outbreaks of Forest Insects on Different Spatial Scale

The work is dedicated to the discussion of the possibilities of describing the dynamics of the forest insect outbreaks development on different spatial scales. The properties of outbreaks were considered on a microspatial scale, where the distribution patterns of individuals across different food sources within the boundaries of a local territory or a stand were analysed, and on a macrospatial scale, where the focus of the analysis were the indicators of the photosynthetic apparatus (leaves or needles) removal over the entire territory of the locus, including primary, secondary and migratory loci. When analysing the microspatial distribution of caterpillars on trees within loci on different stages of gradation, the model of the individuals’ distribution on fodder trees was used as a second order stage transition. The macrospatial processes that occur during the outbreak development include, firstly, the growth of an existing outbreak and the emergence of new connected damaged areas of the forest, and secondly, the emergence of new unconnected secondary foci. To characterise the outbreaks, their fractal dimension D and the characteristics of the “viscous fingers” on the border of the outbreaks were used. Remote sensing data were used to calculate these characteristics. The proposed approaches can be used to predict the development of forest insects outbreak. When constructing and verifying the models, we used data from the Siberian silkworm census and the trees colonisation rate in the outbreak zone, as well as the remote sensing data on the areas and shapes of the foci in the regions of the Krasnoyarsk Territory during an outbreak of the Siberian silk moth Dendrolimus sibiricus Tschetv. in 2015–2019.

Genome-wide identification and transcriptome-based expression pattern of chemosensory genes in two wild silkmoths,Antheraea pernyi andAntheraea yamamai

Antheraea pernyi Guérin-Méneville andAntheraea yamamai Guérin-Méneville are two closely related wild silkmoths belonging to the family Saturniidae with highly edible and silk-producing value. In this study, we characterised candidate chemosensory genes from the genomes of the two silkmoths. InA. pernyi, 38 odorant-binding proteins (OBPs), 21 chemosensory proteins (CSPs), 3 sensory neuron membrane proteins (SNMPs), 28 ionotropic receptors (IRs), 54 odorant receptors (ORs) and 53 gustatory receptors (GRs) were identified. InA. yamamai, 36 OBPs, 21 CSPs, 3 SNMPs, 30 IRs, 50 ORs and 54 GRs were identified. Phylogenetic analysis showed that the OBP, OR and GR genes were significantly expanded or contracted in the two silkmoths when compared to lepidopteran modelBombyx mori L., while the CSP genes were only expanded. The SNMP and IR genes were greatly conserved in the two silkmoths andB. mori. Most OBP, CSP, SNMP, IR and OR genes had the expression in the antennal transcriptome, but most GR genes showed no expression. This is the first study to characterise chemosensory genes of Saturniidae species in the genome and antennal transcriptome.

Remote Sensing Assessment and Modeling of the Spatial Dynamics of Tree Stand Disturbance after the Impact of Siberian Silk Moth (Dendrolimus sibiricus)

In this study, we have analyzed tree stand disturbance by hthe Siberian Silk Moth (Dendrolimus sibiricus Tschetverikov (Lepidoptera: Lasiocampidae)) in Central Siberia (Krasnoyarsk region, Russia) in 2015–2020. We considered two plots that experienced silk moth outbreaks in 2015–2018 and 2018–2020 and used satellite data (Terra/MODIS, Landsat/ETM/OLI), field forest inventory data, a meteorological data set, and a vegetation cover vector layer. Silk moth-disturbed areas were classified using NDVI, which was calculated for each 15-day period during the growing season (April–September). We obtained formalized descriptions of the temporal dynamics of the disturbed area. Next, we classified the degree of disturbance of the forest stand after the impact of the silk moth by the threshold method according to the ranges of NDVI anomalies. Based on the generalized data from the forest inventory, we performed a correlation analysis of the relationship between the main characteristics of forests and the classes of disturbance. Finally, using a series of regression equations, we described a procedure for predicting the degree of impact on the stand during the time of silk moth outbreaks in the dark-needle coniferous stands of Central Siberia.

Impact of Serratiopeptidase on Bleeding and Clotting Time at Therapeutic Dose

Serratiopeptidase is a proteolytic enzyme that was being used for decades as an anti-inflammatory agent. It was initially synthesized from the larval form of the silk moth. It is ubiquitously prescribed in combination with NSAIDs to relieve pain and inflammation. In addition to desired pharmacological activity, it has some other effects. One among which is fibrinolytic activity. Fibrin is an activated form of fibrinogen formed as a result of injury to mitigate the loss of blood. Inactive plasminogen activates plasmin which is a proteolytic enzyme. As its chemical nature, it solubilizes the fibrin at a specific time to prevent embolism. Serralysin being proteolytic in nature interacts with the fibrin and degrades it into degradation particles which lead to uncontrollable bleeding. This improves the chance of deviation in BT and CT in subjects from initial readings. This analytical study was conducted on 20 participants who are admitted to a public hospital with other ailments and their variations in BT and CT were recorded, analyzed, and represented in the form of charts.