Establishing superfine nanofibrils for robust polyelectrolyte artificial spider silk and powerful artificial muscles.

Spider silk exhibits an excellent combination of high strength and toughness, which originates from the hierarchical self-assembled structure of spidroin during fiber spinning. In this work, superfine nanofibrils are established in polyelectrolyte artificial spider silk by optimizing the flexibility of polymer chains, which exhibits combination of breaking strength and toughness ranging from 1.83 GPa and 238 MJ m-3 to 0.53 GPa and 700 MJ m-3, respectively. This is achieved by introducing ions to control the dissociation of polymer chains and evaporation-induced self-assembly under external stress. In addition, the artificial spider silk possesses thermally-driven supercontraction ability. This work provides inspiration for the design of high-performance fiber materials.

Sustainable appraisal of lipstick tree seeds (Bixa orellana)-based bixin natural orange colorant for green mordanted silk fabrics and wool yarns.

This research aims to optimize the silk and wool dyeing process using natural dyes from Bixa orellana (annatto) through response surface methodology. Central composite design experiments highlight the significant enhancement of color outcomes achieved through microwave treatment. For silk, the optimal conditions (80 °C for 40 min) with annatto extract yield a color strength (K/S) of 17.8588, while wool achieves a K/S of 7.5329. Introducing eco-friendly bio-mordants, such as pomegranate peel and red sumac tannins, enhances color strength. Pre-dyeing treatments with 2% red sumac, 1.5% pomegranate peel, and weld flower extracts for silk produce high color strength, with K/S values of 16.4063, 16.3784, and 12.1658, respectively. Post-dyeing, the K/S values increase to 40.1178, 17.4779, and 21.6494. Wool yarn exhibits similar improvements, with pre-dyeing K/S values of 13.1353, 13.5060, and 16.3232, escalating to 10.5892, 15.3141, and 23.4850 post-dyeing. Furthermore, this research underscores improved colorfastness properties, including notable enhancements in light, wash, and rubbing fastness for both silk fabric and wool yarn. These findings underscore the efficacy of the proposed sustainable dyeing methods, offering valuable insights for eco-friendly textile production.

Intelligent perceptual textiles based on ionic-conductive and strong silk fibers.

Endowing textiles with perceptual function, similar to human skin, is crucial for the development of next-generation smart wearables. To date, the creation of perceptual textiles capable of sensing potential dangers and accurately pinpointing finger touch remains elusive. In this study, we present the design and fabrication of intelligent perceptual textiles capable of electrically responding to external dangers and precisely detecting human touch, based on conductive silk fibroin-based ionic hydrogel (SIH) fibers. These fibers possess excellent fracture strength (55 MPa), extensibility (530%), stable and good conductivity (0.45 S·m-1) due to oriented structures and ionic incorporation. We fabricated SIH fiber-based protective textiles that can respond to fire, water, and sharp objects, protecting robots from potential injuries. Additionally, we designed perceptual textiles that can specifically pinpoint finger touch, serving as convenient human-machine interfaces. Our work sheds new light on the design of next-generation smart wearables and the reshaping of human-machine interfaces.

Membrane-based inverse-transition purification facilitates a rapid isolation of various spider-silk elastin-like polypeptide fusion proteins from extracts of transgenic tobacco.

Plants can produce complex pharmaceutical and technical proteins. Spider silk proteins are one example of the latter and can be used, for example, as compounds for high-performance textiles or wound dressings. If genetically fused to elastin-like polypeptides (ELPs), the silk proteins can be reversibly precipitated from clarified plant extracts at moderate temperatures of ~ 30 °C together with salt concentrations > 1.5 M, which simplifies purification and thus reduces costs. However, the technologies developed around this mechanism rely on a repeated cycling between soluble and aggregated state to remove plant host cell impurities, which increase process time and buffer consumption. Additionally, ELPs are difficult to detect using conventional staining methods, which hinders the analysis of unit operation performance and process development. Here, we have first developed a surface plasmon resonance (SPR) spectroscopy-based assay to quantity ELP fusion proteins. Then we tested different filters to prepare clarified plant extract with > 50% recovery of spider silk ELP fusion proteins. Finally, we established a membrane-based purification method that does not require cycling between soluble and aggregated ELP state but operates similar to an ultrafiltration/diafiltration device. Using a data-driven design of experiments (DoE) approach to characterize the system of reversible ELP precipitation we found that membranes with pore sizes up to 1.2 µm and concentrations of 2-3 M sodium chloride facilitate step a recovery close to 100% and purities of > 90%. The system can thus be useful for the purification of ELP-tagged proteins produced in plants and other hosts.

Chemical species recognition in an adaptive radiation of Hawaiian Tetragnatha spiders (Araneae: Tetragnathidae).

Studies of adaptive radiations have played a central role in our understanding of reproductive isolation. Yet the focus has been on human-biased visual and auditory signals, leaving gaps in our knowledge of other modalities. To date, studies on chemical signals in adaptive radiations have focused on systems with multimodal signalling, making it difficult to isolate the role chemicals play in reproductive isolation. In this study we examine the use of chemical signals in the species recognition and adaptive radiation of Hawaiian Tetragnatha spiders by focusing on entire communities of co-occurring species, and conducting behavioural assays in conjunction with chemical analysis of their silks using gas chromatography-mass spectrometry. Male spiders significantly preferred the silk extracts of conspecific mates over those of sympatric heterospecifics. The compounds found in the silk extracts, long chain alkyl methyl ethers, were remarkably species-specific in the combination and quantity. The differences in the profile were greatest between co-occurring species and between closely related sibling species. Lastly, there were significant differences in the chemical profile between two populations of a particular species. These findings provide key insights into the role chemical signals play in the attainment and maintenance of reproductive barriers between closely related co-occurring species.

CHARACTERISATION OF RESORBABLE AND NON- RESORBABLE SUTURES COATED WITH Punica granatum SEED EXTRACT: AN in vitro PILOT STUDY.

BACKGROUND: In order to achieve uneventful and rapid healing of the tissues, a suture material should be biocompatible, easy to handle, sterile, and have good and uniform tensile strength. Hence, in the present study, characterization of the suture materials was done through a novel green chemistry approach using Punica granatum seed extract. MATERIALS AND METHODS: Ethanolic extract of P. granatum seed was prepared by dissolving 25 g of P. granatum seed powder with 100 mL of ethanol. The obtained extract was coated in silk and Vicryl suture material and was tested for its surface morphology (SEM), tensile strength, anti-microbial activity, biocompatibility, and wound healing potential. RESULTS: Silk and Vicryl sutures coated with P. granatum seed extract showed the uniform coating and deposition of extract with sustaining integrity. Vicryl suture coated with the extract had good tensile strength and antimicrobial activity. The in vitro scratch assay and biocompatibility test showed that the P. granatum seed extract had excellent wound healing potential and can be used without any effect on the viability of the normal cells. CONCLUSION: Within the limitations of the study it can be concluded that P. granatum seed extract coated Vicryl sutures had good tensile strength and anti-microbial activity. P. granatum seed extract also showed excellent biocompatibility and wound healing potential.

Dyeing of Tussah Silk with Reactive Dyes: Dye Selection, Dyeing Conditions, Dye Fixation Characteristics, and Comparison with Mulberry Silk.

Tussah silk is one of the most widely used wild silks. It is usually dyed with acid dyes, despite the shortcoming of poor wet fastness. Reactive dyeing is a good solution to this problem. In our work, sulfatoethylsulfone (SES), sulfatoethylsulfone/monochlorotriazine (SES/MCT), monochlorotriazine (MCT), and bis(monochlorotriazine) (Bis(MCT)) dyes were used to dye tussah silk. All of these dyes showed lower exhaustion and fixation on tussah silk than on mulberry silk under alkaline conditions. Among them, SES dyes were more applicable, with a fixation of 70-85% (at 4%owf dye) at 90 °C when using sodium bicarbonate as an alkali. SES dyes also showed a rapid fixation speed. The dyeing of tussah silk required lower sodium bicarbonate dosage, the use of more neutral electrolytes, and a higher dye quantity to achieve deep effects compared to mulberry silk. Dyed tussah silk displayed lower apparent color depth and brilliance than dyed mulberry silk. The neutral boiling dyeing of tussah silk with SES dyes exhibited higher exhaustion, higher fixation (82-92% at 4%owf dye), and a slower fixation speed compared with alkaline dyeing. Furthermore, in this dyeing method, SES dyes showed higher and more efficient fixation on tussah silk than on mulberry silk. All dyed tussah silk had excellent color fastness to soaping.

Integrated transcriptome and proteome analysis reveals the unique molecular features and nutritional components on the muscles in Chinese Taihe black-bone silky fowl chicken.

The Taihe Black-Bone silky fowl chicken (BB-sfc) is a renowned dietary and medicinal chicken globally recognized for its high nutritional and medicinal value. Compared to the local Black-Bone black-feathered chicken (BB-bfc), the Taihe silky fowl chicken has higher levels of amino acids, trace elements, and unsaturated fatty acids in their muscles, which offer anti-aging, anti-cancer, and immune enhancing benefits. Despite this, the unique nutritional components, genes, and proteins in Taihe silky fowl chicken muscles are largely unknown. Therefore, we performed a comprehensive transcriptome and proteome analysis of muscle development between BB-sfc and BB-bfc chickens using RNA-Seq and TMT-based quantitative proteomics methods. RNA-Seq analysis identified 286 up-regulated genes and 190 down-regulated genes in BB-sfc chickens, with oxidoreductase activity and electron transfer activity enriched in up-regulated genes, and phospholipid homeostasis and cholesterol transporter activity enriched in down-regulated genes. Proteome analysis revealed 186 significantly increased and 287 significantly decreased proteins in Taihe BB-sfc chicken muscles, primarily affecting mitochondrial function and oxidative phosphorylation, crucial for enhancing muscle antioxidant capacity. Integrated transcriptome and proteome analysis identified 6 overlapped up-regulated genes and 8 overlapped down-regulated genes in Taihe silky fowl chicken, related to improved muscle antioxidant status. Taken together, this research provides a comprehensive database of gene expression and protein information in Taihe Black-Bone silky fowl chicken muscles, aiding in fully exploring their unique economic value in the future.

Taxonomy and feeding of Forcipomyia (Microhelea) fuliginosa Meigen and Forcipomyia (Microhelea) esakiana Tokunaga (Diptera: Ceratopogonidae) on Antheraea mylitta Drury (Lepidoptera: Saturniidae).

Taxonomic equivocality and complexity exist in the two species of Ceratopogonids, Forcipomyia (Microhelea) fuliginosa Meigen and Forcipomyia (Microhelea) esakiana Tokunaga. Incongruencies and inaccuracies in species identification restrict further biological and ecological studies on the host-ectoparasite association. Preferential landing and hemolymphophagy of F. fuliginosa and F. esakiana on Antheraea mylitta Drury larva were studied under field conditions. The silkworm A. mylitta is reared in the tasar sericulture industry, contributing 1466 metric tons (202122) of indigenous raw silk in India. Ectoparasitic behavior of the biting midges, F. fuliginosa, and F. esakiana is an increasing threat to the silkworm, necessitating proper identification. Intra and inter-variations of these two closely related species have been stated. Morphological-based identification of these species has been substantiated with COX1 molecular data. A Bayesian-modeled approach to reconstruct the dendrogram of the two species based on the COX1 sequences generated has been presented along with the referred sequences of F. fuliginosa from Genebank. The species F. esakiana is being reported for the first time from India, along with its ectoparasitic hemolymphophagous nature. The role of these insectivorous species in transmitting pathogens to the larvae of tasar silk needs further investigation.

Braided silk sutures coated with photoreduced silver nanoparticles for eradicating Staphylococcus aureus and Streptococcus mutans infections.

BACKGROUND: Infections resulting from surgical procedures and wound closures continue to pose significant challenges in healthcare settings. To address this issue, the investigators have developed antibacterial non-resorbable braided silk sutures using in situ deposited silver nanoparticles (AgNPs) and investigated their efficacy in eradicating Staphylococcus aureus and Streptococcus mutans infections. METHODS: The braided silk sutures were modified through a simple and efficient in situ photoreduction method, resulting in the uniform distribution of AgNPs along the suture surface. The synthesized AgNPs were characterized using scanning electron microscopy (SEM), dynamic light scattering analysis (DLS) and Fourier Transform Infrared Spectroscopy analysis (FTIR) confirming their successful integration onto the silk sutures. The antibacterial activity of the nanoparticle coated sutures were compared and evaluated with non-coated braided silk sutures through in vitro assays against both S. aureus and S. mutans. RESULTS: The surface and cross-sectional analysis of the treated sutures revealed a uniform and homogeneous distribution of silver particles achieved through the photoreduction of silver solution. This observation confirms the successful coating of silver nanoparticles (AgNPs) on the sutures. The antimicrobial studies conducted, demonstrated significant reductions in bacterial colonies when exposed to the silver nanoparticle-coated sutures. Notably, the width of the inhibition zone surrounding the coated sutures remained consistently wide and stable for duration up to 7 days. This sustained and robust inhibitory effect against gram-positive bacteria, specifically S. aureus and S. mutans, serves as strong evidence of the antibacterial efficacy of the coated sutures. CONCLUSION: The coating of silk sutures with AgNPs provided a significant and effective antibacterial capacity to the surgical sutures, with this activity being sustained for a period of 7 days. This suggests that AgNPs-in situ photoreduction deposited sutures have the potential to effectively manage S. aureus and S. mutans infections.

Tyrosinase-Modified UHMW SELP Polymers as Wet and Underwater Adhesives to Achieve Multi-interface Adhesion.

The presence of a hydration layer in humid and underwater environments challenges adhesive-substrate interactions and prevents effective bonding, which has become a significant obstacle to the development of adhesives in the industrial and biomedical fields. In this study, ultrahigh-molecular-weight (UHMW) silk-elastin-like proteins (SELP) with 3,4-dihydroxyphenylalanine (DOPA) converted from tyrosine residues by tyrosinase exhibited excellent adhesive properties on different interfaces, such as glass, aluminum, wood, polypropylene sheets, and pigskin, under both dry and wet conditions. Additionally, by incorporating trace amounts of cross-linking agents like Fe3+, NaIO4, and tris(hydroxymethyl) phosphine (THP), the mussel-inspired adhesives maintained a stable and excellent adhesion, broadening the conditions of application. Notably, the UHMW SELP adhesive exhibited remarkable underwater adhesion properties with a shear strength of 0.83 ± 0.17 MPa on glass. It also demonstrated good adhesion to biological tissues including the kidney, liver, heart, and lungs. In vitro cytocompatibility testing using L929 cells showed minimal toxicity, highlighting its potential application in the biomedical field. The sustainable, cytocompatible, cost-effective, and highly efficient adhesive provides valuable insights for the design and development of a new protein-based underwater adhesive for medical application.

Molecular mechanism analysis of apoptosis induced by silk fibroin peptides.

Silk fibroin derived from silkworm cocoons exhibits excellent mechanical properties, good biocompatibility, and low immunogenicity. Previous studies showed that silk fibroin had an inhibitory effect on cells, suppressing proliferation and inducing apoptosis. However, the source of the toxicity and the mechanism of apoptosis induction are still unclear. In this study, we hypothesized that the toxicity of silk fibroin might originate from the crystalline region of the heavy chain of silk fibroin. We then verified the hypothesis and the specific induction mechanism. A target peptide segment was obtained from α-chymotrypsin. The potentially toxic mixture of silk fibroin peptides (SFPs) was separated by ion exchange, and the toxicity was tested by an MTT assay. The results showed that SFPs obtained after 4 h of enzymatic hydrolysis had significant cytotoxicity, and SFPs with isoelectric points of 4.0-6.8 (SFPα II) had a significant inhibitory effect on cell growth. LC-MS/MS analysis showed that SFPα II contained a large number of glycine-rich and alanine-rich repetitive sequence polypeptides from the heavy-chain crystallization region. A series of experiments showed that SFPα II mediated cell death through the apoptotic pathway by decreasing the expression of Bcl-2 protein and increasing the expression of Bax protein. SFPα II mainly affected the p53 pathway and the AMPK signaling pathway in HepG2 cells. SFPα II may indirectly increase the expression of Cers2 by inhibiting the phosphorylation of EGFR, which activated apoptotic signaling in the cellular mitochondrial pathway and inhibited the Akt/NF-κB pathway by increasing the expression of PPP2R2A.

Harvesting Silk Fibers from Plodia interpunctella: Role of Environmental Rearing Conditions in Fiber Production and Properties.

Silk fibers are produced by a wide variety of insects. The silkworm Bombyx mori (Bombyx) was domesticated because the physical properties of its silk fibers were amenable to the production of fine textiles. Subsequently, engineers have regenerated silk fibroin to form biomaterials. The monocular focus on Bombyx silk has underutilized the expanse of diverse silk proteins produced by more than 100,000 other arthropods. This vast array of silk fibers could be utilized for biomedical engineering challenges if sufficient rearing and purification processes are developed. Herein, we show that the moth, Plodia interpunctella (Plodia), represents an alternative silk source that is easily reared in highly regulated culture environments allowing for greater consistency in the silk produced. We controlled the temperature, resource availability (larvae/gram diet), and population density (larvae/mL) with the goal of increasing silk fiber production and improving homogeneity in Plodia silk proteins. We determined that higher temperatures accelerated insect growth and reduced life cycle length. Furthermore, we established initial protocols for the production of Plodia silk with optimal silk production occurring at 24 °C, with a resource availability of 10 larvae/gram and a population density of 0.72 larvae/mL. Population density was shown to be the most prominent driving force of Plodia silk mat formation among the three parameters assessed. Future work will need to link gene expression, protein production and purification, and resulting mechanical properties as a function of environmental cues to further transition Plodia silk into regenerated silk fibroin biomaterials.

Genipin-Cross-Linked Silk Fibroin/Alginate Dialdehyde Hydrogel with Tunable Gelation Kinetics, Degradability, and Mechanical Properties: A Potential Candidate for Tissue Regeneration.

Genipin-cross-linked silk fibroin (SF) hydrogel is considered to be biocompatible and mechanically robust. However, its use remains a challenge for in situ forming applications due to its prolonged gelation process. In our attempt to facilitate the in situ fabrication of a genipin-mediated SF hydrogel, alginate dialdehyde (ADA) was utilized as a reinforcement template. Here, SF/ADA-based hydrogels with different compositions were synthesized covalently and ionically. Incorporating ADA into the SF hydrogel increased pore size (44.66-174.66 µm), porosity (61.59-80.40%), and the equilibrium swelling degree (7.60-30.17). Moreover, a wide range of storage modulus and compressive modulus were obtained by adjusting the proportions of SF and ADA networks within the hydrogel. The in vitro cell analysis using preosteoblast cells (MC3T3-E1) demonstrated the cytocompatibility of all hydrogels. Overall, the covalently and ionically cross-linked SF/ADA hydrogel represents a promising solution for in situ forming hydrogels for applications in tissue regeneration.

Making Yellows Last with Nitric Acid: Exploring Colour Permanence in Art and Knowledge, 1600-1850.

Nitric acid became commonly available in the seventeenth century. Since then, it held the interest of chemists, especially those interested in the art of dyeing. Due to what is now called the xanthoproteic reaction (from Greek xanthós, describing shades of yellow), nitric acid produces a stable yellow colouration in proteinaceous materials, such as wool, silk, and bones. The chemistry of this reaction is well understood today. Less well-known is that it held the interest of dyers in the past. Dyers considered the ability of nitric acid to give a yellow colour to certain substances a solution to giving materials a durable, that is, a lasting, yellow colour. Yellow, indeed, posed a problem in the art of dyeing. Before the discovery of synthetic dyes in the mid-nineteenth century, there were no organic yellow dyes with long-term colour stability. Using historical dyeing manuals and chemistry treatises, combined with our practical engagement with the processes they describe, this paper traces how, between the seventeenth and nineteenth centuries, dyers explored nitric acid while examining the durability of yellow colourations. Based on these explorations into nitric acid, the chemical arts developed theories about the nature of colour, and about the causes for its relative permanence.

Tuning the Biodegradation Rate of Silk Materials via Embedded Enzymes.

Conventional thinking when designing biodegradable materials and devices is to tune the intrinsic properties and morphological features of the material to regulate their degradation rate, modulating traditional factors such as molecular weight and crystallinity. Since regenerated silk protein can be directly thermoplastically molded to generate robust dense silk plastic-like materials, this approach afforded a new tool to control silk degradation by enabling the mixing of a silk-degrading protease into bulk silk material prior to thermoplastic processing. Here we demonstrate the preparation of these silk-based devices with embedded silk-degrading protease to modulate the degradation based on the internal presence of the enzyme to support silk degradation, as opposed to the traditional surface degradation for silk materials. The degradability of these silk devices with and without embedded protease XIV was assessed both in vitro and in vivo. Ultimately, this new process approach provides direct control of the degradation lifetime of the devices, empowered through internal digestion via water-activated proteases entrained and stabilized during the thermoplastic process.

Polydopamine-Coated Silk Fiber with Controllable Length for Enhanced Hemostatic Application.

The development of highly effective hemostatic materials with high biocompatibility and outstanding performance is vital to the field of biomaterials. In this study, we develop a hemostatic fiber material that exhibits high biocompatibility and excellent performance. By incorporating polydopamine (PDA) into the alkaline treatment of silk fibroin (SF), we achieve PDA-coated SF fibers with lengths that can be controlled by the alkaline concentration. The PDA coating significantly enhances the hemostatic ability of the silk fibers and exhibits superior performance in both in vitro and ex vivo experiments. By performing animal studies involving a mouse liver puncture model and a femoral vein incision model, we demonstrate the remarkable hemostatic capability of the PDA-coated SF fibers, as evidenced by the lower blood loss compared to that of a commercial hemostat powder. These findings highlight the potential of applying a PDA-assisted alkaline treatment to SF fibers to efficiently create hemostatic fibers with controllable lengths, which would be promising candidates for clinical hemostatic applications.

A silk-based hydrogel containing dexamethasone and lipoic acid microcrystals for local delivery to the inner ear.

Local drug delivery has been exploited recently to treat hearing loss, as this method can both bypass the blood-labyrinth barrier and provide sustained drug release. Combined drug microcrystals (MCs) offer additional advantages for sensorineural hearing loss treatment via intratympanic (IT) injection due to their shape effect and combination strategy. In this study, to endow viscous effects of hydrogels, nonspherical dexamethasone (DEX) and lipoic acid (LA) MCs were incorporated into silk fibroin (SF) hydrogels, which were subsequently administered to the tympanic cavity to investigate their pharmaceutical properties. First, we prepared DEX and LA MCs by a traditional precipitation technique followed by SF hydrogel incorporation (SF+DEX+LA). After characterization of the physicochemical features, including morphology, rheology, and dissolution, both a suspension of combined DEX and LA MCs (DEX+LA) and SF+DEX+LA were administered to guinea pigs by IT injection, after which the pharmacokinetics, biodegradation and biocompatibility were evaluated. To our surprise, compared to the DEX+LA group, the pharmacokinetics of the SF+DEX+LA hydrogel group did not improve significantly, which may be ascribed to their nonspherical shape and deposition effects of the drugs MCs. The cochlear tissue in each group displayed good morphology, with no obvious inflammatory reactions. This combined MC suspension has the clear advantages of no vehicle, easy scale-up preparation, and good biocompatibility and outcomes, which paves the way for practical treatment of hearing loss via local drug delivery.

Supramolecular coordination platinum metallacycle-based multilevel wound dressing for bacteria sensing and wound healing.

The exploitation of novel wound healing methods with real-time infection sensing and high spatiotemporal precision is highly important for human health. Pt-based metal-organic cycles/cages (MOCs) have been employed as multifunctional antibacterial agents due to their superior Pt-related therapeutic efficiency, various functional subunits and specific geometries. However, how to rationally apply these nanoscale MOCs on the macroscale with controllable therapeutic output is still challenging. Here, a centimeter-scale Pt MOC film was constructed via multistage assembly and subsequently coated on a N,N'-dimethylated dipyridinium thiazolo[5,4-d]thiazole (MPT)-stained silk fabric to form a smart wound dressing for bacterial sensing and wound healing. The MPT on silk fabric could be used to monitor wound infection in real-time through the bacteria-mediated reduction of MPT to its radical form via a color change. The MPT radical also exhibited an excellent photothermal effect under 660 nm light irradiation, which could not only be applied for photothermal therapy but also induce the disassembly of the Pt MOC film suprastructure. The highly ordered Pt MOC film suprastructure exhibited high biosafety, while it also showed improved antibacterial efficiency after thermally induced disassembly. In vitro and in vivo studies revealed that the combination of the Pt MOC film and MPT-stained silk can provide real-time information on wound infection for timely treatment through noninvasive techniques. This study paves the way for bacterial sensing and wound healing with centimeter-scale metal-organic materials.

Insecticidal Effects of Transgenic Maize Bt-Cry1Ab, Bt-Vip3Aa, and Bt-Cry1Ab+Vip3Aa against the Oriental Armyworm, Mythimna separata (Walker) in Southwest China.

The oriental armyworm, Mythimna separata (Walker), an important migratory pest of maize and wheat, is posing a severe threat to maize production in Asian countries. As source areas of spring-summer emigratory populations, the control of M. separata in southwestern China is of great significance for East Asian maize production. To assess the toxicity of Bt maize against the pest, bioassays of Bt-(Cry1Ab+Vip3Aa) maize (event DBN3601T), Bt-Cry1Ab maize (event DBN9936), and Bt-Vip3Aa maize (event DBN9501) were conducted in Yunnan province of southwest China. There were significant differences in insecticidal activity between the three Bt maize events, and DBN3601T presented the highest insecticidal role. The results also indicated that the insecticidal effect of various Bt maize tissues took an order in leaf > kernel > silk, which is highly consistent with the expression amounts of Bt insecticidal protein in leaf (69.69 ± 1.18 µg/g), kernel (11.69 ± 0.75 µg/g), and silk (7.32 ± 0.31 µg/g). In field trials, all larval population densities, plant damage rates, and leaf damage levels of DBN3601T maize were significantly lower than the conventional maize. This research indicated that the DBN3601T event had a high control efficiency against M. separata and could be deployed in southwest China for the management of M. separata.