Preparation of Ag@3D-TiO2 Scaffolds and Determination of its Antimicrobial Properties and Osteogenesis-promoting Ability.

OBJECTIVES: The micro-nano structure of 3D-printed porous titanium (Ti) alloy with excellent performance in avoiding stress shielding and promoting bone tissue differentiation provides a new opportunity for the development of bone implants, but it necessitates higher requirements for bone tissue differentiation and the antibacterial properties of bone implants in clinical practice. METHODS: This study investigated the preparation, antimicrobial properties, and osteogenesis-promoting ability of the 3D printed porous Ti alloy anodic oxidized Ag-carrying (Ag@3D-TiO2) scaffolds. The 3D printed porous Ti alloy (3D-Ti), anodized 3D printed porous Ti alloy (3D-TiO2), and Ag@3D-TiO2 scaffolds were synthesized using electron beam melting. The antimicrobial properties of the scaffolds were examined using antibacterial tests and their cytocompatibility was assessed using a cell proliferation assay and acridine orange/ethidium bromide (AO/EB) staining. In vitro cellular assays were used to investigate the effects of the scaffold microstructural features on cell activity, proliferation, and osteogenesis-related genes and proteins. In vivo animal experiments were used to evaluate the anti-inflammatory and osteogenesis-promoting abilities of the scaffolds. RESULTS: The Ag@3D-TiO2 scaffolds exhibited sustained anti-microbial activity over time, enhanced cell proliferation, facilitated osteogenic differentiation, and increased extracellular matrix mineralization. In addition, alkaline phosphatase (ALP), collagen type I (COL-I), and osteocalcin (OCN)-related genes and proteins were upregulated. In vivo animal implantation experiments, the anti-inflammatory effect of the Ag@3D-TiO2 scaffolds were observed using histology, and a large amount of fibrous connective tissue was present around it; the Ag@3D-TiO2 scaffolds were more bio-compatible with the surrounding tissues compared with 3D-Ti and 3D-TiO2; a large amount of uniformly distributed neoplastic bone tissue existed in their pores, and the chronic systemic toxicity test showed that the 3D-Ti, 3D-TiO2, and Ag@3D-TiO2 scaffolds are biologically safe. CONCLUSION: The goal of this study was to create a scaffold that exhibits antimicrobial properties and can aid bone growth, making it highly suitable for use in bone tissue engineering.

Meteorin-like protein elevation post-exercise improved vascular inflammation among coronary artery disease patients by downregulating NLRP3 inflammasome activity.

BACKGROUND: Coronary artery disease (CAD) has become the most common cause of death worldwide. However, the negative effects of CAD are able to be alleviated via exercises, possibly via increased production of meteorin-like protein (Metrnl). In this study, we aim to evaluate the connection between Metrnl production during exercise with lowered CAD risk and severity. METHODS: Two age and gender-matched groups of 60 human patients, one with CAD, and one without were randomly recruited. The CAD group were subjected to continuous training exercises. Mice were exercised by using a treadmill, establishing an animal exercise model. ELISA was used to measure plasma Metrnl and inflammatory factors. To determine the impact of Metrnl on glucose metabolism, oxygen consumption and extracellular acid rates were taken for untreated, palmitic acid (PA)-treated, and PA+Metrnl co-treated human umbilical vein endothelial cells. Western blot was used to measure expression levels for the NLR family pyrin domain containing 3 inflammasome. RESULTS: CAD patients had lower Metrnl levels compared to non-CAD controls. Furthermore, higher Metrnl levels post-exercise were inversely associated with LDL, inflammatory cytokines, and CAD severity, as well as being positively associated with HDL. Metrnl was able to counteract against PA-induced HUVEC glucose metabolic dysfunction via reducing ROS production, which in turn lowered NLRP3 inflammasome expression, thereby serving as the basis behind the inverse correlation between Metrnl and inflammatory cytokines. CONCLUSIONS: Exercise was able to increase Metrnl production from skeletal muscle among CAD patients, and subsequently improve patient atherosclerosis via counteracting against endothelial metabolic dysfunction and pro-inflammatory activities.

[Application of flat-sided culture tubes during prenatal diagnosis].

OBJECTIVE: To assess the value of using flat-sided culture tubes for preparing chromosomes through chorionic villi (CV) and amniotic fluid (AF) cell cultures during prenatal diagnosis. METHODS: From February to March 2020, 157 CV samples and 147 AF samples subjected to prenatal diagnosis at the Maternal and Child Health Care Hospital of Guangxi Zhuang Autonomous Region were selected as the study subjects. For each sample, one flat-sided tube and one flask culture were set up by following the standard protocols. The methods were evaluated by comparing the cell growth, experimental process, quality of chromosome preparation and costs. RESULTS: The success rates for the culturing of CV and AF samples by the flat-sided culture tube method were 97.45% (153/157) and 97.96% (144/147), respectively. By contrast, the success rates for the conventional flask method were 98.72% (155/157) for CV and 98.64% (145/147) for AF samples. No significant difference was found between the two methods (P > 0.05). The average harvest time required by the flat-sided culture tube method was 8.45 days for CV and 9.43 days for AF cultures, whilst the average harvest time for conventional flask method was 9.05 days and 9.54 days, respectively. The flat-sided culture tube method for CV had required significantly shorter average harvest time than the conventional method (P < 0.001). No statistical significant difference was found in the average harvest time for AF by the two methods (P > 0.05). The conventional culturing method had required three containers with two sample transfers. By contrast, the flat-sided culture tube method was carried out in one tube without any sample transfer. The average total amount of medium used was 3.91 mL for each flat-sided culture tube and 6.26 mL for each conventional flask. CONCLUSION: The flat-sided culture tube method can provide a simple, cost-effective and error-reducing procedure for the CV and AF samples culture during prenatal diagnosis.

Antibacterial Structure Design of Porous Ti6Al4V by 3D Printing and Anodic Oxidation.

Titanium alloy Ti6Al4V is a commonly used bone implant material, primarily prepared as a porous material to better match the elastic modulus of human bone. However, titanium alloy is biologically inert and does not have antibacterial properties. At the same time, the porous structure with a large specific surface area also increases the risk of infection, leading to surgical failure. In this paper, we prepared three porous samples with different porosities of 60%, 75%, and 85%, respectively (for short, 3D-60, 3D-75, and 3D-85) using 3D printing technology and clarified the mechanical properties. Through tensile experiments, when the porosity was 60%, the compressive modulus was within the elastic modulus of human bone. Anodic oxidation technology carried out the surface modification of a 3D-printed porous titanium alloy with 60% porosity. Through change, the different voltages and times on the TiO2 oxide layer on the 3D-printed porous titanium alloy are different, and it reveals the growth mechanism of the TiO2 oxide layer on a 3D-printed unique titanium alloy. The surface hydrophilic and antibacterial properties of 3D-printed porous titanium alloy were significantly improved after modification by anodic oxidation.

Diversity of Wolbachia infection and its influence on mitochondrial DNA variation in the diamondback moth, Plutella xylostella.

Plutella xylostella is a pest that severely damages cruciferous vegetables worldwide and has been shown to be infected with the maternally inherited bacteria Wolbachia, with the main infected strain was plutWB1. In this study, we performed a large-scale global sampling of P. xylostella and amplified 3 mtDNA genes of P. xylostella and 6 Wolbachia genes to analyze the infection status, diversity of Wolbachia in P. xylostella, and its effect on mtDNA variation in P. xylostella. This study provides a conservative estimate of Wolbachia infection rates in P. xylostella, which was found to be 7% (104/1440). The ST 108 (plutWB1) was shared among butterfly species and the moth species P. xylostella, revealing that Wolbachia strain plutWB1 acquisition in P. xylostella may be through horizontal transmission. The Parafit analyses indicated a significant association between Wolbachia and Wolbachia-infected P. xylostella individuals, and individuals infected with plutWB1 tended to cluster in the basal positions of the phylogenetic tree based on the mtDNA data. Additionally, Wolbachia infections were associated with increased mtDNA polymorphism in the infected P. xylostella population. These data suggest that Wolbachia endosymbionts may have a potential effect on mtDNA variation of P. xylostella.

Phenotypic Spectrum of Trisomy 18 Mosaicism: a New Patient and Literature Review.

BACKGROUND: Trisomy 18 syndrome, also called Edwards syndrome, is the second most common autosomal trisomy after trisomy 21 that is caused by the presence of an extra copy of chromosome 18. Approximately 50% of infants with trisomy 18 cannot survive for more than 1 week and about 5 - 10% of children die within 1 year after birth. The aim of this study is to describe a 4-year-old female patient of mosaic trisomy 18 with normal prenatal ultrasound findings and maternal serum markers and to investigate the relationship between the percentage of trisomic cells and the major clinical phenotypes combined with other nine patients through a review of the literature. METHODS: The patient's peripheral blood was examined by cytogenetic G-banding technique. RESULTS: The cytogenetics results reported following the ISCN 2020 guideline as mos 47,XX,+18[87]/46,XX[13]. CONCLUSIONS: There is little correlation between various phenotypes of mosaic trisomy 18 and the percentage of trisomy cells in the patient's peripheral leukocytes. Although most of fetuses with mosaic trisomy 18 have abnormal ultrasound findings, it is necessary to highlight the possibility of normal findings during the pregnancy.

Oxygen stress on age-stage, two-sex life tables and transcriptomic response of diamondback moth (Plutella xylostella).

Elucidating the genetic basis of local adaption is one of the important tasks in evolutionary biology. The Qinghai-Tibet Plateau has the highest biodiversity for an extreme environment worldwide, and provides an ideal natural laboratory to study adaptive evolution. The diamondback moth (DBM), Plutella xylostella, is one of the most devastating pests of the global Brassica industry. A highly heterozygous genome of this pest has facilitated its adaptation to a variety of complex environments, and so provides an ideal model to study fast adaptation. We conducted a pilot study combining RNA-seq with an age-stage, two-sex life table to study the effects of oxygen deprivation on DBM. The developmental periods of all instars were significantly shorter in the hypoxic environment. We compared the transcriptomes of DBM from Fuzhou, Fujian (low-altitude) and Lhasa, Tibet (high-altitude) under hypoxia treatment in a hypoxic chamber. Some DEGs are enriched in pathways associated with DNA replication, such as DNA repair, nucleotide excision repair, base excision repair, mismatch repair and homologous recombination. The pathways with significant changes were associated with metabolism process and cell development. Thus, we assumed that insects could adapt to different environments by regulating their metabolism. Our findings indicated that although adaptive mechanisms to hypoxia in different DBM strains could be similar, DBM individuals from Tibet had superior tolerance to hypoxia compared with those of Fuzhou. Local adaptation of the Tibetan colony was assumed to be responsible for this difference. Our research suggests novel mechanisms of insect responses to hypoxia stress.

Facile construction of Z-scheme AgCl/Bi3TaO7 photocatalysts for effective removal of tetracycline under visible-light irradiation.

A string of AgCl/Bi3TaO7 two-component composite was synthesized by hydrothermal and deposition-precipitation process initially. The photocatalytic activities of mixed-phase AgCl/Bi3TaO7 were evaluated toward the decomposition of tetracycline (TC). Among these as-prepared materials, AgCl/Bi3TaO7 nanocomposites when the molar ratio of baked materials between AgCl and Bi3TaO7 was 1:5 presented the optimal photocatalytic quantum efficiency for TC dissociation (86.82%) with visible-light exposure, which was 1.69 and 2.38 folders higher than that of single Bi3TaO7 and AgCl, respectively. What is more, it illustrated that the photo-generated carriers were markedly isolated on account of the formation of heterojunction confirmed by EIS analysis. Meanwhile, radical trapping experiments implied that the photo-induced holes (h+), hydroxyl radical (·OH), and superoxide radical (·O2-) were the major active species. The escalated photocatalytic activity could be ascribed to the unique construction of Z-scheme AgCl/Bi3TaO7 heterojunction, which could expedite charge separation and transmission, cement light absorption capability and retain the strong redox ability of photo-generated electrons and holes. Our finding suggests that AgCl/Bi3TaO7 nanocomposites possess great potential for photocatalytic oxidation of residual TC in the wastewater effluents and the reported strategy can contribute to the development of novel high-performance photocatalyst.

Functional Characterization of the Ryanodine Receptor Gene in Diaphorina citri.

The Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae) is a major citrus pest spread around the world. It is also a vector of the bacterium 'Candidatus Liberibacter asiaticus', considered the cause of the fatal citrus disease huanglongbing (HLB). Insect ryanodine receptors (RyRs) are the primary target sites of diamide insecticides. In this study, full-length RyR cDNA from D. citri (named DcRyR) was isolated and identified. The 15,393 bp long open reading frame of DcRyR encoded a 5130 amino acid protein with a calculated molecular weight of 580,830 kDa. This protein had a high sequence identity (76-79%) with other insect homologs and a low sequence identity (43-46%) with mammals. An MIR domain, two RIH domains, three SPRY domains, four RyR repeat domains, an RIH-associated domain at the N-terminus, two consensus calcium-binding EF-hands, and six transmembrane domains were among the characteristics that DcRyR shared with insect and vertebrate RyRs. In expression analysis, the DcRyR gene displayed transcript abundance in all tissues and developmental stages as well as gene-differential and stage-specific patterns. In addition, diagnostic PCR experiments revealed that DcRyR had three potential alternative splice variants and that splicing events might have contributed to the various functions of DcRyR. However, diamide resistance-related amino acid residue mutations I4790M/K and G4946E were not found in DcRyR. These results can serve as the basis for further investigation into the target-based diamide pesticide resistance of D. citri.

[Comparison of performance of two prenatal diagnostic techniques for the detection of chromosomal mosaicisms in amniocytes].

OBJECTIVE: To assess the value of chromosomal karyotyping analysis and single nucleotide polymorphism-based microarray (SNP-array) for the detection of chromosomal mosaicisms in amniotic fluid samples. METHODS: Seventy four pregnant women with fetal mosaicisms detected by both methods were retrospectively analyzed. RESULTS: Among the 74 mosaicisms, 12 were pseudo and 62 were true mosaicisms, which included 1 Robertsonian translocation, 3 deletions, 4 supernumerary markers, 19 autosomal aneuploidy mosaicisms, 30 sex chromosome aneuploidy mosaicisms and 5 isometric chromosome mosaicisms. CONCLUSION: Chromosome karyotyping analysis and SNP-array have their own advantages and limitations for the diagnosis of mosaicisms. When the two methods have yielded inconsistent results, fluorescence in situ hybridization may be used for further verification.

Culture-dependent and culture-independent methods reveal microbe-clay mineral interactions by dissimilatory iron-reducing bacteria in an integral oilfield.

Fe(III) may be reasonably considered as one of the most important electron acceptors in petroleum reservoir ecosystems. The microbial mineralization of clay minerals, especially montmorillonite, is also of great significance to the exploration of petroleum and gas reservoirs. The bioreduction mechanisms of iron-poor minerals in petroleum reservoirs have been poorly investigated. This study investigated the bioreduction of montmorillonite by dissimilatory iron-reducing bacteria (DIRB) in petroleum reservoirs based on culture-independent and culture-dependent methods. Microbial diversity analysis revealed that Halolactibacillus, Bacillus, Alkaliphilus, Shewanella, Clostridium, and Pseudomonas were the key genera involved in the bioreduction of Fe(III). Through the traditional culture-dependent method, most of the key genera were isolated from the samples collected from petroleum reservoirs. Traditional culture-dependent methods can be used to reveal the metabolic characteristics of microorganisms (such as iron-reduction efficiency) to further elucidate the roles of different species (B. subtilis and B. alkalitelluris) in the environment. Moreover, many species with high iron-reduction efficiencies and relatively low abundances in the samples, such as Tessaracoccus and Flaviflexus, were isolated from petroleum reservoirs for the first time. The combination of culture-dependent and culture-independent methods can be used to further the understanding of the microbial communities and the metabolic characteristics of DIRB in petroleum reservoirs. Structural alterations that occurred during the interactions of microorganisms and montmorillonite were revealed through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRD). The physical and chemical analysis results demonstrated that microorganisms from petroleum reservoirs can dissolve iron-poor montmorillonite and promote the release of interlayer water. The secondary minerals illite and clinoptilolite were observed in bioreduced smectite. The formation of secondary minerals was closely related to the dissolution degrees of minerals based on iron reduction.

Ofloxacin-loaded HMPB NPs for Klebsiella pneumoniae eradication in the surgical wound with the combination of PTT.

Klebsiella pneumoniae (K. pneumoniae) is a common bacterium whose drug-resistant can cause surgical failures and incurable infections in hospital patients. Thus, how to reverse or delay the resistance induction has become a great challenge for development antiresistant drug. Recently, the combination of nanomaterial-loaded antibiotics with photothermal therapy showed the efficient antibacteria ability under a low dosage of antibiotics. In this study, a nanocomposite of HMPB NPs with inherent photothermal therapy capability was used to eradicate K. pneumoniae after loading with Ofloxacin, an antibiotic against K. pneumoniae in vitro and in vivo. The nanocomplexes named as Ofloxacin@HMPB@HA NPs showed a higher effect against K. pneumoniae by destroying cell integrity and inducing ATP leakage with the assistance of laser irradiation, compared with sole Ofloxacin@HMPB@HA NPs or laser irradiation. Surgical wound infection assay further demonstrated the efficient killing K. pneumoniae and promoting the formation of new tissues, as well, which was reflected by the rapid healing of surgical wound. In summary, these results indicate the great potential of this combinational tactic based on Ofloxacin@HMPB@HA NPs for preventing the failure caused by K. pneumoniae infection.

Effect of the Addition of Steel Fibers on the Bonding Interface and Tensile Properties of Explosion-Welded 2A12 Aluminum Alloy and SS-304 Steel.

First of all, the explosion-welding method was adopted to prepare steel fiber-reinforced steel-aluminum composite plates. Secondly, the smooth particle hydrodynamic (SPH) method was used to investigate the effect of introducing steel fibers to a vortex region created at the bonding interface of the steel-aluminum composite plate. Thirdly, the following conclusions were drawn through an analysis of the vortex region with the assistance of scanning electron microscopy and energy-dispersive X-ray spectroscopy. A brittle intermetallic compound FeAl was produced in the vortex region in an environment characterized by high temperature, high pressure, and high strain rate, resulting in cracks, holes and pores. In addition, the hardness of the vortex area was less than the estimated value, which is mainly because the main element in the vortex area was 2A12 aluminum with low hardness, and there were cracks, holes, pores and other defects that caused hardness reduction. Although the addition of steel fibers caused defects at the bond interface, the addition of steel fibers was effective in improving the tensile resistance performance of steel-aluminum composite panels to a certain extent. In addition, the larger the fiber diameter, the more significant the increase in tensile resistance.

Styphnolobium japonicum (L.) Schott Flower Extract Alleviates Oxidative Stress and Inflammatory Factors in the Adjuvant-Induced Arthritis Rat Model.

INTRODUCTION: This research was to evaluate the beneficial effects of Styphnolobium japonicum (L.) Schott flower extract (SJF) on the adjuvant-induced arthritis rat model. METHODS: Arthritis was evoked by injection of complete Freund's adjuvant (CFA) in the hind paw. SJF (150 or 300 mg/kg/day) or Celecoxib (5 mg/kg/day) were administered intragastrically from the 0th day to the 28th day. The arthritis symptoms (paw edema, arthritic scores, mechanical hyperalgesia, and thermal hyperalgesia), inflammation biomarkers (RT and CRP), related enzymes (MMP1 and MMP13), oxidative stress markers (CAT, SOD, GPx, and MDA), and inflammatory cytokines (IL-6, IFN-γ, TNF-α, and IL-1ß) of SJF-treated CFA rats were evaluated. RESULTS: CFA rats exhibited severe arthritis symptoms, increased oxidative stress, and inflammatory cytokines. Interestingly, SJF treatment relieving arthritis symptoms and restored body weight gain compared with those in the CFA group. SJF treatment decreased the levels of CRP, RF, MMP1, and MMP13 in the CFA group. Besides, SJF treatment increased the activities of antioxidant enzymes and decreased the MDA content and inflammatory cytokines compared with those in the CFA group. Moreover, SJF could increase the mRNA expression of GPx-1 and CAT and inhibit the mRNA expression of IL-6 and TNF-α in the ankle tissue of CFA rats.

Molecular and pharmacological characterization of biogenic amine receptors from the diamondback moth, Plutella xylostella.

BACKGROUD: Insect biogenic amines play important roles in mediating behavioral and physiological processes. They exert their effects by binding to biogenic amine receptors (BARs), which are specific receptor proteins in the G-protein-coupled receptor superfamily. BAR genes have been cloned and characterized from multiple model insects, including Drosophila melanogaster, Anopheles gambiae, Bombyx mori, Apis mellifera and Tribolium castaneum. However, relatively little work has addressed the molecular properties, expression profiles, and pharmacological characterization of BARs from other insects, including important pests. RESULTS: In this study, we cloned 17 genes encoding putative biogenic amine receptor proteins from Plutella xylostella, a global pest of Brassica crops. These PxBAR genes were five octopamine receptors (PxOA1, PxOA2B1, PxOA2B2, PxOA2B3, and PxOA3), three tyramine receptors (PxTAR1A, PxTAR1B, and PxTAR2), four dopamine receptors (PxDOP1, PxDOP2, PxDOP3, and PxDopEcR), and five serotonin receptors (Px5-HT1A , Px5-HT1B , Px5-HT2A , Px5-HT2B , and Px5-HT7 ). All PxBARs showed considerable sequence identity with orthologous BARs, and phylogenetic analysis clustered the receptors within their respective groups while preserving organismal evolutionary relationships. We investigated their molecular properties and expression profiles, and pharmacologically characterized the dopamine receptor, PxDOP2. CONCLUSIONS: Our study provides important information and resources on biogenic amine receptors from P. xylostella, which suggests potential target sites for controlling this pest species. © 2021 Society of Chemical Industry.

Silver nanoparticles coated by green graphene quantum dots for accelerating the healing of MRSA-infected wounds.

Bacterial infection, especially multidrug-resistant bacteria-induced infection, threatens human health seriously, which has posed great challenges for clinical therapy. The overuse of conventional antibiotics has given rise to bacterial resistance that severely restricts the clinical treatment options of conventional antibiotics. The development of highly effective antibacterial materials and therapeutic strategies to inhibit the multidrug-resistant bacteria-induced infections is of great urgency. Although silver nanoparticles (AgNPs) have exhibited certain effectiveness in killing multidrug-resistant bacteria, their antibacterial efficacy and biosafety are still unsatisfactory. In this work, we prepared graphene quantum dots (GQDs) by a green synthesis method with the natural polymer starch as a precursor for uniformly decorating AgNPs to form GQDs coated AgNPs (GQDs@Ag). The nanocomplex was comprehensively characterized, and its antibacterial activity and biosafety were systematically investigated. The characterization results revealed that the successfully constructed GQDs@Ag hybrids with improved dispersion and stability are composed of AgNPs closely and uniformly surrounded by the GQDs. Furthermore, in vitro and in vivo results demonstrated that GQDs@Ag hybrids with superior biosafety showed a markedly enhanced effect in killing MRSA and accelerating MRSA-infected wound healing as compared to AgNPs alone. Collectively, these results suggest that the biocompatible nanosystem of GQDs@Ag exhibits great potential in clinical application for MRSA infection.

Broad-Spectral-Range Sustainability and Controllable Excitation of Hyperbolic Phonon Polaritons in α-MoO3.

Hyperbolic phonon polaritons (HPhPs) in orthorhombic-phase molybdenum trioxide (α-MoO3 ) show in-plane hyperbolicity, great wavelength compression, and ultralong lifetime, therefore holding great potential in nanophotonic applications. However, its polaritonic response in the far-infrared (FIR) range remains unexplored due to challenges in experimental characterization. Here, monochromated electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) is used to probe HPhPs in α-MoO3 in both mid-infrared (MIR) and FIR frequencies and correlate their behaviors with microstructures and orientations. It is found that low structural symmetry leads to various phonon modes and multiple Reststrahlen bands (RBs) over a broad spectral range (over 70 meV) and in different directions (55-63 meV and 119-125 meV along the b-axis, 68-106 meV along the c-axis, and 101-121 meV along the a-axis). These HPhPs can be selectively excited by controlling the direction of swift electrons. These findings provide new opportunities in nanophotonic and optoelectronic applications, such as directed light propagation, hyperlenses, and heat transfer.

Mechanism and consequences for avoidance of superparasitism in the solitary parasitoid Cotesia vestalis.

A parasitoid's decision to reject or accept a potential host is fundamental to its fitness. Superparasitism, in which more than one egg of a given parasitoid species can deposit in a single host, is usually considered sub-optimal in systems where the host is able to support the development of only a single parasitoid. It follows that selection pressure may drive the capacity for parasitoids to recognize parasitized hosts, especially if there is a fitness cost of superparasitism. Here, we used microsatellite studies of two distinct populations of Cotesia vestalis to demonstrate that an egg laid into a diamondback moth (Plutella xylostella) larva that was parasitized by a conspecific parasitoid 10 min, 2 or 6 h previously was as likely to develop and emerge successfully as was the first-laid egg. Consistent with this, a naive parasitoid encountering its first host was equally likely to accept a healthy larva as one parasitized 10 min prior, though handling time of parasitized hosts was extended. For second and third host encounters, parasitized hosts were less readily accepted than healthy larvae. If 12 h elapsed between parasitism events, the second-laid egg was much less likely to develop. Discrimination between parasitized and healthy hosts was evident when females were allowed physical contact with hosts, and healthy hosts were rendered less acceptable by manual injection of parasitoid venom into their hemolymph. Collectively, these results show a limited capacity to discriminate parasitized from healthy larvae despite a viability cost associated with failing to avoid superparasitism.

Variation among 532 genomes unveils the origin and evolutionary history of a global insect herbivore.

The diamondback moth, Plutella xylostella is a cosmopolitan pest that has evolved resistance to all classes of insecticide, and costs the world economy an estimated US $4-5 billion annually. We analyse patterns of variation among 532 P. xylostella genomes, representing a worldwide sample of 114 populations. We find evidence that suggests South America is the geographical area of origin of this species, challenging earlier hypotheses of an Old-World origin. Our analysis indicates that Plutella xylostella has experienced three major expansions across the world, mainly facilitated by European colonization and global trade. We identify genomic signatures of selection in genes related to metabolic and signaling pathways that could be evidence of environmental adaptation. This evolutionary history of P. xylostella provides insights into transoceanic movements that have enabled it to become a worldwide pest.

Herbivore range expansion triggers adaptation in a subsequently-associated third trophic level species and shared microbial symbionts.

Invasive species may change the life history strategies, distribution, genetic configuration and trophic interactions of native species. The diamondback moth, Plutella xylostella L., is an invasive herbivore attacking cultivated and wild brassica plants worldwide. Here we present phylogeographic analyses of P. xylostella and one of its major parasitoids, Cotesia vestalis, using mitochondrial markers, revealing the genetic diversity and evolutionary history of these two species. We find evidence that C. vestalis originated in Southwest China, then adapted to P. xylostella as a new host by ecological sorting as P. xylostella expanded its geographic range into this region. Associated with the expansion of P. xylostella, Wolbachia symbionts were introduced into local populations of the parasitoid through horizontal transfer from its newly associated host. Insights into the evolutionary history and phylogeographic system of the herbivore and its parasitoid provide an important basis for better understanding the impacts of biological invasion on genetic configuration of local species.