Insecticidal Activity and Insect Repellency of Four Species of Sea Lily (Comatulida: Comatulidae) From Taiwan

Gut microbial composition in developmental stages of gall inducing thrips Gynaikothrips uzeli and associated plant pathogenesis

Gut bacteria play a crucial role in the several metabolic activity of the insects. In the present work, effort has been made to decipher the gut microbiota associated with the developmental stages of Gynaikothrips uzeli a gall inducing thrips along with their predicted functional role. Further, an effort has been made to correlate the bacterial communities with plant pathogenesis and thelytoky behaviour of G. uzeli. Findings obtained revealed that genus Arsenophonus dominated the total bacterial diversity and was transmitted vertically through the developmental stages. Further, it was observed that the high abundance of genus Arsenophonus promotes the thelytoky behaviour in G. uzeli and results in the killing of males. Furthermore, strong connecting link between Arsenophonus abundance and gall induction in F. benjamina was observed in the current dataset. G. uzeli being in the category of phloem sucking insect was known for the induction of galls and the current findings for the first time unveiled the facts that high abundance of genus Arsenophonus a well-known plant pathogen may be one of the major reason for inducing galls in F. benjamina. Moreover, PICRUSt2 analysis revealed that predicted functional pathways like biosynthesis of amino acids, and metabolism of carbon, nitrogen, carbohydrates and amino acids (e.g. Arginine, Alanine, Aspartate, Glutamate, Proline, Cysteine, Methionine, Glycine, Threonine, and Serine) were frequently noticed in profiles associated with all the developmental stages of G. uzeli. More to this, the high abundance of Arsenophonus in G. uzeli suggest that representatives of this genus may be resistant and/or tolerant to different antibacterial agents, alkaloids, flavonoids, and glycosides (e.g. quercetin). The correlation of bacterial diversity in pathogenicity can be extrapolated in different pest and vector species of other arthropods.

Deconstruction of Lignin: From Enzymes to Microorganisms

Lignocellulosic residues are low-cost abundant feedstocks that can be used for industrial applications. However, their recalcitrance currently makes lignocellulose use limited. In natural environments, microbial communities can completely deconstruct lignocellulose by synergistic action of a set of enzymes and proteins. Microbial degradation of lignin by fungi, important lignin degraders in nature, has been intensively studied. More recently, bacteria have also been described as able to break down lignin, and to have a central role in recycling this plant polymer. Nevertheless, bacterial deconstruction of lignin has not been fully elucidated yet. Direct analysis of environmental samples using metagenomics, metatranscriptomics, and metaproteomics approaches is a powerful strategy to describe/discover enzymes, metabolic pathways, and microorganisms involved in lignin breakdown. Indeed, the use of these complementary techniques leads to a better understanding of the composition, function, and dynamics of microbial communities involved in lignin deconstruction. We focus on omics approaches and their contribution to the discovery of new enzymes and reactions that impact the development of lignin-based bioprocesses.

Diversity structure of the microbial communities in the guts of four neotropical termite species

The termite gut microbiome is dominated by lignocellulose degrading microorganisms. This study describes the intestinal microbiota of four Argentinian higher termite species with different feeding habits: Microcerotermes strunckii (hardwood), Nasutitermes corniger (softwood), Termes riograndensis (soil organic matter/grass) and Cornitermes cumulans (grass) by deep sequencing of amplified 16S rRNA and ITS genes. In addition, we have performed a taxonomic and gut community structure comparison incorporating into the analysis the previously reported microbiomes of additional termite species with varied diets. The bacterial phylum Spirochaetes was dominant in the guts of M. strunckii, N. corniger and C. cumulans, whereas Firmicutes predominated in the T. riograndensis gut microbiome. A single bacterial genus, Treponema (Spirochaetes), was dominant in all termite species, except for T. riograndensis. Both in our own sequenced samples and in the broader comparison, prokaryotic α-diversity was higher in the soil/grass feeders than in the wood feeders. Meanwhile, the β-diversity of prokaryotes and fungi was highly dissimilar among strict wood-feeders, whereas that of soil- and grass-feeders grouped more closely. Ascomycota and Basidiomycota were the only fungal phyla that could be identified in all gut samples, because of the lack of reference sequences in public databases. In summary, higher microbial diversity was recorded in termites with more versatile feeding sources, providing further evidence that diet, along with other factors (e.g., host taxonomy), influences the microbial community assembly in the termite gut.

Comparative characterization of microbiota between the sibling species of tea geometrid moth Ectropis obliqua Prout and E. grisescens Warren

For a wide range of insect species, the microbiota has potential roles in determining host developmental programme, immunity and reproductive biology. The tea geometrid moths Ectropis obliqua and E. grisescens are two closely related species that mainly feed on tea leaves. Although they can mate, infertile hybrids are produced. Therefore, these species provide a pair of model species for studying the molecular mechanisms of microbiotal involvement in host reproductive biology. In this study, we first identified and compared the compositions of microbiota between these sibling species, revealing higher microbiotal diversity for E. grisescens. The microbiota of E. obliqua mainly comprised the phyla Firmicutes, Proteobacteria and Cyanobacteria, whereas that of E. grisescens was dominated by Proteobacteria, Actinobacteria and Firmicutes. At the genus level, the dominant microbiota of E. grisescens included Wolbachia, Enterobacter and Pseudomonas and that of E. obliqua included Melissococcus, Staphylococcus and Enterobacter. Furthermore, we verified the rate of Wolbachia to infect 80 samples from eight different geographical populations, and the results supported that only E. grisescens harboured Wolbachia. Taken together, our findings indicate significantly different microbiotal compositions for E. obliqua and E. grisescens, with Wolbachia possibly being a curial factor influencing the reproductive isolation of these species. This study provides new insight into the mechanisms by which endosymbiotic bacteria, particularly Wolbachia, interact with sibling species.

Veteran trees are a source of natural enemies

Predation of invertebrate pest by natural enemies is a critical contribution of nature to people, because invertebrate pests cause a vast amount of economic damage and pesticides use has many long-term costs. Veteran trees are keystone structures and hotspots for biodiversity, and are a potential source of natural enemies. To explore this, we used a balanced experimental design where we measured predatory beetle diversity and attack marks on three colors of artificial caterpillars placed around 20 veteran oaks and 20 nearby young oaks, in Southern Norway. We predicted that around the veteran oaks there would be a greater diversity of predatory beetles and more invertebrate attacks on artificial caterpillars. Sampling for predatory beetles was conducted in summer 2017 and 2018, and invertebrate attacks were measured in 2018. We found support for the predictions: diversity of predatory beetles was higher around veteran trees and there were more arthropod attack marks on artificial caterpillars placed around veteran trees. Our results indicated that veteran trees are a source of natural enemies. Valuing and protecting veteran trees and their communities is an essential step towards a more sustainable system of management that has the possibility of promoting both the wellbeing of people and biodiversity.

Neotropical termite microbiomes as sources of novel plant cell wall degrading enzymes

In this study, we used shotgun metagenomic sequencing to characterise the microbial metabolic potential for lignocellulose transformation in the gut of two colonies of Argentine higher termite species with different feeding habits, Cortaritermes fulviceps and Nasutitermes aquilinus. Our goal was to assess the microbial community compositions and metabolic capacity, and to identify genes involved in lignocellulose degradation. Individuals from both termite species contained the same five dominant bacterial phyla (Spirochaetes, Firmicutes, Proteobacteria, Fibrobacteres and Bacteroidetes) although with different relative abundances. However, detected functional capacity varied, with C. fulviceps (a grass-wood-feeder) gut microbiome samples containing more genes related to amino acid metabolism, whereas N. aquilinus (a wood-feeder) gut microbiome samples were enriched in genes involved in carbohydrate metabolism and cellulose degradation. The C. fulviceps gut microbiome was enriched specifically in genes coding for debranching- and oligosaccharide-degrading enzymes. These findings suggest an association between the primary food source and the predicted categories of the enzymes present in the gut microbiomes of each species. To further investigate the termite microbiomes as sources of biotechnologically relevant glycosyl hydrolases, a putative GH10 endo-β-1,4-xylanase, Xyl10E, was cloned and expressed in Escherichia coli. Functional analysis of the recombinant metagenome-derived enzyme showed high specificity towards beechwood xylan (288.1 IU/mg), with the optimum activity at 50 °C and a pH-activity range from 5 to 10. These characteristics suggest that Xy110E may be a promising candidate for further development in lignocellulose deconstruction applications.

First Insight into Microbiome Profiles of Myrmecophilous Beetles and Their Host, Red Wood Ant Formica polyctena (Hymenoptera: Formicidae)-A Case Study

Formica polyctena belongs to the red wood ant species group. Its nests provide a stable, food rich, and temperature and humidity controlled environment, utilized by a wide range of species, called myrmecophiles. Here, we used the high-throughput sequencing of the 16S rRNA gene on the Illumina platform for identification of the microbiome profiles of six selected myrmecophilous beetles (Dendrophilus pygmaeus, Leptacinus formicetorum, Monotoma angusticollis, Myrmechixenus subterraneus, Ptenidium formicetorum and Thiasophila angulata) and their host F. polyctena. Analyzed bacterial communities consisted of a total of 23 phyla, among which Proteobacteria, Actinobacteria, and Firmicutes were the most abundant. Two known endosymbionts-Wolbachia and Rickettsia-were found in the analyzed microbiome profiles and Wolbachia was dominant in bacterial communities associated with F. polyctena, M. subterraneus, L. formicetorum and P. formicetorum (>90% of reads). In turn, M. angusticollis was co-infected with both Wolbachia and Rickettsia, while in the microbiome of T. angulata, the dominance of Rickettsia has been observed. The relationships among the microbiome profiles were complex, and no relative abundance pattern common to all myrmecophilous beetles tested was observed. However, some subtle, species-specific patterns have been observed for bacterial communities associated with D. pygmaeus, M. angusticollis, and T. angulata.

First insight into microbiome profile of fungivorous thrips Hoplothrips carpathicus (Insecta: Thysanoptera) at different developmental stages: molecular evidence of Wolbachia endosymbiosis

Insects' exoskeleton, gut, hemocoel, and cells are colonized by various microorganisms that often play important roles in their host life. Moreover, insects are frequently infected by vertically transmitted symbionts that can manipulate their reproduction. The aims of this study were the characterization of bacterial communities of four developmental stages of the fungivorous species Hoplothrips carpathicus (Thysanoptera: Phlaeothripidae), verification of the presence of Wolbachia, in silico prediction of metabolic potentials of the microorganisms, and sequencing its mitochondrial COI barcode. Taxonomy-based analysis indicated that the bacterial community of H. carpathicus contained 21 bacterial phyla. The most abundant phyla were Proteobacteria, Actinobacteria, Bacterioidetes and Firmicutes, and the most abundant classes were Alphaproteobacteria, Actinobacteria, Gammaproteobacteria and Betaproteobacteria, with different proportions in the total share. For pupa and imago (adult) the most abundant genus was Wolbachia, which comprised 69.95% and 56.11% of total bacterial population respectively. Moreover, similarity analysis of bacterial communities showed that changes in microbiome composition are congruent with the successive stages of H. carpathicus development. PICRUSt analysis predicted that each bacterial community should be rich in genes involved in membrane transport, amino acid metabolism, carbohydrate metabolism, replication and repair processes.

Investigation of the Antioxidant Capacity, Insecticidal Ability and Oxidation Stability of Chenopodium formosanum Seed Extract

To maximize the extraction of antioxidants from Chenopodium formosanum seeds, the process factors, such as the ethanol concentration (0⁻100%), extraction time (30⁻180 min) and temperature (30⁻70 °C), for the extraction of the bioactive contents as well as the antioxidant capacity are evaluated using response surface methodology (RSM). The experimental results fit well with quadratic models. The extract was identified by GC/MS, and it was found that some active compounds had antioxidant, repellency and insecticidal activities. Various concentrations of the extract were prepared for the evaluation of the insecticidal activity against Tribolium castaneum, and the toxicity test results indicated that the extract was toxic to Tribolium castaneum, with an LC50 value of 354.61 ppm. The oxidative stability of the olive oil determined according to the radical scavenging activity and p-anisidine test demonstrates that the extract obtained from the Chenopodium formosanum seeds can retard lipid oxidation.

Molecular and biochemical responses in the midgut of the silkworm, Bombyx mori, infected with Nosema bombycis

BACKGROUND

Microsporidia are a group of eukaryotic intracellular parasites that infect almost all vertebrates and invertebrates. However, there is little information available of how microsporidia obtain nutrients and energy from host cells. The purpose of this study was to investigate the energy and material requirements of Nosema bombycis for the invasion procedure through analyzing the global variation of the gene expression, protein abundance, fatty acids level and ATP flux induced by the microsporidia N. bombycis infection in the midgut of the silkworm Bombyx mori.

METHODS

A suppression subtractive hybridization (SSH) and quantitative real-time PCR (qPCR) analysis were performed to identify the genes upregulated in the midgut of B. mori 48 h following N. bombycis infection. Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were used to annotate and summarize the differentially expressed genes, according to the categories 'molecular function', 'cellular component' and 'biological process'. To evaluate the nutrition material and energy costs in B.mori infected by N. bombycis, biochemical analysis was performed to determine the variation of protein abundance, fatty acid levels and ATP flux with or without the microsporidia N. bombycis infection in the midgut of the silkworm B. mori.

RESULTS

A total of 744 clones were obtained, 288 clones were randomly selected for sequencing, and 110 unigenes were generated. Amongst these, 49.21%, 30.16% and 14.29% genes were involved in 19 molecular functions, 19 biological processes and nine cellular components, respectively. A total of 11 oxidative phosphorylation- and eight proton-coupled ATP synthesis-related genes were upregulated. Seven protein degradation-, three fat degradation-related genes were upregulated, and no genes related to the de novo synthesis of amino acids and fatty acids were significantly upregulated. The data from the biochemical analysis showed the contents of total protein and ATP of B. mori midgut tissues decreased significantly, whereas the fatty acid content did not significantly change after four days of N. bombycis infection. Microsporidia N. bombycis infection upregulated the expression level of genes involved in host ATP synthesis, protein and fat degradation, which eventually causes the obvious decline of protein content and ATP synthesis in the host midgut, whereas the fatty acids content did not change significantly.

CONCLUSIONS

This study suggested to some extent that N. bombycis invasion can activate the host protein degradation and accelerate the production of host ATP. Microsporidia of N. bombycis show preference for proteins rather than fatty acids from the host to ensure the material preparation required by their parasitic life-cycle. Requirements of N. bombycis for energy were also mainly dependent on the host ATP production. This study provides a new data that may help our understanding of the molecular mechanisms of obtaining energy and nutrients from the host by the microsporidium N. bombycis.

Nymph and Adult Biology of Euschistus cornutus Dallas: a Potential Soybean Pest in the Neotropics

Laboratory studies with Euschistus cornutus Dallas indicated that nymphs complete development when feeding on green bean, Phaseolus vulgaris L. pod, on soybean, Glycine max (L.) Merrill pod, and on raw shelled peanut, Arachis hypogaea L., but not on fruit (berry) of privet, Ligustrum lucidum Ait. Total mortality was lower on green bean pod (45%), and higher on soybean pod and peanut raw (75 and 80%, respectively). Nymph developmental time was significantly longer for females feeding on green bean pod (37.4 days) than on soybean pod (27 days); a single data was observed on peanut raw (32 days). Males showed no significant differences in total nymph developmental time among foods (31.3 to 33.0 days). At adult emergency, fresh body weight of females (52.2 to 68.5 mg) and males (61.9 to 71.3 mg) did not show statistical differences among foods tested nor between genders. Survivorship of E. cornutus adult after 50 days was greater on peanut raw than on green bean or soybean pod; on privet berry, the majority of males and females (>80%) were dead after 20 days. The reproductive performance data was, in general, greater on peanut raw than on green bean or soybean pod; on privet fruit, no female laid eggs. Fresh body weight gain occurred on all foods, except on privet berry, on which adults lost weight over time. Records of specimens from insect collections in Brazil indicated that E. cornutus occurs in the Southeast and South regions (19° to 31° S latitude). The most common host plant is soybean, suggesting a potential pest status of this stink bug on this crop in the future.

Identification of microRNAs and their response to the stress of plant allelochemicals in Aphis gossypii (Hemiptera: Aphididae)

BACKGROUND

MicroRNAs (miRNAs) are a group of short non-coding RNAs involved in the inhibition of protein translation or in mRNA degradation. Although the regulatory roles of miRNAs in various biological processes have been investigated, there is as yet an absence of studies about the regulatory roles of miRNAs involved in the metabolism of plant allelochemicals in insects.

RESULTS

We constructed five small RNA libraries from apterous Aphis gossypii adults that had fed on an artificial diet containing various allelochemicals. Using Illumina sequencing, a total of 73.27 million clean reads was obtained, and 292 miRNAs were identified from A. gossypii. Comparative analysis of read counts indicated that both conserved and novel miRNAs were differently expressed among the five libraries, and the differential expression was validated via qRT-PCR. We found that the transcript levels of several miRNAs were increased or decreased in all of the allelochemical treatment libraries compared to the control. The putative target genes of the miRNAs were predicted using in silico tools, and the target genes of several miRNAs were presumed to be involved in the metabolism of xenobiotic compounds. Furthermore, the target prediction results were confirmed using dual luciferase reporter assay, and Ago-miR-656a-3p was demonstrated to regulate the expression of CYP6J1 post-transcriptionally through binding to the 3' UTR of CYP6J1.

CONCLUSION

Our research results indicate that miRNAs may be involved in the metabolism of plant allelochemicals in A. gossypii, and these results also represent an important new small RNA genomics resource for further studies on this topic.

Biochemical and histological biomarkers in the midgut of Apis mellifera from polluted environment at Beheira Governorate, Egypt

The aim of this study was to analyze the impact of organophosphorus (OP) pollutants on oxidative stress and ultrastructural biomarkers in the midgut of the honeybee Apis mellifera collected from three locations that differ in their extent of spraying load with OP insecticides: a weakly anthropised rural site, Bolin which is considered as a reference site; moderately spraying site, El Kaza; and a strongly anthropised urban site, Tiba with a long history of pesticide use. Results showed that high concentrations of chlorpyrifos, malathion, diazinon, chlorpyrifos-methyl, and pirimiphos-methyl were detected in midgut at locations with extensive pesticide spraying. Reduced glutathione content, superoxide dismutase, catalase, and glutathione peroxidase displayed lowest activities in the heavily sprayed location (Tiba). Lipid peroxidation level in the midgut of honeybees in the sprayed locations was found to be significantly higher compared to the reference values. Meanwhile, various ultrastructural abnormalities were observed in the epithelial cells of midgut of honeybees collected from El Kaza and Tiba, included confluent and disorganized microvilli and destruction of their brush border, the cytoplasm with large vacuoles and alteration of cytoplasmic organelles including the presence of swollen mitochondria with lysis of matrices, disruption of limiting membranes, and disintegration of cristae. The nuclei with indented nuclear envelope and disorganized chromatin were observed. These investigated biomarkers indicated that the surveyed honeybees are being under stressful environmental conditions. So, we suggest using those biomarkers in the assessment of environmental quality using honeybees in future monitoring of ecotoxicological studies.

Ecology and Management of Kudzu Bug (Hemiptera: Plataspidae) in Southeastern Soybeans

Kudzu bug, Megacopta cribraria Fabricius (Hemiptera: Plataspidae), is an invasive exotic pest of soybeans that has been present in the southeastern United States since 2009 and has been rapidly spreading through soybean-producing states. Their primary reproductive hosts in the United States are soybean, kudzu, pigeon pea, black eye pea, lima bean, pinto bean, wisteria, white sweet clover, white clover, red clover, alfalfa, perennial peanut, and American joint vetch. In soybeans, the kudzu bug feeds on vascular fluids at the stem, petiole, and nodes, causing yield losses of up to 60%. The current management recommendation for this pest includes spraying of pyrethroids such as bifenthrin, but this method is not environmentally friendly, as this negatively impacts beneficial insect populations. Sustainable management tactics, including the development of economic thresholds for insecticide sprays, assessing the spatial and temporal distribution of this pest, manipulating cultivation practices, use of biological control, and host plant resistance, are currently being explored. We present an overview of the ecology of the kudzu bug in soybeans and available management tactics to assist with the management of this potentially devastating pest of soybeans as it spreads westward.