Luminescent Two-Dimensional Metal-Organic Framework Nanosheets with Large π-Conjugated System: Design, Synthesis, and Detection of Anti-Inflammatory Drugs and Pesticides.

Two-dimensional (2D) metal-organic framework (MOF) nanosheets, with largely exposed surface area and highly accessible active sites, have emerged as a novel kind of sensing material. Here, a luminescent 2D MOF nanosheet was designed and synthesized by a facile top-down strategy based on a three-dimensional (3D) layered MOF {[Zn(H2L)(H2O)2]·H2O}n (Zn-MOF; H4L = 3,5-bis(3',5'-dicarboxyphenyl)-1H-1,2,4-triazole). With a large π-conjugated system and rigid planar structure, ligand H4L was elaborately selected to construct the bulk Zn-MOF, which can be readily exfoliated into 2D nanosheets, owing to the weak interlayer interactions and easy-to-release H2O molecules in the interspaces of 2D layers. Given the great threat posed to the ecological environment by anti-inflammatory drugs and pesticides, the developed luminescent Zn-MOF nanosheets were utilized to determine these organic pollutants, achieving highly selective and sensitive detection of diclofenac sodium (DCF) and tetramethylthiuram disulfide (TMTD). Compared to the detection limits of 3D Zn-MOF (7.72 ppm for DCF, 6.01 ppm for TMTD), the obviously lower detection limits for 2D Zn-MOF nanosheets toward DCF (0.20 ppm) and TMTD (0.18 ppm) further revealed that the largely exposed surface area with rigid planar structure and ultralarge π-conjugated system greatly accelerated electron transfer, which brought about a vast improvement in response sensitivity. The remarkable quenching performance for DCF and TMTD stems from a combined effect of photoinduced electron transfer and competitive energy absorption. The possible sensing mechanism was systematically investigated by the studies of powder X-ray diffraction, UV-vis, luminescence lifetime, and density functional theory calculations.

Fabrication of Protonated Two-Dimensional Metal-Organic Framework Nanosheets for Highly Efficient Iodine Capture from Water.

Radioactive iodine (129I and 131I), produced or released from nuclear-related activities, posed severe effects on both human health and environment. The efficient removal of radioiodine from aqueous medium and vapor phase is of paramount importance for the sustainable development of nuclear energy. Herein, a metal-organic framework (MOF) nanosheet with a positive charge was constructed for the capture of iodine for the first time. The as-synthesized ultrathin nanosheets, with a thickness of 4.4 ± 0.1 nm, showed a record-high iodine adsorption capacity (3704.08 mg g-1) from aqueous solution, which is even higher than that from the vapor phase (3510.05 mg g-1). It can be ascribed to the fully interactions between the extensive accessible active sites on the largely exposed surface of 2D MOF nanosheets and the target pollutants, which also gave rise to fast adsorption kinetics with relative high removal efficiencies in the low concentrations, even in seawater. Moreover, a facile recyclability with fast desorption kinetics can also be achieved for the MOF nanosheets. The excellent iodine removal performance in aqueous solution demonstrated that the electrostatic attraction between MOF nanosheets with a positive charge and the negatively charged triiodide (I3-, the dominant form of iodine in aqueous solution) is the driving force in adsorption, which endows the adsorbents with the characteristics of fast adsorption and desorption kinetics. The adsorption mechanism was systematically verified by the studies of ζ potential, Fourier transform infrared, X-ray photoelectron spectroscopy, and Raman spectra.

Comparative phylogeography of two hemipteran species (Geisha distinctissima and Megacopta cribraria) in the Zhoushan Archipelago of China reveals contrasting genetic structures despite concordant historical demographies.

Continental islands are useful models to explore the roles of shared historical factors in the evolution of sympatric species. However, China's largest continental group of islands, the Zhoushan Archipelago, was neglected by most studies focusing on biodiversity hotspots. Here we investigated the phylogeographic patterns and the historical demography of two sympatric hemipteran insects (Geisha distinctissima and Megacopta cribraria), which shared historical factors in the Zhoushan Archipelago. The results based on mtDNA (COX1, COX2-COX3, and CYTB) and nDNA (28S and ITS2) showed that G. distinctissima diverged into three genetic lineages (L1-L3) ~8.9-13.7 thousand years ago (kya), which coincided with the period of island isolation. However, the three lineages exhibit no clear phylogeographic patterns for frequent asymmetrical gene flow (starting around 5 kya) from the mainland and adjacent islands to other distant islands due to subsequent human activities. In contrast, only one genetic lineage exists for M. cribraria, without any phylogeographic structures. The ancestral range in the mainland as well as in neighboring islands, together with the frequent asymmetrical gene flow of M. cribraria (from the mainland and neighboring islands to more distant islands) within the last 5000 years suggests that human activities may have lead to the colonization of this species in the Zhoushan Archipelago. The contrasting genetic structures indicate shared historical factors but independent evolutionary histories for the two sympatric species in the Zhoushan Archipelago. Our demographic analysis clearly showed that both species underwent population expansion before 5 kya during the post-LGM (Last Glacial Maximum), which indicates that the two species shared concordant historical demographies. This result suggests that the population size of the two species was affected similarly by the climatic oscillations of post-LGM in Eastern China. Together, our findings reveal that the two insect species in the Zhoushan Archipelago exhibit contrasting genetic structures despite concordant historical demographies, which provides an important framework for the exploration of the evolution patterns of sympatric species in the continental island.

The Complete Mitochondrial Genome of Ugyops sp. (Hemiptera: Delphacidae).

The complete mitochondrial genome (mitogenome) of Ugyops sp. (Hemiptera: Delphacidae) was sequenced, making it the first determined mitogenome from the subfamily Asiracinae, the basal clade of the family Delphacidae. The mitogenome was 15,259 bp in length with A + T content of 77.65% and contained 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosomal RNA genes (rRNAs), and a control region. The gene order was identical with that of the ancestral insect. The nucleotide composition analysis indicated that the whole mitogenome was strongly A-skewed (0.288) and highly C-skewed (-0.270). For PCGs on the J-strand, the AT skew was positive, and the GC skew was negative. All PCGs started with canonical ATN codons, except for cox1 and nad5, which used CTG and GTG as start codon, respectively. All tRNAs could fold into typical cloverleaf secondary structures, with the exception of trnS1 (AGN), in which the dihydrouridine arm was reduced to a simple loop. The control region included a poly-T stretch downstream of the small rRNA gene (rrnS), a subregion of higher A + T content and tandemly repeated sequence near trnI. The mitogenome of Ugyops sp. could be very helpful in exploring the diversity and evolution of mitogenomes in Delphacidae.

Hemiptera Mitochondrial Control Region: New Sights into the Structural Organization, Phylogenetic Utility, and Roles of Tandem Repetitions of the Noncoding Segment.

As a major noncoding fragment, the control region (CR) of mtDNA is responsible for the initiation of mitogenome transcription and replication. Several structural features of CR sequences have been reported in many insects. However, comprehensive analyses on the structural organization and phylogenetic utility, as well as the role of tandem replications (TRs) on length variation, high A+T content, and shift of base skew of CR sequences are poorly investigated in hemipteran insects. In this study, we conducted a series of comparative analyses, using 116 samples covering all 11 infraorders of the five currently recognized monophyletic groups in the Hemiptera. Several structural elements (mononucleotide stretches containing conserved sequence blocks (CSBs), TRs, and GA-rich region) were identified in the mitochondrial control region in hemipteran insects, without showing a consistent location. The presence and absence of certain specific structural elements in CR sequences show the various structural organizations of that segment among the five monophyletic groups, which indicates the diversification of the control region’s structural organization in Hemiptera. Among the many groups within Hemiptera, eight monophyletic groups and three consistent phylogenetic trees were recovered, using CSBs datasets by maximum likelihood and Bayesian methods, which suggests the possible utility of CR sequences for phylogenetic reconstruction in certain groups of Hemiptera. Statistical analyses showed that TRs may contribute to the length variation, high AT content, and the shift of base skewing of CR sequences toward high AT content in the Hemiptera. Our findings enrich the knowledge of structural organization, phylogenetic utility, and roles of tandem replication of hemipteran CR, and provide a possible framework for mitochondrial control region analyses in hemimetabolous insects.

Phylogeography of the Rice Spittle Bug (Callitettix versicolor) Implies Two Long-Term Mountain Barriers in South China.

South China is a region of remarkable topographic complexity. However, the impact of climate fluctuations in the Pleistocene on the local fauna and especially insects has not been extensively studied. We integrated mitochondrial DNA (mtDNA) and microsatellite data of the rice spittle bug, Callitettix versicolor, to determine the genetic structure, potential biogeographic barriers, and historical demography of this species. The mtDNA data revealed two distinct lineages (Western and Eastern) congruent with the geographically separated western and eastern sub-regions of the Hengduan Mountains. The Eastern lineage was subdivided into two sub-lineages, E1 and E2, congruent with the geographically separated northern and southern sub-regions of the Dabie Mountains. E2 was further subdivided into two sub-groups, E2-1 and E2-2, with a hybrid zone (Guizhou and Hunan Provinces) in which their areas were contiguous. The genetic structures constructed using mtDNA were corroborated by four clusters (G1-G4) of microsatellite data. The populations of each cluster were nearly consistent with a sub-lineage of the mtDNA gene tree (G1-G4 corresponded to the Western, E1, E2-2 and E2-1 lineages, respectively). The divergence time estimated between the Western and Eastern lineages was 1.17 (0.50-2.37) to 0.89 (0.39-1.78) Mya, indicating that the lineages diversified on both geographic and temporal scales. The historical demography of the Eastern lineage showed continuous population growth after the Last Interglacial (LIG) and a stable population during the Last Glacial Maximum (LGM) period. However, the Western lineage remained largely unchanged during the LIG and LGM periods. This suggests that the historical demography of C. versicolor is probably related not only to the paleoclimate of South China, but also to the geological restriction and specific habitat preferences of species.

Identification of a self-regulatory pheromone system that controls nymph aggregation behavior of rice spittlebug Callitettix versicolor.

BACKGROUND: Nymphs of many spittlebug species are known to aggregate in one spittle mass, a behavior which greatly benefits the survival of the developing nymphs. Little is known, however, about the precise mechanisms that induce and regulate aggregation. Here, we investigated the aggregation behavior of nymphs of the rice spittlebug Callitettix versicolor, and analyzed the chemical composition of spittle masses. RESULTS: We identified six n-alkane compounds, namely un-, do-, tri-, tetra-, penta- and hexadecane in the spittle mass. Importantly, we showed that solitary spittle mass (SSM) and aggregation spittle mass (ASM) differed significantly in the amounts and composition of these compounds. While un-, do-, tri-, tetra-and hexadecane were overrepresented in SSM, pentadecane was found at significantly higher levels in ASM. Electrophysiological experiments showed that antennae responses to these six compounds were significantly higher than to both the hexane and the docosane control, which suggests a specific role of the six volatile alkanes as pheromones. In agreement with this hypothesis, behavioral tests revealed that five of the six compounds (e.g. un-, do-, tri-, tetra-, and hexadecane) acted as attractants across a wide concentration range. Thus, these five compounds allow recruitment of additional nymphs to a growing spittle mass. The sixth compound, pentadecane, attracted nymphs at low doses, whereas at higher doses, this effect vanished, suggesting that this alkane functioned as a repellent, thus preventing recruitment of additional individuals to a full aggregation in a spittle mass. CONCLUSIONS: In summary, our study identified a simple, yet fully functional feedback mechanism which allows aggregation at low nymph numbers, while preventing over-crowding beyond a set number of nymphs within one spittle mass. In conclusion, our study provides new insights into C. versicolor development and behavior that should greatly facilitate the identification of new approaches for pheromonal control of this pest.

Review of the genus Anasta Emeljanov (Hemiptera: Dictyopharidae: Hastini) from the Australasian region.

The dictyopharid planthopper genus Anasta Emeljanov from the Australasian region is revised to include six species including a new one: A. australiaca (Lallemand, 1935) comb. nov. (North Australia), A. lobosa sp. nov. (Papua New Guinea), A. minuta (Lallemand, 1935) comb. nov. (Timor, Indonesia), A. prognatha (Distant, 1906) (North Australia, Papua New Guinea), A. timorina (Lallemand, 1935) (Timor, Indonesia), and A. vitiensis Emeljanov et Wilson, 2009 (Fiji). Descriptions or redescriptions of A. australiaca, A. lobosa sp. nov., and A. prognatha are provided together with dorsal habitus and structural illustrations of male genitalia. A key to the species of the genus and distribution map are provided. The biogeography of the genus is discussed.

The Oriental spittlebug genus Paracercopis Schmidt (Hemiptera: Cercopoidea: Cercopidae) revisited, with description of one new species from Hubei, China.

The generic diagnostic characters of Paracercopis (Hemiptera: Cercopoidea: Cercopidae) are redefined and the autapomorphies are proposed to support the monophyly of the genus. Scanning electron micrographs of antennal sensilla and sensilla on rostral apex of P. seminigra (Melichar, 1902) are provided for the first time. A checklist together with new distribution records and key to the species of the genus are provided. Host plant associations of Paracercopis species are reported for the first time. Paracercopis unicolor Liang, Zhang & Xiao, sp. nov., representing the seventh and largest species of the genus is described from Hubei Province in south central China.

Three new species of the genus Philagra Stål (Hemiptera: Cercopidea: Aphrophoridae) from China and Bangladesh.

Three new species of Philagra Stål, P. bimaculata sp. nov., P. fuscofasciata sp. nov. and P. straminea sp. nov. are described and illustrated from China with P. bimaculata sp. nov. also recorded from Bangladesh. Morphological descriptions and structural illustrations of the new species are provided with distributional data given. Scanning electron micrographs of antennal sensilla of P. bimaculata sp. nov. and P. straminea sp. nov. and sensilla on rostral apex of P. bimaculata sp. nov. are provided for the first time.

A review of the planthopper genus Armacia Stål (Hemiptera: Fulgoromorpha: Ricaniidae) with descriptions of four new species from Indonesia and Papua New Guinea.

The genus Armacia Stål (Hemiptera: Fulgoromorpha: Ricaniidae) is reviewed taxonomically. Four new species of the genus are described and illustrated from West-Pacific region: A. madangensis sp. nov. (Papua New Guinea), A. rubilimba sp. nov. (Indonesia), A. spinae sp. nov. (Indonesia) and A. vigorata sp. nov. (Indonesia), A. albipes (Walker 1868), A. clara (Stål 1859), A. divisura (Walker 1868), A. fusca Melichar 1898, A. hyalinata (Donovan 1805), A. latipennis (Walker 1868), A. nigrifrons (Walker 1858), A. simaethis Fennah 1956 , and A. spatiosa (Walker 1868) are redescribed and illustrated. A checklist of all known species and a diagnosis of the genus are provided. A key to all species in the genus is provided.

The complete mitochondrial genome sequence of the planthopper, Sivaloka damnosus.

The complete mitochondrial genome (mitogenome) sequence was determined from the plant hopper, Sivaloka damnosus Chow and Lu (Hemiptera: Issidae), a representative of the insect family Issidae. The genome is a circular molecule of 15,287 bp with a total A+T content of 76.5%. The gene content, order, and structure are identical to that in Drosophila melanogaster, which is considered ancestral for insects. All 13 protein-coding genes of the S. damnosus mitogenome have a putative inframe ATR methionine or ATT isoleucine codons as start signals. The usual termination codons (TAA and TAG) were found in 11 protein-coding genes. However, atp6, and nad4 have incomplete termination codons. All tRNAs show stable canonical clover-leaf structures similar to other insect mitochondrial tRNAs, except for tRNA(Ser(AGN)), which has a reduced DHU arm. The A+T-rich region or putative control region includes two extensive repeat regions. The first repeat region is composed of two sets of complicated repeat units, and these repetitive sequences are arranged alternately; the second contains ten 20 bp tandemly repetitive sequences. In the phylogenetic analyses based on protein-coding genes, Cicadomorpha is a sister to Fulgoromorpha+Sternorrhyncha, and Heteroptera is a sister to all other Hemiptera.

A new structure on the frons of male adults of the Asian rice spittlebug Callitettix versicolor (Hemiptera: Auchenorrhyncha: Cercopidae).

A new structure, here tentatively named the "frontal gland," specifically found on frons of male adults of the Asian rice spittlebug, Callitettix versicolor (Fabricius, 1794) (Hemiptera:  Auchenorrhyncha: Cercopidae), is reported. Adult C. versicolor is distinctly dimorphic in frons morphology. The frons in female adults, like that in most cercopid species, is normally swollen and nearly bulbose and is covered with short pilosity, while the frons in male adults is visibly different, with the lower 3/5 of the postclypeus and anteclypeus being centrally flat, bare and smooth on the surface. SEM observations revealed that the flat frons surface of the male adults is covered with numerous, very fine pores. In total, each frons has over 4500 pores on the central flat area, with an average density of 55.5 ± 1.50 pores per 100 µm2. The distance among the pores averages 10.63 ± 1.8 µm. Each pore unit is composed of a round, deep cavity in which one central conical process is set. The cavity is delimited by a cuticular rim and the opening of the cavity averages 2.89 ± 0.20 µm in diameter. The central, conical process has a sponge-like apex and measures 2.52-2.70 µm in diameter. In addition, one or two (two in most cases) extremely fine pits (0.42-0.56 µm in diameter) are located on the marginal cuticle rim surrounding the cavity and its central conical process. These cuticular, fine pits are located proximal to the pores, at a distance of 0.98-1.96 µm. These porous structures are not present on the frons in female adults. They are assumed to be an exocrine gland system and are possibly the male sex pheromone-releasing glands, as they are only present in male adults. Observations of mating behavior showed that it is likely that the secretions made by the frontal gland constitute short-range attractants and may fulfil aphrodisiac functions to stimulate mating. The species of Auchenorrhyncha were previously thought to communicate via acoustic signals, but the findings described here suggest that at least one Auchenorrhynchan species also uses chemicals for sexual communication.

Complete mitochondrial genome of the small brown planthopper, Laodelphax striatellus (Delphacidae: Hemiptera), with a novel gene order.

We determined the first complete mitochondrial genome (mitogenome) sequence from a representative of the insect family Delphacidae, Laodelphax striatellus. The 16,513 bp long L. striatellus mitogenome encodes 13 putative proteins, two ribosomal RNAs, and 22 transfer RNAs, and contains a putative control region (or A+T-rich region). The nucleotide composition is biased toward adenine and thymine (77.2% A+T), and the amino acid composition is affected to a similar degree by the AT mutational bias. All 13 protein-coding genes (PCGs) start with a typical ATN initiation codon. Eight of 13 PCGs in L. striatellus have a complete termination codon (TAA), whereas the remaining five have incomplete termination codons. The anticodons of the L. striatellus tRNAs are identical to those in Drosophila yakuba, and all tRNAs except for tRNA(Ser-AGN) can be folded in the form of a typical cloverleaf structure. The A+T-rich region of L. striatellus was found between srRNA and tRNA(lle), and the entire region was 2040 bp long. The gene content of the L. striatellus mitogenome is identical to other completely sequenced insect mitogenomes, while the gene order is different from the common arrangement found in most insects: five tRNA genes and three PCGs in the L. striatellus mitogenome have changed positions relative to the ancestral arrangement of mitochondrial genes in D. yakuba. Besides describing the above contents, we also aligned the mitogenome sequence of L. striatellus with other hemipterans to analyse the phylogenetic relationships of Hemiptera. The results show that Heteroptera is the sister group to all other Hemiptera, and Cicadomorpha is the sister group to the clade Fulgoromorpha+Sternorrhyncha.

Three New Species of Brevitobrilus (Nematoda) with a Discussion on Relationships within the Genus.

Three new species of the genus BrevitobriusTsalolikhin, 1981 are described. Brevitobrilus glandulatus n. sp. is characterized by conspicuous sphincter between pars dilatata and uterus; two pairs of vaginal glands; spicules having elliptical capitula with small proximal stiffening piece; proximally-arcuate gubernaculum; S3 and S4 smaller than other supplements; S6 out of spicular range and 57-60 micropapillae. Brevitobrilus dimorphicus n. sp. is diagnosed by sexual dimorphism in labial sensilla and amphids; thick-walled rectum with a diverticulum protruding into intestinal lumen and males with boat-shaped spicules and S6 occasionally slightly smaller than other supplements. Brevitobrilus allahabadensis n. sp. possesses large amphids of 28-33% of corresponding labial diameter in both sexes; vagina and uterus with muscular, plicate walls; well developed sphincter between vas deferens and ejaculatory duct; capitulate spicules with sloping ventral and angular dorsal walls; S3, S4 and S6 smaller than other supplements, S6 close to cloaca and 28-37 micropapillae. The relationships of the species of genus Brevitobrilus have been assessed using morphological characters subjected to parsimony and a non cladistic key to identification of species is given.

The complete mitochondrial genome of Unkanodes sapporonus (Hemiptera: Delphacidae).

In this study, we sequenced and analyzed the complete mitochondrial genome of Unkanodes sapporonus (Matsumura) (Hemiptera: Delphacidae). The mitogenome was 17,765 bp in length with A + T content of 75.87%, containing 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and a control region. All protein-coding genes started with ATN, except for nad5, which used noncanonical codon GTG. All tRNAs could fold into typical clover-leaf secondary structures, with the exception of trnS1 (AGN).

Description of the immature and adult stages of the jujube tube spittlebug, Machaerota planitiae Distant (Hemiptera: Cercopoidea: Machaerotidae) in Bangladesh.

The immatures and adults of the jujube tube spittlebug, Machaerota planitiae Distant (Hemiptera: Cercopoidea: Machaerotidae) are described and illustrated. A key to nymphal instars is included. Recently introduced to Bangladesh, most likely from adjacent South and Southeast Asian countries, this species has become a serious pest of jujube (Ziziphus jujuba Mill., Rhamnaceae) causing severe damages to jujube production in Bangladesh.

Redescription and redefinition of the genus Chiltana Shakila-Mushtaq & Akbar, 1995 (Hemiptera, Fulgoromorpha, Dictyopharidae, Dictyopharini), with description of a new species from Pakistan.

The genus Chiltana Shakila-Mushtaq & Akbar, 1995 is redescribed and redefined based on the types and new material from Pakistan. Chiltana includes two species, C.acarinata sp. n. and C.baluchi Shakila-Mushtaq & Akbar, 1995 (the type species), both from Chiltan, Balochistan, Pakistan. A key to the species of the genus is provided. Nomenclatorial remarks on original publication, author, and date of Chiltana are given.

Relating antennal sensilla diversity and possible species behaviour in the planthopper pest Lycorma delicatula (Hemiptera: Fulgoromorpha: Fulgoridae).

Antennal sensory units in nymphs and adults of the spotted Lanternfly, Lycorma delicatula (White) (Hemiptera: Fulgoromorpha: Fulgoridae), an economically important plant pest, are studied with scanning electron microscopy. Sensilla trichodea / chaetica type recognition is based on their external morphology and ratio of their size to diameter. The flagellum Bourgoin's organ is a complex sensory unit with 2-3 internal sensilla coeloconica. During nymphal stages, the sensory surface available for a chemoreceptive function particularly increases with the number and size of sensilla placodea on the antennal pedicel. From first to fourth instar and to adult males and females, plate organ sensory surface is estimated to increase respectively by 33x, 68x and 125x (= 2.72 mm2 and 5.02 mm2 respectively for males and females). The most important increase (5x) occurs between second and third instar. In parallel, a distinctive pair of plate organs on the flagellum decreases in size from first to third instar, and disappears. Sexual dimorphism occurs in sensilla placodea in adults. Diversity, disparity and evolution of nymphal sensilla, and their sexual dimorphism in adults are discussed in the context of the species and planthopper behaviour.

Zanna robusticephalica sp. nov. (Hemiptera: Fulgoromorpha: Fulgoridae) from China, with comments on some ultrastructural characters of the new species.

Zanna robusticephalica sp. nov. (Hemiptera: Fulgoromorpha: Fulgoridae: Zanninae: Zannini), representing the third species of the planthopper genus Zanna Kirkaldy, 1902 from China, is described and illustrated from Yunnan in southwestern China. Scanning electron micrographs of the antennal sensilla, rostral apex, hind tarsal segments, gonoplac and wax glands of the new species are provided. The generic diagnostic characters of Zanna are redefined and the autapomorphies are proposed to support the monophyly of the genus. A check-list of the Oriental Zanna species is included.