An acoustical and physiological analysis of buzzing in cicada killer wasps (Sphecius speciosus )

Cicada killers (Sphecius speciosus) are large solitary wasps capable of producing a high-amplitude buzzing sound. The buzz was acoustically characterized and its thermal and energetic effects examined. The sound was amplitude modulated, variable in frequency, had many harmonics, and was sometimes interrupted by broad-band buzz pulses. Cicada killer body size was directly related to sound pressure level and inversely related to frequency. Buzzing in males was 70 ± 0.8(21) dB (re 20 μPa measured 3 cm from the dorsum of the thorax) in sound pressure amplitude, with a fundamental frequency of 209 ± 6(20) Hz, while in females buzzes were 72.6 ± 8.3(30) dB and 152.5 ± 5.2(29) Hz. Males, the smaller of the sexes, had buzzes of significantly lower amplitude and higher frequency. Metabolic rate was 0.293 ± 0.024(13) W g⁻¹, or 88% of maximal, during buzzing, and was 5–100 times more costly than file-and-scraper stridulation. Thorax temperature climbed rapidly during sound production and peaked at levels that were nearly optimal for flight. Buzzing may play a role in both interspecific and intraspecific defensive interations. Accepted: 16 July 1998     

Aromatic-Aromatic Interactions Database, A(2)ID: an analysis of aromatic π-networks in proteins

The geometrical arrangement of the aromatic rings of phenylalanine, tyrosine, tryptophan and histidine has been analyzed at a database level using the X-ray crystal structure of proteins from PDB in order to find out the aromatic-aromatic (π-π) networks in proteins and to understand how these aromatic rings are connected with each-other in a specific π-π network. A stringent examination of the 7848 proteins indicates that close to 89% of the proteins have occurrence of at least a network of 2π or a higher π-π network. The occurrence of π-π networks in various protein superfamilies based on SCOP, CATH and EC classifiers has also been probed in the present work. In general, we find that multidomain and membrane proteins as well as lyases show a more number of these networks. Analysis of the distribution of angle between planes of two proximal aromatic rings (?) distribution indicates that at a larger cutoff distance (between centroid of two aromatic rings), above 5?, C-H?π interactions (T-shaped orientation) are more prevalent, while π-π interactions (stacked orientation) are more prevalent at a smaller cutoff distance. The connectivity patterns of π-π networks propose strong propensity of finding arrangement of aromatic residues as clusters rather than linear arrangement. We have also made a public domain database "Aromatic-Aromatic Interactions Database" (A(2)ID) comprising of all types of π-π networks and their connectivity pattern present in proteins. It can be accessed by url http://203.199.182.73/gnsmmg/databases/aidb/aidb.html.     

Symbionin,an aphid endosymbiont-specific protein—I: Production of insects deficient in symbiont

Pea aphids, Acyrthosiphon pisum, injected with rifampicin gave birth to extremely undersized insects (RF-insects). RF-insects born later were significantly smaller in size than those born earlier by the same parents both at birth and 20 days later. RF-insects never produced progeny. Upon separation of the proteins from 20 days RF-insects, it was demonstrated that these insects neither contained nor synthesized symbionin, a protein synthesized by the endosymbiont of the aphid. Gel electrophoresis of RNA from RF-insects suggested that no ribosomal RNA species of the endosymbiont was present. Based on these results, it was concluded that RF-insects do not contain the endosymbiont.     

Aliphatic substituents in place of thymine methyl promote zig-zag character of the poly(dA-dT)·poly(dA-dT) backbone

This work compared circular dichroism and phosphorus n.m.r. of poly(dA-dU)·poly(dA-dU), poly(dA-dT)·poly(dA-dT), poly(dA-ethyl⁵dU)·poly(dA-ethyl⁵dU), and poly(dA-butyl⁵dU)·poly(dA-butyl⁵dU) at low-salt and in concentrated caesium chloride and caesium fluoride solutions. It is demonstrated that growing bulk of the substituent increases the conformationl anomaly residing in the purine(3′–5′)pyrimidine steps while the backbone is less affected in the pyrimidine (3′–5′)purine steps. As the length of the substituent increases, conformation of the polynucleotides alters more dramatically at increasing concentrations of caesium cations. At high CsF concentrations, all the polynucleotides adopt a novel conformer which we call X-DNA and its formation is promoted by larger substituents. The X-DNA conformation of poly(dA-butyl⁵dU)·poly(dA-butyl⁵dU) gives two phosphorus n.m.r. resonances separated as much as in the case of the left-handed zig-zag Z-DNA double helix of poly(dG-dC)·poly(dG-dC) but X-DNA and Z-DNA differ qualitatively by an opposite dinucleotide repeat. Phosphorus n.m.r. spectra of poly(dA-dT)·poly(dA-dT) and poly(dA-butyl⁵dU)-poly(dA-butyl⁵dU) differ quantitatively at high CsF concentrations, which may reflect conformational variability of the X-DNA backbone. Poly(dA-butyl⁵dU)·poly(dA-butyl⁵dU), but not poly(dA-ethyl⁵dU)·poly(dA-ethyl⁵dU) and the related polynucleotides with shorter substituents in position 5 of uracil, exhibits one more reversible transition at very high caesium fluoride concentrations. It is accompanied by polynucleotide associations and has a slow kinetics. This transition may involve one more radical change in the double helix architecture from X-DNA into another conformation.     

The Comstockiella system of chromosome behavior in the armored scale insects (Coccoïdea: Diaspididae)

Summary The Comstockiella chromosome system occurs in the armored scale insects and the closely allied palm scales. During development of the males, the paternal chromosome set becomes heterochromatic and remains so until spermatogenesis. With the exception of one chromosome, the heterochromatic complement loses its differential aspect during early spermatogenesis and its members pair with their euchromatic homologues There is but one division during which the two components of each bivalent separate to opposite poles. Both division products form sperm.One pair of chromosomes, the D pair, always shows differential behavior. The D pair usually does not form a bivalent. The heterochromatic homologue, D^H, divides equationally and is eliminated by anaphase lagging or telophase ejection; its daughter halves remain as pycnotic residues during the early phases of spermiogenesis. The euchromatic homologue, D^E, also divides equationally to contribute to both of the telophase nuclei. Compensation for the division of the D^E univalent may occur during either the early or late phases of spermatogenesis.In some species the D pair is a fixed entity, analogous to the sex chromosomes in this regard. In other species, more than one pair may be elected to the D role, but only one at a time, and always the same one within each cyst.Taxonomic evidence indicates the Comstockiella system was derived from the lecanoid system, previously known from the work of the Schraders and others. In the lecanoid system, the paternally derived heterochromatic set divides equationally, along with the euchromatic set, during the first spermatogenic division. During the second spermatogenic division, the two sets are segregated from each other. The two euchromatic derivatives form sperm while the heterochromatic derivatives persist for a while as pycnotic residues. Both the lecanoid and Comstockiella systems occur in some species often in the same testis, but only one of the two systems within any one cyst.The discussion is devoted to an analysis of the mode of inheritance expected in the Comstockiella system and its evolutionary derivation. The Comstockiella system may have been derived in a step-by-step fashion from the lecanoid. The two systems differ by four processes which occur at spermatogenesis in the Comstockiella but not the lecanoid system; these are (1) deheterochromatization, (2) chromosome pairing, (3) compensation for the extra division of the D^E chromosome, and (4) lagging or ejection to eliminate the D^H chromosome.In addition, the residual genetic effects of the heterochromatic set may have undergone considerable change before the lecanoid system could evolve into a Comstockiella. Once the evolutionary step were otherwise possible, mechanistic features would aid and abet the emergence of the new system even though it lacked immediate selective advantage.The variable-D aspect of some examples of the Comstockiella system cannot be readily understood in terms of known examples of chromosome behavior; an admittedly highly speculative hypothesis is offered in an attempt to explain the situation.The diaspidid system, in which the paternal chromosomes are eliminated at late cleavage, is believed on taxonomic grounds to have stemmed from the Comstockiella, and forms the final stage of the four-step evolutionary sequence. Necessary changes for the derivation of the diaspidid system from the Comstockiella are discussed.This work was begun during the tenure of a Guggenheim Memorial Fellowship, 1956–57, and has subsequently been supported in part by grants from the National Science Foundation (G-4497 and G-9772).     

Exopolysaccharide (EPS) synthesis in Bradyrhizobium japonicum : sequence, operon structure and mutational analysis of an exo gene cluster

The nucleotide sequence of a 8330-bp DNA fragment from Bradyrhizobium japonicum 110spc4 was determined. Sequence analysis revealed that six ORFs were present and the deduced amino acid sequences were homologous to enzymes involved in exopolysaccharide (EPS) biosynthesis. The genes appear to be organized into at least four different operons. One gene was found to be homologous to exoB, which encodes a UDP-galactose 4′-epimerase. Other ORFs were homologous to UDP-hexose transferases and one ORF showed similarity to Sinorhizobium (Rhizobium) meliloti ExoP, which has been suggested to be involved in EPS chain-length determination. A set of deletion and insertion mutants was constructed and the resulting B. japonicum strains were tested for their symbiotic traits. Deletion mutant ΔP22, which lacks the C-terminal part of ExoP, the UDP-hexose transferase ExoT and the N-terminal part of ExoB, shows a delayed nodulation phenotype and induces symptoms of plant defense reactions; its EPS does not contain galactose and no high molecular weight fraction is synthesized. In contrast, insertion mutant EH3, which expresses an exoP gene product that is truncated in its putative periplasmic domain, produced an EPS containing both HMW and LMW fractions. However, the interaction of EH3 with soybeans was severely perturbed. As a rule, only the initial steps of nodule formation were observed.     

Diversity of social wasps (Hymenoptera: Vespidae) in Cerrado fragments of Uberlândia, Minas Gerais State, Brazil

Studies of species survey are important to know the available natural resources and to get useful information about the ecological characteristics of a specific area. There are not studies, on this issue, related to social wasps, in the Triangulo Mineiro region. The present study describes the diversity of species found in fragments of the cerrado region in Uberlandia, MG, and their temporal distribution. The field study was conducted from October 2003 to September 2004, and 43 samplings were carried out using active searching (24) and point sampling (19) methodologies. Twenty-nine species were found in 10 genera, Polybia and Polistes corresponding to 51.5% of the total listing. Mischocyttarus cerberus styx Richards represented 26.5% of the total individuals recorded by active searching and Agelaia pallipes (Olivier) corresponded to 57.6% by point sampling. Two species had their first record for the state of Minas Gerais: Polybia striata (Fabricius) and M. cerberus styx. The studied fragments presented a high level of diversity (H' = 0.66 to 1.16), a large number of rare species and a few common species. To collect the more common species the point sampling method was satisfactory while active searching was better to collect the rarer species. The active searching methodology was more efficient than point sampling, however some species could only be collected by point sampling. These factors showed that in order to carry out a wasp survey, a combination of different collection methodologies seems to be more appropriate.     

New distribution and host records of chalcidoid parasitoids (Hymenoptera: Chalcidoidea) of scale insects (Hemiptera: Coccoidea) in Espírito Santo,Brazil

Three species of chalcidoid parasitoids of scale insects are recorded for the first time in Brazil: Adelencyrtus moderatus, Homalopoda sp., and Diglyphomorpha sp.; and new parasitoid–host associations are recorded between the chalcidoids Encarsia lounsburyi with Hemiberlesia palmae, Encarsia lounsburyi with Melanaspis smilacis, and Diglyphomorpha sp. with Dysmicoccus brevipes.     

Ultrastructure of the dendritic outer segments of sensory cells in poreless (‘no-pore’) sensilla of insects

Summary Poreless sensilla with inflexible sockets in insects presumably house hygro- and thermoreceptors (type-1, type-2 receptors). The dendritic outer segments of these receptor cells were studied mainly in cryofixed antennae of two species of moth (Antheraea pernyi, A. polyphemus) and one beetle (Aleochara curtula). As a rule two type-1 receptor cells are present. Their dendritic outer segments do not branch. They project into the distal cuticular parts of the sensillum and are in close contact with its four-layered wall. The segments differ in shape and microtubule density. As well, in A. curtula, the microtubules are interconnected by electron-dense material for some distance, thus forming a tubular body-like structure of 1.3 m length. The dendritic outer segment of the single type-2 receptor cell is branched and lamellated. Its lamellae are connected by structures similar to septate junctions, which occupy about 70% of the total surface of the lamellated portion of the dendrite. In tangential sections, the septa appear as parallel strands approximately perpendicular to the long axis of the dendritic segment. The structure of type-1 receptors is discussed with regard to the hypothesis for a mechano-electrical transduction. The possible functions of lamellation and junctional connections in type-2 receptors are discussed.Supported by the Deutsche Forschungsgemeinschaft (SFB 4/G1)     

Bamboo flowers visited by insects: do insects play a role in the pollination of bamboo flowers?

Relatively little is known about pollination and other aspects of the reproductive biology of bamboos, but wind pollination is assumed to be the rule, at least in woody bamboos. Documenting the reproductive biology of woody bamboos is a complex task due to the long periods of time between flowering cycles, which range from 3 to 120 years. Insects visiting Guadua paniculata and G. inermis flowers were collected in the field. Scanning electron micrographs were taken of the visiting insects. Four species of bees, three from tribe Meliponini (Geotrigona acapulconis, Plebeia frontalis and Trigona fulviventris) and one from tribe Apini (Apis mellifera), along with a syrphid fly (Toxomerus teligera) were found visiting bamboo flowers. Some species of Hemiptera were also found feeding on the flowers, such as Neortholomus jamaicensis (Lygaeidae), or preying on the flower visitors (Apiomerus pictipes (Reduviidae)). Insects visiting bamboo inflorescences may facilitate the release of pollen grains into the air, promoting outcrossing and genetic flow among the individuals of the flowering bamboo populations.     

Nesting biology of Asian paper wasps Polistes chinensis antennalis Pérez,and Australian paper wasps P. humilis (Fab.) (Hymenoptera: Vespidae) in northern New Zealand

Abstract

We recorded the numbers of cells, and where possible distinguished between cells containing pupating larvae and vacated cells, from 585 paper wasp nests from the northern North Island, New Zealand, plus nest site characteristics of 540 of these nests. Nests of Polistes chinensis antennalis and P. humilis developed at similar rates in early summer. P. c. antennalis nests were larger at the Post‐emergence stage than those of P. humilis, and contained more vacated cells but less capped cells. All of the P. c. antennalis nests had reached the Post‐emergence stage by February in Northland, but not in the other regions. P. c. antennalis nests in the Post‐emergence stage were larger in Northland than further south, and contained the most capped or vacated cells. Nests of both species were usually found in northern‐facing sites. Substrate did not affect nest size. Differences between the species in nest sites included greater use of manmade structures by P. c. antennalis; the use of leaves by P. humilis only; and a higher average nest site height in P. humilis. These differences in nest site selection may reduce competition between the species.     

Functional diversity of phyllostomid bats in an urban–rural landscape: A scale-dependent analysis

Urbanization is one of the most pervasive processes of landscape transformation, responsible for novel selection agents promoting functional community homogenization. Bats may persist in those environments, but the mechanisms responsible for their adaptability and the spatial scales in which the landscape imposes environmental filtering remain poorly studied in the Neotropics. We tested the hypothesis that landscape composition interacts with the spatial scale to affect the functional diversity of phyllostomids in an urban–rural gradient. Based on functional traits, we calculated indices of functional richness, divergence, evenness, and community-weighted means of morphological traits, and classified species into functional groups. We evaluated the changes in those variables in response to forest, grassland, and urbanized areas at 0.5, 1.25, and 2km scales. The number of functional groups, functional richness, and functional evenness tended to be higher in areas far from cities and with higher forest cover, whereas functional divergence increased in more urbanized areas. Our results show that the mean value of wing loading in the assemblage was negatively associated with landscape transformation at several spatial scales. However, environmental filtering driven by grass cover was particularly robust at the 0.5km scale, affecting big-sized species with long-pointed wings. Retaining natural forest in cattle ranging systems at ~12 km² appears to favor the functional evenness and number of functional groups of phyllostomids. Recognizing the scale of the effect on phyllostomid functional responses appears to be a fundamental issue for elucidating the spatial extent to which phyllostomid conservation planning in urban–rural landscapes should be addressed.     

Identification and functional analysis of an ovarian form of the egg activation factor phospholipase C zeta (PLCζ) in pufferfish

Recent studies suggest that egg activation in mammals is triggered by a sperm-specific phospholipase C, PLCzeta. In other vertebrate species such as medaka fish, chickens, and quail, PLCzeta is also expressed as a testis-specific mRNA. Functional studies suggest that PLCzeta plays a similar role as a trigger of egg activation in these species. Here, we report the identification of PLCzeta orthologues in pufferfish species Takifugu rubripes (Fugu) and Tetraodon nigroviridis (Tetraodon). Unexpectedly in these species PLCzeta is expressed not in the testis, but in ovary and brain. Injection of pufferfish PLCzeta copy ribonucleic acid (cRNA) into mouse eggs failed to trigger calcium oscillations, unlike medaka PLCzeta cRNA. Our findings provide the first evidence that PLCzeta may be expressed in the egg, rather than the sperm, in some vertebrate species, and that its mechanism of action and physiologic role at fertilization may differ in different vertebrate species.     

Molecular analysis of the major cellulase (CelV) of Erwinia carotovora: evidence for an evolutionary “mix-and-match” of enzyme domains

The structural gene for the major cellulase of Erwinia carotovora subspecies carotovora (Ecc) was isolated and expressed in Escherichia coli. Sequencing of the gene (celV) revealed a typical signal sequence and two functional domains in the enzyme; a catalytic domain linked by a short proline/threonine-rich linker to a cellulose-binding domain (CBD). The deduced amino acid sequence of the catalytic domain showed homology with cellulases of Family A, including enzymes from Bacillus spp. and Erwinia chrysanthemi CelZ, whereas the CBD showed homology with cellulases from several diverse families, supporting a “mix-and-match” hypothesis for evolution of this domain. Analysis of the substrate specificity of CelV showed it to be an endoglucanase with some exoglucanase activity. The pH optimum is about 7.0 and the temperature optimum about 42°C. CelV is secreted by Ecc and by the taxonomically related Erwinia carotovora subspecies atroseptica (Eca) but not by E. coli. Overproduction of the enzyme from multicopy plasmids in Ecc appears to overload the secretory mechanism.     

Five decades of tick–man interaction in Denmark – an analysis

The tick Ixodes ricinus (L.) is a known vector of several zoonotic diseases such as Tick Borne Encephalitis (TBE), Lyme borreliosis and ehrlichiosis. The interaction between humans and ticks are at the very core of our understanding of the epidemiology of tick borne zoonoses, but only few experimental studies have been performed. Hence our understanding of the epidemiology of tick-borne disease has to rest on the assumption that the potential tick activity, which is reflected in tick samples from the vegetation or samples from animals, corresponds with tick–human interaction. Observations which may reflect the long term tick–human contact are available in Denmark. These observations are records of requests for information on I. ricinus forwarded to the Danish Pest Infestation Laboratory (DPIL). This article was based on the assumption that the request could be seen as a measure of tick–human interaction reflecting the tick densities in relative terms. The perceived tick densities given by the number of requests on I. ricinus divided by the total number of requests to DPIL was fairly stable from 1965 to 1985, while it doubled during the late 1980s reaching a higher level in the beginning of the 1990s. The perceived density was well explained by the variation in temperature, solar radiation (monthly measurement) and deer abundance (yearly assessments). The measure of deviation, i.e. the ratio between observed requests +1 and modelled requests +1, for the individual years varied between 0.91 and 1.20, with considerable within-year variation. A gradual change in periodicity of the residual might suggest gradually changing tick population dynamics. In conclusion, the perceived tick densities appear to be consistent with the current knowledge of tick ecology and tick-transmitted diseases.This revised version was published online in May 2005 with a corrected cover date.     

New Middle Permian insects from Salagou Formation of the Lodève Basin in southern France (Insecta: Pterygota)

Summary

New insects are described from the Middle Permian (Guadalupian) of Salagou Formation in the Lodève Basin (Languedoc region, France). Palaeopterans are represented by new odonatopterans viz. Huangiopterum lodevense n. gen., n. sp. and Huangiopterum species B, attributed to clade Panodonata (Huangiopteridae n. fam.), already recorded through the family Saxonagrionidae in the same formation, and a diaphanopterodean Martynovia cf. halli Beckemeyer 2004 (Martynoviidae) known from the Lower Permian of Oklahoma. Archaeorthopterans are supplemented by Bethouxia ariegensis n. gen., n. sp., Paralongzhua elongata n. gen., n. sp., Lodevolongzhua incompleta n. gen., n. sp., the caloneurodean Jarmiloptera mouralensis n. gen., n. sp., and a cnemidolestodean cf. Tococladus sp. (Tococladidae). Permophyllum rotundatum n. sp. (?Tettigoniidae) demonstrates the first presence of Orthoptera with wings probably mimicking Peltaspermales reproductive organs in Late Palaeozoic possibly analogous to the known crypsis of roachoid tegmina with pteridosperm pinnules. Frequent occurrence of hardly identifiable grylloblattid wing fragments support their significant role in term of abundance and diversity of the Permian faunas. New taxa based on wing venation pattern as Genera and species undetermined A, B (Liomopteridae), Permobaharellus salagousensis n. gen., n. sp. (family uncertain), Lodevophlebia reticulata n. gen., n. sp. (Sylvaphlebiidae), Oborella lodevensis n. sp. (Euryptilonidae), and Genus and species undetermined C, were described. Paoliida is represented by a paoliid gen. et sp. indet. and three anthracoptilids Strephocladus gandi n. sp., Strephocladus mouralensis n. sp., Lodevocladus subtilis n. gen., n. sp. The first record of miomopteran Palaeomantis sp. (Paleomanteidae) from Salagou Formation is presented. Acercarian insects are represented by the first record of Thripida and diverse new hemipterans, namely Euroscytina lutevanorum n. gen., n. sp. (Cicadomorpha: Scytinopteridae), Prosbole dio n. sp., Prosbole garrici n. sp., Pervestigia cf. veteris Becker-Migdisova 1961 (Prosbolidae), Archescytina species A (Paleorrhyncha: Archescytinidae) and Permopsyllidium lesclansis n. sp. (Sternorrhyncha: Psylloidea: Protopsyllidiidae). Entomofauna from the Salagou Formation demonstrate highly diverse insect communities with some taxa linked to early and late Permian ones known from assemblages in Euramerica and Russia, such as Obora (Czech Republic), Wellington Formation (Kansas and Oklahoma, USA), and Tshekarda (Ural, Russia).     

Dufour’s gland possible role in the evolution of sting morphology and function in hover wasps (Hymenoptera Stenogastrinae)

The sting is the most effective defense of social Hymenoptera against vertebrate predators but in the hover wasps (subfamily Stenogastrinae) it is scarcely used. In these wasps a quite enlarged Dufour’s gland and the extensive use of its secretion in the peculiar rearing of the larvae and defense determined important morphological modifications of the sting structure. Connecting anatomical and morphological data with behavioral observations we determined that in these wasps the Dufour’s gland secretion is attached to the egg during oviposition but can be also channeled to the outside via the sting when it is collected by adult females for larval rearing or construction of the nest ant guards. The anatomical modifications of the sting reduced the function of the sting as a defensive weapon in hover wasps.