Tripius gyraloura n. sp. (Aphelenchoidea: Sphaerulariidae) parasitic in the gall midge Lasioptera donacis Coutin (Diptera: Cecidomyiidae)

A new nematode, Tripius gyraloura n. sp., is described from the arundo gall midge, Lasioptera donacis Coutin (Diptera: Cecidomyiidae). This gall midge is being considered as a biological control agent for use in North America against the introduced giant reed Arundo donax (L.) (Poaceae: Cyperales). Thus the present study was initiated to investigate a nematode parasite that was unknown at the time studies with L. donacis were initiated. The new species has a rapid development in the fly host and the mature parasitic female nematodes evert their uterine cells in the hosts’ hemolymph. Because large numbers of nematodes sterilise the host, eradication of the parasite from laboratory colonies of the midge may be necessary before populations of the fly are released.     

中国钩瘿蚊属分类研究(双翅目,瘿蚊科)

记述了中国鼓瘿蚊亚科钩瘿蚊属7种,其中2种:长角钩瘿蚊C.longicornis sp.nov.(模式产地:陕西凤县)、背折钩瘿蚊C.retrorsa sp.nov.(模式产地:云南屏边)为科学上的新种,另外5种:美丽钩瘿蚊C.formosa(Bremi)(分布:湖南、云南、吉林),日本钩瘿蚊C.mpponensis Yukawa(分布: 甘肃、四川、湖北),尖瓣钩瘿蚊C.hamata (Felt) (分布:湖南、贵州),狭眼钩瘿蚊C.neueitasis (Zetterstedt)(分布:甘肃)和锯齿钩瘿蚊C.serrata Yukawa (分布:陕西、甘肃、福建)为中国新纪录种.编制了钩瘿蚊属中国已知种种类检索表.模式标本保存于南开大学生物系昆虫标本室.     

Effect of surface-screening parameter of the Yukawa potential model on vapour–liquid phase coexistence and critical-point properties of confined Yukawa fluid

We report the effect of surface-screening parameter of Yukawa potential model on vapour–liquid phase coexistence and critical-point properties of slit–pore-confined Yukawa fluid, using grand canonical transition-matrix Monte Carlo along with the histogram reweighting method. The effect of surface-screening parameter on the vapour–phase coexistence density is insignificant for the studied system. On the other hand, significant effect of surface-screening parameter is observed on liquid phase coexistence density. With increasing surface-screening parameter, liquid phase coexistence density decreases. Critical-point properties have shown monotonic decreasing trends with increase in surface-screening parameter. Moreover, the effect of change of surface-screening parameter is least on critical temperature changes as compared to critical density and critical pressure changes for the studied Yukawa system in this work.     

Sex-biased herbivory in Ephedra trifurca: the importance of sex-by-environment interactions

We examined patterns of herbivory in the dioecious desert shrub, Ephedra trifurca (Ephedraceae), along a small watershed in the northern Chihuahuan Desert. We documented significant (p=0.002) sexual dimorphism in densities of Lasioptera ephedrae and L. ephedricola (Diptera: Cecidomyiidae), with male E. trifurca supporting higher densities than did females. Densities of gall midges varied significantly (p<0.001) among four sample populations of E. trifurca arrayed along the watershed and exhibited an inverse gradient with elevation. There was also a significant (p=0.006) sex-by-site interaction such that the degree of intersexual variation in gall densities decreased down the watershed. Variation in gall densities and intersexual variation in gall densities exhibited inverse trends with variation in soil water and inorganic nitrogen concentrations along the watershed.     

Sensilla and Cuticular Appendages on the Female Abdomen of Lasioptera rubi (Schrank) (Diptera,Cecidomyiidae)

Studies by SEM and TEM revealed 6 types of integumental appendages on female uromeres VIII-X in Lasioptera rubi: microtrichia, not innervated; spines, probably without sensory function; nonporous sensory hairs, each containing one dendrite ending with a tubular body indicating a tactile function; uniporous sensory hairs, each innervated partly by 3 dendrites indicating a chemosensory function, partly by an additional dendrite with a tubular body indicating a tactile function; scoop-like sensilla, each containing partly a branched structure of dendrites in the distal half of the sensillum indicating an olfactory function, partly an unbranched dendrite ending at a pore near the base of the sensillum, most probably registrating chemical stimuli by contact or gustation; finally, nonporous bristles, all or some of them innervated, in a manner indicating a tactile function. In addition, two scolopophorous proprioceptors were found inside uromere X. The nonporous sensory hairs, the uniporous sensory hairs and the scolopophores may be used by the midge to determine the mechanical and chemical properties of potential oviposition sites. The spines and nonporous bristles may function as conidia carriers.     

Host range of the European leaf sheath mining midge,Lasioptera donacis Coutin (Diptera: Cecidomyiidae), a biological control of giant reed,Arundo donax L.

The fundamental host range of the arundo leafminer, Lasioptera donacis a candidate agent for the invasive weed, Arundo donax was evaluated. L. donacis collects and inserts spores of a saprophytic fungus, Arthrinium arundinis, during oviposition. Larvae feed and develop in the decomposing leaf sheath channel tissue. Thirty-six closely related and economic grass species along with several key habitat associates were evaluated in no-choice tests. L. donacis and its associated saprophyte completed development only on A. donax, in concurrence with published reports from its native range in Mediterranean Europe. The arundo leafminer feeding leads to premature defoliation, constituting a different mode of attack on the host plant as compared to two previously released insects, the arundo wasp and arundo scale, which feed on shoot tips and rhizomes, respectively. Defoliation of A. donax is expected to increase light penetration into stands of A. donax which increases visibility for law enforcement, reduces the survival of cattle fever ticks, and enhance recovery of the native riparian vegetation along the Rio Grande and other habitats where this weed is invasive.     

Tropical fruitflies (Diptera: Tephritidae) of the Krakatau Archipelago in 1990 and comments on faunistic changes since 1982

Three of the Krakatau islands, in Sunda Strait, some 40 km from both Java and Sumatra, are believed to have been totally devastated by the famous cataclysmic eruption of 1883. The fourth, Anak Krakatau, is an emergent volcanic island which rose from Krakatau's submerged 1883 caldera in 1930, suffered a self-devastating eruption in 1952/3 and several severely damaging ones since then. In 1990 the tephritid fauna was monitored on all the islands with Steiner traps. Nine species were found, five of which appeared to have been found by Yukawa in 1982 (Yukawa 1984) using similar methods and lures, when he noted a total of six species. As in 1982, the fauna in 1990 was characterized by the numerical dominance ofBactrocera albistrigata (de Meijere) although this appeared to be less marked than in 1982 andBactrocera papayae Drew & Hancock appeared to have increased in relative numbers. The distribution of three species over the islands of the archipelago had increased and four species not found in 1982 were present. Rakata, Krakatau's remnant and by far the largest and highest island, carried seven species (six in 1982), Sertung three (two in 1982), Panjang four (one in 1982) and Anak Krakatau four (one in 1982). Capture rates were lower than in 1982 but still higher than those obtained on the Javan mainland in 1982. There was a marked difference between the tephritid faunas of Anak Krakatau's two forelands, which were at different stages of biotic succession.     

Thermodynamic properties of strongly coupled plasma in the presence of an external magnetic field

Thermodynamic properties of a Yukawa system consisting of dust particles in plasma are studied in the presence of an external magnetic field. It is assumed that dust particles interact with each other by a modified potential in the presence of a magnetic field. A molecular dynamics code is developed to calculate this internal energy for the entire system. Based on the values of the internal energy given by the code, the Helmholtz free energy and pressure are calculated for the system.     

中国异瘿蚊属分类研究(双翅目:瘿蚊科)

记述了中国瘿蚊科1新纪录属异瘿蚊属及一新种：横瓣异瘿蚊Heterogenella transversa.spn.nov.,模式产地云南中甸虎跳峡;中国3新纪录种;达氏异瘿蚊H.dolini Berest(四川理县米亚罗）,短须异瘿蚊H.hybrida Mamaev(内蒙古额尔古纳旗莫尔道嘎）和纵缝异瘿蚊H.linearis Yukawa(云南丽江玉龙山）。文中给出了异瘿蚊属中国已知种类分种检索表。模式标本保存于南开大学生物系昆虫标本室。     

Thermal fluctuations of pair interaction forces in liquid Yukawa systems

The dynamics of charged particles in two- and three-dimensional Yukawa systems is studied using numerical methods. Nonideal systems are simulated in a wide range of their parameters. The density of thermal fluctuations of pair interaction forces in liquid structures is obtained and compared with the internal energy density of the systems under study.     

Kinetic studies on the specificity of chelate-iron uptake in Aspergillus.

Three strains of the fungus Aspergillus, Aspergillus quadricinctus (E. Yuill), A. fumigatus (Fresenius), and A. melleus (Yukawa), each producing different iron-chelating compounds during iron-deficient cultivation, were used for 55Fe3+ uptake measurements. Iron from chelates of the ferrichrome-type family was taken up by young mycelia of all strains tested, irrespective of the ferrichrome-type compound these strains predominantly produce in low-iron cultures. Ferrichrysin-producing strains, however, seem to favor ferrichrysin iron uptake, whereas ferrichrome, ferricrocin, and even ferrirubin showed similar iron transport properties in all of these strains. Compared to iron uptake from ferrichrome-type compounds (Km approximately 4 uM) iron uptake from fusigen revealed completely different kinetic values (Km approximately 50 to 80 muM). Iron from exogenous chelates, e.g., from coprogen produced by Neurospora crassa for ferrioxamine B produced by Streptomyces pilosus, can obviously not be taken up by Aspergillus, confirming the pronounced specificity of chelate-iron transport in fungi.     

Two new species of Torymus Dalman, 1820 (Hymenoptera: Torymidae) parasitizing Celticecis japonica Yukawa and Tsuda, 1987 (Diptera: Cecidomyiidae) that induce leaf galls on Celtis species (Ulmaceae) in Japan

Torymus celticolus Matsuo sp. nov. and Torymus celtidigalla Matsuo sp. nov. (Hymenoptera: Torymidae) are described as parasitoids of larvae of Celticecis japonica Yukawa & Tsuda, 1987 (Diptera: Cecidomyiidae) that induce leaf galls on Celtis species (Ulmaceae) in Japan. A key to species of the genus Torymus known in Japan is provided.     

Further studies on the flowering ofLemna paucicostata in Japan

Flowering behavior of 22 strains ofLemna paucicostata collected in Japan by Yukawa and Takimoto (1976) was re-examined. The critical dark periods of the short-day strains (N-1 and N-2 types) were shorter than those determined by Yukawa and Takimoto except for that of one strain. Particularly in strains 391, 381 and 321, the differences were as large as 2.25, 1.75 and 1.5 hr, respectively. Such differences were found to be due at least partly to the difference in night temperature; 25 C for the light and 23 C for the dark periods in the present experiment, and 25 C throughout the light and dark periods in the previous experiment. The S type strains did not flower under our experimental conditions (fluorescent light of 6,000 lux at 25 C) at any photoperiod tested, but flowered as a quantitative long-day plant under natural daylight or high-intensity light (12,000 lux). Addition of sucrose or ammonium ion to the medium suppressed the flowering of these strains under high-intensity light. Addition of benzoic acid (1–5 μM) to 0.5 strength NH₄ ⁺-free Hutner's medium caused daylength-independent flowering in some N-1 type strains and in all N-2 type strains tested. S type strains cultured under fluorescent light of 6,000 lux also flowered rapidly in response to benzoic acid.     

中国扇瘿蚊属六新种(双翅目,瘿蚊科)

报道了双翅目瘿蚊科中国新纪录属:扇瘿蚊属Rhipidoxylomyia Mamaev 6新种,提出了1新组合:Rhipidoxylomyia concava(Yukawa),comb.nov,编制了扇瘿蚊属世界种类检索表.模式标本保存于南开大学生物系.     

A density functional theory for Yukawa chain fluids in a nanoslit

A weighted density functional theory is developed for Yukawa chain fluids confined in a nanoslit. The excess free-energy functional is separated into repulsive and attractive contributions. A simple Heaviside function is used as the weighting function to calculate the weighted density in both contributions. The excess free-energy functional of repulsive interaction is calculated by the equation of state developed by Liu et al., while the contribution to excess free-energy functional by attractive interaction is calculated using the statistical associating fluids theory for chain molecules with attractive potentials of variable range. For pure fluids, the predicted density profiles near the nanoslit wall are in good agreement with simulations. The effect of cut-off introduced in the weighting function for the attractive part is examined; in addition, the surface excess and partition coefficient are calculated. The density profiles are also predicted for mixtures of two Yukawa chain fluids with different chain lengths, hard-core diameters, fluid–fluid and wall–fluid interactions. This work reveals that it is important to decompose the excess free-energy functional into repulsive and attractive contributions, and a simple weighting function can be used for both contributions.     

Formation Conditions and Stability Criteria for Small-Size Cluster Systems

The formation conditions and stability criteria for small-size cluster systems consisting of several particles interacting via an arbitrary isotropic pair potential are considered. Analytical criteria for instability development in horizontal (quasi-two-dimensional) and vertical (chain) structures consisting of three, four, and five charged particles are obtained for the first time. A simple algorithm to search for similar criteria in systems consisting of a larger number of particles is proposed. The obtained relations are verified by numerically solving the problem for Yukawa systems.     

Direct Determination of Fluid Phase Equilibria by Simulation in the Gibbs Ensemble: A Review

This paper provides an extensive review of the literature on the Gibbs ensemble Monte Carlo method for direct determination of phase coexistence in fluids. The Gibbs ensemble technique is based on performing a simulation in two distinct regions in a way that ensures that the conditions of phase coexistence are satisfied in a statistical sense. Contrary to most other available techniques for this purpose, such as thermodynamic integration, grand canonical Monte Carlo or Widom test particle insertions, the Gibbs ensemble technique involves only a single simulation per coexistence point. A significant body of literature now exists on the method, its theoretical foundations, and proposed modifications for efficient determination of equilibria involving dense fluids and complex intermolecular potentials. Some practical aspects of Gibbs ensemble simulation are also discussed in this review. Applications of the technique to date range from studies of simple model potentials (for example Lennard–Jones, square-well or Yukawa fluids) to calculations of equilibria in mixtures with components described by realistic potentials. We conclude by discussing the limitations of the technique and potential future applications.     

Application of the tryptophanase promoter to high expression of the tryptophan synthase gene inEscherichia coli

Summary The application of an inducible regulation system using the trytophanase operon promoter (TPase promoter; P_tna) was examined for its high expression of the tryptophan synthase (TS) gene in Escherichia coli. The main problem in the application of P_tna for industrial purposes is catabolite repression by glucose, since glucose is the most abundant carbon source. However, this problem could be avoided by changing glucose to an organic acid, such as succinate, fumarate, malate and acetate, in the course of cultivation after glucose initially added was completely consumed. Under these conditions, l-tryptophan was also used to induce tryptophan synthase. Thus, the specific activity of TS in E. coli strain no. 168 harbouring pBR322F-P_tnaTS was increased 500-fold compared to that of the cultured host strain. About 1 mol l-tryptophan/l reaction mixture was formed from indole and l-serine at 37° C for 3.5 h. Offprint requests to: H. Yukawa     

Stem-boring insects of fragmented Calamagrostis habitats: herbivore–parasitoid community structure and the unpredictability of grass shoot abundance

Abstract.1. Communities of stem-boring insects attacking the grass Calamagrostis epigeios (L.) Roth were analysed from twenty-five pure stands of C. epigeios differing in area and isolation. Insect communities comprised nine phytophagous and eighteen entomophagous species. Most abundant herbivores (attacking > 1% of all shoots) were Tetramesa eximia (Giraud) (Hym. Eurytomidae), Eurytoma sp. (Hym. Eurytomidae), Lasioptera calamagrostidis (Rübs.) (Dipt. Cecidomyiidae), and Eriopeltis sp. (Hom. Pseudococcidae). About 28% of the twenty-seven species were monophagous, 61% oligophagous (restricted to Poaceae), and 11% polyphagous. Although herbivores generally attacked thick shoots, species-specific differences in the attacked mean diameter were found.2. The main purpose of this study was to analyse the relative effects of area, isolation and unpredictability of available food resources on the abundance of herbivores, parasitoids and resulting tritrophic effects. Variability of shoot abundance varied greatly between years, and even more between habitats within the same year. On average, shoot density per habitat increased or decreased 2.4-fold between succeeding years.3. Variability of grass shoot abundance was not related to habitat characteristics such as area, isolation, biomass, shoot density, changes in area or shoot density between years, or shoot features like internode number or diameter, but was negatively influenced by shading of trees. Similarly, habitat area or isolation did not correlate with other habitat features.4. Grass shoot abundance was the most important predictor of species abundance and attack rate of herbivores. In contrast to expectations, area and isolation of habitats did not explain differences in species richness, and only influenced abundance of three species. In addition, even the experimental removal of all grass shoots (and thereby, of all stem-boring insects) from five habitats in winter did not negatively influence colonization the following year. These results suggest a surprisingly high mobility of this rather specialized community of stem-boring insects that appeared to superimpose on area and isolation effects. Unpredictability of grass shoot abundance was presumably the main selection pressure for the obviously high dispersal abilities of the Calamagrostis insects.5. Per cent parasitism was mainly influenced by the percentage of attacked shoots. Parasitism of T. eximia by its major parasitoid also correlated with habitat connectivity, emphasizing the hypothesis that a continuum of habitats should be particularly favourable for the third trophic level.