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Gudrun Strauss 《BioControl》2009,54(2):163-171
Neodryinus typhlocybae (Ashmead) (Hymenoptera: Dryinidae) is a natural enemy of the planthopper Metcalfa pruinosa (Say) (Hemiptera: Flatidae), introduced from North America into Europe and regionally established as a pest species. Prior to possible utilization of the parasitoid as a biocontrol agent in Austria, its potential negative impacts on eight native plant- and leaf-hopper species were examined in the laboratory. Non-target species were selected according to the following criteria (a) occurrence in Austria, (b) close phylogenetic relationship with M. pruinosa, (c) larvae free-living and surface-dwelling, (d) phenology, (e) larval size, (f) ecological similarity with M. pruinosa and (g) availability of sufficient numbers of individuals. The Auchenorrhyncha species Issus coleoptratus (Fabricius), Chloriona smaragdula (Stål), Conomelus anceps (Germar), Alebra wahlbergi (Boheman), Empoasca sp., Idiocerus stigmaticalis (Lewis), Macrosteles septemnotatus (Fallén) and Japananus hyalinus (Osborn) were chosen for testing. Larvae from both the target and the non-target species were offered separately to N. typhlocybae females in no-choice laboratory tests and all attacks, instances of host feeding and parasitizations were recorded. No non-target species was attacked, fed upon or parasitized by N. typhlocybae, whereas M. pruinosa was attacked frequently. This study supports the assumption that the host range of N. typhlocybae is restricted to Flatidae, of which only the introduced species occurs in Austria. Direct negative effects on other Auchenorryncha species in Austria are therefore unlikely to occur. 相似文献
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Methanogens growing on C-1 substrates synthesize 2-carbon acetyl groups in the form of acetyl-CoA for carbon assimilation
using the multienzyme complex acetyl-CoA decarbonylase/synthase (ACDS) which contains five different subunits encoded within
an operon. In species growing on acetate ACDS also functions to cleave the acetate C-C bond for energy production by methanogenesis.
A number of species of Methanosarcina that are capable of growth on either C-1 compounds or acetate contain two separate ACDS operons, and questions have been
raised about whether or not these operons play separate roles in acetate synthesis and cleavage. Methanosarcina thermophila genomic DNA was analyzed for the presence of two ACDS operons by PCR amplifications with different primer pairs, restriction
enzyme analyses, DNA sequencing and Southern blot analyses. A single ACDS operon was identified and characterized, with no
evidence for more than one. MALDI mass spectrometric analyses were carried out on ACDS preparations from methanol- and acetate-grown
cells. Peptide fragmentation patterns showed that the same ACDS subunits were present regardless of growth conditions. The
evidence indicates that a single form of ACDS is used both for acetate cleavage during growth on acetate and for acetate synthesis
during growth on C-1 substrates.
Electronic Supplementary Material Supplementary material is available for this article at
相似文献
David A. Grahame (Corresponding author)Email: |
Edward DeMoll (Corresponding author)Email: |
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Tomato is the most important vegetable crop in Spain. The mirid bug Nesidiocoris tenuis (Reuter) commonly appears in large numbers in protected and open-air tomato crops where little or no broad-spectrum insecticides
are used. Nesidiocoris tenuis is known to be a predator of whiteflies, thrips and several other pest species. However, it is also considered a pest because
it can feed on tomato plants, causing necrotic rings on stems and flowers and punctures in fruits. Our objectives were to
evaluate predation by N. tenuis on sweetpotato whitefly Bemisia tabaci Gennadius under greenhouse conditions and establish its relationship to N. tenuis feeding on tomato. Two different release rates of N. tenuis were compared with an untreated control (0, 1 and 4 N. tenuis plant−1) in cages of 8 m2. Significant reductions of greater than 90% of the whitefly population and correspondingly high numbers of N. tenuis were observed with both release rates. Regression analysis showed that necrotic rings on foliage caused by N. tenuis were best explained by the ratio of B. tabaci nymphs:N. tenuis as predicted by the equation y = 15.086x − 0.6359.
相似文献
Alberto UrbanejaEmail: |
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Sub-Antarctic Marion Island has had a permanent research station for 50 years and the islands Wandering Albatrosses have been intensively studied for 20 years. The reactions of breeding birds to approaches by a human on foot were recorded. Three response variables were calculated: intensity of vocal reaction (IVR), intensity of non-vocal reaction (INR) and overall response index (ORI). At 5 m from the nest, twice as many birds stood and/or vocalised as at 15 m. Nearest neighbour distance, age and gender did not explain individual variability of responses. Study colony birds had higher IVR scores than non-study colony birds; birds at colonies closest to the station had the highest ORI scores. A better breeding record was associated with lower IVR and ORI scores, but a causative relationship remains to be demonstrated. A minimum viewing distance of 25 m is recommended for breeding Wandering Albatrosses.
相似文献
Marienne S. de VilliersEmail: Fax: +27-21-6503434 |
John CooperEmail: |
Peter G. RyanEmail: |
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Alison M. Strange Geoffrey H. Griffiths Sophie Hine Kim Young Graham J. Holloway 《Journal of Insect Conservation》2007,11(3):241-249
The Small Red Damselfly (Ceriagrion tenellum) (De Villiers) (Odonata: Coenagrionidae: Ceriagrion) is classed as vulnerable (Shirt, British Red Data Book, Nature Conservancy Council, Peterborough, UK, 1987) throughout the
UK, and is included in certain Local Biodiversity Action Plans (LBAPs) in the south. A large proportion of any Biodiversity
Action Plan is concerned with the requirement of conservation and management programmes. In order to guide them, information
about the habitat preferences of the species concerned is vital. Detailed habitat information was collected to include a variety
of physical parameters particularly vegetation, both in-channel and bankside. The species was found to be primarily associated
with in-channel emergent broad-leaved plants, bankside grasses and rushes, and shallow, narrow channels with dark organic
substrate. The consequences of these findings are discussed in relation to the conservation and management of C. tenellum.
相似文献
Alison M. StrangeEmail: |
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M. Irfan-Ullah Giriraj Amarnath M. S. R. Murthy A. Townsend Peterson 《Biodiversity and Conservation》2007,16(6):1917-1925
Aglaia bourdillonii is a plant narrowly endemic to the southern portion of the Western Ghats (WG), in peninsular India. To understand its ecological
and geographic distribution, we used ecological niche modeling (ENM) based on detailed distributional information recently
gathered, in relation to detailed climatic data sets. The ENMs successfully reconstructed key features of the species’ geographic
distribution, focusing almost entirely on the southern WG. Much of the species’ distributional potential is already under
protection, but our analysis allows identification of key zones for additional protection, all of which are adjacent to existing
protected areas. ENM provides a useful tool for understanding the natural history of such rare and endangered species.
相似文献
M. Irfan-UllahEmail: Email: |
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Brad E. Erisman Jorge A. Rosales-Casián Philip A. Hastings 《Environmental Biology of Fishes》2008,82(1):23-33
The sexual pattern and sexual development of the leopard grouper, Mycteroperca rosacea, were investigated from 483 specimens collected from the Gulf of California, Mexico. Histological and population data indicated
a gonochoric sexual pattern. Some juveniles passed through an immature bisexual phase of gonadal development, but no evidence
of post-maturational sex change was found. The immature bisexual phase is believed to be associated only with male development.
The size distribution and size at sexual maturity were similar for both males and females. In accordance with predictions
of the size-advantage model, the gonochoric sexual pattern of M. rosacea is likely influenced by its group-spawning mating system.
相似文献
Brad E. ErismanEmail: |
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Richard J. Robins Roland Molinié Renata A. Kwiecień Piotr Paneth Jacques Lebreton Trixie A. Bartholomeusz Albrecht Roscher Birgit Dräger Anna-Carolin Meier François Mesnard 《Phytochemistry Reviews》2007,6(1):51-63
The reaction of N-demethylation plays an important role in the degradation of some alkaloids in a number of organisms. This review presents
how our understanding of the N-demethylation of nicotine in plants has been improved through studies in cell cultures of Nicotiana plumbaginifolia and N. glutinosa using a variety of isotopic techniques. The overall aim is to understand how metabolism recycles the alkaloid skeleton, both
in terms of the metabolic route(s) exploited and the reaction mechanisms of the enzymes involved. The former has been approached
using high-resolution 2-dimensional NMR and GC-MS methods; the latter by determining kinetic isotope effects and modelling
the potential reaction steps. It appears that the mechanism for nicotine demethylation in plants is similar to but has significant
differences from that described for mammals and Pseudomonas bacteria. These differences are discussed.
相似文献
Richard J. RobinsEmail: |
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Mycena aphanes and Mycena exilis, belonging to section Filipedes and section Polyadelphia, are proposed as new species. They are described and illustrated and compared to other species in the two sections. Mycena aphanes is a strikingly characteristic Mycena with fulvous or yellowish brown colours of both pileus and stipe. Mycena exilis is characterized by its occurrence on fallen Salix leaves, a pale brown pileus, occasionally with a pale pink tinge, narrowly adnate lamellae, four-spored basidia, and the
presence of clamp connections.
相似文献
Gro GuldenEmail: |
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This paper introduces a threshold policy with hysteresis (TPH) for the control of one-predator one-prey models. The models studied are the Lotka–Volterra and Rosenzweig–MacArthur
two species density-dependent predator–prey models and the Arditi–Ginzburg nondimensional ratio-dependent model. The proposed
policy (TPH) changes the dynamics of the system in such a way that a bounded oscillation is achieved confined to a region
that does not allow extinction of either species. The policy can be designed by a suitable choice of so called virtual equilibrium
points in a simple and intuitive manner.
相似文献
Amit Bhaya (Corresponding author)Email: |
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The recent contribution by Jarmila Kukalová-Peck on Hennigian phylogenetics and hexapod limb evolution is critically evaluated.
相似文献
Michael S. Engel (Corresponding author)Email: |
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Marko Herrmann José E. F. Alfaya Mauro L. Lepore Pablo E. Penchaszadeh Jürgen Laudien 《Helgoland Marine Research》2009,63(3):207-218
The reproductive cycle and gonad development of the yellow clam Mesodesma mactroides was studied over a period of 24 months (January 2005–December 2006) at the Argentinean sandy beach Santa Teresita. Histological
examination of gonadal tissue revealed that sex ratios did not significantly deviate from the proportion of 1:1 and no case
of hermaphroditism was found. The reproductive cycle of M. mactroides followed an annual cyclicality, which was significantly correlated to monthly mean sea surface temperatures (SST). Oocytes
showed highest abundance in winter, indicating a process of gonadal development and sexual maturation. The mean oocyte size
decreased significantly during spring. Modal oocyte sizes decreased significantly during winter and late spring of each year,
suggesting spawning events. The condition index was not useful in describing the annual reproductive cycle of M. mactroides. Ash-free, shell-free dry mass was chosen to detect the condition of the specimens, and this significantly correlated with
monthly mean SST and the gametogenic cycle. Annual recruitment patterns during summer–autumn indicated a 3-month-long planktonic
phase of M. mactroides. The reproduction cycle and gonad development of M. mactroides showed only weak differences between data from the present study and those collected 40 years ago.
相似文献
Marko HerrmannEmail: |
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A key point in the analysis of dynamical models of biological systems is to handle systems of relatively high dimensions.
In the present paper we propose a method to hierarchically organize a certain type of piecewise affine (PWA) differential
systems. This specific class of systems has been extensively studied for the past few years, as it provides a good framework
to model gene regulatory networks. The method, shown on several examples, allows a qualitative analysis of the asymptotic
behavior of a PWA system, decomposing it into several smaller subsystems. This technique, based on the well-known strongly
connected components decomposition, is not new. However, its adaptation to the non-smooth PWA differential equations turns
out to be quite relevant because of the strong discrete structure underlying these equations. Its biological relevance is
shown on a 7-dimensional PWA system modeling the gene network responsible for the carbon starvation response in Escherichia coli.
相似文献
Laurent Tournier (Corresponding author)Email: |
Jean-Luc GouzéEmail: |
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Kevin J. Emerson Sabrina J. Dake William E. Bradshaw Christina M. Holzapfel 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》2009,195(4):385-391
For over 70 years, researchers have debated whether the ability to use day length as a cue for the timing of seasonal events
(photoperiodism) is related to the endogenous circadian clock that regulates the timing of daily events. Models of photoperiodism
include two components: (1) a photoperiodic timer that measures the length of the day, and (2) a photoperiodic counter that
elicits the downstream photoperiodic response after a threshold number of days has been counted. Herein, we show that there
is no geographical pattern of genetic association between the expression of the circadian clock and the photoperiodic timer
or counter. We conclude that the photoperiodic timer and counter have evolved independently of the circadian clock in the
pitcher-plant mosquito Wyeomyia smithii and hence, the evolutionary modification of photoperiodism throughout the range of W. smithii has not been causally mediated by a corresponding evolution of the circadian clock.
相似文献
Kevin J. EmersonEmail: |
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Machado RR Lima Filho ES Jardim DF Ferreira MA de Faria CG Duarte RS Lesche B 《European biophysics journal : EBJ》2008,38(1):111-119
An interferometer that measures the refractive index changes due to bacterial metabolism is described. The apparatus permits
simultaneous and real time measurement of bacterial growth in several samples of slowly growing mycobacteria. The error sources
are discussed and the sensitivity of the apparatus is tested. For the species Mycobacterium bovis BCG and M. smegmatis, a relation between refractive index change and bacterial concentration is determined experimentally and the time constant
of bacterial growth is measured.
相似文献
B. LescheEmail: |
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