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51.
52.
Summary. The pollen beetle, Meligethes aeneus, is an important pest of oilseed rape, Brassica napus. Larvae of this species feed only in the buds and flowers of Brassicaceae. One important natural enemy of this beetle is
the parasitoid Phradis morionellus that attacks larvae in buds and flowers and also feeds on the flowers. The preferences for odours of non-infested and infested
rape were tested for both starved and fed parasitoids in Y-tube olfactometer experiments. The volatile blend released from
pollen beetle-infested and non-infested flowering rape and from pollen beetle larvae was identified and quantified. Gas chromatography-electroantennodetection
analyses were performed with female P. morionellus. Parasitoids in both treatment groups preferred infested rape, but the proportion of responding female P. morionellus was significantly lower for the group that was starved. Six of the 20 volatiles identified were released at higher rates
from infested rape than from non-infested. None of these compounds was found in pollen beetle larvae headspace. P. morionellus antennae detected both major and minor components in the volatile blend. The volatiles released at a significantly higher
rate from infested rape and detected by P. morionellus antennae were (Z)-3-hexenylacetate, (Z)-3-hexenol, 3-butenyl isothiocyanate and (E,E)-α-farnesene. 相似文献
53.
Frode Skarstein Ivar Folstad Ståle Liljedal Mats Grahn 《Behavioral ecology and sociobiology》2005,57(4):374-380
Genes of the major histocompatibility complex (MHC) are remarkably polymorphic. Several selection mechanisms have been invoked to account for this diversity, including disassortative mating preferences. In addition, eggs may discriminate between sperm based on MHC. To investigate the effects of MHC-genotype on fertilization success, we obtained mature gametes from ripe Arctic charr (Salvelinus alpinus) males and females captured on spawning grounds. The eggs of each female were divided into two batches, and by letting each of 2 males fertilize 1 of the batches, we obtained a total of 36 half-sibling batch-pairs. The semen was diluted to ensure that the two males in each half-sibling batch-pair contributed with the same number of sperm cells. We found that MHC-heterozygous males had significantly higher fertilization success than MHC-homozygous males and neither initial spermatocrit, sperm motility nor swimming velocity co-varied with difference in fertilization success. There was no effect of female genotype or female-male MHC-similarity on fertilization success. However, one MHC-allele was associated with increased fertilization success. It seems plausible that the difference in fertilization success between homo- and heterozygous males may be due to MHC-dependent sperm selection by the ovum.Communicated by M. Abrahams 相似文献
54.
Significance of platinum group metals emitted from automobile exhaust gas converters for the biosphere 总被引:1,自引:0,他引:1
Intention, Goal, Scope, Background Following the introduction of automobile catalytic converters the platinum group metals (PGM) platinum (Pt), palladium (Pd)
and rhodium (Rh) gain on increasing interest in environmental research as these metals are emitted with exhaust fumes into
the environment. Consequently, elevated PGM levels were found in different environmental matrices uch as road dusts, soils
along heavily frequented roads, sediments of urban rivers etc. Accordingly, the effects of increasing PGM emissions on the
biosphere are controversially discussed.
Objective This paper summarizes the present knowledge on the biological availability of PGM to plants and animals. As biological availability
is one of the most decisive factors determining the toxicologi-cal potential of xenobiotics, this information is very important
to evaluate the possible threat of the noble metals to ecosystems.
Results and Discussion The availability of soluble as well as particle bound PGM to terrestrial plants was demonstrated in several studies. Experimental
investigations revealed uptake of Pt, Pd and Rh also by aquatic plants. Additionally, the biological availability of the noble
metals for animals has been verified in experimental studies using soluble metal salts, catalytic converter model substances,
sediments of urban rivers, road dust or tunnel dust as metal sources. These studies refer mainly to aquatic animals. Beside
of free living organisms, in particular worms parasitizing fish demonstrated a high potential to accumulate PGM. This could
be of great interest in respect of biomonitoring purposes. Generally, for plants as well as for animals Pd turns out to be
the best available metal among the PGM. Compared to other heavy metals, the biological availability of PGM from road dust
to zebra mussels(Dreissena polymorpha) ranged between that of Cd and Pb.
Conclusion Especially chronic effects of PGM on the biosphere can not be excluded due to (1) their cumulative increase in the environment,
(2) their unexpected high biological availability and bioaccumulation and (3) their unknown toxicological and ecotoxicological
potential. However, it appears that acute effects on ecosystems due to anthropogenic PGM emission are not likely.
Recommendation and Outlook Research on environmental PGM contamination of the biosphere, especially the fauna, and on long-term toxiciry of low PGM concentrations
is highly appreciated. These studies require very sensitive analytical techniques to determine PGM even in low sample amounts.
Research has to be done in particular on reliable determination of (ultra) trace levels of Pd and Rh as the lack of data on
these two metals is mainly due to analytical problems. 相似文献
55.
Refractory dissolved organic matter (DOM) from landfill leachate treatment plant was with high dissolved organic carbon (DOC) content. An aminated polymeric adsorbent NDA-8 with tertiary amino groups and sufficient mesopore was synthesized, which exhibited high adsorption capacity to the DOM (raw water after coagulation). Resin NDA-8 performed better in the uptake of the DOM than resin DAX-8 and A100. Electrostatic attraction was considered as the decisive interaction between the adsorbent and adsorbate. Special attention was paid to the correlation between porous structure and adsorption capacity. The mesopore of NDA-8 played a crucial role during uptake of the DOM. In general, resin in chloride form performed a higher removal rate of DOC. According to the column adsorption test, total adsorption capacity of NDA-8 was calculated to 52.28 mg DOC/mL wet resin. 0.2 mol/L sodium hydroxide solution could regenerate the adsorbent efficiently. 相似文献
56.
DUAN Jinming 《环境科学学报(英文版)》2009,21(1):30-34
Colloidal particle stability and some other interfacial phenomena are governed by interfacial force interactions. The two well known
forces are van der Waals force and electrostatic force, as documented by the classical Derjaguin, Landau, Verwey, and Overbeek
(DLVO) theory. Moreover, advances in modern instrumentation and colloid science suggested that some short-ranged forces or structure
forces are important for relevant colloidal systems. The interfacial and/or molecular forces can be measured as a resultant force as
function of separation distance by atomic force microscopy (AFM) colloid probe. This article presents a discussion on AFM colloid
probe measurement of silica particle and silica wafer surfaces in solutions with some technical notifications in measurement and data
convolution mechanisms. The measured forces are then analyzed and discussed based on the ‘constant charge’ and ‘constant potential’
models of DLVO theory. The di erence between the prediction of DLVO theory and the measured results indicates that there is a strong
short-range structure force between the two hydrophilic surfaces, even at extremely low ionic concentration, such as Milli-Q water
purity solution. 相似文献
57.
Caroline S. Chaboo Michael S. Engel Maria Lourdes Chamorro-Lacayo 《Die Naturwissenschaften》2009,96(9):1121-1126
Complex ethological adaptations and intraspecific interactions leave few fossil traces. We document three Dominican (20 million
years old [myo]) and Baltic (45 myo) amber fossils that exhibit firm evidence of highly integrated interactions between mothers
and offspring in the diverse camptosomate lineage of beetles (Chrysomelidae, leaf beetles). As in contemporary species, these
hard cases were initially constructed by mothers, then inherited and retained by offspring, which then elaborate this protective
domicile with an unusual but economical building material, their feces. The three fossils are classified in the Subfamily
Cryptocephalinae; two are classified in the tribe Chlamisini based on morphological evidence—the flattened head lacking a
sharp keel and long legs with simple recurved untoothed claws. These diagnostic features are not clearly visible in the third
specimen to permit more refined identification. These fossils provide more precise paleontological dating of tribal nodes
within the cryptocephaline radiation of leaf beetles. These fossils are the first and earliest evidence of mother–offspring
interaction, building behavior, and fecal recycling in Camptosomata beetles and of inheritance of architectural structures
in beetles. 相似文献
58.
D.C. Goodrich W.G. Kepner L.R. Levick P.J. Wigington Jr. 《Journal of the American Water Resources Association》2018,54(2):400-422
Ephemeral and intermittent streams are abundant in the arid and semiarid landscapes of the Western and Southwestern United States (U.S.). Connectivity of ephemeral and intermittent streams to the relatively few perennial reaches through runoff is a major driver of the ecohydrology of the region. These streams supply water, sediment, nutrients, and biota to downstream reaches and rivers. In addition, they provide runoff to recharge alluvial and regional groundwater aquifers that support baseflow in perennial mainstem stream reaches over extended periods when little or no precipitation occurs. Episodic runoff, as well as groundwater inflow to surface water in streams support limited naturally occurring riparian communities. This paper provides an overview and comprehensive examination of factors affecting the hydrologic, chemical, and ecological connectivity of ephemeral and intermittent streams on perennial or intermittent rivers in the arid and semiarid Southwestern U.S. Connectivity as influenced and moderated through the physical landscape, climate, and human impacts to downstream waters or rivers is presented first at the broader Southwestern scale, and secondly drawing on a specific and more detailed example of the San Pedro Basin due to its history of extensive observations and research in the basin. A wide array of evidence clearly illustrates hydrologic, chemical, and ecological connectivity of ephemeral and intermittent streams throughout stream networks. 相似文献
59.
概述了环境DNA技术目前的研究方向和分析原理,介绍了该技术在水生、土壤和植物生态系统中的应用进展,以及在监测畜舍环境、促进畜禽粪污无害化处理、检测动物营养与健康状况、调查动物群体遗传多样性、监测和预防畜禽疾病等动物生产管理中的应用前景。分析了环境DNA技术的优势与局限,并在此基础上提出了建立标准操作流程、提高检测精确度、积极推广应用环境DNA技术等建议。 相似文献
60.
Nitrogen fertilization and winter pruning are commonly used to control crop production in peach [Prunus persica (L.) Batsch] orchards. They are also known to affect the dynamics of Myzus persicae (Sulzer) (Homoptera: Aphididae) aphid populations via bottom-up regulation processes. Interactions between crops and pests can cause complex system behaviour in response to management practices. An integrated approach will therefore improve the understanding of the effects of these two cultural practices on aphid and peach performances.We developed a simulation model that describes the cultural control of interacting peach tree and aphid population dynamics. It uses the principles of common trophic models while gathering available knowledge and explicit assumptions on peach and aphid functioning and the effects of cultural practices.The model was able to qualitatively reproduce the system behaviour observed in the field. It accounted for actions and feedback such as stimulation of foliar growth by winter pruning, consecutive aphid population increase, subsequent damage to foliage, and partial compensatory growth of foliage. The model also reproduced low losses in fruit production due to aphid infestations. However, it called for further integration of ‘long-term’ effects. Analysis of the model showed the complexity of peach tree and aphid responses to leaf N × winter pruning interactions. Simulations indicated that fruit production losses remained low within a range of realistic values of leaf N and pruning intensity, whereas manipulating peach and aphid dynamics, their interactions and their relationships to practices could result in higher losses.The model is useful to evaluate the relevance of cultural practices for a bottom-up regulation of aphid dynamics in crop-pest management. After considering other control methods and fruit quality, it can be used to find a combination of practices that optimises trade-offs between fruit production and environmental conservation goals. A modelling approach that links crop growth and pest population dynamics and integrates management practice effects has strong potential for improving crop-pest management in an integrated crop production context. 相似文献