Flowers, Nectar and Insect Visits: Evaluating British Plant Species for Pollinator-friendly Gardens

Twenty-four plant species native or naturalized in Britain weregrown in the Cambridge University Botanic Garden, UK and evaluatedas potential resources for nectar-foraging bees, butterfliesand hoverflies. In ten plant species a series of measurementswere made, at regular intervals from dawn to dusk, of nectarsecretion rate and standing crop, and in all species insectvisits were monitored throughout daylight hours. The study revealeddifferences between plant species in the composition of theassemblage of insect visitors, and in the magnitude and temporaldistribution of the nectar reward. In some cases we found interestingcorrelations between temperature and secretion rates or patternsof insect visits. Species that received numerous insect visitsin our study are potentially valuable forage plants that mightbe planted by gardeners to support local pollinator populations.Deep flowers whose nectar is accessible to long-tongued bumblebees(Bombus hortorum, B. pascuorum) but not to honeybees may providelong-tongued pollinators with a resource refuge relatively freefrom honeybee competition. Features that make some of thoseplant species particularly interesting to observe in the gardeninclude robbing by short-tongued bumblebees inSaponaria,baseworkingby honeybees on closed flowers inMalva sylvestris, and apparentdisplacement of bumblebees by territorial behaviour of the solitarybeeAnthidium manicatumon species ofStachys.Copyright 1999 Annalsof Botany Company Wild flowers, gardens, nectar,Silene, Lychnis, Saponaria, Stachys, Malva, Dipsacus fullonum, Lythrum salicaria,pollinators, bumblebees,Bombus,honeybees,Apis,butterflies, Lepidoptera, hoverflies, Syrphidae,Anthidium manicatum, weeds.     

Neonicotinoids override a parasite exposure impact on hibernation success of a key bumblebee pollinator

1. Seasonal adaptations enabling the bridging of periodic challenging abiotic conditions are taxonomically widespread. However, sensitivity to other environmental stresses can be heightened during these periods. 2. Several temperate insects with over‐wintering strategies play key ecosystem and economic roles, including wild bee pollinators. For example, hibernation survival in temperate bumblebees is crucial, as only new queens of future social colonies over‐winter. These bees are also faced with other abiotic and biotic stressors, some of which have been linked to recent pollinator declines, such as exposure to pesticides and parasites. 3. Using a fully crossed experiment, the influence of dietary exposure to neonicotinoid insecticides (thiamethoxam and clothianidin) and/or the prevalent bumblebee parasite Crithidia bombi on hibernation survival and hibernation weight change of Bombus terrestris bumblebee queens was investigated. 4. Both neonicotinoid and C. bombi exposures reduced hibernation success individually, but no additive or synergistic effects between the stressors were found. Further, effects were asynchronous, with early neonicotinoid effects on hibernation mortality overriding later parasite effects under combined exposures. Neonicotinoid exposure also increased hibernation weight loss of surviving queens. 5. Diapause periods, employed by numerous temperate organisms, are likely to be especially vulnerable to environmental stresses, besides the seasonal challenge for which these periods are an adaptation. Thus, diapause requires inclusion during the consideration of the impacts of such stresses. Accordingly, it is demonstrated here that naturally relevant exposures of pesticides and parasites have important detrimental effects on bumblebees during a critical hibernation period, with potential consequences for populations of these key wild pollinators.     

检测HIV-1载量的荧光实时定量PCR技术的建立及其应用

准确测定HIV 1的前病毒载量和病毒载量的技术 ,在感染者预后和艾滋病患者药物治疗效果的评价以及艾滋病的其它研究方面 ,都具有十分重要的应用价值。以定量的HIV 1DNA和RNA为标准外参照 ,利用SYBRGreen荧光染料和GeneAmp5 70 0SequenceDetectionSystem (5 70 0系统 ) ,建立了测定HIV 1的前病毒载量和病毒载量的荧光实时定量PCR技术。以病毒感染细胞和培养上清为材料 ,测定了三种化合物 (AZT ,GL和WT)对细胞内的前病毒载量和培养上清中的病毒载量的抑制活性 ,并与合胞体形成抑制方法测定化合物抗病毒活性的结果进行了比较。根据病毒载量、前病毒载量和合胞体形成计算出的三种化合物的治疗指数均依次变小 ,提出以荧光实时定量PCR技术测定前病毒载量 ,会在评价药物在体内外根除或减少存在于CD4休止或记忆T淋巴细胞中的HIV 1前病毒方面有特别的价值。     

Interpreting the Earliest Metazoan Fossils: What Can We Learn?

SYNOPSIS. The Ediacaran fossils of the latest Precambrian haveat one time or another been grouped with almost every extantkingdom, and also lumped into separate kingdom-level taxa. Thishas often been based on the facile use of a few characters,or on some sort of "overall similarity." This has not been avery fruitful approach; if anything, it has held back understandingof the Ediacaran organisms and of their significance for laterhistory. While many of the simpler forms remain problematic,careful study of the more complex forms gives good reasons toplace at least some of them with the Animalia. A complementaryapproach is to use sources of information such as the distributionof fossils across space, time, and paleoenvironments. The resultsmay feed back into systematic work, allowing us to constructand test more robust hypotheses of these organisms' evolutionaryrelationships.     

Nitrate Uptake by Roots as Regulated by Nitrate Reduction Products of the Shoot

A mechanism is proposed by which secondary products of nitrate reduction in the shoot control the uptake of nitrate by the roots. KNO₃ enters the roots and is translocated to the shoot where nitrate is reduced and, at the same time, malate is produced. The reduction of nitrate is stoichiometric to the synthesis of malate (1). Part of the K-malate moves down to the root system in which malate is oxidized, yielding KHCO₃ which exchanges for KNO₃. Nitrate reduction in the shoot promotes the synthesis of malate which, after its translocation to the root, allows the preferential uptake of nitrate. Thus, plants reducing large amounts of nitrate may take up the anion without a superfluous accumulation of the cation. Furthermore, the utilization of nitrate by the shoot regulates its uptake by the root.     

The importance of canopy complexity in shaping seasonal spider and beetle assemblages in saltmarsh habitats

1. Habitat structure, including vegetation structural complexity, largely determines invertebrate assemblages in semi‐natural grasslands. The importance of structural complexity to the saltmarsh invertebrate community, where the interplay between vegetation characteristics and tidal inundation is key, is less well known. 2. It was hypothesised that canopy complexity would be a more important predictor of spider and beetle assemblages than simple vegetation attributes (e.g. height, community type) and environmental variables (e.g. elevation) alone, measured in two saltmarsh regions, south‐east (Essex) and north‐west (Morecambe Bay) U.K. Canopy complexity (number of non‐vegetated ‘gaps’ in canopy ≥ 1 mm wide) was assessed using side‐on photography. Over 1500 spiders and beetles were sampled via suction sampling, winter and summer combined. 3. In summer, saltmarshes with abundant spider and beetle populations were characterised by high scores for canopy complexity often associated with tussocky grass or shrub cover. Simple vegetation attributes (plant cover, height) accounted for 26% of variation in spider abundance and 14% in spider diversity, rising to 46% and 41%, respectively, with the addition of canopy complexity score. Overwintering spider assemblages were associated with elevation and vegetation biomass. Summer beetle abundance, in particular the predatory and zoophagous group, and diversity were best explained by elevation and plant species richness. 4. Summer canopy complexity was identified as a positive habitat feature for saltmarsh spider communities (ground‐running hunters and sheet weavers) with significant ‘added value’ over more commonly measured attributes of vegetation structure.     

What makes an urban bird?

Urban development is increasing across the globe. This poses a major threat to biodiversity, which is often relatively poor in towns and cities. Despite much interest in identifying species' traits that can predict their responses to environmental degradation this approach has seldom been used to assess which species are particularly vulnerable to urban development. Here we explore this issue, exploiting one of the best available datasets on species' responses to towns and cities in a highly urbanized region, comprising avian densities across approximately 3000 British urban and rural 1 km × 1 km grid cells. We find that the manner in which species' responses to urbanization is measured has a marked influence on the nature of associations between these responses and species' ecological and life history traits. We advocate that future studies should use continuous indices of responses that take relative urban and rural densities into account, rather than using urban densities in isolation, or a binary response recording the presence/absence of a species in towns and cities. Contrary to previous studies we find that urban development does not select against avian long‐distance migrants and insectivores, or species with limited annual fecundity and dispersal capacity. There was no evidence that behavioural flexibility, as measured by relative brain size, influenced species' responses to urban environments. In Britain, generalist species, as measured by niche position rather than breadth, are favoured by urban development as are, albeit to a lesser extent, those that feed on plant material and nest above the ground. Our results suggest that avian biodiversity in towns and cities in urbanizing regions will be promoted by providing additional resources that are currently scarce in urban areas, and developing suitable environments for ground‐nesting species.     

RÔLE DE L'EAU DE BOISSON SUR LA PRISE DE NOURRITURE SÈCHE ET LE DÉVELOPPEMENT OVARIEN DE LOCUSTA MIGRATORIA MIGRATORIOIDES

Pour déterminer la ration minimale d'eau nécessaire à la survie de Locusta migratoria migratorioides (R. et F.) adulte et les repercussions d'un stress hydrique prolongé sur le fonctionnement ovarien, nous avons séparé le facteur eau du facteur aliment en élevant les criquets de l'éclosion à l'âge adulte avec des germinations de blé lyophilisé, selon une technique décrite par Louveaux et al. (1980). Il est montré que la quantité d'aliments ingérée augmente avec la quantité d'eau bue (r = 0,91). La relation linéaire déterminée permet inversement, connaissant les quantités d'aliments ingérés, d'évaluer à 300 μl la ration quotidienne d'un criquet ayant un accès non limité à l'eau de boisson. Les femelles qui n'ont reçu que 50 μl d'eau par jour (j.) sont mortes avant le 9ème jour de traitement. La survie est assurée à partir de 100 μl/j. L'avancement de la vitellogenèse est également en relation avec la quantité d'eau absorbée quotidiennement. Aucun développement ovarien ne se produit jusqu'à 100 μl/j. Une vitellogenèse ralentie commence à partir de 150 μl/j. et elle devient normale à 300 μl/j. avec des pontes comparables à celles des témoins nourris de blé frais.