Journal ArticleDOI
Humidity, nectar and insect visits to flowers, with special reference to Crataegus, Tilia and Echium
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TLDR
Field observations on diel changes in the nectars of Crataegus, Tilia and Echium in relation to microclimate and insect visits are described.Abstract:
. 1. This paper describes field observations on diel changes in the nectars of Crataegus, Tilia and Echium in relation to microclimate and insect visits.
2. Nectar concentration is highly correlated with ambient relative humidity, but the concentrative properties of the nectars differ from those of pure sugar solutions in ways that could be accounted for by microclimate or chemical effects.
3. The microclimate inside flowers may influence the rate of equilibration of nectar with the relative humidity of the air, or the equilibrium concentration itself.
4. The vapour pressure relationships of nectars may be influenced by the presence of components with low r/P values (that is, solutes in which solution show a relatively large lowering of vapour pressure, P, for a small change in refraction, r). Such components might be released by micro-organisms in the nectar.
5. The quantity of sugar per flower depends on the relative rates of secretion and reabsorption, among other things. The flowers we studied showed evidence for morning and evening peaks of secretion, and in Crataegus substantial quantities of sugar were ‘sequestered’ around midday.
6. The pattern of visits by bumblebees to the flowers of Tilia and Echium can be related to the changing concentration of sugar in the nectar; caloric reward was probably not limiting for bumblebees visiting Tilia.read more
Citations
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Journal ArticleDOI
Insects as Flower Visitors and Pollinators
and P G Kevan,Herbert G. Baker +1 more
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Ecology and conservation of butterflies
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Weather-Dependent Pollinator Activity in an Apple Orchard, with Special Reference to Osmia cornuta and Apis mellifera (Hymenoptera: Megachilidae and Apidae)
Narcís Vicens,Jordi Bosch +1 more
TL;DR: For both managed bee species, daily activity started at lower temperatures than it ceased, whereas solar radiation did not differ between these two events, and O. cornuta was the only bee species seen visiting apple flowers under strong wind or light rain.
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Effects of plant size, plant density and sex differential nectar reward on pollinator visitation in the protandrous Echium vulgare (Boraginaceae).
TL;DR: The number of bumblebee approaches to viper's bugloss (Echium vulgare L.) plants increased with the number of flowers per plant, but the proportion of thenumber of flowers visited after an approach was smaller in plants with many flowers.
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Nectar sugar content: estimating standing crop and secretion rate in the field
TL;DR: La quantite de nectar est souvent distribuee irregulierement parmi les fleurs d'une parcelle et the quantite moyenne de sucre par fleur rencontree par un insecte qui butine systematiquement peut depasser celle echantillonnee par un ecologiste non selectif.
References
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Control of humidity with potassium hydroxide, sulfuric acid, or other solutions
TL;DR: Methods of preparing solutions of graded density for the accurate control of atmospheric relative humidity are described, and some pitfalls in their use and in the use of saturated salt solutions are indicated.
Journal ArticleDOI
Control of Humidity with Potassium Hydroxide, Sulphuric Acid, or other Solutions
TL;DR: In this article, the International Critical Table or more recent sources are used as the basis of tables giving the concentrations (wt.%) and densities corresponding to relative humidity in steps of 5 per cent.
Journal ArticleDOI
Types of nectar in angiosperms
TL;DR: The nectar of 889 species and some fifty varieties of Angiosperms has been analysed by paper partition chromatography and the types of nectar in some honey-bee flowers are explored.
Journal ArticleDOI
Resource Partitioning Among Some Eusocial Insects: Bumblebees
TL;DR: Four common species of bumblebees in central Maine each utilized the nectar from a great variety of both native and exotic flowers, and the number of individuals that utilized a nectar resource was directly related to supplies available.
Journal ArticleDOI
Sun-tracking solar furnaces in high arctic flowers: significance for pollination and insects.
TL;DR: Heliotropic flowers act, in sunshine, as solar reflectors, their corollas focusing heat on the sporophylls, and these phenomena are important in maximizing the small heat budget.