Amots Dafni

LINKING BEES AND FLOWERS: HOW DO FLORAL COMMUNITIES STRUCTURE POLLINATOR COMMUNITIES?

Pollinators provide essential ecosystem services, and declines in some pollinator communities around the world have been reported. Understanding the fundamental components defining these communities is essential if conservation and restoration are to be successful. We examined the structure of plant-pollinator communities in a dynamic Mediterranean landscape, comprising a mosaic of post-fire regenerating habitats, and which is a recognized global hotspot for bee diversity. Each community was characterized by a highly skewed species abundance distribution, with a few dominant and many rare bee species, and was consistent with a log series model indicating that a few environmental factors govern the community. Floral community composition, the quantity and quality of forage resources present, and the geographic locality organized bee communities at various levels: (1) The overall structure of the bee community (116 species), as revealed through ordination, was dependent upon nectar resource diversity (defined as the variety of nectar volume-concentration combinations available), the ratio of pollen to nectar energy, floral diversity, floral abundance, and post-fire age. (2) Bee diversity, measured as species richness, was closely linked to floral diversity (especially of annuals), nectar resource diversity, and post-fire age of the habitat. (3) The abundance of the most common species was primarily related to post-fire age, grazing intensity, and nesting substrate availability. Ordination models based on age-characteristic post-fire floral community structure explained 39-50% of overall variation observed in bee community structure. Cluster analysis showed that all the communities shared a high degree of similarity in their species composition (27-59%); however, the geographical location of sites also contributed a smaller but significant component to bee community structure. We conclude that floral resources act in specific and previously unexplored ways to modulate the diversity of the local geographic species pool, with specific disturbance factors, superimposed upon these patterns, mainly affecting the dominant species.

Role of nesting resources in organising diverse bee communities in a Mediterranean landscape

Abstract.  1. The habitat components determining the structure of bee communities are well known when considering foraging resources; however, there is little data with respect to the role of nesting resources.

Pollen viability and longevity: practical, ecological and evolutionary implications.

The present article reviews the various definitions and terminology of pollen viability and longevity as well as the various tests of its assessment. We compare the advantages and the disadvantages of each method and suggest some practical implications as revealed by the extensive data. We recognize eight main hypotheses concerning the ecology and the evolution of pollen longevity and critically evaluated them according to the literature. The hypotheses are grouped as follows: (1) Desiccation risk-carbohydrate content; (2) Pollen packaging; (3) Pollen competitive ability; (4) Pollinator activity-stigma receptivity duration; (5) Self-pollination chance; (6) Pollen exposure schedule; (7) Pollen travel distance, and (8) Pollen removal chance.

Plants used for the treatment of diabetes in Israel

In an extensive ethnobotanical survey (130 informants) of the medicinal plants of Israel, 16 species were found to be used for hypoglycaemic treatments. The list includes Achillea fragrantissima (Forssk.) Sch.-Bip, Ammi visnaga (L.) Lam, Atriplex halimus L., Capparis spinosa L., Ceratonia siliqua L., Cleome droserifolia (Forssk.) Del., Eryngium creticum Lam., Inula viscosa (L.) Ait., Matricaria aurea (Loefl.) Sch.-Bip, Origanum syriaca L., Paronychia argentea Lam, Prosopis farcta (Banks et Sol.) Macbride, Salvia fruticosa Mill., Sarcopoterium spinosum (L.) Sp., and Teucrium polium L.; eight of them (marked with an asterisk) are first recorded here as used for this purpose.

A new procedure to asses pollen viability

Abstract We tested pollen viability of eight species using four vital dyes, a new peroxidase test together with three other established methods (MTT, Baker’s and X-Gal), to determine their potential to differentiate fresh pollen from pollen heated for 2 h and 24 h at 80°C (killed pollen) and compared the results with in vitro germination. We found that two of three dyes previously employed to determine viability also stained killed pollen, while the new peroxidase test and MTT did not. We suggest that the latter two are the best methods to test pollen viability, since they do not normally stain either killed or aborted pollen.

A framework for comparing pollinator performance: effectiveness and efficiency

Measuring pollinator performance has become increasingly important with emerging needs for risk assessment in conservation and sustainable agriculture that require multi‐year and multi‐site comparisons across studies. However, comparing pollinator performance across studies is difficult because of the diversity of concepts and disparate methods in use. Our review of the literature shows many unresolved ambiguities. Two different assessment concepts predominate: the first estimates stigmatic pollen deposition and the underlying pollinator behaviour parameters, while the second estimates the pollinators contribution to plant reproductive success, for example in terms of seed set. Both concepts include a number of parameters combined in diverse ways and named under a diversity of synonyms and homonyms. However, these concepts are overlapping because pollen deposition success is the most frequently used proxy for assessing the pollinators contribution to plant reproductive success. We analyse the diverse concepts and methods in the context of a new proposed conceptual framework with a modular approach based on pollen deposition, visit frequency, and contribution to seed set relative to the plants maximum female reproductive potential. A system of equations is proposed to optimize the balance between idealised theoretical concepts and practical operational methods. Our framework permits comparisons over a range of floral phenotypes, and spatial and temporal scales, because scaling up is based on the same fundamental unit of analysis, the single visit.

SPATIAL FLOWER PARAMETERS AND INSECT SPATIAL VISION

The present article reviews recent and older literature on the spatial parameters that flowers display, as well as on the capacities of anthophilous insects to perceive and use these parameters for optimizing their foraging success. Although co‐evolution of plants and pollinators has frequently been discussed with respect to floral colours and insect colour vision, it has rarely been assessed with respect to insect spatial vision and spatial floral cues, such as shape, pattern, size, contrast, symmetry, spatial frequency, contour density and orientation of contours. This review is an attempt to fill this gap. From experimental findings and observations on both flowers and insects, we arrive at the conclusion that all of the spatial and spatio‐temporal parameters that flowers offer are relevant to the foraging task and are tuned to the insects visual capacities and visually guided behaviour. We try, in addition, to indicate that temporal cues are closely related to spatial cues, and must therefore be included when flower–pollinator interactions are examined. We include results that show that colour vision and spatial vision have diverged over the course of evolution, particularly regarding the processing of spatio‐temporal information, but that colour vision plays a role in the processing of spatial cues that are independent of temporal parameters. By presenting this review we hope to contribute to closer collaboration among scientists working in the vast fields of botany, ecology, evolution, ethology and sensory physiology.

RED BOWL-SHAPED FLOWERS: CONVERGENCE FOR BEETLE POLLINATION IN THE MEDITERRANEAN REGION

ABSTRACT Anemone coronaria, Papaver rhoeas, Ranunculus asiaticus, and Tulipa agenensis are pollinated primarily by scarabaeid beetles (Amphicoma, Glaphyridae) and secondarily by bees (Lasioglossum marginatum Br., Halictidae, and Synhalonia plumigera Kohl, Anthophoridae). The four plant species have large bowl-shaped flowers which are orange-red in color with a black center, radial symmetry, weak scent (to humans), and filamentous stamens. It is suggested that there is a convergent evolution of red bowl-shaped flowers in the East Mediterranean region, concordant with a center of diversity in the genus Amphicoma. The floral phenology of these “Poppy guild” species correlated positively with the amount of edible pollen produced by each of them and with the visiting frequencies of their pollinators. Field experiments showed that Amphicoma beetles also preferred red, odorless flower models over odorless models of different colors, and models with a dark center over plain red ones. This evidence extends the cla...

Ethnobotanical survey of medicinal plants in northern Israel.

An ethnobotanical survey was conducted in Israel on native plants which are known as medicinal plants by different ethnic groups practicing traditional medicine. In this work 43 species are reported, based on quotations and frequency of utilization. Their current medicinal uses, as well as methods of preparation and administration are described and compared with literary evidence.

Floral Symmetry and Its Role in Plant‐Pollinator Systems

Floral symmetry has a relevant status in the study of both pollination biology and animal behavior. In this work, a brief review and classification of symmetry types in flowers is provided as a basis for understanding the role of floral symmetry in pollination phenomena. We focus on insects as a fundamental group of pollinators, and we discuss symmetry from the perspective of insect perception. We conclude that symmetry is a specific cue with a signal value that is perceived by insect pollinators. A simple nervous system, such as that of honeybees, is capable of an extremely flexible and adaptive processing of symmetry. Performances consistent with categorization and concept building may be observed, provided that appropriate learning paradigms are employed. Perfectly symmetrical flowers might signal a high quality and/or quantity of nectar or pollen to pollinators that, in turn, might exert strong selection pressure on symmetric features. However, coadaptation arguments in the strict sense are not adequate because it is impossible to determine whether the insects capacity to perceive symmetry is younger or older than is the origin of flower symmetry.