Entomophilous Plants Research Articles

Airborne pollen of entomophilous plants and spores of pteridophytes in Rzesz�w and its environs (SE Poland)

Airborne pollen of entomophilous plants occurred in low or very low concentrations, and constituted 4 of the total pollen sum. In 1997–2002, between 18 and 26 taxa were identified. Out of this large group the following taxa were represented in larger concentrations every year– Salix, Acer, Morus, Cichorioideae, Asterioideae, Plantago major/media, Sambucus nigra and Tilia. Microscopic examination revealed that pollen grains of the above mentioned species were often glued together, which is a typical adaptation to this kind of pollination. Club moss (Lycopodium spp.) and horsetail (Equisetum spp.) spores were recorded sporadically. Fern spores were found frequently but in very low numbers. In 2002 the occurrence of the airborne pollen of entomophilous plants in the city and in the countryside was compared. A higher percentage value of pollen was found in the atmosphere of the city rather than in the countryside, due to the high concentration of Acer pollen, which is a partly entomophilous species and common in municipal plantings. In the countryside air there was a higher concentration of pollen from purely entomophilous species, such as Viburnum and Asteroideae.

Native birds and insects, and introduced honey bees visiting Echium wildpretii (Boraginaceae) in the Canary Islands

In this paper, we report observations of flower visitors of the endemic Echium wildpretii in Tenerife, Canary Islands. This plant inhabits the high altitudinal sub-alpine zone, which is characterized by a harsh climate, low species diversity and a short growing season. Echium wildpretii is a monocarpic perennial, producing a 2–3 m column-shaped, red-flowered, nectar-rich inflorescence. Although these floral traits have previously been suggested as being typical of ornithophilous flowers, this is the first study reporting observations of native birds (Phylloscopus collybita and Serinus canarius) in addition to insects visiting the flowers for nectar. The purposes of this study were firstly to investigate levels of visitation by native birds, native insects, and introduced honey bees. Secondly, we studied the influence of floral display (plant height and number of flowers), nearest neighbours (distance and size) and local vegetation structure on visitation rate. Finally, we discuss the evolution of ornithophily in an otherwise entomophilous plant lineage. We found that the level of bird visitation was relatively high early in the flowering season, but decreased in mid/late season, while the opposite pattern was found for introduced honey bees. For native insects, the frequency of visits was similar in early and late season. Bird visits were correlated with floral display. In the early season, visitation rates of honey bees and the two most common native bee species were correlated with size of the plant or its nearest neighbours, consistent with preference patterns for larger resource patches. Since only insects visit the flowers of other species in the Echium clade, E. wildpretii appears to have evolved from a truly insect-pollinated lineage.

Population differentiation and phylogeography of Hygrophila pogonocalyx based on RAPDs fingerprints

Genetic variation of the endangered species, Hygrophila pogonocalyx Hayata (Acanthaceae), was estimated based on RAPD fingerprints. According to the criteria of the International Union for Conservation of Nature and Nature Resources, H. pogonocalyx is on the Red List Category due to its endangered status. Entomophilous plants of H. pogonocalyx are mostly pollinated by honeybees. Gene flow between populations is constrained by the migratory capacity of the pollinators. A survey based on RAPD fingerprinting using 50 random primers revealed the distribution of genetic variation following an “isolation by distance” model. A hierarchical AMOVA analyses indicated significant differentiation between geographical regions ( Φ ct=0.934; P=0.048), among populations ( Φ st=0.945; P<0.001), and among populations within region ( Φ sc=0.169; P<0.001). The differentiation between geographic populations may be ascribed to a long isolation since the formation of the Central Mountain Range 1 million years ago. In contrast to low levels of genetic variation in many endangered species, some genetic processes avoiding selfing may have evolved in H. pogonocalyx. Somatic mutation also possibly contributed to the variability maintenance within populations with limited size.

Sex Allocation and Reproductive Success in the Andromonoecious Perennial Solanum carolinense (Solanaceae). II. Paternity and Functional Gender.

According to Bateman's principle, male fitness in entomophilous plant species should be limited by mating opportunity, which is influenced by the size or number of flowers. We determined male-specific fitness consequences of floral phenotype in andromonoecious Solanum carolinense, examined the relationship between male and female reproductive success within plants, and evaluated the distribution of functional gender among plants. A maximum likelihood-based paternity analysis, based on multilocus allozyme phenotypes of parents and offspring from four experimental plots, was used to determine male reproductive success and its relationship to floral phenotype. Male success was enhanced by an increase in the proportion of male flowers produced but not by an increase in total flower number, even though all flowers contain male parts. Larger flower size increased male success in only one plot. Male and female reproductive success were negatively correlated, and plants varied in functional gender from completely female to completely male. This gender specialization may occur because hermaphroditic and male flowers differ in their ability to contribute to male and female success. Although sex allocation theory predicts a positive relationship between the size or number of plant parts and reproductive success, this study indicates that aspects of floral morphology that affect gender specialization should also be considered.

Biogenesis and function of the lipidic structures of pollen grains

Pollen grains contain several lipidic structures, which play a key role in their development as male gametophytes. The elaborate extracellular pollen wall, the exine, is largely formed from acyl lipid and phenylpropanoid precursors, which together form the exceptionally stable biopolymer sporopollenin. An additional extracellular lipidic matrix, the pollen coat, which is particularly prominent in entomophilous plants, covers the interstices of the exine and has many important functions in pollen dispersal and pollen-stigma recognition. The sporopollenin and pollen coat precursors are both synthesised in the tapetum under the control of the sporophytic genome, but at different stages of development. Pollen grains also contain two major intracellular lipidic structures, namely storage oil bodies and an extensive membrane network. These intracellular lipids are synthesised in the vegetative cell of the pollen grain under the control of the gametophytic genome. Over the past few years there has been significant progress in elucidating the composition, biogenesis and function of these important pollen structures. The purpose of this review is to describe these recent advances within the historical context of research into pollen development.

Efficiency of various insects in germplasm regeneration of carrot, onion and turnip rape accessions

AbstractSeed regeneration is one of the most important tasks in genebank work. To regenerate germplasm of allogamous, entomophilous plant species in isolation facilities, insects are often used as pollen vectors. The objective of this study was to determine the effect of pollinator species, pollinator densities, pollinator combinations, and flower preferences on the seed quantity and quality of Daucus carota, Allium cepa, and Brassica rapa. The isozyme phosphoglucoisomerase (PGI) served as genetic marker in determining outcrossing rates and pollen dispersal distances. Field plots and isolation cages without insects were used as controls. The pollinators studied consisted of the following insect species from German native fauna: red mason bees (Osmia rufa L.), hoverflies (Eristalis tenax L.), and blowflies (Calliphora sp. and Lucilia sp.). In D. carota and B. rapa, higher seed yields were achieved in isolation cages than in field plots, but in A. cepa lower seed yields were obtained in the isolation cages. Although O. rufa showed no liking for A. cepa, unintentional pollination was effected by this insect in isolation cages. Lower insect densities were necessary for O. rufa than for the various fly species.

Effects of Pollen Vector and Plant Geometry on Floral Sex Ratio in Monoecious Plants

-Size-related patterns of floral sex allocation were examined in 14 anemophilous and eight entomophilous monoecious plants. Among the anemophilous species, eight increased male floral allocation and six increased female floral allocation with increased plant size. An increase in female floral allocation with increased plant size occurred in all eight entomophilous monoecious species examined. Pollination vector has a significant effect on size-related floral sex ratio patterns. We present a heuristic model that considers pollen dispersal of anemophilous monoecious plants as a function of plant geometry. The surface area to volume ratio of plants approximating geometric extremes (cylindrical or spherical forms) should affect pollen dispersal and floral sex ratio due to aerodynamic effects on the whole plant. Plants approximating cylinders should increase male floral allocation with increasing height. Plants that approximate a more spherical form should increase in female floral allocation with increasing size. All entomophilous plants conformed to a resource limitation model; however, anemophilous plants increased in either male or female floral allocation with increased size. Results for 13 anemophilous species support the predictions of our geometric model. One species does not approximate an extreme geometry and does not appear to conform to the geometrical model's predictions.

To make a meadow it takes a clover and a bee: the entomophilous flora of N.W. Europe and its insects

An analysis of the anthophilous fauna of N.W. Europe is presented, stressing the role plants play for insects. The study is based on some 29,000 relations between about 2,600 insect species and 1,300 plant species (569 genera). The data are derived from our database (“CrypTra”) of biotic relations between Cryptobiota and Tracheophyta, that is based on published sources. It is suggested that a ratio of 2 to 5 anthophilous insect species per entomophilous plant species is the rule in N.W. Europe, where other types of zoophily are virtually absent. A small minority of the plant species/generaplay a disproportionally important role as hosts to flower visitors; many of these so-called cornucopian taxa belong to the commonest entomophilous plants in the region, and occur also in moderately disturbed habitats. There is a significant positive correlation between the commonness of a plant species and the fraction this plant represents of the trophic resources exploited by an insect species. There is, on the other hand, a significant negative correlation between the number of insect species visiting a given plant species, and the number of plant species visited by a given insect species. These two elements together demonstrate that the anthophilous fauna and the entomophilous flora of N.W. Europe as a whole form a loose system, not predominantly characterised by specialisation. In accordance with this, factor analysis suggests that there is no ground to recognise more than three visitor types, viz., the allotropous, hemitropous, and eutropous visitors as defined by Loew. A minorityof the plant taxa - essentially the cornucopian ones - can with some difficulty be associated with these three types of visitors, and a very few narrowly specialised plant taxa can be associated with more specific visitor groups. However, the large majority of plants cannot be fitted in any typology. These results have practical implications for the nature management of the anthophilous fauna, in that the important role of the cornucopian floral element is underlined. The fact that the majority of the cornucopian species are perennial, or evenwoody, places constraints to agricultural practices intended to foster beneficial anthophilous insects.

Variable floral phenology: temporal resource heterogeneity and its implication for flower visitors

I investigated within‐ and between‐year patterns of flowering phenology of entomophilous plants in an isolated old field in northern Michigan, USA. The number of open flowers was censused at 5‐d intervals from June‐September of 1984–1986, and the data analyzed by detrended correspondence analysis. DCA axis 1 reflected within‐year phenology, was highly correlated with date of censusing, and implied substantial constancy in flowering sequences. However, DCA axis 2 revealed significant between‐year variation in abundances of flowers; years differed significantly in their scores on axis 2, and these differences were driven by variable plant species abundances during late summer. Within‐year patterns showed that the floral community consisted of three more‐or‐less distinct temporal “guilds” of plants, and that the rate of turnover in community composition throughout the season was not uniform. The appearance of these guilds was not synchronous across years.Insects foraging on these species throughout the floral season can expect constancy in the relative timing of blooming, but are exposed to considerable temporal heterogeneity in flower resource abundance both between‐ and within‐years. Opportunities for coevolutionary specialization are therefore likely to be constrained.

BUMBLE BEE POLLINATION AND FLORAL MORPHOLOGY: FACTORS INFLUENCING POLLEN DISPERSAL IN THE ALPINE SKY PILOT, POLEMONIUM VISCOSUM (POLEMONIACEAE)

Pollen dispersal success in entomophilous plants is influenced by the amount of pollen produced per flower, the fraction of pollen that is exported to other flowers during a pollinator visit, visitation frequency, and the complementarity between pollen donor and recipients. For bumble bee‐pollinated Polemonium viscosum the first three determinants of male function are correlated with morphometric floral traits. Pollen production is positively related to corolla and style length, whereas pollen removal per visit by bumble bee pollinators is a positive function of corolla flare. Larger‐flowered plants receive more bumble bee visits than small‐flowered individuals. We found no evidence of tradeoffs between pollen export efficiency and per visit accumulation of outcross pollen; each was influenced by unique aspects of flower morphology. Individual queen bumble bees of the principal pollinator species, Bombus kirbyellus, were similar in male, female, and absolute measures of pollination effectiveness. An estimated 2.9% of the pollen that bumble bees removed from flowers during a foraging bout was, on average, deposited on stigmas of compatible recipients. Significant plant‐to‐plant differences in pollen production, pollen export per visit, and outcross pollen receipt were found for co‐occurring individuals of P. viscosum indicating that variation in these fitness related traits can be seen by pollinator‐mediated selection.

The effect of aerial insecticide spraying for spruce budworm control on the fecundity of entomophilous plants in New Brunswick

Eight entomophilous plants, Aralia nudicaulis L., Clintonia borealis (Ait.) Raf., Cornus alternifolia L., Cornus canadensis L., Cornus stolonifera Michx., Kalmia angustifolia L., Maianthemum canadense Desf., and Viburnum trilobum Marsh., all of which bloom shortly after forest spray application in New Brunswick, were shown by bagging experiments to be dependent on insect visitation for seed set. All species showed significantly lower fecundity in fenitrothion-treated than in unsprayed areas. No depression of fecundity in Clintonia borealis or Kalmia angustifolia was found associated with aminocarb (Matacil) spraying.

The pollination biology of a pavement plain: pollinator visitation patterns.

The pollination biology of the 20 plant species of a treeless, pavement plain in the San Bernardino Mountains of southern California was studied throughout one flowering season.Several patterns of pollinator activity recorded during the season underline the necessity for noting the activity of all insect pollinators whether specialized, non-specialized, regular, or occasional: 1) Occasional insect visitors were a feature of the visitation to nine of the twelve entomophilous plant species and were the sole pollinators for three of these twelve species. 2) The eight entomophilous plant species which had open, generalized flower morphologies received the heaviest pollinator visitation, while three of the four entomophilous species with specialized flower morphologies received little visitation. 3) Most regular flower visitors, whether bees, flies, or wasps, appeared to be similar with respect to number of plant species visited regularly, purity of pollen load, length of residence and localization of activity on the site. The question is raised as to whether such similarity of behavior as pollen vectors is a function of the low plant diversity or a feature commonly found when the pollen loads and behavior of different pollinator types are actually monitored.

Soya-Bean Flowers: Nectary Ultrastructure, Nectar Guides, and Orientation on the Flower by Foraging Honeybees

SummarySoya-bean flowers possess most, if not all, of the anatomical adaptations characteristic of entomophilous plant species. A description of the flower is presented, based on photomicrographs and scanning electron micrographs. Specifically described and illustrated are: nectar guides, including those differentiated by ultraviolet light; the tongue channel and tongue guides; the ultrastructure of a highly developed nectary. The structure of the flower ensures that most foraging honeybees will contact an exposed sexual column with their ventral or facial hairs, thus effecting the transfer of pollen.

DENSITY DEPENDENT FORAGING ON LIATRIS PYCNOSTACHYA.

One of the distinguishing features of flowering plants is the reliance of many species on animal vectors, particularly insects, for cross pollination. For an outcrossing entomophilous plant, the behavior of pollinators directly determines the mating relations within a population and strongly affects the overall pattern of gene dispersal (Levin and Kerster, 1974). In their studies of gene dispersal in several entomophilous species, Levin and Kerster (1969a,b) have shown that within a plant population, the pollen component of gene dispersal is non-random and density dependent. Bee pollinator moves on Liatris aspera are predominantly to near-neighbor plants (Levin and Kerster, 1969a). As the distance between the plant near neighbors increases, the flight distance of the pollinators also increases. Thus, at a given density, the probability of two plants crossing is proportional to the distance between them; mating within an entomophilous plant population can conform to an isolation by distance model. When mating in a population is non-random as in some entomophilous plants, the population may become genetically divided into neighborhoods. Studies on genetic structure in the entomophilous species Liatris cylindracea have shown that subdivision does occur and that genetic differentiation conforms to an isolation by distance model (Schaal, 1974, 1975). Since genetic subdivision is known to exist in some entomophilous plant populations, and because, according to Wright (1969) it is an important characteristic that affects the evolutionary potential of a population, further studies of pollinator behavior, particularly the near-neighbor foraging pattern, seem to be warranted. The following is a report of density-dependent near-neighbor foraging of Bombus pennsylvanicus on Liatris pycnostachya.

EVOLUTIONARY TRANSITION FROM AMMONITE SUBPRIONOCYCLUS TO REESIDITES-PUNCTUATED OR GRADUAL?

indicate that the foraging pattern of bees and consequently the neighborhood size in plant populations may be density related. The number of individuals comprising a neighborhood at high density would be greater than at very low densities. Neighborhood area would be greater at the low densities. (This is a direct consequence of the greater frequency of near neighbor moves at low densities.) This result must, however, be modified somewhat since at very low densities pollinator foraging trip length is quite short in relation to the high density population. At extremely low plant densities one may expect neighborhood size to again increase. The proportion of long distance flights is increased. The results of this study indicate that genetic structure in an entomophilous plant may be density related. A final aspect of this study is related to the attractiveness of a population to pollinators. Populations of high density are presumably more attractive to pollinators since they offer more reward per unit area than populations of low densities. The data from the average number of plants visited per bee foraging trip are consistent with this hypothesis. The denser the population the greater is the proportion of the flower population visited per bee. At very low densities the experimental population attracted few bees and only few plants were visited while at high densities many bees were attracted and each plant was repeatedly visited. ACKNOWLEDGMENTS

Phylogeny, hologeny and coenogeny, basic concepts of environmental biology.

Some data from earlier work concerning the evolutionary correlation of anthophilous insects, entomophilous plants, herbivorous animals, and natural soil groups are briefly summarized. Presumed successive evolution of plant and animal communities from the early Paleozoic era to the more recent formation of prairies, steppes and other grassland areas is described and pictured in Fig. 6. A definite correlation has been found among the coevolution of flowering plants, pollinating insects, ruminant animals and fertility grades of natural soil groups (Fig. 7). Plants, insects, animals and soil are interrelated in evolution as reciprocal selective and regulating factors in certain biotic and abiotic environments. This complex system can be better studied by application of the coenogenic concept and hologenic and syngenic methods. Various stages of the development of an agricultural environment in the prairie areas of the North American plains are briefly described and illustrated in Plates I–VII. A new radical change in the development by the introduction of so-called “Circle Farming” is pictured in Plates VIII–IX. This new irrigated farming system is not only profitable for the increasing of yields, but promises to some extent the restoration of a biologically balanced environment in an extensively cultivated agricultural landscape.

The Ecology of the Pollinators and Predators of Frasera Speciosa

Frasera speciosa is a conspicuous perennial in the Rocky Mountains where it forms discrete colonies whose inflorescences are characterized by almost total absence in some years and greater abundance in others. This sporadic yet synchronous flowering was the most conspicuous feature of the reproductive biology of the species and its adaptive value was worth investigation. In a three—mile stretch of the East River Valley, Colorado, the following data were gathered over a period of three years: the distribution and abundance of colonies, the floral biology, the dispersal of insect visitors among the flowers of Frasera and its floral associates, the frequency of floral predation and seed—set. Although the percentage of plants with inflorescences was always very low and despite the occasional wide spatial separation of individuals, Frasera invariably attracted the greatest number and diversity of floral visitors and never yielded less than 52% seed—set. It was also shown that pollination was affected by a wide variety of inset visitors that maintained cross—pollination at a frequency of approximately 15%. In no colonies was floral predation nearly as heavy as in its sympatric associate Lupinus and it was concluded that seed—set Frasera was not significantly affected by predispersal herbivory. The local synchrony revealed by the occurrence of discrete colonies and the overall synchrony revealed in the almost total absence of floral colonies in some years and their abundance in others is viewed as a strategy for predator avoidance. These mechanisms, together with other aspects of the reproductive biology, also reduce pressure from sympatric species competing for pollinators. It is out that they confer reproductive advantage to a minority species which may otherwise rapidly decline to extinction in the presence of intense competition. The flowering regime of Frasera combines a predator avoidance system which yields widely dispersed colonies in space and in time with a pollination system which successfully exploits the maximum diversity of floral visitors and maintains excellent seed—set whenever and wherever the colonies appear. The systems are clearly complementary in preventing the build—up of predator populations while maintaining an attractive forage source for potential pollen vectors. The combined effect is to maintain the abundance of the species in a variety of stress environments, in turn resulting in a remarkably wide geographic success. It is considered likely that similar systems will turn out to be very common among entomophilous plants in both temperate and tropical regions.

THE DEPENDENCE OF BEE-MEDIATED POLLEN AND GENE DISPERSAL UPON PLANT DENSITY.

Pollen dispersal and pollen-mediated gene dispersal in flowering plants are effected primarily by animals and air currents. It is generally accepted that the dispersal of pollen within a colony of a given species is under the control of these agents and beyond the control of the colony. This view may be valid in the case of anemophilous plants where alterations of colony parameters ostensibly would have no effect upon the characteristics of pollen flow, since these parameters would not affect the transferal agent. However, in entomophilous plants, pollen and associated gene movements are mediated by vectors which may be sensitive to stimuli emanating from the colony. If pollinators respond to such stimuli, permutations of which would alter foraging behavior, the colony, wittingly or unwittingly, would control the dispersal of its pollen and genes. A recent study on pollinator flight patterns in Liatris aspera (Levin and Kerster, 1969) has shown that plant density and spacing control the feeding-flight behavior of bees and the movement of pollen which they bear. The present investigation was undertaken to determine whether the dependence of bee-flight characteristics and bee-mediated pollen dispersal upon plant spacing is a general phenomenon. We will show that bees are highly responsive to plant spacing and that bee-mediated pollen dispersal and associated gene dispersal is strongly correlated with plant spacing, the plant species and floral mechanism notwithstanding.

THE EFFECT OF COROLLA COLOR AND OUTLINE ON INTERSPECIFIC POLLEN FLOW IN PHLOX.

Flowers of related species of entomophilous plants typically differ in pigmentation, form or scent. These differences form the basis for ethological or mechanical isolation by limiting or precluding interspecific pollen flow. The effectiveness of disparate floral contrivances in precluding interspecific pollination has been demonstrated in numerous genera (cf. Grant, 1963; van der Pijl and Dodson, 1967). On the other hand, there is a paucity of information on the effectiveness of floral differences in retarding interspecific pollination in genera where mechanical barriers are absent. Even where such knowledge is available, the role of specific signals in aiding pollinator recognition remains obscure. If pollinator perception of color, form and odor were understood, we could predict pollinator response to specific floral signals or to the signal complex. However, with the exception of bees, little is known of the ability of nectar-feeding insects to discriminate between variants of the signals in question. Pollinator perception is germane to the issue of ethological isolation for the level of pollinator fidelity to a given floral type depends in part upon the ability of the pollinator to discriminate between the signals eminating from a given type and others which also may be present. The purpose of this investigation was to determine the effect of corolla color and outline on pollen flow from Phlox glaberrima L. to P. drummondii Hook. These species are pollinated almost exclusively by lepidopterans (Grant and Grant, 1965; personal observations) which are wellsuited for feeding within the salverform

EVOLUTIONARY RELATIONSHIP BETWEEN ENTOMOPHILOUS PLANTS AND ANTHOPHILOUS INSECTS

Journal Article EVOLUTIONARY RELATIONSHIP BETWEEN ENTOMOPHILOUS PLANTS AND ANTHOPHILOUS INSECTS Get access E. E. Leppik E. E. Leppik The Hormel Institute of the University of Minnesota Austin Minnesota Search for other works by this author on: Oxford Academic Google Scholar Evolution, Volume 11, Issue 4, 1 December 1957, Pages 466–481, https://doi.org/10.1111/j.1558-5646.1957.tb02918.x Published: 01 December 1957 Article history Received: 04 April 1957 Published: 01 December 1957