In Central Europe,
L. is a late summer/autumn bloomer (August/November). The disc florets produce both nectar and pollen. Floral reward is available in male-phase flowers (pollen and nectar) and in ...female-phase flowers (nectar). The floral reward is attractive to a variety of insect visitors (honey bees, wasps, flies and butterflies). The season of blooming as well as the total sugar yield (25.4 – 47.4 kg ha
) and pollen yield (57.8 – 212.7 kg ha
) indicate that
is important in the enhancement of food resources for pollinators. The generative reproduction in
is impaired (the species does not set seeds/fruits). However, due to its attractiveness for a variety of pollinators in both rural and urban areas, the spread of
should be monitored. Moreover, its propagation needs to be attended with restrictions.
Low plant species richness and abundance, as well as contamination, can lead to a lack of nutrients in the diets of pollinators. This can cause increased oxidative stress, low resistance to disease ...and reduced detoxification ability. We proposed three forage mixtures with different botanical compositions, all of which should provide continuous forage for a wide range of pollinators. The monitored mixtures were treated by foliar application with selenium and zinc. Both elements should increase the quality of pollen and nectar. The effect of meadow mixtures and microelements on pollinator abundance, richness, and preference was evaluated using data obtained via the line transect method. Furthermore, the amount of selenium and zinc in the flowers was determined. It was found that the microelement treatment did not have any effect on the abundance and richness of the main pollinator taxa, which were affected only by a botanical composition of meadow mixtures. However, a preference for zinc-treated forage was observed in Apis mellifera, and a preference for selenium-treated forage was observed in Bombus spp. These two eusocial taxa appear to respond to an increased amount of microelements in the treated meadow mixtures. On the contrary, Lepidoptera was tied to untreated forage, where they were probably pushed by social bee species due to the competition.
Males of the closely related species Bombus terrestris and Bombus lucorum attract conspecific females by completely different marking pheromones. MP of B. terrestris and B. lucorum pheromones contain ...mainly isoprenoid (ISP) compounds and fatty acid derivatives, respectively. Here, we studied the regulation of ISP biosynthesis in both bumblebees. RNA‐seq and qRT‐PCR analyses indicated that acetoacetyl‐CoA thiolase (AACT), 3‐hydroxy‐3‐methylglutaryl‐CoA reductase (HMGR), and farnesyl diphosphate synthase (FPPS) transcripts are abundant in the B. terrestris labial gland. Maximal abundance of these transcripts correlated well with AACT enzymatic activity detected in the LG extracts. In contrast, transcript abundances of AACT, HMGR, and FPPS in B. lucorum were low, and AACT activity was not detected in LGs. These results suggest that transcriptional regulation plays a key role in the control of ISP biosynthetic gene expression and ISP pheromone biosynthesis in bumblebee males.
Regulation of pheromone biosynthesis is of key importance for insect reproductive isolation and speciation. We show that the production of isoprenoid male pheromones in two closely related and agriculturally important bumblebee species, B. lucorum and B. terrestris, is regulated transcriptionally at the level of isoprenoid biosynthetic genes.
Researchers increasingly recognize the important role of mutualisms in structuring communities and view positive interactions in a community context rather than as simple pairwise interactions. ...Indirect effects, such as those that predators have on lower trophic levels, are a key process in community ecology. However, such top‐down indirect effects have rarely been extended to mutualisms. Antagonists of one mutualist have the potential to negatively affect the second mutualist through negative effects on their partner, and the magnitude of such effects should vary with mutualism strength. Bumble bees are ecologically and economically important pollinators that are an ideal system to determine if such indirect effects play an important role in mutualisms. Bumble bees are attacked by an array of parasites and predators, and they interact with a range of plants that vary in their dependence on bumble bees for reproduction. We tested whether variation in parasitism rates by Nosema bombi, Crithidia bombi, and conopid flies correlated with reproduction of greenhouse‐raised plants placed in the field. At multiple sites over two years, we studied four plant species that varied in reliance on bumble bees as pollinators. We found a consistent negative relationship between Nosema parasitism and measures of pollination for Trifolium pratense and Solanum carolinense, plant species with high bumble bee visitation, whereas Rudbeckia hirta and Daucus carota, plant species with generalized pollination, experienced no impacts of Nosema. However, both Crithidia and conopids showed inconsistent relationships with pollination service. Although these patterns are correlational, they provide evidence that parasites of bumble bees may have negative indirect effects on plants, and that mutualism strength can moderate the magnitude of such effects.
Recent concerns about the potential for pathogens to be transmitted from managed bumble bees and honey bees to local natural populations of bumble bees and other native pollinators have resulted in ...questions about the role of pathogen introductions in declines of some native Bombus species. It is in the interest of the bumble bee rearing industry, which succeeds best when managed colonies are healthy and vigorous, and the safety of the environment into which the bees are introduced, to ensure that managed bees are not foci of disease. Visual detection methods using gross pathology and light microscopy, while generally efficacious if a thorough inspection routine is followed, have the disadvantage of detecting most pathogens only after maturation to the transmissible stage. Koppert Biological Systems, the only company currently rearing bumble bees in the US, has instituted a detection method using multiplex real-time PCR to evaluate colonies for presence of three pathogens, Nosema bombi, Crithidia bombi, and Apicystis bombi, all chronic pathogens with potential to build to high prevalence in rearing facilities. Added to a rigorous inspection system, PCR methods ensure that these pathogens are detected quickly and are eliminated.
Most anthropogenic activities are known to have deleterious effects on pollinator communities. However, little is known about the influence of urbanization on pollination ecosystem services.
Here, we ...assessed the pollination service on Lotus corniculatus (L.), a self-sterile, strictly entogamous Fabaceae commonly observed in urban and suburban areas. We assessed the pollination success of artificial Lotus corniculatus populations at three levels: at large scale, along an urbanization gradient; at intermediate scale, based on landscape fragmentation within a 250 m radius and at local scale based on floral resource abundance and local habitat type.
The main findings were that the pollination success, when assessed with the number of fruit produced per inflorescence, was lower in urban areas than in suburban ones, and was negatively affected by the number of impervious spaces in the neighborhood. The relationship between the number of fruits and the distance to the nearest impervious space was either positive or negative, depending on the gray/green ratio (low vs. high). Finally, on a local scale, floral resource abundance had a negative effect on pollination success when L. corniculatus populations were located in paved courtyards, and a positive one when they were located in parks.
Pollination success seems to be explained by two intertwined gradients: landscape fragmentation estimated by the number of impervious spaces in a 250 m radius around L. corniculatus populations, and the behavior of bumblebees toward birdsfoot trefoil and floral displays, which appears to differ depending on whether a neighborhood is densely or sparsely urbanized. An abundance of attracting floral resources seems to enhance pollination success for L. corniculatus if it is not too isolated from other green spaces.
These results have important implications for the sustainability of pollination success in towns by identifying local and landscape factors that influence reproductive success of a common plant.
► Pollination service of Lotus corniculatus was assessed across spatial scales in an urban area. ► The pollination was negatively affected by the number of built areas. ► The impact of distance to built area depended on the urbanization intensity. ► The floral resource had a negative impact in courtyards and a positive one in parks. ► Birdsfoot trefoil pollination is increased by local resource only if not too isolated.
Nectar robbers are birds, insects, or other flower visitors that remove nectar from flowers through a hole pierced or bitten in the corolla. This paper is a review of the effects of nectar robbers on ...pollinators, pollination, and fitness of the plants they rob. Charles Darwin assumed that nectar robbers had a negative impact on the plants that they visit, but research done in the last 50 years indicates that they often have a beneficial or neutral effect. Several studies document that robbers frequently pollinate the plants that they visit. Robbers may also have an indirect effect on the behavior of the legitimate pollinators, and in some circumstances, the change in pollinator behavior could result in improved fitness through increased pollen flow and outcrossing. The effects of nectar robbers are complex and depend, in part, on the identity of the robber, the identity of the legitimate pollinator, how much nectar the robbers remove, and the variety of floral resources available in the environment.
Mites of the genus Pneumolaelaps Berlese are often found in association with bumble bees (Hymenoptera: Apidae). Approximately sixty species of the genus have been described worldwide but only two of ...them have been recorded in New Zealand, viz. Pneumolaelaps bombicolens (Canestrini, 1885) and P. breviseta (Evans & Till, 1966). A new species, Pneumolaelaps niutirani, collected from hives of honeybee Apis mellifera (Apidae) and nests of the German wasp Vespula germanica (Vespidae) brings the number of species in New Zealand to three. We herein review P. bombicolens and P. breviseta, describe the new species, Pneumolaelaps niutirani, with notes on its biology, and provide a key to the species known in New Zealand. This is the first report of Pneumolaelaps in association with a vespid wasp.
For insect-pollinated plant species, reproductive success and genetic exchange via the transfer of pollen between flowers depends (i.a.) on the efficiency, abundance and behaviour of floral visitors. ...These in turn are expected to respond to plant population size and flower density. High floral densities for example usually attract large numbers of pollinators that visit more flowers per plant or patch, which increases pollen deposition at short distances. Thus, population characteristics might serve as indicators for pollen dispersal patterns and help to identify suitable habitat size and quality for conservation measures. To test this hypothesis, we observed floral visitors of a generalist, entomophilous species, Comarum palustre, and compared their abundance and visitation rates in populations of different sizes and flower densities. At the same time, we mimicked pollen flow using fluorescent dye. In the large and dense populations, pollinator abundance and visitation rates were high and dye was dispersed to the edges of the populations (up to 200m). In the medium-sized population with high flower density, insect abundance and visitation rates were unexpectedly low and dye dispersal declined very quickly. On the contrary, in the smallest population with scattered flowers, especially bumble bee abundance was similar to the large populations and dye dispersal mirrored this high bumble bee activity. Thus, our results indicate that in smaller habitat fragments, the mere size of a population might be insufficient to suggest pollen flow for a plant species. Instead, the abundance of its major pollinators should be considered.
Die Ausbreitung von Pollen hängt bei insektenbestäubten Pflanzen u.a. von der Effizienz, der Häufigkeit und dem Verhalten der Blütenbesucher ab. Diese wiederum werden häufig durch die Größe der Pflanzenpopulationen sowie deren Dichte an Blüten bedingt. Zum Beispiel locken hohe Blütendichten meist auch eine große Bestäuberzahl an, die dann mehr Blüten pro Pflanze bzw. Standort besuchen. Folglich wird Pollen zwar in großen Mengen, aber nur über kurze Distanzen ausgebreitet. Populationsgröße und Blütenangebot könnten daher als gute Indikatoren für Pollenfluss dienen, was im Naturschutz helfen könnte, die geeignete Größe und Qualität von Lebensräumen zu definieren. Um diese Hypothese zu testen, beobachteten wir die Blütenbesucher einer insektenbestäubten, generalistischen Pflanzenart (Comarum palustre) und verglichen deren Häufigkeit und Besuchsraten in Populationen von unterschiedlicher Größe und Blütendichte. Gleichzeitig imitierten wir den Pollentransfer mit fluoreszierendem Puder. In den großen und dichten Populationen waren die Häufigkeit und Besuchsraten der Bestäuber erwartungsgemäß hoch, und der Puder wurde über die gesamte Fläche der Populationen ausgebreitet (bis zu 200m). Überraschenderweise waren die Abundanz und Besuchsraten von Insekten in einer mittelgroßen Population mit hoher Blütendichte sehr niedrig und die Übertragung von Puder nahm schnell ab. In der kleinsten Population dagegen mit nur geringem Blütenaufkommen, war besonders die Anzahl der Hummeln vergleichbar mit den großen Populationen, was sich in der Verteilung des Puders widerspiegelte. Unsere Ergebnisse legen den Schluss nahe, dass in kleineren Habitatfragmenten, die Größe und Dichte einer Population allein nur unzureichende Rückschlüsse auf den Pollenfluss einer Pflanze erlaubt. Stattdessen sollte auch die Häufigkeit der effizientesten Bestäuber in Betracht gezogen werden.
Different biotic interactions may influence one another to produce complex patterns of direct and indirect effects, which together influence plant reproductive success. However, so far most studies ...on plant-animal interactions have focused on single interactions in isolation. In this study, we studied the effect of florivory by the weevil
Cionus nigritarsis on pollinator visitation rate in the self-incompatible perennial herb
Verbascum nigrum by combining observations of florivory and pollination in natural populations with records of pollinator visitation to plants with different levels of experimentally inflicted damage.
Increasing levels of damage through either natural or simulated florivory resulted in fewer pollinator visits per plant and per flower. As expected, the magnitude of the indirect effect of florivory on pollinator visitation was proportional to the intensity of florivory. Our results indicate that biotic non-pollinating agents, such as florivores, may induce substantial changes in pollinator availability. Therefore, studies addressing different plant-animal interactions in parallel are necessary to better comprehend the factors influencing the reproductive performance and demography of flowering plants.
Verschiedene biotische Interaktionen können sich gegenseitig beeinflussen und so komplizierte Muster von direkten und indirekten Auswirkungen erzeugen, die zusammen den Fortpflanzungserfolg von Pflanzen beeinflussen. Bisher haben sich die meisten Untersuchungen von Pflanze-Tier-Interaktionen jedoch auf eine einzelne Interaktion in Isolation konzentriert. In dieser Studie untersuchten wir den Effekt der Herbivorie durch den Rüsselkäfer
Cionus nigritarsis auf die Besuchsrate der Bestäuber bei dem selbstinkompatiblen, perennierenden Kraut
Verbascum nigrum, indem wir die Beobachtungen von Blütenfraß und Bestäubung in natürlichen Populationen mit den Aufzeichnungen von Bestäuberbesuchen auf Pflanzen mit unterschiedlich ausgeprägten, experimentell verursachten Schäden kombinierten.
Zunehmende Beschädigung sowohl durch natürliche wie simulierte Herbivorie führte zu weniger Bestäuberbesuchen pro Pflanze und pro Blüte. Wie erwartet, war die Größenordnung der indirekten Effekte der Herbivorie auf die Bestäuberbesuche proportional zur Intensität des Blütenfraßes. Unsere Ergebnisse weisen darauf hin, dass biotische nicht-bestäubende Organismen, wie z.B. blütenfressende Herbivore, substanzielle Veränderungen in der Bestäuberverfügbarkeit verursachen können. Deshalb sind Untersuchungen notwendig, die verschiedene Pflanze-Tier-Interaktionen parallel bearbeiten, um die Faktoren besser zu verstehen, welche die reproduktive Performanz und die Demographie der blühenden Pflanzen beeinflussen.
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