536 resultados para Cycad Pollination


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Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

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Pós-graduação em Ciências Biológicas (Zoologia) - IBRC

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Pós-graduação em Ciências Biológicas (Botânica) - IBB

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Pós-graduação em Zootecnia - FMVZ

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Pós-graduação em Ciência Florestal - FCA

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Crops have different levels of dependence on pollinators; this holds true even for cultivars of the same species, as in the case of cucumber (Cucumis sativus). The aim of this research was to assess the attractiveness of flowers of three Japanese parthenocarpic cucumber cultivars and evaluate the importance of Africanized bees (Apis mellifera), and the Brazilian native stingless bees, Jata (Tetragonisca angustula) and Ira (Nannotrigona testaceicornis) on fruit production. Several parameters, including frequency of bee visits to flowers as well as duration of nectar collection and fruit set were examined; additionally, fruit weight, length and diameter were evaluated. Three greenhouses located in Ribeirao Preto, SP, were used for planting three cucumber cultivars (Hokushin, Yoshinari and Soudai). The female flowers were more attractive than male flowers; however, Jata bees were not observed visiting the flowers. The Africanized and the Ira bees collected only nectar, with a visitation peak between 10 and 12h. Visits to female flowers had a longer duration than visits to male flower visits in all three cultivars. Africanized bee colonies declined due to loss of bees while in the greenhouse; the native stingless bee colonies did not suffer these losses. When bees were excluded, fruit set was 78%; however, when bees had access to the flowers, fruit set was significantly (19.2%) higher. Fruit size and weight did not differ with and without bees. This demonstrates that even in parthenocarpic cucumber cultivars, which do not require pollination in order to from fruits, fruit production is significantly increased by bee pollination.

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Pós-graduação em Agronomia (Horticultura) - FCA

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Pós-graduação em Biociências - FCLAS

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Bees have a crucial role in pollination; therefore, it is important to determine the causes of their recent decline. Fipronil and imidacloprid are insecticides used worldwide to eliminate or control insect pests. Because they are broad-spectrum insecticides, they can also affect honeybees. Many researchers have studied the lethal and sublethal effects of these and other insecticides on honeybees, and some of these studies have demonstrated a correlation between the insecticides and colony collapse disorder in bees. The authors investigated the effects of fipronil and imidacloprid on the bioenergetic functioning of mitochondria isolated from the heads and thoraces of Africanized honeybees. Fipronil caused dose-dependent inhibition of adenosine 5'-diphosphate-stimulated (state 3) respiration in mitochondria energized by either pyruvate or succinate, albeit with different potentials, in thoracic mitochondria; inhibition was strongest when respiring with complex I substrate. Fipronil affected adenosine 5'-triphosphate (ATP) production in a dose-dependent manner in both tissues and substrates, though with different sensitivities. Imidacloprid also affected state-3 respiration in both the thorax and head, being more potent in head pyruvate-energized mitochondria; it also inhibited ATP production. Fipronil and imidacloprid had no effect on mitochondrial state-4 respiration. The authors concluded that fipronil and imidacloprid are inhibitors of mitochondrial bioenergetics, resulting in depleted ATP. This action can explain the toxicity of these compounds to honeybees. (c) 2014 SETAC

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The Cerrado is home to important biodiversity areas in the state of Sao Paulo. Therefore, research on the reproduction of species of this biome are essential to help conservation programs. Pollination is the main mechanism by which outcrossing plants perpetuate their populations, and the attractive, such as nectar, are of vital importance to many anthophilous animals and essential to the maintenance of interactions with pollinators. In this context, the objective of this study was to investigate the ecological dynamics of secretion and sugar composition of floral nectar in Zeyheria montana, an ornithophilous exclusive Cerrado species, visited preferentially by Colibri serrirostris, also exclusive to this biome. This dynamic was assessed in isolated flowers in pre-anthesis, using microsyringes to collect nectar and manual refractometer to measure the concentration. Experiments were carried out to evaluate production throughout anthesis, including the assessment of total daily production, the effect of successive removal, the rate of production during the day and night and changes in concentration and composition of sugars, which was performed in HPLC (High Performance Liquid Chromatography). The rate of nectar production was about three times greater at night with a concentration two times lower, resulting in a supply of large amounts of dilute nectar in the early morning hours, peak of visitation for hummingbirds. Moreover, the production of nectar was more pronounced before the anthesis, and is available to visitors already in newly opened flowers, which are preferentially visited by C. serrirostris. There was an increase in the nectar production of flowers in the group with successive manual removal upon the control group, suggesting that the withdrawal by visitors stimulates the production, ensuring the availability of the resource including flowers previously visited... (Complete abstract click electronic access below)

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The bee Apis mellifera has a great importance because it is the most economically valuable pollinator for crops worldwide, ensuring cross-pollination and increasing fruit yield. Moreover, agriculture increasingly develops chemicals to control weeds, fungi and insect pests to ensure productivity. Insecticides are used on a large scale in the state of São Paulo, in cultures of citrus for control of greening. Applications are usually made by aircraft and as a result of the effect derives a significant mortality is observed in apiaries near the plantations. Honey bees can get in contact with such chemical agent through their activities of water harvesting, plant resins, pollen and nectar. Intoxication resulting from this exposure can be lethal, which is easily detectable, or cause effects on the physiology and behavior of the insect. These, in turn are hardly detectable, such as paralysis, disorientation, behavioral changes, but can compromise the entire social structure of the colony, therefore aimed to study the effects of the insecticide Thiamethoxam behavior of honeybees A. mellifera. Newly emerged individuals and with 10 days of age were tested. Applications of 1 μL de Thiamethoxam, diluted in acetone, were made on the dorsal thorax with a microapplicator. Preliminarily, it was observed LD50 twenty four hours after topical treatment of Thiamethoxam. It was found that the LD50 for newly emerged honeybees is 8 ng/bee and for honeybees with 10 days of age is 18 ng/bee. The behaviors were analyzed 1 hour after application of insecticide at doses corresponding to LD50/100, LD50/50, LD50/10 and LD50, besides the control group. In the test reflex proboscis extension, there was impairment of behavior at doses of 8 and 18 ng/bee workers in newly emerged workers and 10 days of age, respectively. And in locomotor behavior was no change only at a dose of 18 ng/bee workers at 10 days of age... (Complete abstract click electronic access below)