【摘要】 【目的】显花植物大多具有多种传粉者,判断最有效传粉者的直接证据是对主要传粉者的传粉效率进行研究。‘凤丹’(Paeonia ostii‘Feng Dan’)为一种新型木本食用油料植物,繁育系统为部分自交亲和、异交,需要传粉者活动才能完成授粉过程。笔者对‘凤丹’居群的访花昆虫种类及其传粉行为进行研究,旨在查清‘凤丹’主要传粉昆虫种类及其传粉效率,为提高‘凤丹’结籽率、改善种子质量、加大栽培规模提供传粉生物学参考。【方法】采用定点调查法对‘凤丹’主要传粉昆虫及其访花频率、单花停留时间、访花时柱头接触率进行观测,采用跟踪调查法对主要传粉昆虫连续两次访花的飞行距离、访固定花朵数目时的被访植株数进行观测,通过田间采集与室内镜检对主要传粉昆虫体表携粉量与单次访花后柱头花粉落置量进行统计。【结果】‘凤丹’访花昆虫主要有蜂类、蚁类、甲虫类及蝇类共4个类群,主要传粉昆虫为意大利蜜蜂(Apis mellifera)、中华蜜蜂(A.cerana)与黄熊蜂(Bombus flavescens)。意大利蜜蜂与中华蜜蜂的访花行为相似。黄熊蜂的访花频率极显著高于意大利蜜蜂和中华蜜蜂的(P<0.01),单花停留时间极显著低于意大利蜜蜂和中华蜜蜂的(P<0.01);黄熊蜂的柱头接触率与意大利蜜蜂及中华蜜蜂的差异不显著。黄熊蜂的访花飞行距离极显著高于意大利蜜蜂和中华蜜蜂的(P<0.01),访固定花朵数目时的被访植株数极显著高于意大利蜜蜂和中华蜜蜂的(P<0.01),更能促进植株的异交授粉。黄熊蜂的体表携粉量极显著高于意大利蜜蜂和中华蜜蜂的(P<0.01),单次访花后柱头花粉落置量极显著高于意大利蜜蜂和中华蜜蜂的(P<0.01),花粉转移能力更高。【结论】黄熊蜂、意大利蜜蜂和中华蜜蜂均为‘凤丹’有效传粉昆虫,以黄熊蜂传粉效率最高,中华蜜蜂与意大利蜜蜂其次,二者具有相近传粉效率。更多还原

【Abstract】 【Objective】 Many Paeonia plants have poor fecundity. Paeonia ostii ‘Feng Dan’is a shrub that originated from Anhui Province and now planted widely in Hunan, Chongqing, Shandong, Sichuan and Henan in China. P. ostii seed contains abundant monounsaturated fatty acid, including α-linolenic acid(ALA), an essential fatty acid that humans cannot synthesize. Thus, the seed of P. ostii is an excellent raw material for the production of a new type of edible oil. Compared with the low fruit set of other Paeonia plants, the fruit set of P. ostii is high, which provides the possibility for large-scale production of its seed. The seed set of P. ostii from cross-pollination is significantly higher than that from self-pollination, which means that seed production is outcross pollinated and pollinator dependent. Thus, the foraging behavior of the main P. ostii pollinators is still unclear, which is important for gaining higher yield and seed quality. 【Method】 We investigated the pollination behavior of the major pollinators of P. ostii in Dianjing, Northeastern Chongqing, China in March and April from 2015 to 2017. Through fixed-point observations, we examined the visiting frequency, residence time, and rate of stigma contact of major pollinators. Through tracking observation, we measured the flying distance of main pollinators between two consecutive visits using a portable infrared rangefinder(Shendawei SW-A/B, Dongguan, China). Occasionally, honeybees flew away and returned to revisit the same flower, which was regarded as a single visit. Through field collections and laboratory observations under a microscope, we observed the pollen load of the main pollinators by netting the forager from the visited flower, and then transferring them to a poison flask and taking to the laboratory. All pollen grains on the poison flask and on the surface of the pollinator body were flushed with 50% alcohol and transferred onto a glass slide before being observed and counted under a microscope. The source of pollen grains was not identified; in our preliminary observation, all pollen grains carried by bees were found to be from P. ostii under a scanning electron microscope. To confirm pollen deposition by the main pollinators on the stigma after a single visit, the unopen flower was bagged until opening. The petals of the large flower were taped to form a half closure after fully opening, which allowed the pollinator to contact the stigma before collecting pollen grains. When the stigma was visited by a pollinator, it was transferred into a centrifuge tube and brought into the laboratory to observe and count under microscope. 【Result】 ①Visitors to P. ostii flowers included ants(Plagiolepis wroughtoni Forel, Pheidole rhombinoda Mayr., Crematogaster politula Forel, Paratrechina bourbonica Forel), beetles(Oxycetonia bealiae Gory et Percheron, Themus sp., Altica cyanea Weber, Basilepta sp.), flies(Lucilia cuprina Wied, Metallea notate Wulp) and bees(Apis mellifera, A. cerana, Bombus flavescens). The main pollinators of P. ostii flowers were Apis mellifera, A. cerana, and B. flavescens, due to their large numbers, speed when moving between different flowers, and the obvious pollen grains stuck to their body surface during visiting. ② Among three species of bees, both A. mellifera and A. cerana were similar in terms of pollinating behavior. Apis mellifera and A. cerana collected pollen grains from anthers with legs, while B. flavescens applied buzz foraging pollen during visiting. Compared to A. mellifera and A. cerana, B. flavescens had a shorter handle time(P<0.01) and a higher visiting frequency(P<0.01). Rates of stigma contact by all three bee species were low because of the relative spatial separation between anther and stigma in the large-sized flower after its opening. There was no significant difference in the rate of stigma contact among the three bee species(P=0.28), partly due to B. flavescens occasionally laying on the basal flower to collect pollen, which reduced its rate of stigma contact. ③ A. mellifera and A. cerana preferred to collect pollen grains from nearby flowers and plants. Bombus flavescens would continue its flight to reach distant flowers after foraging one-three flowers in the neighborhood. The flying distance of B. flavescens was significantly greater than that of A. mellifera and A. cerana(P<0.01). When visiting a fixed number of peony flowers, B. flavescens was distributed more widely(visiting more trees) than A. mellifera and A. cerana(P<0.01). ④ The surface of the pollen grain from P. ostii was dry, while that of its stigma was wet, and an obvious exudate could be observed on the stigma if it remained unpollinated on the third flowering day. During foraging, pollen grains could be stuck to the legs, abdomen, and proboscis of the three bee species, and to the back of B. flavescens. Pollen load and deposition after a single visit of B. flavescens were significantly higher than those of A. mellifera and A. cerana(P<0.01), indicating that the bumble bee had a greater ability to transfer pollen.【Conclusion】 Apis mellifera, A. cerana and B. flavescens were effective pollinators of P. ostii flowers. The most efficient pollinator was B. flavescens, followed by A. cerana and A. mellifera with similar pollination efficiency.更多还原