Pollen grain morphology is not exclusively responsible for pollen collectability in bumble bees
Pollen grain morphology is not exclusively responsible for pollen collectability in bumble bees
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DOI：
10.1038/s41598-019-41262-6
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发表时间：
2019-03-18
影响因子：
4.6
通讯作者：
Lunau, Klaus
中科院分区：
文献类型：
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作者：
Konzmann, Sabine;Koethe, Sebastian;Lunau, Klaus
蜜蜂授粉的植物面临着一个困境，蜜蜂既被动地在同种花之间运输花粉粒，又主动收集花粉来喂养幼虫。因此，减少蜜蜂收集花粉的机制已经在嗜蜂植物中进化出来。锦葵科花粉对于珊瑚蜂来说是无法采集的，此前人们将其归因于花粉大小、刺和花粉基。我们分析了花粉粒特性（直径、刺长度、刺密度）对熊蜂（Bombus terrestris）采集海刺（刺）花粉的影响。工蚁分别在六个科的八种植物中的一种上采食，对具有大的刺状花粉粒的植物的花粉采食显着减少。然而，花粉颗粒大小、刺长度和刺密度都不是收集性的绝对因素。虽然花粉采集者没有转向花蜜采集，而是用无法采集的花粉捕获来访的花朵，但花蜜采集者对这些植物进行定期采集。对于珊瑚蜂来说无法采集的花粉限制了通用大黄蜂和蜜蜂的花粉消耗，同时保持它们作为传粉媒介，这是解决花粉困境的有效解决方案。由于先前关于花粉形态对其可采集性影响的假设被推翻，因此讨论了潜在的决定因素。
Bee-pollinated plants face a dilemma in that bees both passively transport pollen grains among conspecific flowers and actively collect pollen to feed their larvae. Therefore, mechanisms that reduce pollen collection by bees have evolved in melittophilous plants. Malvaceae pollen is uncollectable for corbiculate bees which has previously been ascribed to pollen size, spines, and pollenkitt. We analysed the influence of pollen grain properties (diameter, spine length, spine density) on the collectability of echinate (spiny) pollen by bumble bees (Bombus terrestris). Workers individually foraging on one of eight plant species from six families performed significantly less pollen foraging on plants which have large, echinate pollen grains. Nevertheless, neither pollen grain size, spine length, nor spine density prove to be an absolute disqualifier for collectability. While pollen foragers did not shift to nectar collection but seized visiting flowers with uncollectable pollen, nectar foragers performed regular foraging bouts on these plants. Pollen that is uncollectable for corbiculate bees limits pollen depletion by generalist bumble bees and probably also honey bees while maintaining them as pollinators, which is an effective solution to the pollen dilemma. As previous assumptions about the impact of pollen morphology on its collectability are disproved, potentially determining factors are discussed.