Nocturnal pollination plays an important role in sexual plant reproduction but has been overlooked, partially because of intrinsic difficulties in field experimentation. Even less attention has received the effect of within-inflorescence spatial position (distal or proximal) on nocturnal pollinators of columnar plants, despite numerous studies examining the relationship between such position and reproductive success. Woody endemic Echium simplex possesses large erect inflorescences bearing thousands of flowers which are visited by a wide array of diurnal and nocturnal animals. In this study, we identified nocturnal visitors and compared their pollination effectiveness with that of diurnal pollinators in different inflorescence sections by means of selective exclosures in NE Tenerife (Canary Islands). Nocturnal visitors included at least ten morphospecies of moths (such as Paradrina rebeli and Eupithecia sp.), two coleopteran species (mainly Alloxantha sp.), neuropterans (Chrysoperla carnea), dictyopterans (Phyllodromica brullei), dermapterans (Guanchia sp.) and julidans (Ommatoiulus moreletii). In general, plants excluded from pollinators set less fruits than open-pollination (control) plants which set fruits homogeneously across sections. Diurnally pollinated plants set more fruit in their upper parts whereas nocturnally pollinated plants set fruit in both upper and bottom sections. We conclude that although the frequency and diversity of diurnal pollinators is far higher than that of nocturnal pollinators, both exhibit different foraging behaviour that generates complementary effects on the reproductive success of E. simplex.

中文翻译：

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日间授粉和夜间授粉对花粉虫生殖成功的影响

夜间授粉在有性植物繁殖中起着重要作用，但由于在田间试验中存在固有的困难，因此被忽略了。尽管有许多研究检查了这种位置与繁殖成功之间的关系，但花序内空间位置（远端或近端）对柱状植物的夜间授粉媒介的影响受到了更少的关注。伍迪地方性Echium simplex拥有大型的直立的花序，上面有成千上万朵花，许多昼夜动物都拜访它。在这项研究中，我们确定了夜间来访者，并通过特内里费岛（加那利群岛）的选择性排泄，将他们的授粉效果与不同花期的昼间传粉者的授粉效果进行了比较。夜间游客包括在飞蛾的至少十个形态种（如Paradrina rebeli和球果尺蛾属属），两个鞘翅目昆虫物种（主要是Alloxantha属），neuropterans（Chrysoperla吉祥草），dictyopterans（Phyllodromica brullei），dermapterans（Guanchia SP）和julidans （雨豆）。通常，排除在授粉媒介上的植物结实的果实要少于开放传粉（对照）的植物，后者在各部分均能均匀结实。每日授粉的植物在其上部结出更多的果实，而夜间授粉的植物在其上部和下部结出的果实。我们得出的结论是，尽管昼夜授粉的频率和多样性远高于夜间授粉的频率和多样性，但它们都表现出不同的觅食行为，从而对E. simplex的繁殖成功产生互补作用。