Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)

Nectar robbing typically reduces nectar availability to pollinators, damages flower structure, and/or induces secondary robbing. Consequently, it may reduce pollen deposition and seed set, increase pollination efficiency and outcrossing, and/or not affect reproduction in some species. However, spati...

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Main Authors: Han-Wen Xiao, Yan-Bo Huang
Format: Article
Language:English
Published: MDPI AG 2025-07-01
Series:Plants
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Online Access:https://www.mdpi.com/2223-7747/14/15/2266
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author Han-Wen Xiao
Yan-Bo Huang
author_facet Han-Wen Xiao
Yan-Bo Huang
author_sort Han-Wen Xiao
collection DOAJ
description Nectar robbing typically reduces nectar availability to pollinators, damages flower structure, and/or induces secondary robbing. Consequently, it may reduce pollen deposition and seed set, increase pollination efficiency and outcrossing, and/or not affect reproduction in some species. However, spatiotemporal variations in nectar robbing and their effects on plant reproduction have received little attention. In this study, we assessed the effects of nectar robbing on floral visits, seed set, nectar volume and concentration, and flower longevity in two populations of <i>Salvia castanea</i> Diels (Lamiaceae) in the Himalayan region of Southwestern China in 2014–2020. We also examined whether one or a few visits by pollinators can result in the stigma receiving sufficient pollen to fertilize all ovules of <i>S. castanea</i>. We found that significant differences in the nectar robbing rate did not affect seed set in any of the years for either population of <i>S. castanea</i>. In the robbed and unrobbed flowers, nectar was consistently replenished every night at higher concentrations. Bagging, nectar robbing, and sufficient pollination did not affect flower longevity. <i>Salvia castanea</i> required only 5–10 pollen grains to achieve the maximum seed set. However, pollinators depositing more than 10 pollen grains after a single visit ensured a high seed set of >80%. Our results suggest that nectar availability, floral longevity maintenance, and sufficient pollen deposition mitigate the effects of nectar robbing on the reproductive success of <i>S. castanea</i>. These results are expected to further our understanding of plant–animal interactions and the ecological consequences of nectar robbing.
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spelling doaj-art-286682b832c34e2d8b97e61c5c40673d2025-08-20T03:02:58ZengMDPI AGPlants2223-77472025-07-011415226610.3390/plants14152266Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)Han-Wen Xiao0Yan-Bo Huang1Eastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, ChinaEastern China Conservation Centre for Wild Endangered Plant Resources, Shanghai Chenshan Botanical Garden, Shanghai 201602, ChinaNectar robbing typically reduces nectar availability to pollinators, damages flower structure, and/or induces secondary robbing. Consequently, it may reduce pollen deposition and seed set, increase pollination efficiency and outcrossing, and/or not affect reproduction in some species. However, spatiotemporal variations in nectar robbing and their effects on plant reproduction have received little attention. In this study, we assessed the effects of nectar robbing on floral visits, seed set, nectar volume and concentration, and flower longevity in two populations of <i>Salvia castanea</i> Diels (Lamiaceae) in the Himalayan region of Southwestern China in 2014–2020. We also examined whether one or a few visits by pollinators can result in the stigma receiving sufficient pollen to fertilize all ovules of <i>S. castanea</i>. We found that significant differences in the nectar robbing rate did not affect seed set in any of the years for either population of <i>S. castanea</i>. In the robbed and unrobbed flowers, nectar was consistently replenished every night at higher concentrations. Bagging, nectar robbing, and sufficient pollination did not affect flower longevity. <i>Salvia castanea</i> required only 5–10 pollen grains to achieve the maximum seed set. However, pollinators depositing more than 10 pollen grains after a single visit ensured a high seed set of >80%. Our results suggest that nectar availability, floral longevity maintenance, and sufficient pollen deposition mitigate the effects of nectar robbing on the reproductive success of <i>S. castanea</i>. These results are expected to further our understanding of plant–animal interactions and the ecological consequences of nectar robbing.https://www.mdpi.com/2223-7747/14/15/2266floral longevitynectar availabilitynectar robbingpollen depositionreproductive success<i>Salvia</i>
spellingShingle Han-Wen Xiao
Yan-Bo Huang
Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)
Plants
floral longevity
nectar availability
nectar robbing
pollen deposition
reproductive success
<i>Salvia</i>
title Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)
title_full Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)
title_fullStr Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)
title_full_unstemmed Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)
title_short Spatiotemporal Variations in Nectar Robbing and Its Effects on Reproduction in <i>Salvia castanea</i> Diels (Lamiaceae)
title_sort spatiotemporal variations in nectar robbing and its effects on reproduction in i salvia castanea i diels lamiaceae
topic floral longevity
nectar availability
nectar robbing
pollen deposition
reproductive success
<i>Salvia</i>
url https://www.mdpi.com/2223-7747/14/15/2266
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AT yanbohuang spatiotemporalvariationsinnectarrobbinganditseffectsonreproductioninisalviacastaneaidielslamiaceae