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Plant secondary metabolites in nectar: impacts on pollinators and ecological functions

Plant secondary metabolites in nectar: impacts on pollinators and ecological functions

Stevenson, Philip C. ORCID: 0000-0002-0736-3619, Nicolson, Susan W. and Wright, Geraldine A. (2016) Plant secondary metabolites in nectar: impacts on pollinators and ecological functions. Functional Ecology, 31. pp. 65-75. ISSN 0269-8463 (Print), 1365-2435 (Online) (doi:

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1. The ecological function of secondary metabolites in plant defence, against herbivores is well established, but their role in plant-pollinator interactions is less obvious. Nectar is the major reward for pollinators, so the occurrence of defence compounds in the nectar of many species is unexpected. However, increasing evidence supports a variety of potential benefits for both plant and pollinator from these components.

2. Secondary metabolites in nectar can be toxic or repellent to flower visitors, but they can also go undetected or make nectar attractive . For example, caffeine in nectar improves pollinator memory for cues associated with food rewards and enhances pollen transfer. All of these effects depend on the concentration of nectar metabolites so should be evaluated experimentally at a range of ecologically relevant doses.

3. Beneficial effects may include the following: a) increasing specialization in plant-pollinator interactions, b) protecting nectar from robbery or larceny, and c) preservation of nutrients in nectar from microbial degradation and reducing microbial disease levels in flower visitors.

4. This review synthesises evidence from recent literature that supports selection for secondary metabolites in floral nectar as an adaptation that drives the co-evolution between plants and their pollinators. However, their presence in nectar could simply be a consequence of their occurrence elsewhere in the plant for defence (pleiotropy). We draw attention to the need for studies demonstrating benefits to the plant, the importance of levels of exposure and a effects on target species beyond the current emphasis on alkaloids and bees.

Item Type: Article
Additional Information: This is the peer reviewed version of the above cited article, which has been published in final form at This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Uncontrolled Keywords: Pollinators; Toxins; Nectar; Bees
Subjects: S Agriculture > SB Plant culture
Faculty / School / Research Centre / Research Group: Faculty of Engineering & Science
Faculty of Engineering & Science > Natural Resources Institute
Faculty of Engineering & Science > Natural Resources Institute > Agriculture, Health & Environment Department
Last Modified: 04 Oct 2017 00:38

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