Oecologia

, Volume 173, Issue 4, pp 1345–1354

Florivore impacts on plant reproductive success and pollinator mortality in an obligate pollination mutualism

  • David M. Althoff
  • Wei Xiao
  • Sarah Sumoski
  • Kari A. Segraves
Plant-microbe-animal interactions - Original research

DOI: 10.1007/s00442-013-2694-8

Cite this article as:
Althoff, D.M., Xiao, W., Sumoski, S. et al. Oecologia (2013) 173: 1345. doi:10.1007/s00442-013-2694-8

Abstract

Florivores are present in many pollination systems and can have direct and indirect effects on both plants and pollinators. Although the impact of florivores are commonly examined in facultative pollination mutualisms, their effects on obligate mutualism remain relatively unstudied. Here, we used experimental manipulations and surveys of naturally occurring plants to assess the effect of florivory on the obligate pollination mutualism between yuccas and yucca moths. Yucca filamentosa (Agavaceae) is pollinated by the moth Tegeticula cassandra (Lepidoptera: Prodoxidae), and the mutualism also attracts two florivores: a generalist, the leaf-footed bug Leptoglossus phyllopus (Hemiptera: Coreidae), and a specialist, the beetle Hymenorus densus (Coleoptera: Tenebrionidae). Experimental manipulations of leaf-footed bug densities on side branches of Y. filamentosa inflorescences demonstrated that feeding causes floral abscission but does not reduce pollen or seed production in the remaining flowers. Similar to the leaf-footed bugs, experimental manipulations of beetle densities within individual flowers demonstrated that beetle feeding also causes floral abscission, but, in addition, the beetles also cause a significant reduction in pollen availability. Path analyses of phenotypic selection based on surveys of naturally occurring plants revealed temporal variation in the plant traits important to plant fitness and the effects of the florivores on fitness. Leaf-footed bugs negatively impacted fitness when fewer plants were flowering and leaf-footed bug density was high, whereas beetles had a positive effect on fitness when there were many plants flowering and their densities were low. This positive effect was likely due to adult beetles consuming yucca moth eggs while having a negligible effect on floral abscission. Together, the actions of both florivores either augmented the relationship of plant traits and fitness or slightly weakened the relationship. Overall, the results suggest that, although florivores are always present during flowering, the impact of florivores on phenotypic selection in yuccas is strongly mitigated by changes in their densities on plants from year to year. In contrast, both florivores consistently influenced pollinator larval mortality through floral abscission, and H. densus beetles additionally via the consumption of pollinator eggs.

Keywords

Yucca Florivory Leptoglossus Floral abscission Community context 

Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • David M. Althoff
    • 1
  • Wei Xiao
    • 2
  • Sarah Sumoski
    • 3
  • Kari A. Segraves
    • 1
  1. 1.Department of BiologySyracuse UniversitySyracuseUSA
  2. 2.Department of Environmental and Forest BiologySUNY-ESFSyracuseUSA
  3. 3.College of William and Mary–Virginia Institute of Marine ScienceGloucester PointUSA

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