Non-additive benefit or cost? Disentangling the indirect effects that occur when plants bearing extrafloral nectaries and honeydew-producing insects share exotic ant mutualists

Abstract

It was demonstrated that strong non-additive benefits and costs can both occur when a plant and herbivore share mutualist partners. These findings suggest that broadening the community context of mutualism studies can reveal important non-additive effects and increase understanding of the dynamics of species interactions.

Infiltration of a facultative ant–plant mutualism by the introduced Argentine ant: effects on mutualist diversity and mutualism benefits

“…Existing studies on the role of introduced ants in facultative ant-plant mutualisms report inconsistent results (Ness & Bronstein, 2004;Lach et al, 2010;Lach & Hoffmann, 2011;Savage & Rudgers, 2013). In a review of this topic, Ness and Bronstein (2004) found that just over half (9/15) of studies published at the time found evidence for plants benefiting from protection by introduced ants.…”

Foliar Extrafloral Nectar of Humboldtia brunonis (Fabaceae), a Paleotropic Ant‐plant, is Richer than Phloem Sap and More Attractive than Honeydew

“…). Our results therefore suggest that H. brunonis EFN is likely a more attractive food resource for ants than honeydew and might distract them from tending Hemiptera (Becerra & Venable , Savage & Rudgers ). This may explain why during our study period spanning over five field season years, we only once came across ant‐tended Hemiptera colonies (mealybugs, Suborder: Stennorrhyncha, Family: Pseudococcidae) on H. brunonis .…”

Vanduzea segmentata (Fowler) (Hemiptera: Membracidae): Seasonality and Habits in the Southeastern United States, with Review of Its U.S. Distribution and Host Plants

“…The presence of HPHs on plants with EFNs adds an interesting layer of complexity to assessing the role of sugar-loving ants as bodyguards (Savage and Rudgers 2013). Ants may harm the plant both directly by protecting its HPHs and indirectly by removing non-honeydew producing herbivorous competitors, although generally plants gain more than they lose from the presence of sugar-loving ants and HPHs (Styrsky and Eubanks 2007).…”

“…Ants may harm the plant both directly by protecting its HPHs and indirectly by removing non-honeydew producing herbivorous competitors, although generally plants gain more than they lose from the presence of sugar-loving ants and HPHs (Styrsky and Eubanks 2007). HPHs and EFN-bearing plants may compete for ant mutualists, but their combined presence might also increase the overall attractiveness of an EFNbearing plant to ants (Savage and Rudgers 2013). The Vanduzea-Argentine ant system seems an excellent candidate for exploring the subtleties of this type of tritrophic interaction, especially if female V. segmentata target (whether directly or indirectly) plants with EFNs.…”