Adaptive functions of defensive plant phenolics and a non-linear bee response to nectar components

Abstract

1. Secondary compounds such as phenolics, usually present in floral nectar, may act in combination with sugar components to influence the evolution of pollination mutualism. 2. Previous work on the significance of secondary compounds in nectar considers honey bee responses to those compounds alone, but neglects sugar. Our experiments demonstrated that phenolic sugar syrups were attractants to free-flying Asian Apis cerana Fab. when sugar concentrations were 15-35%, but were deterrents below or above this range. 3. Synergism between nectar phenolics and sugar may thus provide a novel mechanism for plants to encourage pollinating bees and reduce energy investment in nectar, operating as exaptations by co-opting defence mechanisms against herbivores. © 2006 The Authors.