Volatile organic compound emissions and reproductive output of Solidago altissima in response to herbivory and conspecific density

Pollinators are presented with an array of olfactory and visual cues while searching for pollen and nectar. Both olfactory and visual cues may be influenced by the biotic and abiotic environment. Volatile organic compound (VOC) emissions of plants, which mediate pollinator attraction, may be influenced by herbivory and the density and identity of neighboring plants. Therefore, herbivory and density of conspecific and heterospecific plants may potentially affect plant fitness by influencing pollinator attraction. In this study, we investigated whether herbivory and density of conspecific plants influence plant reproductive output and VOC emissions of S. altissima plants. We measured plant reproductive output by counting the number of fertilized seeds and unfertilized seeds (seed set). We also recorded herbivory levels on leaves of the focal plant and collected VOCs from flowers of the focal plant. We found that neighboring conspecific amount, but not herbivory intensity influenced VOC emission richness. However, conspecific amount and herbivory intensity did not influence the reproductive output of S. altissima. These results suggest that conspecifics in natural settings can work in synchrony by varying VOC emission output to maximize reproductive output.