The effect of Eurosta solidaginis parasitism on pollinator preference in Solidago canadensis

Abstract

Solidago canadensis is a self-incompatible perennial species indigenous to North America that reproduces asexually via rhizomes and sexually via seeds. It is the favoured host of the gall fly, Eurosta solidaginis. Sexual reproduction leads to faster rates of adaptation in stressful environments and may be advantageous in the maintenance of host-parasite coevolution. The effect of infection by the gall fly on pollinator visitations at the patch and at the ramet level was assessed as a proxy for the ability to sexually reproduce. The study was conducted by analyzing pollinator preference at both the patch level and individual ramet level through successive observations of pollinator visitations. Though the variation in the number of pollinator visitations could be accounted for by time of day and median bloom stage, the percentage of infected ramets in a patch was not a significant explanatory variable. This suggests that gall formation does not affect pollinator preference and that the capacity to sexually reproduce is likely not reduced because of the host-parasite interaction. Broadly, this study served as an example of how pollinator preference may be utilized as a measure of fitness, and to further understand how selective pressures affect plant populations that reproduce both sexually and asexually.