Ant aphid interactions on pollination and seed production of common milkweed (Asclepias syriaca)

Abstract

Interactions between ants and aphids have been studied extensively and provide an ecologically important example of a mutualistic relationship. Common Milkweed (Asclepias syriaca) is often host to the ant-aphid mutualism and studies suggest that this relationship discourages pollinators. Examining this mutualism and its effects on plant fitness and plant health could further understanding of its role at the community level. In our study, we measured the coloration of milkweed stems, height, number and size of the seed pods, and number of seeds in seed pods. Seed count and seed pod production was used as a measure of plant fitness. These measures were compared to the relative abundances of ants and aphids on Common Milkweed plants. Out of 47 measurements, our findings suggest that there is no significant effect of ant-aphid interactions on the seed pod production (P=0.6560), seed count (P=0.2054), and stem coloration (P>0.6170). Our results suggest ant-aphid interactions do not affect Common Milkweed fitness, and ants and aphids have no stem color preference. Our study offers information for future studies to look further into the effects of ant-aphid interactions on plant health, plant pollination, which might have long-term effects on plant fitness.