Exploring the Potential Role of Ants as Pollinators in a Tallgrass Prairie Following Varied Prescribed Burns

Prescribed burns are used to restore the herbaceous plant communities of tallgrass prairies. Unfortunately, land-use change has driven declines in animal communities that use that habitat, including insect pollinators. Flowering forbs in tallgrass prairies likely depend on insect pollinators for their reproduction, suggesting that restoration efforts may be limited if insect pollinators continue to decline. Further, prescribed burns may lead to the direct mortality of insect pollinators. We thus explore whether Formica ants may be able to compensate for the loss of insect pollinators in tallgrass prairies by monitoring visitation rates of ants and insect pollinators to the milkweed Asclepias tuberosa. Using replicated experimental plots burned at different times (summer, fall, or spring), we found that ants were robust to the timing of prescribed burns and that they averaged 50% of all visits across plots. The distribution of ants and other insect pollinators may be regulated by competitive interactions, as there was a negative relationship between the two potential pollinator communities: the more ant visits, the fewer pollinator visits, and vice versa. The high visitation rates suggest ants may potentially compensate, especially as competitive interactions decrease, but whether that may occur likely depends on their efficiency as pollinators, current plant features, or subsequent plant adaptations to utilize ants.