Midge Flies and Botryosphaeria dothidea Fungus Form a Symbiotic Relationship on Goldenrod Plant Leaves

Goldenrod, Solidago sp. (Asteraceae) is a native plant in the TWU Butterfly Garden that provides nectar for pollinators. In fall 2021, Goldenrod plant had high number of white leaf spots. The goal of this study was to determine the nature of spots to know how to care for plants. Spots were collected, dissected, and examined with a scanning electron microscope. The white spot portion was filamentous and identified as Botryosphaeria dothidea fungus. Inside the leaf structure, midge fly (Asteromyia carbonifera) larvae were identified. Female midge flies inoculate fungal spores when they lay eggs inside the leaves. Growing hyphae from spores provide food and also protection for larvae by encapsulating them until they mature. This creates a three-way symbiosis between the midge fly, fungus, and plant, mutualistic between larvae and fungus, parasitic between fungus and plant. The newly-established TWU Butterfly Garden is a significant resource for educational and research projects.