An Assessment of the Population Densities of the Goldenrod Gall Midge, Rhopalomyia solidaginis, and the Effects of Various Treatments on Gall Formation at Purdue Wildlife Area

Introduction Plant-insect interactions in a natural ecosystem are under a lot of pressure from recent global changes that are occurring. These global changes can include alterations in climate, fluctuations in precipitation, and changes in atmospheric and soil compositions, among several others. Two of the most prevalent global change factors in this area, however, are changes in precipitation patterns and the addition of nitrogen to our ecosystems. These precipitation patterns are skewed recently because of the increasing intensity of climate change, and the addition of nitrogen is an important factor due to our agricultural systems and fertilizers. Certain insects and their environment can be good indicators of these changes. Gallmakers in particular are useful in determining some of the effects of these changes on an ecosystem, because their success in an area is visible and very clear due to the galls they induce on plants. The system at Purdue Wildlife Area utilizes a certain gallmaking species, Rhopalomyia solidaginis, and the rosette gall. The Goldenrod Gall Midge adult females deposit their eggs into the leaf bud of a developing Goldenrod plant, and this causes a gall to form, which serves as a shelter and nutrient sink for the developing larvae. In this experiment, I wanted to examine the ways in which global change factors such as nitrogen addition and extreme precipitation regimes can have an effect on plant communities and the insects that rely on the fitness of these plants.