Comparison of leaf damage and trichomes of Wisconsin Helianthus populations grown in varying environments

Madilyn Vetter and Dr. Nora Mitchell, Biology Department, University of Wisconsin - Eau Claire, 105 Garfield Avenue, Eau Claire, WI 54702

Defenses against predators are an important adaptation in plants. Plants use both mechanical defenses (such as leaf hairs, trichomes) and chemical defenses to deter insect herbivores. Under global climate change, plants may encounter novel insect predators as species move northward and growing seasons lengthen. It is important to understand what mechanisms will enable crops and their wild relatives to respond to selective pressures. Traits, such as trichomes, may exhibit phenotypic plasticity in response to environmental differences or change genetically (evolve). Here, we ask: can sunflower species alter mechanical defenses to better defend against insect damage? Sunflowers (Helianthus) are an important crop and exhibit natural diversity throughout North America. Previous research has documented phenotypic plasticity in Helianthus traits, but knowledge of plasticity related to insect damage is limited. We assessed plant mechanical defenses and insect damage on three species of sunflower (H. grosseserratus, H. maximiliani, and H. giganteus), in three types of settings: greenhouse, common garden, and wild populations throughout Wisconsin, leaves were sampled from over 600 plants in total. This allowed us to compare growth in controlled and natural environments. Plants were assessed for leaf damage in situ and trichome (leaf hair) types and density were assessed using a dissecting microscope on the dried leaf samples taken. We found differences in insect damage and trichome densities between growing environments within species, indicative of environmentally driven plasticity. This research illustrates how sunflower species change their defenses in response to predators, which can inform us about how they may respond to novel predators and help to focus agricultural efforts such as pesticide development. 

Additional Abstract Information

Presenter: Madilyn Vetter

Institution: University of Wisconsin - Eau Claire

Type: Poster

Subject: Ecology

Status: Approved

Time and Location

Session: Poster 5
Date/Time: Tue 12:30pm-1:30pm
Session Number: 4117