Grad Students 2020

Thorsten (Thor) Hansen

Thorsten (Thor) Hansen is from Rockford, IL. He attended the University of Illinois Urbana-Champaign, where he graduated with his BS in Integrative Biology in 2015. He received his master’s degree, in Entomology, in 2017 at the University of Kentucky at Lexington working with Dr. Jennifer White on insect ecology. He is currently a PhD student at Purdue University working with Dr. Laramy Enders.  

Microbes isolated from milkweed rhizospheres growing on standard LB plates

Evolutionary and ecological interactions of plants and insects are diverse and plentiful, due to consistent antagonistic relationships between these organisms. Most plants have defenses to fend off herbivorous insects and insects counter with their own biological tools to overcome plant defenses. Microorganisms frequently act as a co-conspirator in these interactions, providing a range of functions to their hosts (e.g., produce deadly chemicals that harm insects; help insects digest tough plant tissues). Plant-insect microbiomes are an important area of study, as they have large potential impacts on control of agricultural pest insects and conservation of native plants and insects. 

Thor’s recent greenhouse experiment comparing milkweed and monarch microbiomes

The monarch butterfly is a native North American insect, whose conservation could be affected by the microbes associated with it and their host plants, milkweeds. Monarchs are completely dependent on milkweeds as a food source. To combat monarch feeding, milkweeds produce a toxic group of chemicals called cardenolides, but monarchs have evolved ways to  deal with these plant toxins, such as storing them in their own tissues. While the effect of cardenolides on monarch ecology is well studied, there is a glaring gap of knowledge related to how microbes influence milkweed-monarch interactions. Some research shows cardenolides have antimicrobial effects, which when produced by milkweed could have cascading effects on monarch microbial communities. 

Two of Thor’s field sites in Indiana where he collected milkweed rhizosphere soil for greenhouse experiments

Thor’s research employs molecular techniques to understand if toxic milkweed chemicals shape the microbiomes associated with both monarchs and milkweeds. Using 16S rRNA metagenomic sequencing, he is investigating differences in microbiome composition between the common milkweed (A. syriaca) and tropical milkweed (A. curassavica) and the monarchs that feed on them. Interestingly, his research suggests a significant portion of the monarch gut microbiome is similar to the root-associated microbial communities if their host plants. Thor also plans to do shotgun metagenomic sequencing and metagenomic transcriptomic sequencing to better characterize monarch and milkweed microbial communities. This will provide a metaphorical molecular ‘toolbox’ of what functions microbial communities perform. Lastly, Thor plans to test if monarch and milkweed associated microbial communities can metabolize and potentially detoxify toxic plant chemicals. Ultimately, Thor wants to use the information from his research to help with monarch and milkweed conservation.  

For more background on the project and people involved, visit: 

Plant-Insect Microbiomes Laboratory Website 



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