Congratulations to Johanna Nifosi, who successfully defended her Master’s Thesis in Ecology & Evolutionary Biology on April 20th. Johanna studied the effects of rising temperatures on the interactions between monarch butterflies and their parasites. Her work has shown that, when monarchs are co-infected with multiple parasites, the virulence of the protozoan parasite, OE, increases with temperature. In general, monarchs perform very well at higher temperatures, around 28 degrees centigrade. But, when co-infected with parasites, monarchs lose all of the gains that they receive from life in a warmer world. Overall, Johanna’s work suggests that, as global warming continues, any potential benefits that monarchs might gain could be eradicated by greater parasite virulence.