December 16, 2019

Katherine Malinski (University of North Carolina, Chapel Hill)

Thermal Mismatch Among Hosts, Parasitoids, and Symbionts

Fall 2019 Graduate Student Award in Pathogenic and Commensal Organisms

Understanding how ongoing and future climate change will alter pathogens, parasites, and their hosts is a fundamental challenge in infectious disease research. In nature, most hosts and parasites also interact with symbionts and other ecological players. If hosts, parasites, and symbionts differ in their tolerance to high temperatures and other extreme environmental conditions, this will alter both the interactions between these species and the ecological responses of the system. This phenomenon, known as thermal mismatch, has been documented in pairwise interactions between hosts and symbionts (e.g. coral bleaching) and hosts and parasites (e.g. fungal parasites in amphibians), but has not been investigated for complex, multispecies interactions. In order to better understand how such interacting species respond to changes in their thermal environment, the proposed research will explore the three-way interaction among an insect host (Manduca sexta), its insect parasitoid (Cotesia congregata), and the parasitoid’s endosymbiont (C. congregata bracovirus). Previous studies have shown a thermal mismatch in this system – in M. sexta parasitized by C. congregata, high temperatures result in parasitoid mortality, but not host mortality. It is presently unclear whether parasitoid death and host rescue are caused by heat directly, or by the heat-induced disruption of the viral endosymbiont. This study aims to uncover the mechanisms and consequences thermal mismatch in this multifaceted biological system.