Parasites can control hosts turning them into vehicles for parasite genes. To achieve transmission the behavior of the host can become an extended phenotype of the parasite[1]. Research into extended phenotypes can provide novel insights into parasite-host interactions because it integrates across a number of biological levels of the antagonism: expression of parasite genes leading to parasite phenotypes (e.g. secreted metabolites) that affect host process (CNS and motor-physiology) leading to altered behavior that affects con- and heterospecific responses (e.g. defense and predation respectively). If the altered behavior is non-transient then effects at the ecological level can occur as well. My work explores the integrative nature of parasite manipulation to address general issues in disease dynamics and virulence evolution. I recently developed as a model system one of the most dramatic examples of adaptive parasite manipulation of host behavior, the ‘death grip’ of ants infected by a fungus.
