Resisting suppression: Elucidating the mechanisms that allow a specialist moth to feed on immune-suppressive phytochemicals

• Applicant: Dr. Yannick Pauchet, since 12/2016
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: from 2011 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 203324618

A major theme in evolutionary biology is the co-adaptation of interacting organisms. One well-known example of reciprocal adaptation is the co-evolutionary arms race between plants and their insect herbivores. This arms race has resulted in more specialized herbivore species consuming a few closely related host plants compared to generalist herbivore species consuming plants from several genera or families. The mechanisms that enable specialists to feed on their host plant with impunity however, are only poorly understood. We found that the specialist moth Heliothis subflexa has modified its immune system to benefit from the antibacterial properties of withanolide, a normally immune-suppressive compound found in Physalis host plants. A close relative of H. subflexa, H. virescens, does not benefit from withanolides in the same way. This project aims to identify the causes and consequences of this unique adaptation by H. subflexa. The first aim focuses on the mechanisms that enable H. subflexa to avoid or prevent immune-suppression by withanolides. Avoidance by modifying the structure of the ecdysteroid receptor and other potential targets of withanolides will be examined by molecular modelling. Prevention by metabolic detoxification of withanolides will be studied by feeding assays with subsequent analysis of feces and body parts for metabolites by LC-MS. The second aim is to identify the consequences of withanolides on the bacterial colonization of Physalis plants as well as on the bacterial gut environment of H. sublfexa. Feeding assays and sampling of plants grown under natural conditions are planned with subsequent sequencing of bacterial rRNA to elucidate the role of withanolides on bacterial composition and density on plants and insect guts. The proposed project will shed new light onto the evolutionary mechanisms of host plant adaption in insects and will thereby also add to our understanding of general molecular adaptation mechanisms.

• DFG Programme: Research Grants
• Ehemalige Antragstellerin: Dr. Hanna M. Heidel-Fischer, until 11/2016