Uncovering blowfly feeding habits evolution with functional genetics

Abstract

Blowflies (Diptera: Calliphoridae) are a diverse group of dipterans whose larvae commonly feed on protein-rich substrates, relying mainly on animal tissues. Such tissues may either be from a living or dead host depending on the fly species (which defines them as parasites or necro-saprophagous, respectively). Some may even choose either option, successfully developing on both substrates (these are called facultative parasites). It is commonly assumed that parasitism (either facultative, or obligate) is a derived behavior that has independently emerged more than once within Calliphoridae therefore constituting an example of convergent evolution. In my Master's project, I compare transcriptomic and genomic information of a set of species looking for convergent molecular patterns (e.g., expression profile or rate of evolution of coding sequences) that correlate with the observed behavioral convergence, especially focusing on the obligate parasites Cochliomyia hominivorax and Chrysomya bezziana. Based on findings made by my laboratory colleagues and some of the work I have done, I have selected three candidate genes (pgant5, Mvl, and Npf) to be tested with functional genetics. To do so, I intend to visit Dr. Maxwell J. Scott's laboratory in North Carolina State University (Raleigh, NC, United States) for six months where I will be trained in CRISPR/Cas-9 genome editing to try to develop a knock-out stocks of Lucilia cuprina, a facultative parasite, for my candidate genes. Once the mutant strains are established, I intend to perform behavioral and survival/development assays with the larvae to assess their food preference and their ability to develop on different media to verify whether they display any shifts compared to wild-type individuals. (AU)