Corresponding Author: Mike Strand, mrstrand@uga.edu
Just as humans depend on our gut bacteria for efficient digestion, many insects also harbor bacterial symbionts that facilitate healthy functioning and provide protection. For example, pea aphids (A. pisum) depend on the bacterial symbiont H. defensa, which protects them from parasitic wasps (A. ervi). This bacteria is often infected by bacteriophages, known as APSEs, which can enhance the bacteria’s survival and effectiveness by providing new traits and altering its abundance. In fact, in some cases, H. defensa only protects aphids against wasps when it contains an APSE strain. However, little is known about the interacting resistance mechanisms between aphids, their bacterial symbionts, and different strains of APSE. In a recent 2017 study, CEID member Mike Strand and a collaborative team of researchers developed methods for culturing various strains of H. defensa that contained different amounts and types of APSEs. Their goal was to test the resistance of each unique strain to the exposure of parasitoid wasp eggs. They found that the APSE bacteriophages facilitate the transfer of new traits, which is an important mechanism for maintaining novelty in host symbionts, thus improving their protection capabilities. More broadly, their study provides foundational data critical for understanding the role symbionts play in host protection.
Brandt, J. W., Chevignon, G., Oliver, K. M., & Strand, M. R. (2017). Culture of an aphid heritable symbiont demonstrates its direct role in defence against parasitoids. Proceedings of the Royal Society B: Biological Sciences, 284(1866), 20171925. doi:10.1098/rspb.2017.1925