Cayetano, L., Rothacher, L., Simon, J. C., & Vorburger, C. (2015). Cheaper is not always worse: strongly protective isolates of a defensive symbiont are less costly to the aphid host. Proceedings of the Royal Society B: Biological Sciences, 282(1799), 20142333 (10 pp.). https://doi.org/10.1098/rspb.2014.2333