Neo-sex chromosomes in tortricid pests

In this work published in PNAS we present conclusive evidence on the evolutionary origin of sex chromosomes in tortricid moths.

We performed comparative physical mapping of the Z chromosome in the major pome fruit pest, the codling moth, Cydia pomonella (Lepidoptera: Tortricidae), and showed that it is a neo-Z chromosome that arose by fusion between an ancestral Z chromosome and an autosome corresponding to chromosome 15 in the Bombyx mori reference genome. We further showed that the fusion originated in a common ancestor of the main tortricid subfamilies, Olethreutinae and Tortricinae, comprising almost 700 pest species worldwide. The Z-autosome fusion brought two major genes conferring insecticide resistance and clusters of genes involved in detoxification of plant secondary metabolites under sex-linked inheritance. We suggest that this fusion significantly increased the adaptive potential of tortricid moths. Our findings thus not only contribute to management of tortricid pests but also allow a unique perspective concerning the role of neo-sex chromosomes in the adaptive radiation and speciation of phytophagous insects.  

Nguyen P., Sýkorová M., Šíchová J., Kůta V., Dalíková M., Čapková Frydrychová R., Neven L.G., Sahara K., Marec F. (2013) Neo-sex chromosomes and adaptive potential in tortricid pests.Proceedings of the National Academy of Sciences of the United States of America 110: 6931-6936. DOI: 10.1073/pnas.1220372110