Botanophila flies, vectors of Epichloë fungal spores, are infected by Wolbachia

Abstract

Epichloë fungi are endophytes within grasses that can form stromata on culms of their hosts. Botanophila flies visit the stromata for egg laying and in the process can vector spermatial spores, thereby cross fertilising the fungus. Following egg hatch, larval flies consume fungal tissue and spores. Thus, Epichloë individuals with traits that limit larval consumption could be at a selective advantage. We assessed Botanophila fly larvae from sites within the United States and Europe for infection by the bacterial sexual parasite Wolbachia through amplification of the Wolbachia surface protein gene (wsp). Nearly 70% of fly larvae in our samples were infected by Wolbachia. This is the first record of infection by Wolbachia within Botanophila and could have far reaching effects on not only the fly host, but also the Epichloë fungi upon which Botanophila feeds as well as the grass host within which the fungi live. For example, infection by Wolbachia could limit consumption of Epichloë spores by Botanophila larvae if the bacteria promoted premature larval death.

Does the Degree of Mutualism between Epichloë Fungi and Botanophila Flies Depend upon the Reproductive Mode of the Fungi?

“…This could be tested by collecting many adults and/or larvae from stromata representing the two groups of reproductive systems and assessing Wolbachia infection. Some data of this sort exist see [30], but they are too limited to draw any firm conclusions.…”