An unusual <i>Botanophila</i> – <i>Epichloë</i> association in a population of orchardgrass ( <i>Dactylis glomerata</i> ) in Poland

Abstract

Grass-infecting Epichloë fungi depend on flies of the genus Botanophila (Diptera: Anthomyiidae) for the transfer of spermatia (gametes) and fertilization. Flies lay eggs on fungal structures and their larvae use this as a source of food, hence, this interaction is generally considered to be obligatory and mutualistic. In the present study, we monitored the occurrence of Botanophila flies in a population of Epichloë-infected wild orchardgrass (Dactylis glomerata) in central Poland. The number of eggs per stroma ranged from 0 to 14. Overall, 24.83% of all examined stromata had no eggs or brood chambers, whereas the incidence of fertilized stromata ranged from 89.66% to 100% depending on the year. Nearly all stromata that exhibited no signs of fly visitation were fertilized. These results suggest that in the Polish population of D. glomerata, sexual reproduction of Epichloё fungi depends on spermatia-carrying vectors other than Botanophila.