The occurrence and preference of Botanophila flies (Diptera: Anthomyiidae) for particular species of Epichloë fungi infecting wild grasses

Marlena Lembicz,Karolina Górzyńska,Verner Michelsen,Ziemowit Olszanowski,Adrian Leuchtmann

doi:10.14411/eje.2013.018

Abstract

Specific associations between species frequently occur in ecological interactions. The aim of this study was to determine the preferences of anthomyiid flies of the genus Botanophila for particular species of fungi as sites for laying eggs and as food for both larvae and adults. The associations of their eggs, larvae and flies with the stromata of different species of EpichloĂŤ fungi infecting 7 species of grass in Poland were analyzed. Scanning electron microscopy of the surface of their eggs and an analysis of the genetic sequences of their mitochondrial cytochrome oxidase (COII) were used to identify the taxa of the flies studied. Three types of eggs were distinguished based on their shape, colour and the presence of dorsal folds and sculpturing on the shells. Tentatively, these eggs were assigned to the following species: B. laterella, B. phrenione, B. dissecta and B. lobata. COII sequences obtained from larvae that hatched from two of the types of eggs formed three distinct clades associated with the reference sequences for Botanophila phrenione, B. lobata (new to the fauna of Poland) and a putative species, "Taxon 1". Only one of these flies (B. lobata) was restricted to a single species of EpichloĂŤ (E. bromicola on Elymus repens); B. phrenione was recorded mainly from E. typhina infecting three different species of grass. The results of this study confirm that there is not a close species specific association between this fungus and this insect.

Highlights

The genus Botanophila currently includes approximately 70 species (Michelsen, 2011)
Three types of eggs were laid by female Botanophila on stromata of Epichloë fungi
COII sequences of the 33 fly larvae collected from the stromata of different species of Epichloë formed three distinct clades (Fig. 3)

Summary

Introduction

The genus Botanophila currently includes approximately 70 species (Michelsen, 2011). Initially, only one of these species, B. phrenione (Séguy) [earlier described as Anthomyia spreta Meigen and Phorbia phrenione (Séguy)] was thought to be associated with Epichloë fungi (Kohlmeyer, 1956; Williams, 1971). More recently the mitochondrial gene of subunit 2 of cytochrome oxidase (COII) of species of the genus Botanophila collected from different species of fungus in Switzerland, Poland and the USA was sequenced. These studies revealed that at least six distinct Botanophila taxa are associated with Epichloë fungi (Leuchtmann, 2007). Flies of the genus Botanophila in transferring spermatia between different mating types of heterothallic fungi behave like pollen-transferring insects (Bultman, 1995). In both cases, this process results in the fertilisation and production of dispersal structures. New information has emerged that indicate that this fly-fungus interaction is not always a prerequisite for the initiation of the reproductive cycle of the fungus, as previously supposed (Rao & Baumann, 2004; Rao et al, 2005; Górzyńska et al, 2010, 2011)

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Conclusion