4.1.1. Hyperparasites of powdery mildews
Species of Erysiphaceae (Leotiomycetes: Helotiales; Haelewaters et
al., 2021b), the powdery mildews, are frequently attacked by species of
hyperparasitic fungi belonging to the genus Ampelomyces , such as
the type species A. quisqualis (Faticov et al., 2022; Huth et al., 2021; Parratt and Laine, 2016; Tillenaere et al.,
2014). This is a destructive, obligate, intracellular parasite that
occurs on both the sexual and asexual stages of Erysiphaceae
(Hawksworth, 1981). Ampelomyces quisqualis is able to form
pycnidia inside the fungal host perithecia and/or hyphae, resulting on
the reduction or complete halt of sexual and asexual sporulation of the
powdery mildew species (Hawksworth, 1981; Legler et al., 2016).
Powdery mildew colonies infected by Ampelomyces spp. are easily
identified by a change in color, from white to brown (Faticov et
al., 2022; Németh et al., 2019). While molecular studies have
revealed that Ampelomyces may comprise at least four to seven
species, the taxonomy within the genus is unresolved (Németh et
al., 2019, 2021).