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).