3. Types of hyperparasitic relationships
One of the ways fungal hyperparasites are defined is based on the state
(living or dead) of the primary parasite (Barnett and Binder, 1973).
Fungi that exploit living host tissue or cytoplasm are considered
biotrophs, whereas necrotrophs kill host cells and then utilize host
biomass (Benjamin et al., 2004; Jeffries and Young, 1994).
Biotrophic hyperparasites typically have a narrower range of hosts and
develop specialized structures to interact with their hosts (Jeffries,
1985, 1995). Examples of biotrophic hyperparasites and their parasitic
hosts are given in Table 1. Many of these biotrophic hyperparasites form
haustoria or specialized hyphal branches involved in absorption of food
from host mycelia or sclerotia (Kirk et al., 2008). Necrotrophs
frequently use antifungal compounds in so-called hyphal interference
(when the host is a fungus) or destroy the cell wall and membranes of
host tissue to gain access to cellular contents, or use a combination of
these strategies (Jeffries and Young, 1994).