The role of hyperparasitism in microbial pathogen ecology and evolution

Abstract

Many micro-organisms employ a parasitic lifestyle and, through their antagonistic interactions with host populations, have major impacts on human, agricultural and natural ecosystems. Most pathogens are likely to host parasites of their own, that is, hyperparasites, but how nested chains of parasites impact on disease dynamics is grossly neglected in the ecological and evolutionary literature. In this minireview we argue that the diversity and dynamics of micro-hyperparasites are an important component of natural host–pathogen systems. We use the current literature from a handful of key systems to show that observed patterns of pathogen virulence and disease dynamics may well be influenced by hyperparasites. Exploring these factors will shed light on many aspects of microbial ecology and disease biology, including resistance–virulence evolution, apparent competition, epidemiology and ecosystem stability. Considering the importance of hyperparasites in natural populations will have applied consequences for the field of biological control and therapeutic science, where hyperparastism is employed as a control mechanism but not necessarily ecologically understood.

Laboulbeniales hyperparasites (Fungi, Ascomycota) of bat flies: Independent origins and host associations

“…Hyperparasitism, whereby parasites infect other parasites, is thought to be a common phenomenon in nature (Parratt & Laine, ). Few examples of obligate hyperparasites among fungi, however, have been well studied.…”

Microbe-mediated host defence drives the evolution of reduced pathogen virulence

“…Specifically, we predict that defensive microbes will result in the evolution of increased pathogen virulence if pathogen resistance and virulence are positively associated (Fig. 1a), for example, pathogens could increase in competitive ability against the defensive microbe via a faster growth rate or inducing inflammation, both of which are also detrimental to the host10111213. Alternatively, if a trade-off exists between pathogen resistance and virulence traits, for example, resistance is costly and slows pathogen growth rate141516, then defensive microbes will drive lower levels of virulence (Fig.…”

GFP transformation sheds more light on a widespread mycoparasitic interaction

“…fungi that parasitize other fungi, are commonly found in most terrestrial ecosystems, the best known species being those that attack fungal plant pathogens [1][2][3][4] . A number of mycoparasites have been long studied and commercially utilized as biocontrol agents (BCAs) of crop pathogens 3,4 ; others have been in focus as components of natural multitrophic relationships 2,[5][6][7][8][9] . Direct observation of interfungal parasitic relationships is notoriously difficult at cellular or hyphal level, using classical light, scanning and transmission electron microscopy (LM, SEM and TEM) and other visualization methods 1,[10][11][12][13] .…”