Editing Parasitism (section)

==== Hyperparasitism ====

{{main|Hyperparasite}}

[[Hyperparasite]]s feed on another parasite, as exemplified by protozoa living in helminth parasites,<ref name=Dissanaike1957>{{cite journal |last1=Dissanaike |first1=A. S. |title=On Protozoa hyperparasitic in Helminth, with some observations on ''Nosema helminthorum'' Moniez, 1887 |journal=Journal of Helminthology |date=1957 |volume=31 |issue=1–2 |pages=47–64 |pmid=13429025 |doi=10.1017/s0022149x00033290|s2cid=35487084 }}</ref> or facultative or obligate parasitoids whose hosts are either conventional parasites or parasitoids.<ref name=PoulinRandhawa2015/><ref name=GullanCranston2010/> Levels of parasitism beyond secondary also occur, especially among facultative parasitoids. In [[oak gall]] systems, there can be up to four levels of parasitism.<ref>{{cite journal |last=Askew |first=R. R. |url=https://www.researchgate.net/publication/238289888 |title=On the Biology of the Inhabitants of Oak Galls of Cynipidae (Hymenoptera) in Britain |journal=Transactions of the Society for British Entomology |date=1961 |volume=14 |pages=237–268}}</ref>

Hyperparasites can control their hosts' populations, and are used for this purpose [[biological pest control|in agriculture]] and to some extent in [[medicine]]. The controlling effects can be seen in the way that the [[Hypovirus#CHV1–Chestnut blight hypovirulence|CHV1 virus]] helps to control the damage that [[chestnut blight]], ''Cryphonectria parasitica'', does to [[American chestnut]] trees, and in the way that [[bacteriophage]]s can limit bacterial infections. It is likely, though little researched, that most pathogenic microparasites have hyperparasites which may prove widely useful in both agriculture and medicine.<ref name="ParrattLaine2016">{{cite journal |last1=Parratt |first1=Steven R. |last2=Laine |first2=Anna-Liisa |title=The role of hyperparasitism in microbial pathogen ecology and evolution |journal=The ISME Journal |volume=10 |issue=8 |date=January 2016|doi=10.1038/ismej.2015.247 |pmid=26784356 |pages=1815–1822|pmc=5029149 |bibcode=2016ISMEJ..10.1815P }}</ref>