Superparasitism occurs when a female parasitoid oviposits in a host that has already been parasitized before by a member of the same species. This usually results in intraspecific competition among the offspring of the parasitoids, resulting in some of them not surviving to adulthood or poorer development. Multiparasitism is a term that refers to a related occurrence where a host is parasitized by more than one parasitoid species, resulting in interspecific competition among their offspring.
Occurrences of superparasitism were typically once thought to be errors, but research shows that under certain conditions, superparasitism would be the best option for parasitoids and an evolutionarily stable strategy (ESS).
The first published observation of parasitoids ovipositing in already-parasitized hosts was made in 1897 by American entomologist Leland Ossian Howard, who observed a wasp superparasitize the moth Orgyia leucostigma.[1][2] In 1910, William F. Fiske coined the term superparasitism
There are two distinct categories of superparasitism. The first type is self-superparasitism, where the host has been parasitized more than once by the same parasitoid.[3] The second type is known as conspecific superparasitism or intraspecific superparasitism, where the host is parasitized by more than once by the same species of parasitoid.[3]
The consequences of superparasitism vary between gregarious parasitoids and solitary parasitoids. By gregarious parasitoids, who usually oviposit many eggs in one parasitization, superparasitism results in
Despite the drawbacks of larval competition and the fact that parasitoids do have the ability to avoid superparasitization, there are certain cases where the best option for the female would be to oviposit even in a parasitized host. Such cases are when the female's egg supply is not limited and the host population is low.
The ability of parasitoids to distinguish between parasitized hosts from unparasitized ones is known as host discrimination. This ability is present in certain species of parasitoids and is used to avoid superparasitism and thus competition from other parasites.[4]