Hyperparasite

 ( Hyperparasites ) 

A well-studied case is that of the small white butterfly ( Pieris rapae), a serious horticultural pest of Brassica species such as cabbage and Brussels sprouts. Its larvae are parasitized by the larvae of the wasps Cotesia glomerata and C. rubecula, both of which are in turn parasitized by the wasp Lysibia nana.

Plant volatiles are emitted from plants as a defense against herbivory. The volatiles emitted attract parasitic wasps that in turn attack the herbivores. Hyperparasitoids are known to find their victims through herbivore-induced plant volatiles emitted in response to attack by caterpillars that in turn had been parasitized by primary parasitoids. The larvae of parasitic wasps developing inside the caterpillar alter the composition of the oral secretions of their herbivorous host and thereby affect the cocktail of volatiles the plant produces. The pupae of primary parasitoid species are parasitized by many hyperparasitoid species.

Hyperparasites are not limited to insects. There are parasitic flatworms that are parasite on crustaceans, themselves parasite on fish. An example is the Cyclocotyla bellones, found on Ceratothoa parallela, a cymothoid isopod parasite of the sparid fish Boops boops.

Hyperparasitism is to an extent analogous to predation on herbivores, which in turn eat plants, as there are three involved. However, hyperparasites are smaller than predators, breed more rapidly than their hosts and are generally found in larger numbers, while especially in the case of micro-organisms, their hosts can sometimes clear their infection. Hyperparasitism may thus behave differently from three-level predator-prey systems: apex predator can exert control of prey populations, for instance as keystone species, but given the differences between hyperparasites and predators, their effects may need to be modelled differently.

• Hyperparasitoid