Parasitoid wasp
Parasitoid wasps lay eggs in other arthropods, eventually killing them.
Parasitoid wasps are a large group of hymenopteran superfamilies, with all but the wood wasps (Orussoidea) being in the wasp-waisted Apocrita. As parasitoids, they lay their eggs on or in the bodies of other arthropods, sooner or later causing the death of these hosts. Different species specialise in hosts from different insect orders, most often Lepidoptera, though some select beetles, flies, or bugs; the spider wasps (Pompilidae) exclusively attack spiders. Parasitoid wasp species differ in which host life-stage they attack: eggs, larvae, pupae, or adults. They mainly follow one of two major strategies within parasitism: either they are endoparasitic, developing inside the host, and koinobiont, allowing the host to continue to feed, develop, and moult; or they are ectoparasitic, developing outside the host, and idiobiont, paralysing the host immediately.
- field
- Entomology, Parasitology
- known_for
- Parasitoidism, biological pest control, mutualism with polydnaviruses
- key_groups
- Chalcidoidea, Ichneumonidae, Braconidae, Pompilidae
Lore & Background
Parasitoidism evolved only once in the Hymenoptera, during the Permian, leading to a single clade called Euhymenoptera, but the parasitic lifestyle has secondarily been lost several times including among the ants, bees, and vespid wasps. As a result, the order Hymenoptera contains many families of parasitoids, intermixed with non-parasitoid groups. Host insects have evolved a range of defences against parasitoid wasps, including hiding, wriggling, and camouflage markings.
Reader's Guide
Parasitoid wasps are considered beneficial to humans because they naturally control agricultural pests. Some are applied commercially in biological pest control, starting in the 1920s with Encarsia formosa to control whitefly in greenhouses. Historically, parasitoidism in wasps influenced the thinking of Charles Darwin. Many parasitoid wasps use larval Lepidoptera as hosts, but some groups parasitize different host life stages of nearly all other orders of insects, especially Coleoptera, Diptera, Hemiptera and other Hymenoptera. Some attack arthropods other than insects, such as spiders. Host size is important for the development of the parasitoid, as the host is its entire food supply until it emerges as an adult; small hosts often produce smaller parasitoids. Some species preferentially lay female eggs in larger hosts and male eggs in smaller hosts. Parasitoid wasps are vulnerable to hyperparasitoid wasps. Some parasitoid wasps change the behavior of the infected host, causing them to build a silk web around the pupae of the wasps after they emerge from its body to protect them from hyperparasitoids.
Did You Know?
- Some endoparasitic wasps of the superfamily Ichneumonoidea have a mutualistic relationship with polydnaviruses, which suppress the host's immune defenses.
- Spider wasps (Pompilidae) exclusively attack spiders, often as large as the wasp itself.
- Parasitoid wasps range from some of the smallest species of insects to wasps about an inch long.
- Some parasitoid wasps mark the host with chemical signals to deter rivals from ovipositing.
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