A spectrum of strategies Parasitoid

parasitoid strategy compared typical parasite (not killing host) , predator (killing prey immediately). there continuum between them.


definition

parasitoidy 1 of 6 major evolutionary strategies within parasitism, others being parasitic castrator, directly transmitted parasite, trophically transmitted parasite, vector-transmitted parasite, , micropredator. these adaptive peaks, many possible intermediate strategies, organisms in many different groups have consistently converged on these six.

parasitoids feed on living host killed, typically before can produce offspring. while conventional parasites kill hosts under conditions, not. many species of true parasites can cause death of host if present in overwhelming numbers, host in poor condition, or host s health compromised secondary infections. example, blood-sucking mites overwhelm nestlings of birds such swallows point young birds cannot fledge.

in extreme forms, conventional parasitism , parasitoidy distinct: there no doubt larva of tarantula hawk wasp behaves more parasitoid, or predator, parasite; , biting midges suck blood large insects plainly ectoparasites; many intermediate forms exist. @ opposite extreme, parasitoidy grades predation. differences between various hunting wasps provide convenient illustrations. predatory social wasps hunt flies, caterpillars , like, kill, cut up, , carry them nest feed young. similarly, solitary wasps such beewolves, sting prey, fatally, before saving it, entire, in nest or burrow young feed on. in contrast, best-known protelean solitary hunting wasps sting prey paralyse before storing young in nest. other wasps paralyse prey in plant or other environment in feeds, before laying eggs nearby; emerging young feed on paralysed prey in own home.

parasitoid strategies

a hyperparasitoid chalcid wasp (pteromalidae) on cocoons of host, braconid wasp (microgastrinae), koinobiont parasitoid of lepidoptera.

parasitoids can classified either endo- or ectoparasitoids idiobiont or koinobiont developmental strategies. endoparasitoids live within host s body. ectoparasitoids feed on host outside. idiobiont parasitoids prevent further development of host after immobilizing it. koinobiont parasitoids allow host continue development while feeding upon it. ectoparasitoids idiobiont, host damage or dislodge external parasitoid if allowed move , or molt. endoparasitoids koinobionts, giving them advantage of host continue grow larger , avoid predators.

primary parasitoids have simplest parasitic relationship 2 organisms involved: host , parasitoid. hyperparasitoids parasitoids of parasitoids. secondary parasitoids hyperparasitoids use primary parasitoid host. in case there 3 organisms involved. hyperparasitoids either facultative (can primary parasitoid or hyperparasitoid depending on situation) or obligate (always develop hyperparasitoid). levels of parasitoids beyond secondary occur, among facultative parasitoids. in oak gall systems, there can 5 levels of parasitism. cases in 2 or more species of parasitoids simultaneously attack same host without parasitizing each other called multi- or multiple parasitism. in many cases, multiple parasitism still leads death of 1 or more of parasitoids involved. if multiple parasitoids of same species coexist in single host, called superparasitism. gregarious species purposefully lay multiple eggs or polyembryonic eggs lead multiple larvae in single host. end result of gregarious superparasitism can single surviving parasitoid individual or multiple surviving individuals, depending on species. if superparasitism occurs accidentally in solitary species larvae fight among until 1 left.