Ecological Entomology (2011) 36, 52-61

Evan C. Lampert, Arthur R. Zangerl, May R. Berenbaum and Paul J. Ode (2011)
Generalist and specialist host-parasitoid associations respond differently to wild parsnip (Pastinaca sativa) defensive chemistry
Ecological Entomology 36 (1), 52-61
Abstract: 1. Plant defensive chemistry is predicted to have a more negative effect on generalist herbivores and their parasitoids than on specialist herbivores and their parasitoids.
2. This prediction was examined by comparing the effects of the wild parsnip (Pastinaca sativa L.) toxin, xanthotoxin, on a generalist herbivore-parasitoid association [the cabbage looper, Trichoplusia ni Hübner, and its polyembryonic parasitoid, Copidosoma floridanum (Ashmead)] and a specialist herbivore-parasitoid association [the parsnip webworm, Depressaria pastinacella (Duponchel), and its polyembryonic parasitoid, Copidosoma sosares (Walker)].
3. Copidosoma floridanum brood sizes were smaller and experienced lower survivorship when reared in a host feeding on an artificial diet containing a low concentration of xanthotoxin. No T. ni hosts, parasitised or unparasitised, survived on a diet high in xanthotoxin. In contrast, C. sosares brood size and survivorship were unaffected by the presence of low levels of xanthotoxin in the host diet. Copidosoma sosares experienced reduced brood size and survivorship only when its host consumed a diet containing 15 times the level of xanthotoxin as the diet adversely affecting its congener.
4. The differences in response to xanthotoxin exhibited by C. floridanum and C. sosares are explained partly by a differential reduction in host quality and partly by differential exposure to xanthotoxin in host haemolymph. Unlike D. pastinacella, T. ni experienced reduced pupal weight and survivorship and prolonged developmental time on a low-xanthotoxin diet. More xanthotoxin passed unmetabolised into the haemolymph of T. ni than into the haemolymph of D. pastinacella.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Paul J. Ode, May R. Berenbaum

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
resistance/tolerance/defence of host
Research topic(s) for beneficials or antagonists:
environment/habitat manipulation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Trichoplusia ni	Parsnip (Pastinaca sativa)
	Depressaria pastinacella	Parsnip (Pastinaca sativa)
Copidosoma floridanum (parasitoid)	Trichoplusia ni	Parsnip (Pastinaca sativa)
Copidosoma sosares (parasitoid)	Depressaria pastinacella	Parsnip (Pastinaca sativa)