Parasitism rates and sex ratios of a parasitoid wasp: effects of herbivore and plant quality

We studied interactions among collards, Brassica oleracea var. acephala, the diamondback moth (DBM), Plutella xylostella (Lepidoptera: Yponomeutidae) and its parasitoid Diadegma insulare (Hymenoptera: Ichneumonidae) by manipulating plant nitrogen (N) concentrations in field and laboratory experiment...

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Bibliographic Details
Published in:	Oecologia Vol. 83; no. 3; pp. 414 - 419
Main Authors:	Fox, L.R, Letourneau, D.K, Eisenbach, J, Nouhuys, S.V
Format:	Journal Article
Language:	English
Published:	Berlin Springer-Verlag 01-01-1990 Springer
Subjects:	Animal and plant ecology Animal, plant and microbial ecology Biological and medical sciences Brassica oleracea brassica oleracea var. acephala Diadegma insulare Female animals Fertilizers Field experiments Fundamental and applied biological sciences. Psychology host-parasite relationships Hymenoptera Ichneumonidae Insect larvae Instars Invertebrates Lepidoptera nitrogen content Parasite hosts Parasitism Parasitoids Plants Plutella xylostella Sex ratio Synecology Terrestrial ecosystems total leaf nitrogen Yponomeutidae Host parasite relation Insecta Nitrogen Sex ratio Plutella xylostella Brassica oleracea var. acephala Cruciferae Animal plant relation Arthropoda Dicotyledones Angiospermae Lepidoptera Spermatophyta Ichneumonidae Fodder crop Hymenoptera Hyponomeutidae Invertebrata Host-parasitoid interactions Diadegma insulare
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Summary:	We studied interactions among collards, Brassica oleracea var. acephala, the diamondback moth (DBM), Plutella xylostella (Lepidoptera: Yponomeutidae) and its parasitoid Diadegma insulare (Hymenoptera: Ichneumonidae) by manipulating plant nitrogen (N) concentrations in field and laboratory experiments. Parasitoid abundance strongly reflected DBM abundance and was related to total leaf N. Parasitism rates were high (70.7%) and density-independent. Wasp sex ratios varied markedly (3-93% female) in response to the herbivores, the plants, or both. Higher proportions of female wasps emerged from DBM larvae on plants with high leaf N than on unfertilized plants. More female wasps also emerged from larvae parasitized as larger instars. We suggest that wasps have the potential to control DBM populations through long-term numerical responses mediated by variable sex ratios.
Bibliography:	ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0029-8549 1432-1939
DOI:	10.1007/BF00317569