Oecologia

, Volume 83, Issue 3, pp 414–419

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

  • Laurel R. Fox
  • Deborah K. Letourneau
  • Jamin Eisenbach
  • Saskya Van Nouhuys
Original Papers

DOI: 10.1007/BF00317569

Cite this article as:
Fox, L.R., Letourneau, D.K., Eisenbach, J. et al. Oecologia (1990) 83: 414. doi:10.1007/BF00317569

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.

Key words

Sex ratio Host-parasitoid interactions Nitrogen Plutella xylostella Diadegma insulare Brassica oleracea var. acephala 

Copyright information

© Springer-Verlag 1990

Authors and Affiliations

  • Laurel R. Fox
    • 1
  • Deborah K. Letourneau
    • 2
  • Jamin Eisenbach
    • 1
  • Saskya Van Nouhuys
    • 1
  1. 1.Department of BiologyUniversity of CaliforniaSanta CruzUSA
  2. 2.Environmental Studies BoardUniversity of CaliforniaSanta CruzUSA