Predation on adult Aphytis parasitoids in the field

George E. Heimpel, Jay A. Rosenheim, Marc Mangel

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111 Scopus citations


We report on predation on adult females of the parasitoids Aphytis aonidiae and A. vandenboschi (Hymenoptera: Aphelinidae) foraging in the field. During 89.6 h of observation, we witnessed 18 encounters with predators, 6 of which resulted in parasitoid capture. Three classes of generalist predators attacked Aphytis: spiders (unidentified Salticidae and Thomisidae) workers of the Argentine ant, Linepithema humile, and nymphs of the assassin bug Zelus renardii (Hemiptera: Reduviidae). Although observations were conducted during most months of the year, encounters with predators occurred only during September, October and November. During these months, encounters with predators occurred on average every 3.2 h of observation, with one in three encounters resulting in parasitoid capture. Peaks in predation coincided with population peaks of A. aonidiae, but were unrelated to population dynamics of any of the predators. We compare these results with previously published laboratory studies on longevity of Aphytis parasitoids, and conclude that predation pressure has the potential to severely limit parasitoid fitness in the field.

Original languageEnglish (US)
Pages (from-to)346-352
Number of pages7
Issue number3
StatePublished - Apr 2 1997

Bibliographical note

Funding Information:
Acknowledgements We thank Edward Sills for allowing us to use his private land for this study; D. Kattari, J.M. Adams and F. Hernandez for assistance in the field and laboratory; D. Rosen for parasitoid identification and P. Ward for ant identification. We also thank S. Ben-Shalom, T.R. Collier, L.E. Ehler, K. Hobson, A.R. Ives, M.A. Jervis, P.J. Ode, M.S. Strand and an anonymous reviewer for comments on the manuscript. This research was supported in part by USDA competitive grant 9202357 to JA Rose-nheim, and a University of California Statewide IPM project grant to GE Heimpel and JA Rosenheim.

Copyright 2004 Elsevier Science B.V., Amsterdam. All rights reserved.


  • Aphytis parasitoids
  • Population dynamics
  • Predation pressure


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