Advances in PARASITOLOGY VOLUME 25 Editorial Board W. H. R. Lumsden University of Dundee Animal Services Unit, Ninewells Hospital and Medical School, P.O. Box 120, Dundee DD19SY, UK A. Capron Director, Institut Pasteur, Centre d’Immunologie et de Biologie Parasitaire, 15 Rue Camille GuCrin, 59019 Lille, Cedex, France P. Wenk Tropenmedizinisches Institut, Universitat Tubingen, D7400 Tubingen 1, Wilhelmstrasse 31, Federal Republic of Germany C. Bryant Department of Zoology, Australian National University, Box 4, G.P.O., Canberra, A.C.T. 2600, Australia E. J. L. Soulsby Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 OES, UK K. S. Warren Director for Health Sciences, The Rockefeller Foundation, 1133 Avenue of the Americas, New York, N.Y. 10036, USA J. P. Kreier Department of Microbiology, College of Biological Sciences, Ohio State University, 484 West 12th Avenue, Columbus, Ohio 43210, USA M. Yokogawa Department of Parasitology, School of Medicine, Chiba University, Chiba, Japan Advances in PARASITOLOGY Edited by J. R. BAKER Institute of Terrestrial Ecology Culture Centre of Algae and Protozoa Cambridge, England and R. MULLER Commonwealth Institute of Parasitology St. Albans, England VOLUME 25 1986 ACADEMIC PRESS Harcourt Brace Jovanovich, Publishers London Orlando SanDiego New York Austin Boston Montreal Sydney Tokyo ACADEMIC PRESS INC. (LONDON) LTD 24/28 Oval Road London NWl United States Edition published by ACADEMIC PRESS INC. Orlando, Florida 32887 Copyright 0 1986, by ACADEMIC PRESS INC. (LONDON) LTD AN Right Reserved No part of this book may be reproduced in any form by photostat, microfilm, or any other means, without written permission from the publishers ISBN 0-12-031725-7 ISSN 0065-308X Photoset in Great Britain by Rowland Phototypesetting Ltd, Bury St Edmunds, Suffolk and printed by St Edmundsbury Press Ltd Bury St Edmunds, Suffolk CONTRIBUTORS TO VOLUME 25 C. BRYANT, Department of Zoology, Australian National University, Canberra, A C T 2600, Australia I . A. CLARK,Department of Zoology, Australian National University, Canberra, ACT2600, Australia W . B . COWDEN, John Curtin School of Medical Research, Australian National University, Canberra, A C T 2600, Australia H . A. FLOCKHART, Winches Farm Field Station, London School of Hygiene and Tropical Medicine, St. Albans A L 4 OXQ,U K H . C. GIBBS, Department of Animal and Veterinary Sciences, University of Maine, Orono, Maine 04469, U S A N . H . HUNT,John Curtin School of Medical Research, Australian National University, Canberra, A C T 2600, Australia G. C. KEARN, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, U K J . RILEY,Department of Biological Sciences, The University, Dundee D D1 4HN, Scotland V This Page Intentionally Left Blank PREFACE This volume includes two papers on purely helminthological topics, by Dr. Kearn and Drs. Bryant and Flockhart, two on more general parasitological subjects, by Dr. Gibbs and Dr. Clark, and one, by Dr. Riley, on that very interesting but too little known group of animals, the pentastomid “worms”. Thus we hope that the volume will contain material of interest to a wide range of parasitologists. Dr. Clark’s paper on the role of “free” oxygen in pathogenesis complements that by Dr. Thorne and Dr. Blackwell, in volume 22, which dealt, among other things, with the role of oxygen radicals in the intracellular killing of parasites. In volume 24 we printed the first part of a two-part treatment of nematodes as agents of biological control, by Dr. J. J. Petersen; the second part, by Dr. R. Bedding, has been held over and will appear in volume 26. Readers may note that, in this volume, Advances in Parasitology h