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DYNAMICS OF FOREST INSECT POPULATIONS Patterns, Causes, Implications
POPULATION ECOLOGY: Theory and Application Series Editor: Alan A. Berryman
Washington State University Pullman, Washington
POPULATION SYSTEMS: A General Introduction Alan A. Berryman
FOREST INSECTS: Principles and Practice of Population Management Alan A. Berryman
DYNAMICS OF FOREST INSECT POPULATIONS: Patterns, Causes, Implications
Edited by Alan A. Berryman
DYNAMICS OF FOREST INSECT POPULATIONS Patterns, Causes, Implications
Edited by
Alan A. Berryman Washington State University
Pullman, Washington
SPRINGER SCIENCE+BUSINESS MEDIA, LLC
Library of Congress Cataloging in Publication Data
Dynamics of forest insect populations.
(population ecology) IncIudes bibliographies and indexes. 1. Forest insects-Control. 2. Forest insects-Ecology. 3. Forest insects-Host
plants. 4. Insect populations. 5. Forest ecology. 1. Berryman, A. A. (Alan Andrew), 1937- . II. Series. SB761.D96 1988 634.9'67
© 1988 Springer Science+Business Media New York Originally published by Plenum Press, New York in 1988
Softcover reprint ofthe hardcover Ist edition 1988
Ali rights reserved
88-12631
No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microftlming,
recording, or otherwise, without written permission from the Publisher
ISBN 978-1-4899-0791-2 ISBN 978-1-4899-0789-9 (eBook) DOI 10.1007/978-1-4899-0789-9
In Memory of
George C. Varley
First Chairman of IUFRO Working Party S2.07-06
"Population Dynamics of Forest Insects"
CONTRIBUTORS
ALF BAKKE Norwegian Forest Research Institute, N-1432 As-NLH, Norway
WERNER BALTENSWEILER Department of Plant Sciences, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland
YURI N. BARANCHIKOV V.N. Sukachev Institute of Forestry and Wood, Siberian Branch, U.S.S.R. Academy of Sciences, Krasnoyarsk, 660036 U.S.S.R.
DAVID A. BARBOUR British Forestry Commission, Forest Research Station, Wrecclesham, Farnham, Surrey GU10 4LH, England
BRODER BEJER Department of Forest Entomology and Ecology, Royal Veterinary and Agricultural University, Copenhagen, Denmark, DK 1870
C. WAYNE BERISFORD Department of Entomology, University of Georgia, Athens, Georgia 30602
ALAN A. BERRYMAN Department of Entomology, Washington State University, Pullman, Washington 99164-6432
JOHN H. BORDEN Center for Pest Management, Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 Canada
ERIK CHRISTIANSEN Norwegian Forest Research Institute, N-1432 As-NLH, Norway
ROBERT N. COULSON Department of Entomology, Texas A&M University, College Station, Texas 77843
GEORGE T. FERRELL U.S. Forest Service, Pacific Southwest Forest and Range Experiment Station, Berkeley, California 94701
ANDREAS FISCHLIN Department of Plant Sciences, Project Centre IDA/Celtia, Swiss Federal Institute of Technology, CH-8092 Zurich, Switzerland
RICHARD 0. FLAMM Department of Entomology, Texas A&M University, College Station, Texas 77843
vii
viii CONTRIBUTORS
IMOGEN M. GATE British Forestry Commission, Forest Research Station, Wrecclesham, Farnham, Surrey GUIO 4LH, England
CLAUDE GERI Institut National de la Recherche Agronomique, INRA-CRF-Station de Zoologie Forestiere, Ardon 45160, Olivet, France
JEAN-CLAUDE GREGOIRE Biologie Animale-C.P. 160, Universite Libre de Bruxelles, B-1050 Brussels, Belgium
FRED PAUL HAIN Departments of Entomology and Forestry, North Carolina State University, Raleigh, North Carolina 27695-7626
SINIKKA HANHIMAKI Department of Biology, University of Turku, SF-20500 Turku 50, Finland
ERKKI HAUKIOJA Department of Biology, University of Turku, SF-20500 Turku 50, Finland
ALEXANDER S. ISAEV V. N. Sukachev Institute of Forestry and Wood, Siberian Branch, U.S.S.R. Academy of Science, Krasnoyarsk, 660036 U.S.S.R.
NElLA. C. KIDD DepartmentofZoology, University College, CardiffCF11XL, Wales
FUJIO KOBA Y ASID Forestry and Forest Products Research Institute, Tsukuba, lbaraki, 305 Japan
SIMON R. LEATHER Forestry Commission, Northern Research Station, Roslin, Midlothian EH26 9SJ, Scotland
GARRELL E. LONG Department of Entomology, Washington State University, Pullman, Washington 99164-6432
JOHN L. MADDEN Faculty of Agricultural Science, University of Tasmania, Hobart, Tasmania 7000, Australia
VERA S. MALUTINA V. N. Sukachev Institute of Forestry and Wood, Siberian Branch, U.S.S.R. Academy of Sciences, Krasnoyarsk, 660036 U.S.S.R.
RICHARD R. MASON U.S. Forest Service, Forestry and Range Sciences Laboratory, La Grande, Oregon 97850
WILLIAM J. MATTSON U.S.D.A. Forest Service, North Central Forest Experiment Station, Pesticide Research Center, Michigan State University, East Lansing, Michigan 48824
MARKS. McCLURE The Connecticut Agricultural Experiment Station, Valley Laboratory, Windsor, Connecticut 06095
MICHAEL E. MONTGOMERY U.S.D.A. Forest Service, Northeastern Forest Experiment Station, Center for Biological Control of Northeastern Forest Insects and Diseases, Hamden, Connecticut 06514
F. DAVID MORGAN Department of Entomology, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia 5064, Australia
CONTRIBUTORS ix
K. S. S. NAIR Division of Entomology, Kerala Forest Research Institute, Peechi 680 653, Kerala, India
SEPPO NEUVONEN Department of Biology, University of Turku, SF-20500 Turku 50, Finland
PEKKA NIEMELA Department of Biology, University of Turku, SF-20500 Turku 50, Finland
THOMAS L. PAYNE Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061
KENNETH F. RAFFA Department of Entomology, University of Wisconsin, Madison, Wisconsin 53706
ALAIN ROQUES Institut National de la Recherche Agronomique, INRA-CRF-Station de Zoologie Forestiere, Ardon 45160, Olivet, France
GARY A. SIMMONS Department of Entomology, Michigan State University, East Lansing, Michigan 48824
GARY S. TAYLOR Department of Entomology, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, South Australia 5064, Australia
DAVID W AINHOUSE British Forestry Commission, Forest Research Station, Wrecclesham, Farnham, Surrey GUlO 4LH, England
WILLIAM E. WALLNER U.S.D.A. Forest Service, Northeastern Forest Experiment Station, Center for Biological Control of Northeastern Forest Insects and Diseases, Hamden, Connecticut 06514
ALLAN D. WATI Natural Environment Research Council, Institute of Terrestrial Ecology, Edinburgh Research Station, Penicuik, Midlothian EH26 OQB, Scotland
BOYD E. WICKMAN U.S. Forest Service, Forestry and Range Sciences Laboratory, La Grande, Oregon 97850
JOHN A. WITIER School of Natural Resources, University of Michigan, Ann Arbor, Michigan 48109
PREFACE
Insects multiply. Destruction reigns. There is dismay, followed by outcry, and demands to Authority. Authority remembers its experts or appoints some: they ought to know. The experts advise a Cure. The Cure can be almost anything: holy water from Mecca, a Government Commission, a culture of bacteria, poison, prayers denunciatory or tactful, a new god, a trap, a Pied Piper. The Cures have only one thing in common: with a little patience they always work. They have never been known entirely to fail. Likewise they have never been known to prevent the next outbreak. For the cycle of abundance and scarcity has a rhythm of its own, and the Cures are applied just when the plague of insects is going to abate through its own loss of momentum. -Abridged, with insects in place of voles, from C. Elton, 1924, Voles, Mice and Lemmings, with permission of Oxford University Press
This book is an enquiry into the "natural rhythms" of insect abundance in forested ecosystems and into the forces that give rise to these rhythms. Forests form unique environments for such studies because one can find them growing under relatively natural (primeval) conditions as well as under the domination of human actions. Also, the slow growth and turnover rates of forested ecosystems enable us to investigate insect population dynamics in a plant environment that remains relatively constant or changes only slowly, this in contrast to agricultural systems, where change is often drastic and frequent. These characteristics enhance our ability to investigate the stability of rapidly changing insect populations, as well as the stabilizing and destabilizing forces, something that is difficult or impossible to do in most agricultural settings. Finally, again because of slow turnover, the genetics of tree species occupying most forests have not been significantly altered by human selection. This provides us with an opportunity to study the interactions between trees and insects that have evolved over eons of coadaptation.
This book, being composed of a number of selected studies on individual forest insects, is of an empirical nature. We attempt to present the facts, both biological and ecological, on which our interpretations are based. Yet the aim of the book is to provide empirical support for a general unified theory of population dynamics, a theory that grew out of the "Great Debate" between Nicholson and Andrewartha during the 1950s. Although this theory has been consolidated in recent years from somewhat different perspectives, its underlying construct rests on the same critical question that haunted the "Great Debate": Are natural populations stabilized by density-induced negative feedback pro-
xi
xii PREFACE
cesses? Even today the literature bears testament to those who resist this notion. Does the "natural rhythm" emerge from some intrinsic properties of the system or is it merely an expression of chaotic external forces? The reader of this book is challenged to draw personal conclusions.
Out of the general unified theory of population dynamics has emerged a theory of outbreaks that focuses on the instabilities that arise in natural systems and the forces that tend to destabilize them. Critical questions can also be posed about the roots of this theory: Are natural populations destabilized by density-induced positive feedback processes and/or by the action of delayed negative feedback? In other words, is the apparent chaos that pest outbreaks seem to generate also an intrinsic property of the natural system-and, therefore, amenable to human manipulation?
This book should also be read with the view of understanding the human impact on the global ecosystem. Forests are just a reflection of other ecosystems, some of which are much more heavily affected by humans, some less so. Relevant questions are: Have human activities led to more or less stable interactions between forests and insects? What kinds of activities tend to destabilize these ecosystems? How can we mitigate the interaction between man and forests and so create more stable ecosystems? If this book can help ' answer these questions, our time will have been well spent.
This book was conceived and written while I was chairman of a working party entitled "Population Dynamics of Forest Insects" within the International Union of Forestry Research Organizations (IUFRO), and many of the contributors have been active participants in this group. Working party S2.07-06 was formed by G. C. Varley, F. Schwerdtfeger;, and A. D. Voute at a meeting in Amheim in 1955. George 1Varley, to whom we dedicate this volume, became the first chairman of S2.07-06 the following year at the IUFRO World Congress in Oxford. When George retired in 1976 at the Oslo World Congress, Werner Baltensweiler assumed the chair and I became his co-chairman. My tenure as co-organizer of "Population Dynamics of Forest Insects" ended 10 years later at the World Congress in Ljubljana (Yugoslavia) and I view this book as the culmination of this enjoyable and productive experience.
Finally, this book represents the work and thoughts of numerous individuals from many countries. Each chapter tells a story in itself that is both interesting and provocative. Yet out of this diversity emerge common themes, generalities, and conclusions. The reader is invited to join us in the search for those commonalities that affect us all as we play our part in the dynamic patterns of nature.
Alan A. Berryman Pullman, Washington
CONTENTS
CHAPTER 1
THE LARCH CONE FLY IN THE FRENCH ALPS Alain Roques
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Biology and Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Ecological Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 4. Numerical Population Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. Hypothesis for the Cause of Population Fluctuations . . . . . . . . . . . . . . . . . . . . . . 17 6. Management Implications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
CHAPTER 2
THE LARCH GALL MIDGE IN SEED ORCHARDS OF SOUTH SIBERIA Alexander S. lsaev, Yuri N. Baranchikov, and Vera S. Malutina
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2. Biology and Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 3. Effects on the Host Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4. Factors Affecting Population Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 5. Causes of Population Fluctuations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 6. Management Alternatives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
CHAPTER 3
THE ARMORED SCALES OF HEMLOCK Mark S. McClure
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 2. Biology and Life History ............................................ 47
xiii
xiv CONTENTS
3. Factors Affecting Scale Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 4. Hypotheses for the Causes of Observed Population Patterns ................ 56 5. Implications for Developing Management Strategies . . . . . . . . . . . . . . . . . . . . . . 60 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
CHAPTER 4
THE BEECH SCALE
David Wainhouse and Imogen M. Gate
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 2. Biology and Life History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71 3. Population Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 4. Hypotheses for the Causes of Observed Population Behavior . . . . . . . . . . . . . . . 79 5. Implications for the Development of Management Strategies . . . . . . . . . . . . . . . 81 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
CHAPTER 5
THE BALSAM WOOLLY ADELGID IN NORTH AMERICA
Fred Paul Hain
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 2. Biology and Ecological Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89 3. Factors affecting Distribution and Abundance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97 4. Hypotheses for the Causes of Observed Population Dynamics .............. 101 5. Management Implications ............................................ 103 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
CHAPTER 6
THE LARGE PINE APHID ON SCOTS PINE IN BRITAIN
Neil A. C. Kidd
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 2. Biology and Life History ............................................ 113 3. Population Dynamics ................................................ 116 4. Implications for Management .......................................... 123 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
CHAPTER 7
THE WHITE LACE LERP IN SOUTHEASTERN AUSTRALIA
F. David Morgan and Gary S. Taylor
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 2. Biology and Ecology ................................................ 131
CONTENTS XV
3. Causes of Population fluctuations ..................................... 133 4. Management Implications ............................................ 139 References ........................................................... 139
CHAPTER 8
THE NANTUCKET PINE TIP MOTH C. Wayne Berisford
1. Introduction ....................................................... 142 2. Biology and Life History ............................................ 145 3. Natural Enemies ................................................... 150 4. Host Interactions ................................................... 152 5. Hypotheses for Population Behavior ................................... 156 6. Management Strategies .............................................. 157 References ........................................................... 158
CHAPTER 9
THE AUTUMNAL MOTH IN FENNOSCANDIA Erkki Haukioja, Seppo Neuvonen, Sinikka Hanhimaki, and Pekka Niemala
1. Introduction ....................................................... 164 2. Biology and Ecology ................................................ 165 3. Patterns of Numerical Population Behavior ............................... 170 4. Hypotheses for the Causes of Population Cycles ......................... 172 5. Management Implications ............................................ 175 References ........................................................... 176
CHAPTER 10
THE DOUGLAS-FIR TUSSOCK MOTH IN THE INTERIOR PACIFIC NORTHWEST
Richard R. Mason and Boyd E. Wickman
1. Introduction ....................................................... 180 2. Biology and Life History ............................................ 181 3. Patterns of Numerical Behavior ....................................... 192 4. Hypotheses for the Causes of Observed Population Behavior ......... · ...... 197 5. Implications for Developing Management Strategies ...................... 202 References ........................................................... 205
CHAPTER 11
THE NUN MOTH IN EUROPEAN SPRUCE FORESTS Broder Bejer
1. Introduction ....................................................... 212 2. Biology and Life History ............................................ 213
xvi CONTENTS
3. Patterns of Numerical Population Behavior .............................. 219 4. Hypotheses for the Causes of Outbreaks ................................ 223 5. Implications for Developing Management Strategies ...................... 226 6. Conclusion ........................................................ 229 References ........................................................... 229
CHAPTER 12
THE LARCH CASEBEARER IN THE INTERMOUNTAIN NORTHWEST Garrell E. Long
1. Introduction ....................................................... 234 2. Biology ........................................................... 234 3. Interactions with Host Trees .......................................... 236 4. Interactions with Natural Enemies ..................................... 237 5. Other Influences .................................................... 239 6. Population Dynamics ................................................ 239 7. Management Implications ............................................ 242 References ........................................................... 242
CHAPTER 13
THE PINE BEAUTY IN SCOTTISH LODGEPOLE PINE PLANTATIONS Allan D. Watt and Simon R. Leather
1. Introduction ....................................................... 244 2. Biology and Life History ............................................ 246 3. Patterns of Numerical Behavior ....................................... 251 4. Hypotheses for the Causes of Observed Population Behavior ............... 258 5. Implications for Developing Management Strategies ...................... 262 References ........................................................... 264
CHAPTER 14
THE TEAK DEFOLIATOR IN KERALA, INDIA K. S. S. Nair
1. Introduction ....................................................... 268 2. Biology ........................................................... 269 3. Ecological Relationships ............................................. 272 4. Population Dynamics ................................................ 275 5. Management Implications ............................................ 286 References ........................................................... 288
CONTENTS xvii
CHAPTER 15
THE PINE LOOPER IN BRITAIN AND EUROPE
David A. Barbour
l. Introduction ....................................................... 292 2. Economic Significance .............................................. 292 3. Biology and Ecological Relationships .................................. 292 4. Patterns of Numerical Behavior ....................................... 294 5. Hypotheses for Causal Mechanisms .................................... 299
6. Management Strategies .............................................. 304 References ........................................................... 306
CHAPTER 16
THE SPRUCE BUDWORM IN EASTERN NORTH AMERICA
William J. Mattson, Gary A. Simmons, and John A. Witter
1. Introduction ....................................................... 310 2. Biology and Behavior ............................................... 311 3. Ecological Relationships ............................................. 313 4. Outbreak Patterns .................................................. 319 5. Management Implications ............................................ 323 6. Concluding Remarks ................................................ 325 References ........................................................... 326
CHAPTER 17
THE LARCH BUDMOTH IN THE ALPS
Werner Baltensweiler and Andreas Fischlin
I. Introduction ....................................................... 332 2. Biology and Ecological Relationships .................................. 334 3. Patterns of Numerical Behavior ....................................... 339 4. Hypotheses for the Causes of Observed Population Dynamics .............. 341 5. Implications for Developing Management Strategies ...................... 346 References ........................................................... 348
CHAPTER 18
THE GYPSY MOTH: A WESTWARD MIGRANT
Michael E. Montgomery and William E. Wallner
1. Introduction ....................................................... 354 2. Biology ........................................................... 355
3. Natural Enemies ................................................... 357 4. Numerical Patterns ................................................. 359
xviii CONTENTS
5. Factors Affecting Numerical Dynamics ................................. 364 6. Management Implications ............................................ 369 References ............................................................ 372
CHAPTER 19
THE PINE SAWFLY IN CENTRAL FRANCE Claude Geri
1. Introduction ....................................................... 378 2. Biology and Behavior ............................................... 380 3. Relationships with Natural Enemies .................................... 384 4. Relationships with the Physical and Forest Environment ................... 387 5. Numerical Population Dynamics ...................................... 389 6. Explanation of Population Behavior .................................... 393 7. Implications for Pest Management ..................................... 401 References ........................................................... 401
CHAPTER 20
SIREX IN AUSTRALASIA John L. Madden
1. Introduction ....................................................... 408 2. Life History and Ecological Relationships ............................... 409 3. Patterns of Numerical Behavior ....................................... 415 4. Hypotheses for Cause of Observed Population Behavior ................... 420 5. Management Implications ............................................ 425 References ........................................................... 426
CHAPTER 21
THE JAPANESE PINE SAWYER Fujio Kobayashi
1. Introduction ....................................................... 432 2. Biology and Ecological Relationships .................................. 435 3. Population Behavior ................................................ 441 4. Causes of Observed Population Behavior ............................... 445 5. Management Strategies .............................................. 449 References ........................................................... 452
CHAPTER 22
THE GREATER EUROPEAN SPRUCE BEETLE Jean-Claude Gregoire
1. Introduction ....................................................... 456 2. Biology and Behavior ............................................... 456
CONTENTS xix
3. Ecological Relationships ............................................. 460 4. Patterns of Numerical Behavior ....................................... 465 5. Hypotheses for the Causes of Observed Population Behavior ............... 470 6. Implications for Developing Management Strategies ...................... 473 References ............................................................ 474
CHAPTER 23
THE SPRUCE BARK BEETLE OF EURASIA Erik Christiansen and Alf Bakke
l. Introduction ....................................................... 480 2. Biology and Ecology ................................................ 481 3. Population Patterns: Case Histories .................................... 491 4. Implications for Forest Managers .. : ................................... 499 References ........................................................... 500
CHAPTER 24
THE MOUNTAIN PINE BEETLE IN WESTERN NORTH AMERICA Kenneth F. Raffa
1. Introduction ....................................................... 506 2. Biology and Ecological Relationships .................................. 507 3. Population Patterns ................................................. 516 4. Hypothesis for the Causes of Outbreaks ................................ 518 5. Managing Populations ............................................... 522 References ........................................................... 525
CHAPTER 25
THE SOUTHERN PINE BEETLE Richard 0. Flamm, Robert N. Coulson, and Thomas L. Payne
1. Introduction ....................................................... 532 2. Life Cycle and Behavior ............................................. 533 3. Ecological Relationships ............................................. 538 4. Population Patterns and Their Causes .................................. 541 5. Management Implications ............................................ 54 7 References ........................................................... 550
CHAPTER 26
THE FIR ENGRAVER BEETLE IN WESTERN STATES Alan A. Berryman and George T. Ferrell
1. Introduction ....................................................... 556 2. Biology and Behavior ............................................... 556
XX CONTENTS
3. Ecological Relationships ............................................. 559 4. Population Patterns and Their Causes .................................. 568 5. Management Implications ............................................ 572 References ........................................................... 575
CHAPTER 27
THE STRIPED AMBROSIA BEETLE John H. Borden
1. Introduction ....................................................... 580 2. Biology and Life History ............................................ 581 3. Patterns of Numerical Behavior ....................................... 587 4. Hypothesis to Explain Observed Population Behavior ..................... 588 5. Implications for Pest Management ..................................... 590 References ........................................................... 593
TAXONOMIC INDEX ................................................. 597
SUBJECI' INDEX ..................................................... 601
