AN ABSTRACT OF THE THESIS OF DONALD W. SCOTT for the degree of DOCTOR OF PHILOSOPHY in Entomology, Forest presented on August 11, 1978 Title: SURVIVAL AND DEVELOPMENT OF THE FLATHEADED FIR BORER IN FOREST RESIDUES AS AFFECTED BY HOST AND MICROC TIC CONDI ONS Abstract approved: Redacted for Privacy The purpose of this study was to examine various host and microclimatic influences affecting the survival and development of the flatheaded fir borer, Melanophila drummondi (Kirby) in Douglas - fir, Pseudotsuga menziesii (Mirbel) Franco residues. It also expands current knowledge of the biology, bionomics, life history, ecology, and biotic potential for decomposition of forest residues by this insect. The primary study objective was to determine the optimum host and microclimatic conditions for development of the flatheaded fir borer by measuring the rate of beetle development with an index employed in other studies on forest insects. The monthly rates of development of larvae from clearcut and partial cut (shelterwood system) logs and from 15.6°, 21.1o, and 26.7oC controlled-temperature rearings were determined over the develop- ment season. Inner phloem moisture content and pH were monitored monthly from four quadrants (south-top, south-bottom, north-bottom, and north-top) on logs from each treatment throughout the season. Measurements of ambient air temperature and precipitation for the two field sites were used to correlate the microclimate of the host to these physical factors of weather. In addition, various other studies examined the relationship between inner phloem temperature and ambient air temperature on cloudy and clear days and also between logs of different bark thicknesses, and at the top and bottom of a log. Forest residues are attacked immediately after they become available from timber cutting or tree mortality in the spring and summer. Tops down to 7.62 cm in dia- meter are utilized by this beetle, although thinner bark of small diameter residues afford less protection from temperature extremes, parasites and avian predators than thick-barked residues. Eggs are typically deposited on the tops or upper sides of logs and residues by woodborers, and they also prefer clearcuts over partial cuts. Furthermore, larval densities are higher on the tops and sides of residues and on clearcuts, compared to other locations. The top portion and upper sides of residues are characterized by warmer inner phloem temperatures, lower moisture contents, and less acidity than the bottom half of logs and residues on the ground. In addition, clearcut logs are generally characterized by these qualities. Temperature and moisture differences around the logs are believed to affect the distribution of the flatheaded woodborers within logs. Although the flatheaded fir borer invades residues on both clearcuts and partial cuts, the clearcuts are preferred because of warmer temperatures. The rate of development is also greatest on clearcuts, and maturity to adult is reached sooner due to faster accumulation of heat units on these sites. The clearcut represents optimal conditions for development and survival of this insect. Larvae reared at three different constant temperatures in the laboratory failed to develop past the 3rd instar (pre-pupa), presum- ably because of the lack of a cold period which is required to break diapause in this resting stage. Parasitism accounts for the greatest proportion of woodborer mortality. Other mortality factors include resinoisis, predation, and unknown causes. Various parasites were reared and identi- fied as mortality factors, but Atanycolus longifemoralis Shenefelt was most frequently observed. Other parasites and predators are discussed in their role as natural enemies of the flatheaded fir borer. An accurate and precise linear regression method is described which enables the estimation of inner phloem surface area of larval galleries from measurements of the gallery length. Its use in esti- mating woodborer-caused deterioration in forest residue surveys is emphasized. Survival and Development of the Flatheaded Fir Borer in Forest Residues as Affected by Host and Microclimatic Conditions by Donald Wayne Scott A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Completed August 1978 Commencement June 1979 APPROVED: Redacted for Privacy Professor of Entomology in charge of major Redacted for Privacy Chairman of Department of Ento gy Redacted for Privacy Dean of Graduate School Date thesis is presented August 11, 1978 Typed by Ilene Anderton for Donald Wayne Scott ACKNOWLEDGEMENTS I am gratefully indebted to the many individuals who contributed valuable advice and assistance during the course of this study. Appreciation is extended to Dr. William P. Nagel for accepting me into a graduate study program under his guidance at Oregon State University. I am especially grateful to Dr. Ralph E. Berry for taking over the major responsibility of guiding my graduate program following the resignation of Dr. Nagel from the university, and also for the many helpful comments and suggestions he offered on the research and in writing the thesis. Special thanks are due to Boyd E. Wickman of the U.S. Forest Service's Pacific Northwest Forest and Range Experiment Station for serving in the capacity of research director. I am grateful for his encouragement and the valuable technical advice and consultation he provided in the conduct of my research. I would also like to thank the other members of graduate committee: Drs. Robert I. Cara, Clarence G. Thompson, Richard G. Clarke, and Lyle R. Brown who offered many useful comments and advice during the course of the study. I wish to thank Dr. Kuo C. Lu, John D. Lattin, Julius A. Rudinsky, William P. Stephen, Dennis M. Burgett, and Robert L. Goulding for the use of laboratory facilities and equipment. Finally, I wish to express my sincere appreciation to my parents who have inspired and encouraged me to seek knowledge, and to my loving wife, Kathy, without whose sustain- ing encouragement, enduring patience, and personal sacrifice this would not have been possible. Support for this research was provided by the United States Department of Agriculture, Forest Service, Cooperative Research Agreement 16 USC 581; 581a-581i, Supplement Numbers 131 and 193. TABLE OF CONTENTS Chapter Page I. INTRODUCTION 1 II. OBJECTIVES OF THE STUDY 5 III. DEFINITION OF TERMS 9 IV. SPECIES STUDIED 12 General Description and Terminology of Flatheaded Borers 12 Distribution 15 Host Record 15 Life History and Biology 16 Flight 21 Attack Behavior 25 Basking Behavior 28 Host Selection and Orientation 30 V. MATERLALS AND METHODS 33 Field Study Sites 33 Entomology Farm 33 McDonald Forest Site 34 Experimental Design and Field Plot Layout 36 Design for Development and Survival Studies 36 Log Sampling Method 39 Bark pH Determination 40 Bark Moisture Content Determination 42 Log Sampling Schedule 42 Design for Physicochemical Studies 44 Instrument Calibrations 45 pH Meter 45 Hyg rothe rmographs 46 Yellow Springs Instrument Tele-Thermometer 47 Beetles 48 Identification 48 Ins tar Determination 50 Development Index 54 Flight Occurrence 56 Calculation of Monthly Thermal Units 57 Measurement of Larval Galleries 59 Chapter Page. Weather Measurements 60 Statistical Analysis and Computer Graphics 61 VI. RESULTS AND DISCUSSION 63 Biological Investigations Woodborer Species Attacking Logs 63 Distribution of Woodborers Within Logs 64 Frequency of Woodborer Occurrence by Quadrant 64 Woodborer Densities by Quadrant 74 Relationship Between Log Diameter, Bark Thickness, and Beetle Attack 79 Beetle Development 82 Comparison of Developmental Rates 84 Effect of Temperature 97 Development Related to Log Exposure 103 Beetle Mortality 105 Larval Mortality Distribution Within Logs 105 Larval Mortality Factors and Their Relative Efficacies 108 Parasitism 110 Unknown Causes 111 Resinosis 113 Predation 113 Seasonal Mortality Trends and Population Point Estimates 115 Regression Estimation of Gallery Surface Area 120 The Role of Microclimate on Host Bark and the Flatheaded Fir Borer 124 Host-Microclimate Interactions 124 Moisture Content 124 pH 136 Factorial Analysis (Moisture Content and pH) 143 Temperature Studies 143 Beetle -Microclimate Interactions 162 Effect on Woodborer Distribution 162 Effect on Food Quality 165 Effect on Rate of Development 167 Effect on Mortality 168 Estimation of Insect-Caused Deterioration 171 Chapter Page VII. SUMMARY AND CONCLUSIONS 174 BIBLIOGRAPHY 184 APPENDICES 198 LIST OF FIGURES Figure Page 1. The flatheaded fir borer, Melanophila drummondi (Kirby); a, larvae; b, pupa; c, adult. 13 2. Generalized life cycle of Melanophila drummondi. 17 3. Development of Melanophila drummondi in Douglas-fir logs cut May 3, 1975 at McDonald Forest, Benton County, Oregon. 22 4. Correlation of Melanophila drummondi flight occurrence with ambient air temperature in McDonald Forest, Benton County, Oregon (May- October, 1976). 24 5. Map of McDonald Forest, Benton County, Oregon showing the location of study site. 35 6. Frequency distribution of the clypeus widths of Melanophila drummondi Kirby larvae feeding in inner phloem of Douglas-fir logs from McDonald Forest, Benton County, Oregon, 1975-1977. 53 7. Frequency distribution comparison of all stages (larvae, pupae, and adults) of Melanophila drummondi (M.D.) and Chrysobothris species (C. spp.) in Douglas -fir logs, 1975-1977. 65 8. Comparison of the distribution of Melanophila drummondi larval densities