This dissertation has been 65-12,435 microfilmed exactly as received AHTHUR, Mervyn, 1938- ECOLOGICAL STUDIES ON POLYDESMA UMBRICOLA BOISD. IN HAWAII (LEPIDOPTERA: NOCTUIDAE). University of Hawaii: Ph.D., 1965 Zoology University Microfilms, Inc., Ann Arbor, Michigan ECOLOGICAL STUDIES ON POLYDESMA UMBRICOLA BOISD. IN HAWAII (LEPIDOPTERA: NOCTUIDAE) A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF HAWAII IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN ENTOMOLOGY JANUARY, 1965 By Mervyn Arthur Thesis Committee: Toshiyuki Nishida, Chairman D. Elmo Hardy Henry A. Bess Robert M. Warner Ernst S. Reese ii ACKNCMLEDGEMENT I take this opportunity to thank the faculty of the Department of Entomology and members of my thesis committee for their help and encouragement in this study. I am es­ pecially indebted to Dr. T. Nishida for guidance and help in planning and conducting this research. I am grateful to the Rockefeller Foundation, for making this study possible with the grant of a fellowship. Thanks are also due to Miss Elizabeth A. Thomas and Mrs. Betty Someda for help in typing the thesis. iii TABLE OF CONTENTS ACKNCMLEDGEMENT ii LIST OF TABLES v LIST OF FIGURES vi INTRODUCT ION 1 MATERIALS AND METHODS 5 Laboratory Methods 5 Field Studies 10 HOST PLANTS 15 DISTRIBUTION 19 LIFE HISTORY STUDIES 22 Descriptf.on vf Stages 22 Number of Instars • 26 Duration of Instars 28 PHYS ICAL CHARACTERIST ICS OF THE HOST TREE 33 Bark Conditions 33 Age of Tree 33 Height and Size of Tree 35 DISTRIBUTION OF THE IMMATURE STAGES ON THE HOST TREE 36 Distribution of Eggs •. .. 36 Distribution of Larval Stages • 39 Dfstribution of Pupae lj·2 BEHAVIOR STUDIES 43 Behavior in General 43 Feeding Behavior of L~rvae 50 Daily Rhythm of Activity 51 Response to Light 55 OVIPOSITION STUDIES 59 Effect of Space on Oviposition 59 Rate of Oviposition ...... 61 Age of Imagoes and Egg Viability 63 Oviposition and Longevity of Mated and Unmated Females. 63 iv TABLE OF CONTENTS (CONTINUED) PHENOL<X;Y OF THE MONKEY POD TREE 69 Growth of Trees •.... 69 Relationship between Growth of Trees and Climate 72 Damage to Trees . , 74 Shedding of Leaves .... 75 SEASONAL ABUNDANCE OF X. UMBRICOLA • 77 Egg Population •.... 77 Larval Population ..•... 79 Relationship between Abundance of g. umbrico1a and Growth of Trees 0•••••••••••••• 81 Relationship between X. umbrico1a and E. odora 81 Relationship between X. umbrico1a and Damage t9 Trees 85 NATURAL ENEMIES AND THE IR IMPORTANCE 89 Parasites . 89 Relationship between Abundance of X. umbrico1a and its Parasites 92 Predators 94 DISCUSSION . 99 SUMMARY 106 LITERATURE CITED 108 v LIST OF TABLES TABLE 1. THE HOST PLANTS OF E,. UMBRICOLA AS REPORTED FROM VARIOUS PARTS OF THE WORLD. •••••••• 16 It. THE DIMENSIONS OF EGGS AND PUPAE AND THE HEAD WIDTHS AND BODY LENGTHS OF THE LARVAE OF X. UMBRICOLA • ,. , •••••••••••••••• 23 I II. DURAT ION OF THE IMMATURE STAGES OF P. UMBRICOLA. 31 - < IV. EFFECT OF TYPE OF CAGE AND MALE : FEMALE COMBINA- TION ON THE NUMBER OF EGGS LAID BY X. UMBRICOLA. 60 V. PREOV IPOSITION ) OVIPOSITION) AND POSTOVIPOSITION PERIODS AND FECUNDITY OF !. UMBRICOLA. ••••• 64 VI. THE EFFECT OF AGE ON THE PERCENTAGE OF VIABLE EGGS LAID BY!. UMBRICOLA •••••• •• •• 65 VII. MEAN NUMBER OF EGGS LAID AND LONGEVITY OF MATED AND UNMATED IMAGOES OF !. UMBRICOLA 67 VIII. PARASITES OF !. UMBRICOLA 95 IX. PREDATORS OF !. UMBRICOLA 98 vi LIST OF FIGURES FIGURE 1. THE NOCTUID MorH, POLYDESMA UMBRICOLA BOISD. ,A WELL KNOWN SERIOUS DEFOLIATOR OF MONKEY POD TREES. 2 2. THE MONKEY POD TREE, SAMANEA SAMAN (JACQ.) MERRILL. THIS PARTICULARLY SYMMETRICAL TREE IS GRGlING ON THE GROUNDS OF THE MOANALUA GARDENS, HONOLULU. • • • • • 3 3. SMALL BorTLE WITH A BRASS SCREEN CAP AND THICK CLorH ARRANGED CIRCULARLY INS IDE. THIS TITi OF BorTLE WAS USED FOR THE EMERGENCE OF THE' MarRS. ••••• 6 4. WOODEN CAGE FITTED WITH A SLIDING GLASS PANEL. THIS TYPE OF CAGE WAS USED IN BEHAVIOR STUDIES. •• 7 5 • THE METAL CAGE HAVING FOUR SIDES COVERED WITH NYLON CLorH. THIS TYPE OF CAGE WAS USED IN OVIPOSITION STUDIES. •••••••••••••••••••••• 9 6. GLASS GALLON JARS ARRANGED IN RACKS IN OVIPOSITION STUDIES ••••••••••••••••••••• 11 7. MAP OF THE UNIVERSITY OF HAWAII CAMPUS, SHGlING LO- CATION OF MONKEY POD TREES UNDER STUDY. DARK CIRCLES. DENOfE TREES WITH BURLAP BANDS AROUND THE IR TRUNKS; HALF SHADED CIRCLES, TREES WHICH WERE SAMPLED FOR PHENOLOOICAL DATA; AND OPEN CIRCLES, TREES WHICH WERE Nor STUDIED. •••••••••••••••••••• 12 8. PERMANENT TRAPS USED IN MAKING MONTIU.Y COUNTS OF R.. UMBRICOLA LARVAE. THE TOP PHOfOORAPH SHGlS THE "INTERNAL WOODEN SKELETON"; THE BOTrOM ONE, THE COMPLETED TRAP WITH BURLAP BAND ••••••• 13 9. A TOPPED MONKEY POD TREE SHCMING DAMAGE BY R.. UMBRICOLA. ALL THE BRANCHES ARE SECONDARY GROiITHS FROM THE ORIGINAL TRUNK ••••.••••• 17 10. GALL-LIKE STRUCTURES PRODUCED BY TWIGS WHOSE LEAVES WERE CONTINUOUSLY ATTACKED BY f. UMBRICOLA LARVAE. 18 11. MAP SHCMING THE WORLD-WIDE DISTRIBUTION OF P. UMBRICOLA (STARS) AND ITS HOST TREES. DARK-LINES INDICATE THE NORTHERN AND SOUTHERN DISTRIBlJfION LIMITS OF ITS HOST TREES ••••••••.•.•• 21 vii LIST OF FIGURES (CONTINUED) FIGURE 12. LATE DEVELOPMENTAL STAGES OF 1. illffiRICOLA. LEFr TO RIGlIT: SIXTH INSTAR LJ\RVA, PREPUPA, AND PUPA. 25 13. SETAL MAPS OF THE FIRST ABDOMINAL SEGMENTS OF LARVAE OF 1. UMBRICOLA AND!. ODORA. THE THREE SETAE IN THE ~ (7) GROUP ARE ARRANGED DIFFE~NTLY IN THE TWO SPECIES •••••••••••••••••• 27 14. THE FREQUENCY DISTRIBlITION OF- THE WIDTHS OF HEAD CAPSULES OF LARVAL INSTARS OF 1. UMBIHCOLA. EACH OF THE SIX PEAKS REPRESENTS A SEPARATE LARVAL INSTAR ••••••••••••••••••••• 29 15. THE STRAIGlIT-LINE RELATIONSHIP BETWEEN THE WIDTHS OF LARVAL HEAD-CAPSULES AND THE NUMBER OF LARVAL INSTARS IN . 1. UMBRICOLA ••••••••••••••••• 30 16. THE :R!RK OF AN OLD (TOP), AND A YOUNG (BGrTOM) TREE. THE ROUGH BARK ON OLD TREES PROVID;ES HIDING PLACES PORTHE LARVAE OF 1. UMBRICOLA •••• ; ••••. 34 17. DISTRIBlITION OF EGGS OF 1. UMBRICOLA ON THE TER- MINAL TWIGS OF THE MONKEY POD TREE ••••••• 37 18. DISTRIBlITION OF EGGS OF 1. UMBRICOLA ON THE STEM AND PETIOLES, AND ON PINNULES OF THE LEAFLETS OF THE MONKEY POD TREE ••••.•••••••••••• 38 19. DISTRIBlITION OF EGGS OF 1. UMBRICOLA ON THE TERMINAL LEAFLESS TWIGS OF THE MONKE Y POD TREE ••• •••• 40 20. A DIAGRAMMATIC REPRESENTATION OF THE DISTRIBlITION OF LARVAL STAGES OF 1. UMBRicOLA ON A YOUNG AND OLD MONKEY POD TREE. A, YOUNG AND SMOCYrH - BARKED TREE, AND B, OLD ROUGH-BARKED TREE. THE NUMBERS REPRESENT THE LOCATION OF THE RESPECTIVE INSTARS ••••••••• 41 21. DIAGRAMMATIC REPRESENTATION OF THE RELATIVE ABUNDANCE OF 1. UMBRICOLA LARVAE ON THE FOUR SIDES OF THE TRUNKS OF MONKEY POD TREES •••••••••••. 46 22. PERCENTAGE OF 1. UMBRICOLA LARVAE FOOND AT VARIOUS DISTA~~CES AROUND THE TREE TRUNKS AWAY FROM THEIR ORIGINAL RESTING PLACE •••••• •. '••••. 48 viii LIST OF FIGURES (CONTINUED) FIGURE 23. THE PERCENTAGE OF EGGS LAID BY f. UMBRICOLA ON VARIOUS MATERIALS ••••••••••••• 49 24. THE DAILY RHYrHM OF ACTIVITY OF ,f. UMBRICOLA LARVAE ON MONKEY POD TREES ••••••••. 52 25. THE PERIOD OF NOCTURNAL ACTIVITY OF THE IMAGOES OF ,f. UMBRICOLA ••••••••••••••• 54 26. THE REACTION OF THE SIXTH INSTAR LARVAE OF ,f. UMBRICOLA TO A POINT SOURCE OF LIGHT •• 56 27 • EFFECT OF AGE ON THE NUMBER OF EGGS LAID BY IMAGOES OF ,f. UMBRICOLA. EACH DOT REPRESENTS THE MEAN NUMBER OF EGGS LAID PER DAY BY THREE FEMALES; THE CIRCLES THE MEAN NUMBER OF EGGS FOR EACH DAY. 62 28. LONGEVITY OF MATED AND UNMATED FEMALES OF ,f. UMBR ICOLA ••••••••••••••••• 6 8 29. THE AMOUNT OF NEW GROWTH ON MONKEY POD TREES IN SERIES 1 (TOP), SERIES 3 (MIDDLE), AND SERIES 4 (BCYI'TOM) ••••••.••..••••.••• 71 30. THE RELATIONSHIP BETWEEN THE GRCWIH OF MONKEY POD TREES, AND THE TurAL MONTlfi.Y PRECIPITATION AND THE AMOUNT OF INCIDENT SOLAR RADIATION. THE PRE­ CIPITATION AND SOLAR RADIATION DATA ARE TAKEN FROM METEOROLffi ICAL RECORDS OF P.R. 1., AND H. S•P•A. , RESPECTIVELY •••••••••••••••• 73 31 • THE AMOUNT OF NEW GRCWTH AN!) THE DAMAGE DONE BY ,f. UMBRICOLA LARVAE ON MONKEY POD TREES. • • 76 32. THE ABUNDANCE OF THE EGGS OF ,f. UMBRICOLA 78 33. THE MONTHLY ABUNDANCE OF R. UMBRICOLA IN THE THREE SERIES •••••••••• 80 34. RELATIONSHIP BETWEEN THE NUMBERS OF R. UMBRICOLA AND GRCWTH OF MONKEY POD TREES . •••.•• 82 35. THE SEASONAL ABUNDANCE OF ,f. UMBRICOLA AND~. ODORA LARVAE UNDER THE BURLAP BAND TRAPS ••.••••• 84 36 • GRAPH SHCMING THE FREQUENCY OF CO-OCCURRENCE OF LARVAE OF f. UMBRICOLA AND~. ODORA UNDER THE BURLAP BAND TRAPS ••••••••••••••• 86 ix LIST OF FIGURES (CONTINUED) FIGURE 37. RELATIONSHIP BETWEEN NUMBERS OF 1. UMBRICOLA AND THE VISIBLE DAMAGE TO MONKEY POD TREES 87 38. MONTlll.Y ABUNDANCE OF VARIOUS PARASITES OF 1. UMBRICOLA. COLUMNS WITH FINE STIPPLING REPRESENT THE INCIDENCE OF f. MONTICOLA; SLANTING LINES !. ARMIGERA; HEAVY STIPPLING !. ARCHIPPIVORA; AND CROSSLINES .E. EXIGUAE. 91 3"9. GRAPH SHCMING THE SEASONAL GRaITH OF THE MONKEY POD TREE AND THE FLUCTUATIONS IN THE PEST POPULATION AND ITS PARASITES •••••.•.••••••••••• 93 DITRODUcrION The noctuid moth, Po1ydesma umbrico1a Boisd., commonly known as the monkey pod caterpillar, was first discovered in the Hawaiian Islands by Van Zwa1uwenburg (1945) on Oahu (Figure 1). In quick succession it was reported from the other islands: Mo1okai (Williams, 1945), Maui (Pemberton, 1945), Kauai (Fu11away, 1945), Hawaii (Williams, 1946), and Niihau (Fu11away, 1946). In the Hawaiian Islands g. umbrico1a is a well-known serious de­ foliator of the monkey pod tree, Samanea saman (Jacq.) Merrill (Figure 2). In recent years, this tree has considerably gained in economic importance due to its tough and 1ight- and dark-colored wood which has become very popular for hand-carving platters and bowls (Neal, 1948). The :~rge influx of tourists to Hawaii has helped to identify these carvings as exclusively Hawaiian products. The demand for the wood exceeds the supply to such an extent that monkey pod wood is now imported from Fiji.