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SOIL DISPLACEMENT DURING TUNNEL EXCAVATION by the FORMOSAN SUBTERRANEAN TERMITE, Coptotermes Formosanus Shiraki (ISOPTERA: RHINOTERMITIDAE)

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SOIL DISPLACEMENT DURING TUNNEL EXCAVATION by the FORMOSAN SUBTERRANEAN TERMITE, Coptotermes Formosanus Shiraki (ISOPTERA: RHINOTERMITIDAE) SOIL DISPLACEMENT DURING TUNNEL EXCAVATION BY THE FORMOSAN SUBTERRANEAN TERMITE, Coptotermes formosanus Shiraki (ISOPTERA: RHINOTERMITIDAE) By HOU-FENG LI A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2006 Copyright 2006 by Hou-Feng Li To Dr. How-Jing Lee, who led me into the world of entomology. ACKNOWLEDGMENTS I acknowledge and thank Dr. Nan-Yao Su for guiding me on the scientific road with clear direction. He offered an environment that allowed me to concentrate on cultivating a scientific mind, and provided the funds for researching and living. I would like to thank Dr. William H. Kern, Jr. who taught five good courses that gave me the fundamental knowledge needed for research. He always encouraged me, and I learned how to be a good instructor by observing his instruction. I also would like to acknowledge my committee members, Dr. Rudolf Scheffrahn and Dr. Samira Daroub, for all of their help and for reviewing my thesis. I would like to thank my lab partners for helping me with my research. Dr. Lee Sang-Hee, Dr. Paul Bardunias and Thomas Chouvenc discussed my experiments with me. Ron Pepin created excellent equipment for my experiments. Paul Ban taught me the practical knowledge for termite research and collected termites for my experiments. Ericka Helmick and Sandy Koi taught me to use English in proper ways. Finally, I would like to thank my parents and brother for their support of my wholehearted concentration on entomological research. Rou-Ling supports me with statistical and entomological expertise and shares with me when I am in distress. iv TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................................................................................. iv LIST OF TABLES............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii ABSTRACT....................................................................................................................... ix CHAPTER 1 STRUCTURE AND FUNCTION OF WORKER MOUTHPARTS............................1 Materials and Methods .................................................................................................1 Termite ..................................................................................................................1 Dissecting Mouthparts...........................................................................................1 Experimental Arena...............................................................................................1 Measurement of Capacity of Buccal Cavity..........................................................2 Results and Discussion .................................................................................................2 Structure of Mouthparts.........................................................................................2 Labrum and clypeus .......................................................................................2 Mandibles.......................................................................................................3 Maxillae..........................................................................................................3 Labium ...........................................................................................................3 Movement of Mouthparts......................................................................................4 Tunneling behavior ........................................................................................4 Stuffing behavior and the capacity of buccal cavity ......................................4 Releasing behavior .........................................................................................4 2 DO FORMOSAN SUBTERRANEAN TERMITES COMPACT SAND PARTICLES DURING EXCAVATION OF TUNNELS? ..........................................9 The First Hypothesis: Pushing Soil ..............................................................................9 Materials and Methods ........................................................................................10 Experimental arena.......................................................................................10 Experimental process ...................................................................................10 Analysis........................................................................................................11 Results and Discussion........................................................................................11 The Second Hypothesis: Removing and Then Compacting Soil................................11 v Materials and Methods ........................................................................................12 Experimental arena.......................................................................................12 Experimental process ...................................................................................12 Variable: sand density ..................................................................................12 Variable: available space..............................................................................14 Analysis........................................................................................................14 Results .................................................................................................................14 Discussion............................................................................................................16 Soil density and digging behavior................................................................16 Population density and depositing sand behavior ........................................17 Mechanism to increase space .......................................................................18 Body size and digging strategies of fossorial animals .................................18 3 AVAILABLE SPACE AND WOOD CONSUMPTION...........................................30 Introduction.................................................................................................................30 Materials and Methods ...............................................................................................30 Experimental Process ..........................................................................................30 Decreased Weight and Volume of Wood............................................................31 Biomass Production and Survival Rate ...............................................................31 Volume and Dry Weight of Carton Material.......................................................32 Metabolic Gas......................................................................................................32 Analysis ...............................................................................................................32 Results.........................................................................................................................32 Wood Weight and Volume Loss .........................................................................32 Biomass Production and Survival Rate ...............................................................33 Volume and Dry Weight of Carton Material.......................................................33 Metabolic Gas......................................................................................................33 Increased Available Space...................................................................................34 Discussion...................................................................................................................34 Mechanisms of Consuming Wood to Increase Available Space.........................34 Space in Gallery System......................................................................................35 Other Available Space in the Ground..................................................................36 4 SUMMARY AND CONCLUSIONS.........................................................................38 LIST OF REFERENCES...................................................................................................40 BIOGRAPHICAL SKETCH .............................................................................................42 vi LIST OF TABLES Table page 3-1 Decreased weight and volume of wood after exposure to Co. formosanus. ............36 3-2 Termites’ average dry weight, biomass production, and survival rate.....................37 3-3 Weight, volume, and density of carton material. .....................................................37 3-4 Percentage of production of consumed wood. .........................................................37 3-5 Volume of increased available space for termites....................................................37 vii LIST OF FIGURES Figure page 1-1 Lateral view of the worker head of Co. formosanus. .................................................5 1-2 Dorsal view of the worker head of Co. formosanus...................................................6 1-3 Dorsal view of the mandibles of a worker of Co. formosanus...................................6 1-4 Lateral view of the left maxilla of a worker of Co. formosanus. ...............................7 1-5 Ventral view of the worker
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