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Differentiation in reproductive potential and chemical communication of reproductive status in workers and queens of the ant Myrmecia gulosa Dissertation zur Erlangung des naturwissenschaftlichen Doktorgrades der Bayerischen Julius-Maximilians-Universität Würzburg vorgelegt von Vincent Dietemann aus Mulhouse Würzburg 2002 Eingereicht am: ....................................................................................................................... Mitglieder der Promotionskommission: Vorsitzender: .......................................................................................................................... Gutachter: .............................................................................................................................. Gutachter: ............................................................................................................................... Tag des Promotionskolloquiums: ............................................................................................. Doktorurkunde ausgehändigt am: ............................................................................................ Acknowledgements I am grateful to Pr. Bert Hölldobler for providing excellent work facilities and for his unconditional support throughout my work. I thank Dr. Christian Peeters to whom I owe my introduction to the world of ants in general and “primitive” ants in particular. The fruitful discussions with him considerably improved my knowledge of ant societies. This thesis is not exclusively the product of my work. I tried to associate several disciplines of science to understand certain aspects of the social organisation of ant societies and I therefore needed help in areas outside my competences, either to compensate for gaps in my knowledge or to help me develop new skills. To this many people contributed: I thank Dr. Graeme Jones and Richard Beard for their determining contribution to the chemical part of my work. All the chemical analyses and compound synthesis on which this study is based are the work of Richard Beard. I am indebted to him for the completion of this Herculean task. Thanks also goes to Pr. Jacobus Boomsma, for his work in coordinating the European Community “Training and Mobility of Researchers” and “Improving Human Potential” networks, which made this cooperation possible. Pr. Abraham Hefetz has shared with me his experience of ant-applied chemistry and I thank him very much for this. It is in histology that Pr. Johan Billen, Dr. Bruno Gobin and Karin Möller shared their knowledge with me, and I am grateful to them. For the same reason, as well as for valuable technical assistance and continuous support, I owe much to Malu Obermaier and I thank her. In an area to which the exercise of scientific activity is unavoidably bound, namely administration, Dr. Volker Neese has been an indispensable guide and master to me. I am indebted to him for his help and availability and thanks go to him. Discussions with Dr. Jürgen Gadau, Dr. Matthias Sanetra, and Virginie Cuvillier-Hot helped me in developing my ideas. Dr. Bruno Gobin, Dr. Thibaud Monnin, and Pr. Diana Wheeler commented on chapters of this thesis and helped improve it. In most of the above-mentioned categories and even more, the name of Dr. J. Liebig should have appeared. To avoid repetition, I express here my deep gratitude to him, for contributing greatly to this thesis. I am grateful to Pr. M.P. Schwarz, Dr. K. Hogendoorn, Dr. R. Leijs, Dr. S. Shattuck and A. McArthur for logistic and technical support as well as hospitality during my fieldwork in Australia. I would also like to thank those many people outside Academia in this country, who offered their help willingly on many occasions and for their kindness. Among these, I particularly acknowledge Russell, warden from the Coutts Camp, Waterfall, New South Wales. Richard Gabriel, Jan Geisendorfer, Arnold Kloos, Annette Laudahn, Dr. Christina Sauer, and Valenska Wenzel fed the ants, allowing me to avoid painful stinging and to occasionally leave the institute. Some of them managed to avoid the stings, some did not, but sincere thanks go to all of them for their help. Gerhard Eisenmann and Helga Heilman provided valuable technical help, I thank them, as well as all the people from the Institute who contributed in various ways to my work. I am indebted to Lalitha Thomas-Oppenländer for revising my English and to Anett Endler for the German translation. I am grateful to Anett, Chrimie, Christof, Christoph, Corinna, Jacqueline, Karl, Klaus, Olav and Walter and many others who contributed to a nice work and extra-work environment during my stay in Würzburg. Je remercie aussi chaleureusement mes parents pout leur soutient indéfectible tout au long de ces années. Last but not least, I thank Virginie for her heroic behaviour and her most precious help. Differentiation in reproductive potential and chemical communication of reproductive status in workers and queens of the ant Myrmecia gulosa I. Introduction..........................................................................................................................1 II. Generalities .........................................................................................................................5 II.A. The genus Myrmecia.............................................................................................5 II.B. Myrmecia gulosa...................................................................................................7 II.C. General methodology ............................................................................................8 II.C.a. Ant collection and laboratory rearing.....................................................8 II.C.b. Chemical analysis...................................................................................9 III. Caste specialisation and divergence in reproductive potential...................................11 III.A. Introduction........................................................................................................11 III.B. Methods..............................................................................................................12 III.C. Results................................................................................................................14 III.C.a. Colony size..........................................................................................14 III.C.b. Queen/worker and worker/worker polymorphism..............................15 III.C.c. Egg-laying activity..............................................................................18 III.C.d. Alternative reproductive strategy: gamergates ...................................23 III.C.e. Morphological aberration: ergatandromorphs.....................................24 III.D. Discussion..........................................................................................................25 IV. Queen pheromones..........................................................................................................33 IV.A. Introduction .......................................................................................................33 IV.B. Queen releaser pheromones: queen recognition and worker aggregation .........36 IV.B.a. Introduction.........................................................................................36 IV.B.b. Perception distance of queens by workers..........................................37 Introduction ...............................................................................37 Methods.....................................................................................37 Results .......................................................................................38 Discussion .................................................................................39 IV.B.c. The retinue ..........................................................................................40 Introduction ...............................................................................40 Methods.....................................................................................40 Results .......................................................................................42 Discussion .................................................................................44 IV.B.d. Source of the queen arrestant pheromone...........................................46 IV.B.d.i. Distribution of the arrestant pheromone on the queen’s body .........................................................46 Introduction ...............................................................................46 Methods.....................................................................................47 Results .......................................................................................47 Discussion .................................................................................48 IV.B.d.ii. The role of the cuticular hydrocarbons (CHCs) ...............50 Introduction ...............................................................................50 Methods.....................................................................................53 Results .......................................................................................56 Discussion .................................................................................65 IV.B.d.iii. The role of major glands .................................................68 Introduction ...............................................................................68