ECOPHYSIOLOGY AND LIFE HISTORY theslug, of history Ecophysiology andlife OF THE SLUG, ARION LUSITANICUS ECOPHYSIOLOGY AND LIFE HISTORY The slug Arion lusitanicus is an invasive species which has recently become established in many European countries OF THE SLUG, ARION LUSITANICUS and is considered a serious pest, both in agriculture and private gardens. The aim of this PhD was to describe in PhD thesis 2012 detail the ecophysiology of A. lusitanicus and map its life Stine Slotsbo history traits in order to reveal how life history traits respond to major environmental parameters such as temperature and moisture. Knowledge of the species’ biology is neces- sary to generate eff ective pest management plans. AU AARHUS This PhD project contributes with detailed knowledge of UNIVERSTY the ecophysiology and life history traits of A. lusitanicus. A growth model that enables the prediction of individual slug growth under natural temperature scenarios has been de- veloped. The project has shown how egg developmental time and hatchability are infl uenced by temperature and Arion drought. Furthermore, the cold and drought tolerance limits of A. lusitanicus have been revealed. The results will be a valuable contribution to the development of population lusitanicus growth models to provide a more accurate forecasting of slug abundance as a tool for pest management. ISBN: 978-87-92825-xx-x ECOPHYSIOLOGY AND LIFE HISTORY OF THE SLUG, ARION LUSITANICUS PhD thesis 2012 Stine Slotsbo AARHUS AU UNIVERSITY Data sheet Title: Ecophysiology and life history of the slug, Arion lusitanicus Subtitle: PhD thesis Author: Stine Slotsbo Institute: Department of Agroecology and Department of Bioscience, Aarhus University Publisher: Aarhus University - Denmark URL: http://www.dmu.au.dk Year of publication: 2012 Editing completed: July 2012 PhD supervisors: Professor Martin Holmstrup, Aarhus University, Department of Bioscience Senior Scientist Lars Monrad Hansen, Aarhus University, Department of Agroecology Assessment committee: Professor Hans Ramløv, Department of Science, Systems and Models, Roskilde University, Denmark Professor William O.C. Symondson, Cardiff School of Biosciences, Cardiff University, UK Senior Scientist Niels Holst (chairman), Aarhus University, Department of Agroecology, Denmark Please cite as: Slotsbo, S. 2012. Ecophysiology and life history of the slug, Arion lusitanicus. PhD thesis. Aarhus University, Department of Agroecology, Denmark. 80 pp. Reproduction permitted provided the source is explicitly acknowledged Abstract: The slug Arion lusitanicus is an invasive species which has recently become established in many European countries and is considered a serious pest, both in agriculture and private gardens. The aim of this PhD was to describe in detail the ecophysiology of A. lusitanicus and map its life history traits in order to reveal how life history traits respond to major envi- ronmental parameters such as temperature and moisture. Knowledge of the species’ bio- logy is necessary to generate eff ective pest management plans. This PhD project contributes with detailed knowledge of the ecophysiology and life history traits of A. lusitanicus. A growth model that enables the prediction of individual slug growth under natural temperature scenarios has been developed. The project has shown how egg developmental time and hatchability are infl uenced by temperature and drought. Fur- thermore, the cold and drought tolerance limits of A. lusitanicus have been revealed. The results will be a valuable contribution to the development of population growth models to provide a more accurate forecasting of slug abundance as a tool for pest management. Keywords: Arion lusitanicus, Iberian slug, slug, growth, growth model, freeze tolerance, supercooling, drought, desiccation stress, water conductance, invasive species Layout: Tinna Christensen Cover photo: Arion lusitanicus. Photo: Stine Slotsbo. ISBN: 978-87-92825-xx-x Number of pages: 80 Printed by: Rosendahls – Schultz Grafi sk a/s Circulation: xx Supplementary notes: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx. Time: xxxxxxxxxxxxxxxxxxxxxx Place: xxxxxxxxxxxxxxxxxxxxxxx Content Preface 5 English summary 6 Dansk resumé 7 REVIEW 9 Abstract 10 Introduction 11 Classifi cation and identifi cation 12 Life history traits 13 Cold tolerance of Arion lusitanicus 19 Drought tolerance of Arion lusitanicus 24 Conclusion and perspectives 27 References 29 PAPER I 35 The infl uence of temperature on life history traits in the Iberian slug, Arion lusitanicus PAPER II 51 Low temperature survival in diff erent life stages of the Iberian slug, Arion lusitanicus PAPER III 59 Cold tolerance and freeze-induced glucose accumulation in three terrestrial slugs PAPER IV 69 Drought tolerance in eggs and juveniles of the Iberian slug, Arion lusitanicus Arion lusitanicus. Photo: Stine Slotsbo. Preface This PhD thesis was submitted to the Graduate School of Science and Technology (GSST), Aarhus University, Denmark. Most of the work has been conducted at the Department of Bioscience, Silkeborg, Aarhus University, Denmark. The project was funded by the Department of Agroecology, Flakkebjerg, and the Department of Bioscience, Silkeborg, Aarhus University, Denmark. The objective of this PhD was to describe in detail the ecophysiology of A. lusitanicus and map its life history traits in order to reveal how life history traits respond to major environmental parameters such as temperature and moisture. I would like to thank several people, who have contributed to the completion of this project. First of all, sincere thanks to my two supervisors Martin Holmstrup and Lars Monrad Hansen for your supervision, guidance and great support both sci- entifi cally and personally. Thanks Martin for always being there when needed, and for your critical review of this thesis. Thanks to all my colleagues at Biosci- ence Silkeborg for providing an inspiring research community, for unsurpassed technical assistance, and lots of fun. A very special thank you to Dorthe Waagner, Jesper Givskov Sørensen and Karina V. Fisker for sparring, invaluable discussions and many hours of fun. I would also like to thank my former colleagues Kristine Maraldo, Anne Mette Bindelsbøl, Lars-Henrik Heckman and Vibeke Simonsen. During my stay at the University of Antwerp, Kurt Jordaens introduced me to spe- cies identifi cation of slugs. A special thank you goes to Kurt for always being there with help and guidance, only an email away. I would also like to thank Bjørn Hat- teland and Torstein Solhøj for an inspiring and pleasant stay at the University of Bergen, not to mention Anders Malmendal and Thierry Backeljau for invaluable co-operation. I am grateful to Vagn and Gerda Nielsen for the many interesting photos of A. lusitanicus, and for letting me use their garden for fi eld work. Also thanks to Sussi Pagh for many useful and fun hours in the fi eld. Several other people have helped - I appreciate all your eff orts. Last, but not least, I thank my friends and family for their support and encourage- ment. Especially my husband Mads for caring and support, particularly during my travels. Stine Slotsbo PhD thesis by Stine Slotsbo 5 English summary The slug Arion lusitanicus is an invasive species which has recently become es- tablished in many European countries and is considered a serious pest, both in agriculture and private gardens. The aim of this PhD was to describe in detail the ecophysiology of A. lusitanicus and map its life history traits in order to reveal how life history traits respond to major environmental parameters such as temperature and moisture. Knowledge of the species’ biology is necessary to generate eff ec- tive pest management plans. This PhD project contributes with detailed knowledge of the ecophysiology and life history traits of A. lusitanicus. A growth model that enables the prediction of individual slug growth under natural temperature scenarios has been developed. The project has shown how egg developmental time and hatchability are infl u- enced by temperature and drought. Furthermore, the cold and drought tolerance limits of A. lusitanicus have been revealed. The results will be a valuable contribu- tion to the development of population growth models to provide a more accurate forecasting of slug abundance as a tool for pest management. 6 PhD thesis by Stine Slotsbo Dansk resumé Sneglen Arion lusitanicus er en invasiv art, der for nylig har etableret sig i mange Europæiske lande, hvor den anses for at være et alvorligt skadedyr både i land- bruget og i private haver. Formålet med dette PhD projekt var at beskrive Arion lusitanicus’s økofysiologi i detaljer, samt kortlægge dens livshistorietræk, og hvor- dan disse påvirkes af miljøparametre såsom temperatur og fugtighed. For at være i stand til at udvikle en eff ektiv skadedyrsbekæmpelse er det nødvendigt at have et godt kendskab til artens biologi. Denne PhD bidrager med detaljeret viden om A. lusitanicus´s økofysiologi samt livshistorietræk. En vækstmodel, der kan forudsige den enkelte snegls vækst un- der naturlige temperaturscenarier, er blevet udviklet. Desuden har projektet vist, hvordan ægudviklingen og ægs klækkeevne påvirkes af temperatur og tørke, og fastlagt kulde- og tørkegrænseværdierne for A. lusitanicus. Dette PhD projekt bi- drager med vigtig viden til udviklingen af populationsvækstmodeller og progno- seværktøjer. PhD thesis by Stine Slotsbo 7 REVIEW Mating. Photo: Vagn Nielsen. PhD thesis by Stine Slotsbo 9 Abstract The slug Arion lusitanicus is an invasive species which has recently become