Global Changes and Distribution Modeling of Invasive Insect Pests in the Tropical Andes
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THESIS to obtain the degree of DOCTOR OF PHILOSOPHY OF THE UNIVERSITY PARIS VI – PIERRE ET MARIE CURIE Specialization: DIVERSITY OF THE LIVING WORLD presented by María Verónica CRESPO-PÉREZ Global changes and distribution modeling of invasive insect pests in the Tropical Andes Defended on January 11th 2012 in front of the jury composed by M. Olivier DANGLES, DR, IRD Supervisor Mme. Isabelle CHUINE, DR, CEFE Co-supervisor Mme. Christelle SUPPO, DR. IRBI Rapporteur M. Hervé JACTEL, DR, INRA Rapporteur Mme. Martine MAIBECHE-COISNE, DR, UPMC Examinateur M. Roger ARDITI, DR, INA-PG Examinateur M. Justin TRAVIS, DR. Univ. Aberdeen Examinateur para mi abue Vevita, con todo mi amor ACKNOWLEDGEMENTS First and foremost I would like to express my most sincere gratitude to Olivier Dangles. From the beginning of my career you believed in me and encouraged me to pursuit my studies in ecology. Your love for science and your enthusiasm have motivated me to continue in this path. Thank you for being a guide and true mentor. Also I would like to thank the DEEIT team of the IRD, especially Jean-Francois Silvain, for their hospitality during my stay in Gif and their interest in my work. I would also like to express my thankfulness to Isabelle Chuine for welcoming me into her team at the CEFE, Montpellier. Working with you and your team was a truly enriching learning experience. I am extremely grateful to Jacques Régnière for sharing his knowledge with me on insect phenology modeling and for making my stay in Quebec very productive and fruitful. For his useful advice always accompanied by a great sense of humor and enthusiasm. I am thankful to François Rebaudo for introducing me to cellular automata, for his help during model development and analysis, for sharing his knowledge of R with me and for his hospitality during my time at Gif. Equal thanks go to Rémi Saint Amant for his help developing the phenology model, for always being available when I had questions or problems and for his time and hospitality and for being the best tourist guide I could have asked for in Quebec. My friends at the CEFE Montpellier, Manu, Sylvain, Fred, Tanya, and above all Benedicte, David and Ambalika for opening their home for me and for filling my last months in Montpellier with love, laughter and good times. My friends in Montpellier, especially Elodie Blanchet for her sincere friendship, hospitality, support and good humor and for including me in her busy weekends travelling through France. I am grateful to Catherine and Jean Pohu for receiving me in their home during my time in Gif, filled with good times, delicious food and a little bit of Spanish. 5 The Ormaza family in Paris for always having their doors opened for me, for their support, for making me feel like one of their own and for their constant interest in my work and life during my stay in France, and even afterwards! My friends in Quito and abroad, los entomolocos y los no tanto, for their encouragement, advice, patience and for always believing in me, helping me and rooting for me during rough times. Especial thanks go to Paula Iturralde for her always enthusiastic help with some technical aspects of the PhD and her unconditional friendship, support and loyalty. I am most grateful to my parents for their love, their trust, their patience and for giving me the strength to continue even when I was feeling weakest. My sister and brother for their love and friendship and for always being there with their good humor and advice. My niece, my nephew, my grandmothers, aunts, uncles and cousins for their love and constant support. Last but not least, I want to thank the French Embassy in Quito and the DSF (Département Soutien et Formation des Communautés Scientifiques du Sud) of the IRD for their funding, without which this PhD project would have not been possible. 6 ABSTRACT Physiology, behavior, abundance and distribution of ectotherms, such as insects, are highly influenced by temperature. Knowledge about their responses to temperature allows the development of simulation models that mimic their spatio-temporal dynamics. These constitute important tools for invasive pest management as they allow identification of vulnerable zones and an accurate timing and placement of control measures. In this study we tackled the issue of modeling the spread and distribution of three species of invasive Potato Tuber Moth in the highly heterogeneous North Andean Region. We developed modeling approaches that allowed us to overcome common difficulties associated with modeling invasive dynamics in this region. First, we developed a spatially-explicit cellular automaton that simulated moth spatio-temporal propagation while taking into account the influence of human activity on moth spread. We also developed models capable of accounting for the influence of thermal variation on moth dynamics and of simulating dynamics even when adjusted to small data sets. Finally we developed an individual based model that simulated PTM temperature-related dynamics and was used to construct current and future pest risk maps at the scale of the North Andean Region. This work revealed the importance of both human-induced and environmental heterogeneity as drivers of PTM invasion. Including biotic interactions, as well as more detail in environmental and social heterogeneity constitute interesting perspectives that could enhance the realism and accuracy of future modeling approaches in the region. The methods developed in this thesis could constitute important tools for integrated pest management since they may help to enhance farmers and stakeholders’ understanding of the threats posed by these pests and raise their awareness about the influence of their actions on pests’ invasion dynamics. Key words Agricultural landscapes, cellular automata, climate change, individual based model, invasive pests, North Andean Region, Potato Tuber Moth 7 RESUMÉ CHANGEMENTS GLOBAUX ET MODELISATION DE LA DISTRIBUTION D’INSECTES RAVAGEURS INVASIFS DANS LES ANDES TROPICALES Modélisation de la dynamique des insectes en relation avec la température La physiologie, le comportement, l’abondance et la distribution des êtres vivants sont grandement influencés par leur environnement (Messenger 1959, Angilletta et al. 2010). Dans le cas des organismes ectothermes tels que les insectes, la température constitue un facteur environnemental clé contrôlant leur dynamique. Des études ont montré que ce facteur influence de nombreux aspects de la biologie des insectes depuis les variations temporelles de leur croissance, leur survie et leur reproduction (Angilletta et al. 2002, Savage et al. 2004, Stillwell and Fox 2005, Steigenga and Fischer 2009, Gutiérrez et al. 2010, Opit et al. 2010) jusqu’aux patrons géographiques de la taille de leur corps, de la densité de leurs populations et de la diversité et distribution des différentes espèces (Angilletta et al. 2004, Brown et al. 2004, Hodkinson 2005, Karl et al. 2008, Régnière et al. 2009). La compréhension de l’influence de la température sur la fitness des espèces permet de mieux comprendre la distribution géographique, les fenêtres temporelles d’activités et les interactions compétitives (notion de niches thermiques) des insectes en relation avec la température (Huey and Stevenson 1979). La modélisation écologique de la réponse des insectes à la température est donc une approche courante afin d’analyser et synthétiser au mieux cette information. La réponse des insectes à la température est généralement décrite par des modèles de performance thermique. La performance est définie comme « toute mesure de la capacité d’un organisme à « fonctionner » et est généralement exprimée comme un taux ou une probabilité » (Angilletta 2009). Des mesures usuelles de la performance thermique sont la survie, le développement, la croissance, la fécondité, la locomotion, l’assimilation et le fourragement (Gilchrist 1995, Angilletta 2009). Les modèles de performance thermique consistent en des fonctions mathématiques qui décrivent la relation entre la température et une mesure de la performance des insectes, chaque mesure ayant généralement une fonction mathématique appropriée. Toutefois, dans certains cas, la même mesure de performance peut être décrite à l’aide de plusieurs fonctions différentes. La combinaison de plusieurs modèles décrivant chacun la réponse d’une mesure de performance à la température (p.ex. survie, 8 fécondité, développement) permet la simulation de réponses complexes des organismes à la température (Angilletta 2009). Par exemple, il est possible de simuler la dynamique des populations, la phénologie ou encore la distribution d’un groupe d’individus dans le temps en construisant un modèle intégratif qui inclut les fonction de survie, développement et reproduction de ce groupe en fonction de la température (Buffoni and Pasquali 2010). L’amélioration constante des capacités computationnelles permet la construction de modèles toujours plus complexes à des échelles spatiales et temporelles toujours plus grandes (Logan et al. 2007, Régnière et al. submitted). La plupart des êtres vivants sont confrontés à un environnement hétérogène et fragmenté, ce qui influence grandement la dynamique de leurs populations (Cadotte et al. 2006, Jongejans et al. 2008). Simuler la dispersion des populations dans ce type de paysages ou régions nécessite donc d’inclure une composante spatialement explicite dans les modèles (Sebert-Cuvillier et al. 2008, Vinatier et al. 2011). C’est le cas de nombreux types de modèles tels que les automates cellulaires (CA) (Soons et al. 2005, Herben et al. 2006, Prasad et al. 2010) qui peuvent simuler une dynamique spatiale en intégrant des cartes géographiques, ce qui les rends non seulement spatialement explicites mais également spatialement réalistes (Harris et al. 2009). Ils sont d’un intérêt majeur lorsque l’on cherche à comprendre la dynamique d’une espèce dans un paysage ayant une configuration donnée (Jongejans et al. 2008). Les modèles individus centrés (Goslee et al. 2006, Nehrbass et al. 2007, Harris et al. 2009, Carrasco et al. 2010, Travis et al.