TROPICAL HOST PLANT-INSECT RELATIONSHIPS AS GUIDES TO MEDICINALLY-ACTIVE PLANTS Julie Elizabeth Helson Department of Plant Science - NEO option Mc Gill University, Montreal Submitted August, 2005 A thesis submitted to McGill University in partial fulfilment of the requirements of the degree of Masters of Science © Julie Elizabeth Helson, 2005 Library and Bibliothèque et 1+1 Archives Canada Archives Canada Published Heritage Direction du Branch Patrimoine de l'édition 395 Wellington Street 395, rue Wellington Ottawa ON K1A ON4 Ottawa ON K1A ON4 Canada Canada Your file Votre référence ISBN: 978-0-494-24692-4 Our file Notre référence ISBN: 978-0-494-24692-4 NOTICE: AVIS: The author has granted a non­ L'auteur a accordé une licence non exclusive exclusive license allowing Library permettant à la Bibliothèque et Archives and Archives Canada to reproduce, Canada de reproduire, publier, archiver, publish, archive, preserve, conserve, sauvegarder, conserver, transmettre au public communicate to the public by par télécommunication ou par l'Internet, prêter, telecommunication or on the Internet, distribuer et vendre des thèses partout dans loan, distribute and sell th es es le monde, à des fins commerciales ou autres, worldwide, for commercial or non­ sur support microforme, papier, électronique commercial purposes, in microform, et/ou autres formats. paper, electronic and/or any other formats. The author retains copyright L'auteur conserve la propriété du droit d'auteur ownership and moral rights in et des droits moraux qui protège cette thèse. this thesis. Neither the thesis Ni la thèse ni des extraits substantiels de nor substantial extracts from it celle-ci ne doivent être imprimés ou autrement may be printed or otherwise reproduits sans son autorisation. reproduced without the author's permission. ln compliance with the Canadian Conformément à la loi canadienne Privacy Act some supporting sur la protection de la vie privée, forms may have been removed quelques formulaires secondaires from this thesis. ont été enlevés de cette thèse. While these forms may be included Bien que ces formulaires in the document page count, aient inclus dans la pagination, their removal does not represent il n'y aura aucun contenu manquant. any loss of content from the thesis. ••• Canada 2 ABSTRACT Previous studies have shown that: (1) plant defensive compounds may have medicinal properties; and (2) defensive compounds present in aposematic insects are often sequestered from their host-plantes). This study addresses whether aposematic insects can be used as guides to detect plants containing medicinally-active compounds. First, ten tropical medicinally-active plants and ten non-active plants, selected using previous ICBG bioassay results, were observed regularly to determine their insect populations. Aposematic insects were found more frequently on active than non-active plants (X2=8.l67, P=O.Ol). Second, three aposematic insects feeding on Tithonia diversifolia were examined chemically to determine the fate of the plant's pharmaceutically-active compounds. They were not found to sequester or excrete these compounds. Therefore, using aposematic insects could increase the likelihood of finding plants with medicinally-active compounds; however, these insects may not necessarily utilize these compounds for defensive purposes. The underlying basis for this significant association between aposematic insects and medicinally-active plants requires further investigation. 3 RESUMÉ Des études précédentes ont montré que: (1) certains composés défensifs utilisés par les plantes peuvent également avoir des propriétés médicinales; et (2) les composés défensifs présents chez les insectes aposématiques sont souvent séquestrés de leur plantees) hôte(s). Cette étude évalue si les insectes aposématiques peuvent être utilisés comme indices pour la détection de plantes contenant des substances potentiellement actives médicinalement. Premièrement, dix plantes panaméennes médicinalement actives et dix plantes médicinalement inactives ont été observées régulièrement afin de caractériser leur population d'insectes. Des insectes aposématiques ont été trouvés plus fréquemment sur les plantes médicinalement actives qu'inactives (X2=8.l67, P=O.Ol). Deuxièmement, trois èspeces d'insectes aposématiques se nourisssant sur Tithonia diversifolia ont été examinés chimiquement afin de déterminer s'il séquestrent les composés actifs de la plante. Ils ne séquestrent ni n'excrètent pas ces composés. L'utilisation d'insectes aposématiques pourrait donc augmenter la probabilité de trouver des plantes avec des composés médicinalement actifs; cependant, ces insectes n'utiliseraient pas nécessairement ces composés pour leur défense. Les causes sous-jacentes de l'association significative entre les insects aposématiques et les plantes médicinalement actives requièrent des recherches plus approfondies. 4 ACKNOWLEDGEMENTS l thank my supervisors Todd Capson and Tim Johns for guidance and suggestions during the design of the study and subsequent analysis of the data. l also thank my supervisors for help during the editing process. l also thank my supervisor Todd Capson for finanical support for the fieldwork portion ofmy study, as weIl as for access to materials, equipment, and facilities for performing the laboratory experiments. l thank Jacquie Bede who served on my thesis advisory committee and provided me with many helpful comments on my thesis. l thank Nilka Tejeria for administrative support at STRI, Erika Garibaldo, and Maria HelIer for administrative and technical support at STRI and within the ICBG, and Carolyn Bowes for administrative support from the department of Plant Science at McGill. l thank Donald Windsor, Annette AieIlo, Henry StockweIl, and Fred Vend for their comments concerning my study, for sharing with me their knowledge on insect ecology, for providing me with information regarding the collection, rearing, and mounting of insects, as weIl as for help with the identification of numerous insect species. l thank Jason Hall and Matthew Barnes for help with Lepidoptera identifications. l thank Rafael Aizprua for helping me locate aIl of my study plants, accompanying me in the field, as weIl as for helping me with plant identifications and voucher specimens. l thank Irma Alvarez for advice on making voucher specimens. l thank Johant Lakey, Carlos Rios, and Carlos Jimenez for aIl the instructions and assistance in the chemistry labo l also thank them for helping me determine which chemical procedures and chemical conditions should be used for analyzing my samples. l thank Johant Lakey for the instructions and assistance on HPLC techniques and helping me determine what chemical conditions should be used to run my samples. l thank Roger Linington for guidance on chemistry techniques. l thank everyone in Luis Cubilla's chemistry laboratory at the University of Panama for technical support. l thank the laboratories of Eduardo Ortega and Luz Romero for running the disease bioassays. l am extremely grateful to Erick Sarmiento for assistance and for accompanying me in the field. 5 1 am extremely grateful to Blair Helson and Susan Helson for their constant support and helping to revise my thesis. 1 thank Oscar Puebla for helping with the translation of my abstract to French. 1 thank Oscar Gabriel Lopez Chong for the help collecting insects in the field. 1 am extremely grateful to Catherine Potvin, the NEO students, and the ICBG members. This project was supported financially by a NSERC PGS-A scholarship, as well as a Levinson Fellowship from the NEO Program. 6 TABLE OF CONTENTS ABSTRACT ......................................................................................... 2 RESUMÉ ............................................................................................. 3 ACKNOWLEDGEMENTS .......................................................................4 TABLE OF CONTENTS .......................................................................... 6 LIST OF FIGURES ................................................................................. 7 LIST OF TABLES .................................................................................. 8 1. INTRODUCTION AND LITERATURE REVIEW .................................. 9 1.1. Introduction .........................................................................9 1.2. Bioprospecting in tropical rainforests ......................................... 10 1.3. Primary and secondary plant metabolism .................................... 11 1.4. Insect-plant relationships ....................................................... 13 1.5. Insects and their use of plant secondary metabolites ........................ 14 1.6. Aposematic and other mechanisms to display unpalatability .............. 16 1.7. Improving the bioprospecting process ........................................ 18 1.8. Previous studies on aposematic insects and medicinally-active plants ... .21 1.9. Relevance to science, health, and conservation ............................. .21 1.10. Introduction to the chapters ..................................................... .23 2. CHAPTER 1 ................................................................................ 25 ABSTRACT ................................................................................ 26 2.1. Introduction .......................................................................... 27 2.2. Methods .............................................................................. 30 2.3. Results ...............................................................................