Anopheles Gambiae (Diptera: Culicidae), When Confronted with an Unobtainable Blood-Host, Is of Interest for Vector Control Strategies
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Energy-State Dependent Responses of Anopheles gambiae to an unobtainable host by Simon P. W. Zappia B.Sc., University of British Columbia, 2008 Thesis Submitted in Partial Fulfillment of the Requirements for the Degree of Master of Science in the Department of Biological Sciences Faculty of Science Simon P. W. Zappia 2011 SIMON FRASER UNIVERSITY Fall 2011 All rights reserved. However, in accordance with the Copyright Act of Canada, this work may be reproduced, without authorization, under the conditions for “Fair Dealing.” Therefore, limited reproduction of this work for the purposes of private study, research, criticism, review and news reporting is likely to be in accordance with the law, particularly if cited appropriately. Approval Name: Simon P. W. Zappia Degree: Master of Science Title of Thesis: Energy-State Dependent Responses of Anopheles gambiae to an unobtainable host. Examining Committee: Chair: Dr. Francis Law, Professor Dr. Bernard Roitberg Senior Supervisor Professor Dr. Gerhard Gries Supervisor Professor Dr. Martin Adamson External Examiner Professor, Department of Zoology University of British Columbia Date Defended/Approved: November 25, 2011 ii Declaration of Partial Copyright Licence The author, whose copyright is declared on the title page of this work, has granted to Simon Fraser University the right to lend this thesis, project or extended essay to users of the Simon Fraser University Library, and to make partial or single copies only for such users or in response to a request from the library of any other university, or other educational institution, on its own behalf or for one of its users. The author has further granted permission to Simon Fraser University to keep or make a digital copy for use in its circulating collection (currently available to the public at the “Institutional Repository” link of the SFU Library website <www.lib.sfu.ca> at: <http://ir.lib.sfu.ca/handle/1892/112>) and, without changing the content, to translate the thesis/project or extended essays, if technically possible, to any medium or format for the purpose of preservation of the digital work. The author has further agreed that permission for multiple copying of this work for scholarly purposes may be granted by either the author or the Dean of Graduate Studies. It is understood that copying or publication of this work for financial gain shall not be allowed without the author’s written permission. Permission for public performance, or limited permission for private scholarly use, of any multimedia materials forming part of this work, may have been granted by the author. This information may be found on the separately catalogued multimedia material and in the signed Partial Copyright Licence. While licensing SFU to permit the above uses, the author retains copyright in the thesis, project or extended essays, including the right to change the work for subsequent purposes, including editing and publishing the work in whole or in part, and licensing other parties, as the author may desire. The original Partial Copyright Licence attesting to these terms, and signed by this author, may be found in the original bound copy of this work, retained in the Simon Fraser University Archive. Simon Fraser University Library Burnaby, BC, Canada Last revision: Spring 09 Abstract Understanding how blood-seeking behavior changes with different energy levels in the malaria mosquito Anopheles gambiae (Diptera: Culicidae), when confronted with an unobtainable blood-host, is of interest for vector control strategies. I used a straight-tube olfactometer to mimic a domicile containing (i) a simulated blood-host (human foot smell) protected by either a plain bednet or a DEET impregnated net and (ii) a sugar source (honey scent) some distance away. I manipulated the mosquito’s energy level by withholding sugar sources from females for different lengths of time. Whenever DEET was present, virtually no mosquitoes interacted with the blood-host scent at any energy level. Yet, energy levels influenced response to foot odour, probing persistence, residence time when DEET was not present. This suggests that control strategies using mosquito repellents can ignore the presence of alternative food sources (such as sugar) in the field unless the chemical efficacy is not retained over time. Keywords: Anopheles gambiae, Energy state, DEET, Malaria, Foraging theory. iii Dedication To my parents, who have never questioned my choice of higher education and pursuit of a career in science. iv Acknowledgements I would like to sincerely thank my senior supervisor Dr. Roitberg. His unconditional support and dedication towards his grad students allowed me to overcome the challenges I encountered throughout this period of my life both inside and outside the university walls. I will certainly miss his manners, hands-off approach, trust and kindness. You always made me feel welcome. Thank you for believing in me Bernie, I owe you everything in this thesis and more. For scientific technical support, knowledge, development of methods and counselling I would like to thank my supervisor Dr. Gerhard Gries and his wife Regine Gries, without whom most of this work could never have been done. Their expertise in chemical ecology helped me in the design of the experiments as well as the interpretation of the data. Thank you for believing in me. Many thanks to Dr. Martin Adamson, whose 4th year parasitology course opened my eyes to a fascinating hidden world. You inspired my career choice. Thanks to Dr. David Gillespie for insightful help in the design of the olfactometer. Also, many thanks to Dr. Erika Plettner and two of her post-docs, Dr. Hao Chen and Dr. Yang Yu, for their involvement and help in chemical preparation and assessment. Thanks to my many volunteers, Karen Mok, Mika Philips, Amber Richmond and Rebecca Wiltshire for spending countless hours in a dark, hot, humid, loud, smelly, mosquito filled chamber with minimal complaints. Special thanks to Amber Gigi Hoi who has been my guardian angel for over two years, being involved in every step of this thesis. Finally, many thanks to the numerous characters in the Roitberg lab. Particularly, due to their involvement in my project, thanks to Dr. Brian Ma, Alex Chubaty and Conan Phelan. v Table of Contents Approval .......................................................................................................................... ii Abstract .......................................................................................................................... iii Dedication ...................................................................................................................... iv Acknowledgements ......................................................................................................... v Table of Contents ........................................................................................................... vi List of Figures................................................................................................................ viii Chapter 1: Introduction ................................................................................................. 1 Energy budgeting in insects ............................................................................................ 1 Life cycle of Anopheles gambiae ..................................................................................... 2 Malaria ............................................................................................................................ 4 My questions ................................................................................................................... 5 List of References ........................................................................................................... 7 Chapter 2: Energy-State Dependent Responses of Anopheles gambiae (Diptera: Culicidae) to Simulated Bednet-Protected Hosts. ............................ 12 Abstract ......................................................................................................................... 12 Introduction ................................................................................................................... 13 Materials and Methods .................................................................................................. 15 Colony .................................................................................................................. 15 Experimental Apparatus ....................................................................................... 16 Experimental Procedure ....................................................................................... 17 Data Analysis ....................................................................................................... 18 Results .......................................................................................................................... 18 Discussion ..................................................................................................................... 20 Acknowledgements ....................................................................................................... 23 Figures .......................................................................................................................... 24 List of References ......................................................................................................... 30 Chapter 3: Anopheles gambiae (Diptera: Culicidae) responses