UNIVERSITY OF HAWAI'I LIBRARY NON-TARGET IMPACTS OF INTRODUCED PARASITOIDS AND VALIDA T10N OF PROBABILITISC RISK ASSESSMENT FOR BIOLOGICAL CONTROL INTRODUCTIONS A DISSERTATION SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HA WAr I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHYLOSOPHY IN ENTOMOLOGY MAY 2008 By Leyla Valdivia Kaufman Dissertation committee: Mark Wright, Chairperson Russell Messing Tracy Johnson Peter Follett Lloyd Loope We certify that we have read this dissertation and that, in our opinion, it is satisfactory in scope and quality as a dissertation for the degree of Doctor of Philosophy in Entomology DISSERTATION COMMITTEE ii © Copyright 2008 by Leyla Valdivia Kaufman iii ACKNOWLEDMENTS Over the past five years that I worked on my Ph.D. project, many people and organizations have helped me achieve my goal. First of all, I would like to thank the T­ STAR program for funding this project. I would like to express my sincere gratitude to my major advisor, Mark Wright for all his help in many different aspects. Thanks for being always available not only to provide professional support but also moral support and for always encouraging me when I went through difficult times. Your guidance and friendship has made me grow not only professionally but personally. I would also like to thank my committee members. Russell Messing, Peter Follett, Tracy Johnson and Lloyd Loope for helping me find field sites, proving space to keep my Mamaki plants and for the helpful suggestions and comments to improve early versions of the written document. Many people assisted me when conducting field work. Alexandra Shibata, Tatiana Almeida, Kathrin Huelck, Jaco Le Roux, William Haines, Adam Vorsino, Derek Kabasawa, Koen Van Elsen, Jennifer Schriber, Elsie Burbano, Joselito Diez, Porter Miller, your help made the work enjoyable and safer. I can't imagine the lab and field work without Clesson Higashi, Sasha Grant and Thomas Winkler, my student help. I appreciate your assistance maintaining the insect colonies and the plants always in great shape and for your patience and diligence when we had to go through painful tasks such as measuring head capsule widths! I want to express my gratitude to the staff at The Nature Conservancy of Hawaii Oahu branch and Molokai branch, for allowing me to access some sites and for all your iv assistance. Also, appreciation to the Department of Land and Natural Resources for issuing colleting permits. Research is impossible without assistance from the secretaries. Linda, Lydia and Cori, I appreciate your help with travel arrangements, rushing purchase orders, etc. in order to be able to conduct my work. During this time many special people crossed my path, made my life happier and gave me friendship and support. Special thanks to Ania Wieckzorek, Alexandra Shibata, Tatiana Almeida, Ethel Villalobos, Jaco Le Roux, Roshan Manandhar and Koon-Hui Wang. I want to thank my family and friends in Peru for all they mean to me. My parents Rosa and Antonio, thanks for your love. I never felt lonely; you always managed to be so near me even though we were physically so far. Thank you for always encouraging me to pursue my goals, even when that meant going away from you. Finally I want to thank Andrew Ka,liinan, my partner in life; your love and support help me tremendously. Thanks for always being there for me and for helping me find ways to balance life. v ABSTRACT This dissertation addressed non-target parasitism of the endemic Hawaiian moth Udea stellata (Butler) and validated a probabilistic risk assessment approach for biological control introductions. Udea stellata is distributed across a wide gradient of environmental conditions, which allowed an assessment of non-target effects under a range of ecological conditions. Seven parasitoid species were associated with U. stellata larvae. Trathala flavoorbitalis, Casinaria infesta and Triclistus nr. aitkeni are of adventive origin; Cotesia marginiventris and Meteorus /aphygmae were purposely introduced to Hawaii; and Diadegma blackburni and Pristomerus howaiiemis are of unknown origin. Field surveys and partial life table studies were conducted to assess apparent mortality and marginal attack rate, respectively. Field surveys oflarvae were conducted at eight different sites throughout the Hawaiian Islands, parasitism rates by individual parasitoid species varied significantly among study sites of varying ecological conditions. Adventive parasitoids rather than purposely introduced ones were responsible for the majority of U. stellata apparent mortality. Results from the life table studies showed that predation) was the major larval mortality factor at all study sites and that parasitism contributed minimally to total morta1ity. The two purposely introduced parasitoids were present at high altitude, in relatively undisturbed sites. Multivariate analyses were used to detect patterns in species assemblage among sites. Udea stellata density, elevation, and level of habitat disturbance significantly explained variability in the parasitoid assemblage among sites. Most species increased in vi abundance with higher densities of U. stellata and some were restricted to less disturbed sites. By comparing the use of single point estimates versus probability distributions in quantitative risk assessment modelling, it was demonstrated that the use of point estimates can hide important variability and significantly impact the estimates of risk. It was also demonstrated that, at least in this study system, the use of apparent mortality significantly increased the estimate of risk compared to the use of marginal attack rate. vii TABLE OF CONTENTS ACKNOWLEDGEMENTS ..................................................................... .iv ABSTRACT ........................................................................................vi LIST OF TABLES ..................................................................................xiv LIST OF FIGURES ................................................................................xvi GENERAL INTRODUCTION AND DISSERTATION STRUCTURE .................. 1 Invasive species and control methods .................................................. 1 History of biological control. ........................................................... 2 Non-target effects ofbiologica1 contro!... .............................................. 3 Hawaii and non-target effects ofbiologica1 control.. ................................ 4 Retrospective studies and risk assessment .............................................4 Aims of this dissertation ................................................................. 6 The study system ..........................................................................6 Outline of the dissertation ............................................................... 7 CHAPTER 1: LIFE HISTORY, SEASONAL PHENOLOGY AND PARASmSM OF THE HAWAIIAN ENDEMIC MOTH UDEA STELLATA (LEPIDOPTERA: CRAMBIDAE) .................................................................................... 9 Abstract .................................................................................... 9 Introduction ................................................................................ 10 Materials and Methods ................................................................... 12 Host plants ........................................................................ 12 Sampling sites .................................................................... 27 Udea stellata life history ........................................................14 viii Udea stellata seasonal phenology ............................................. 15 Larval parasitism ................................................................. 16 Statistical analysis ...................................................... 17 Resuits ...................................................................................... 17 Udea stellata larval stages ...................................................... 17 Description of developmental biology ........................................ 17 Udea stellata larval phenology and frequency of encounter ............... 18 Larval parasitism ................................................................. 20 Discussion ................................................................................. 21 CHAPTER 2: PARASmSM OF THE HA WAllAN ENDEMIC MOTH UDEA STELLATA (LEPIDOPTERA: CRAMBIDAE) BY INVASIVE AND PURPOSELY INJRODUCED HYMENOPTERA SPECIES ................................................ 35 Abstract .................................................................................... 35 Introduction ................................................................................ 36 Materials and Methods ................................................................... 40 Study system ...................................................................... 40 Study sites ........................................................................ 41 Sampling and rearing methods .................................................42 Data Analysis .....................................................................43 Results ...................................................................................... 44 Parasitism by species and by larval stage .................................... 44 Parasitism by sites .............................................................. .45 Discussion ................................................................................