FORAGING AND REPRODUCTIVE PATTERNS F THE HYPERPARASITOID WASP, DE OCERUS CARPENTERI (MEGASPILIDAE) Andrew Chow B.Sc. R.), The University of British Columbia, 1984 4.Sc., Simon Fraser University, 1989 THESI JBMITTED IN PARTIAL FULFILLMENT OF QUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Biological Sciences 0 Andrew Chow 1997 SIMON FRASER UNIVERSITY April 1997 All rights reserved. This work may not be reproduced in whole or in part, by photocopy or other means, without permission of the author. National Library Bibliotheque nationale I*[of Canada du Canada Amuisitions and Acquisitions et Bibliographic ~edices services bibliographiques 395 Wellington Street 395. rue Wellington Ottawa ON KIA ON4 Onawa ON KIA ON4 Canada Canada Your hk Vorre relerence Our hle Norre relerence The author has granted a non- L'auteur a accorde une licence non exclusive licence allowing the exclusive pennettant a la National Library of Canada to Bibliotheque nationale du Canada de reproduce, loan, distribute or sell ' reproduire, preter, hstribuer ou copies of hsthesis in microform, vendre des copies de cette these sous paper or electronic formats. la forme de microfiche/film, de reproduction sur papier ou sur format electronique. The author retains ownership of the L'auteur conserve la propriete du copyright in thesis. Neither the droit d'auteur qui protege cette these. thesis nor substantial extracts from it Ni la these ni des extraits substantiels may be printed or othenvise de celle-ci ne doivent ktre imprimes reproduced without the author's ou autrement reproduits sans son permission. autorisation. APPROVAL Name: ' Andrew Chow # Degree: Doctor of Philosophy . Title of Thesis: $ FORAGING AND REPRODUCTIVE PATTE~NSOF THE HYPERPARASITOID WASP, DENDROCERUS CARPENTEN (MEGASPILIDAE). Exahining Committee: Chair: f~r.L. Dill, Prof&or , Senior Supervisor tees, SFU - Dr. G. Gries. As: date ~roksdr Department of &ogical Scie&ks. SFU Dr. B. Roitberg, Professor Department of Biological Sciences. SFU Dr. A. Harestad, Associate rlofessor Department of Biological Sciences, SFU Public Examiner Dr. j.'~osknheim, Associate Professor Department of Entomology Univ. of California. Davis External Examiner Date Approved: ~/+xr2v- iii ABSTRACT Forag in 9 reproductive behaviour of Dendrocerus carpenteri (Hymenopter zgaspilidae), a solitary hyperparasitoid of aphids, was studied in thc 31-atory using as hosts the pea aphid (Acyrthosiphon pisum) and t: primary hymenopterous parasitoids (Aphidius ervi, Ephedrus cal, icus, and Praon pequodorum). Examination and oviposition ti by females of D. carpen teri varied with the species and the deve ~entalstages of the primary parasitoids within mummified a s; host choice was influenced more by the development lge than by the species of primary parasitoid. Female: >.carpenteri located single or clumped mummies on plants with ec success, but the structure of the plant canopy influenced se ing behaviour and efficiency. When the density of mummies on ~fwas increased, females responded by increasing patch time ar ood size in a density-dependent manner. Giving-up time increase th host density and the decision to leave a patch was apparently ir Iced by re-encounters with self-marked hosts, but not by prior 1 ing experience. Brood sex ratio did not vary with host density. Female D. carpenteri produced non-binomial sex ratios of offspring by i ;ting the sequence of male and female eggs laid during a sing iposition bout. Both the order and type of sequentially tlrLumteredhosts influenced the allocation of offspring sexes. The production schedule of sons and daughters was reset after a period during which no hosts were encountered. Re-encounters with self-marked hosts affected the ratio of male to female eggs laid in broods. Females appear to use simple decision rules to ensure that daughters will find mates regardless of variations in host quality and patch size. Pea aphids containing larvae of A. ervi, A. pisivorus, Monoctonus paulensis, and P. pequodorum remained at their feeding sites. In contrast, those containing immature E. californicus generally dispersed from their colonies prior to mummification; dispersal increased with density but was inhibited in the absence of light. The foraging and reproductive xns of D. carpenteri may have evolved as a result of the physiolog ind behavioural interactions among its host complex. ACKNOWLEDGEMENTS The cor tion of this project would not have been possible without the ; ance of many people. I thank my senior supervisor, Dr. M. Macka or his support, guidance and patience. I also thank both Dr. B. Rc rg and Dr. G. Gries for serving on my supervisory committee ar oviding helpful feedback. Gratitu extended to Dr. H. R. MacCarthy for his encourageme ~d a much appreciated 'writing tune-up' when I was misfiring anc ling. Thanks go to Ms. A. Chau, Dr. J. P. Michaud, Dr. C. Nicol, and Mr. M. Otto fc eir friendship and cooperation during my stay in the lab. I am in( ?d to Mr. R. Long for his outstanding photographic work and Dr. asner for identification of specimens from my hyperparasitc Aonies. Finally, ink my parents for both their love and understanding throughout n ademic trials. v i TABLE OF CONTENTS Approval page ii Abstract iii Acknowledgements v List of Tables viii List of Figures xiii CHAPTER 1. Background to the Research 1 INTRODUCTION 2 GENERAL MATERIALS AND METHODS 13 CHAPTER 2. Effects of Immature Aphidiids on Aphid Behaviour 16 INTRODUCTION 17 METHODS 20 RESULTS 26 DISCUSSION 36 CHAPTER 3. Host Handling and Acceptance by Dendrocerus carpen teri INTRODUCTION OVIPOSITION AND HOST HANDLING BEHAVIOUR OF DENDROCERUS CARPENTER1 vii METHODS RESULTS DISCUSSION CHAPTER 4. Foraging Behaviour of Dendrocerus carpen teri INTRODUCTION MEMODS RESULTS DISCUSSION CHAPTER 5. Progeny and Sex Allocation by Dendrocerus carpen teri INTRODUCTION MEMODS RESULTS DISCUSSION CHAPTER 6. General Discussion and Conclusions REFERENCES viii LIST OF TABLES Table 1. Location of mummified Acyrthosiphon pisum containing immature of one of five species of primary parasitoids. One hundred aphids were confined with six female parasitoids of the same species for 2 h. The aphids were released onto a potted broad-bean plant and kept within a plexi-glass cage at 20 _+ l%, 50 _+ 10 % RH, with continuous light until all parasitized aphids had mummified. All aphids were reared at 20% and 72 _+ 4 h old when exposed to parasitoids. 27 Table 2. Location of mummified Acyrthosiphon pisum containing immature of one of three species of primary parasitoids. Fifty aphids were confined for 2 h with six female Ephedrus californicus and another fifty were confined with six female Aphidius ervi or Monocton us paulensis. The two groups of aphids were combined and released onto a potted broad-bean plant and confined in a plex-glass cage at 20 _+ l%, 50 _+ 10 % RH, with continuous light until all parasitized aphids had mummified. All aphids were reared at 20% and 72 _+ 4 h old when exposed to parasitoids. 28 Table 3. Distribution of parasitized and non-parasitized Acyrthosiphon pisum within the canopy of broad bean plants. Forty aphids (72 _+ 4 h old) were confined in a cup with six female parasitoids of the same species or without parasitoids for 2 h. The aphids were released onto a potted broad-bean plant and kept within a plexi- glass cage at 20 _+ PC,50 _+ 10 % RH, with continuous light and their locations were recorded 96 h later. The aphidiid species used to parasitize aphids were A nhidius ervi and Ewhedrus californicus. 3 1 Table 4. Distribution of mummified Acyrthosiphon pisum containing Aphidius ervi or Ephedrus californicus. Forty aphids (72 _+ 4 h old) were confined in a cup with six female parasitoids of the same species for 2 h. The aphids were released onto a potted broad-bean plant and kept within a plexi-glass cage at 20 _+ PC,50 _+ 10 % RH, with continuous light until all parasitized aphids had mummified. 32 Table 5. Influence of light on the location of mummified Acyrthosiphon pisum containing immature of Ephedrus californicus or Aphidius ervi. One hundred aphids were confined with six female parasitoids of the same species for 2 h. The aphids were released onto a potted broad-bean plant and kept at 20 _+ l%, 50 _+ 10 % RH, with continuous light for 240 h or continuous light for 120 h followed by 120 h without light. All aphids were reared at 20% and 72 _+ 4 h old when exposed to parasitoids. 35 Table 6. Combinations of immature A. end and E. californicus used in preference tests for females of Dendrocerus carpen teri. 47 Table 7. Handling behaviour by females of Dendrocerus carpenteri for mummies of three aphidiid species. A female wasp sequentially handled six mummies, three of each kind of mummy, in each of 10 replicates for each combination of hosts. 53 Table 8. Specificity by females of Dendrocerus carpen teri for larval and pupal stages of Aphidius en4 and Ephedrus / californicus. A female wasp was singly confined for 5 h with thirty mummies of each kind of host in each combination of hosts. 58 Table 9. Handling behaviour of mated and non-mated Dendrocerus carpenteri on Aphidius ervi mummies. Each female was given a mummy containing a 9-day old A. ervi. Female A. ervi were given second-instar pea aphids (72 _+ 4 h) to parasitize and all parasitized aphids were reared on broad bean at 20 _+ PC, 40-60% RH, with continuous lighting. Female D. carpen teri were 6 to 8 days old when used for experiments. 62 Table 10. Hyperparasitism of immature aphidiid wasps by female Dendrocerus carpenteri among different numbers of mummified pea aphids on a broad bean leaf. Hosts were 9-day old Aphidius ervi or 11-day old Ephedrus californicus reared on pea aphid at 20% Only one aphidiid species was used as a host in each trial.