Some factors affecting an ant-membracid mutualism Item Type text; Thesis-Reproduction (electronic) Authors Glass, Judith, 1956- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 04/10/2021 04:41:31 Link to Item http://hdl.handle.net/10150/292031 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. 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SOME FACTORS AFFECTING AN ANT-MEMBRACID MUTUALISM by Judith Glass A Thesis Submitted to the Faculty of the DEPARTMENT OF ENTOMOLOGY In Partial Fulfillment of the Requirements For the Degree of MASTER OF SCIENCE In the Graduate College THE UNIVERSITY OF ARIZONA 19 9 1 2 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of requirements for an advanced degree at the University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgement of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgement the proposed use of material is in the interests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED APPROVAL BY THESIS DIRECTORS This thesis has been approved on the date shown below: "N.A.Jloran Assistant Professor of Ecology and Evolutionary Biology D. Wheeler Assistant Professor of Entomology 3 ACKNOWLEDGEMENTS The author gratefully acknowledges the contributions of the following: Dr. Nancy Moran, Dr. Diana Wheeler and Dr. Judith Bronstein for reviewing this manuscript; Drs. Moran and Wheeler for their wisdom, friendship and constant encouragement; Paula Goldberg for her assistance in every aspect of this study; Mrs. Betty Mitchell for her help in financing this study; Wade Sherbrook and the staff of the Southwest Research Station for allowing me access to their insect collection; Dr. D. Brocious and the staff of the Fred Whipple Observatory for their assistance in setting up study sites on Mt. Hopkins; U.S. Forest Service for permission to set up study sites at Florida Canyon, Montosa Canyon and elsewhere in the Santa Rita Mountains; Kathleen Carleton, Karen Corey, Fran Coleman, Patricia Kane, Pamela Izakowitz, Amy Morgan and Nancy Matteson for their astute questions and for listening with open minds and hearts; Dr Snelling for identifying Mvrmecocvstus spp. Portions of this study were funded by a grant from Sigma Xi and the Teddy Roosevelt Grant from the Museum of Natural History in New York. 4 TABLE OF CONTENTS LIST OF ILLUSTRATIONS 5 LIST OF TABLES 6 ABSTRACT 7 INTRODUCTION 8 CHAPTER 1: A REVIEW OF THE LIFE HISTORIES IN THE FAMILY MEMBRACIDAE 11 CHAPTER 2: LIFE HISTORY OF PUBLILIA MODESTA IN THE SANTA RITA MOUNTAINS; A NEW LIFE HISTORY STORY IN THE MEMBRACIDAE 29 CHAPTER 3: RESPONSES OF INDIVIDUAL MYRMECOCYSTUS MENPAX WORKERS TO A HOMOPTERAN RESOURCE 51 APPENDIX: ORIGINAL PHOTOS FOR FIGURES 3A-E..93 LITERATURE CITED 98 5 LIST OF ILLUSTRATIONS Figure 1: Phenology of Publilia modesta 77 Figure 2: Sticky Trap Data 78 Figures 3a-e: Ovarian Development of Publilia modesta..79 Figures 4a-b: Number of Aggregations and Average Number of Hosts per 180 sq. m. in Florida Canyon 1989...80 Figure 5: Headwidths of Tending Ants 81 Figure 6: Headwidths of Workers 81 Figure 7: Number of Ants per Membracid 1988 82 Figure 8: Number of Ants per Membracid 1989 82 Figure 9: Site Fidelity in Membracid-tending Ants 83 Figure 10: Site Fidelity in Membracid-tending Ants 83 Figure 11: Site Fidelity (experiment type 1) M. mendax from two hosts 9/9/90 84 Figure 12: Site Fidelity (experiment type 1) M. mendax from two hosts 8/17/90 84 Figure 13: Site Fidelity (experiment type 2) M. mendax switched on two hosts 85 Figure 14: Food Preference Test M. mendax 9/2/89 86 Figure 15: Food Preference Test M. mendax 9/9/89 86 Figure 16: Resource Fidelity M. mendax at the nest 9/2/89 87 Figure 17: Resource Fidelity M. mendax at the nest 9/23/89 87 Figure 18: Placement of Baits Around a Mvrmecocvstus mendax Nest Entrance for Resource Fidelity Preference Tests 1989 88 Figure 19: Resource Fidelity Control 9/9/89 89 6 LIST OF TABLES Table 1: Host Choice of Publilia modesta along a Mountain Gradient 90 Table 2: Pronotal color change and the onset of ovarian development 91 Table 3: Resource Fidelity of Membracid-tending and Foraging Mvrmecocvstus mendax 92 7 ABSTRACT Two factors affecting the mutualism between Mvrmecocvstus mendax and Publilia modesta are investigated. These factors are the seasonal time frame during which the mutualism is maintained and the behavior of individual workers tending membracid aggregations. Results of this study show that Publilia modesta makes seasonal migrations via flight, makes use of a conifer as a long term host, mates on a substate distant from a suitable oviposition host, and changes color with the onset of ovarian development many months after metamorphosis. Membracid- tending Mvrmecocvstus mendax comprise a behaviorally distinct subcaste and behave in a manner consistent with optimal foraging theory by maintaining both site and resource fidelity. 8 INTRODUCTION The purpose of this study is to investigate two factors that affect the maintenance of the mutualistic relationship between Mvrmecocvstus mendax. a honeypot ant of the desert southwest, and Publilia modesta. a common western treehopper. These factors are the seasonal time frame in which the two species are engaged in the mutualism and the behavior of individual ants tending membracids. M. mendax. found in Colorado, New Mexico, Texas and Arizona at elevations of 3600'-6600' (Snelling, 1976), is active in the Santa Rita Mountains of southeastern Arizona from mid-April through the end of October. JPj. modesta females can be found on desert annuals, all composite species, beginning in mid-July, and aggregations of nymphs are tended by M^_ mendax from August through early October. M. mendax have been observed tending aphids and scale as early as mid-April. Presumably, if P^_ modesta were present earlier, the mutualism would be maintained throughout the ants' active season. If we assume that ant attendance is beneficial for these membracids, then we must ask why the mutualism is maintained for only a few months each year. Kopp and Yonke (1973b) have stated that little is known of P. modesta other than records of host plants, including a variety of Asteraceae species and mesquite. These authors suggest that like other membracids that feed primarily on 9 herbaceous annuals, P^. modesta is most likely bivoltine. However, Cushman and Whitham (1989) stated that Flagstaff populations of this species are univoltine. It is possible that 1) Pi modesta is univoltine with a diapause period from October to July; 2) Pi modesta is univoltine with seasonal movement of adults to and from the ML. mendax habitat, and that at other times adults feed on hosts other than those required for nymphal development; 3) Pj_ modesta is not univoltine, but populations make seasonal movements to and from the Mi mendax habitat with one or more other generations using different host plants and habitats. These hypotheses can be tested only by closely examining the life history of Pi modesta. Chapter 1 reviews the literature regarding the known life histories in the North American Membracidae, while chapter 2 documents the phenology of Publilia modesta and tests these hypotheses. The behaviors of individual Mvrmecocvstus mendax workers that encounter Publilia modesta aggregations affect the initiation and maintenance of the mutualistic association. Ant species achieve efficiency through specialization, i.e., matching a caste to a task (Oster and Wilson, 1978).