Distribution and Morphology of a Phoretic Mite, Anoetus Halictonida (Histiostomatidae) on an Urban Population of Halictus Rubicundus in Central Saskatchewan
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DISTRIBUTION AND MORPHOLOGY OF A PHORETIC MITE, ANOETUS HALICTONIDA (HISTIOSTOMATIDAE) ON AN URBAN POPULATION OF HALICTUS RUBICUNDUS IN CENTRAL SASKATCHEWAN A Thesis Submitted to the College of Graduate and Postdoctoral Studies In Partial Fulfillment of the Requirements For the Degree of Master of Science In the Department of Biology University of Saskatchewan Saskatoon, Saskatchewan, Canada By Kimberley A.R.M. Achtymichuk © Copyright Kimberley A.R.M. Achtymichuk, 2017 All rights reserved. PERMISSION TO USE In presenting this thesis/dissertation in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. Requests for permission to copy or to make other uses of materials in this thesis/dissertation in whole or part should be addressed to: Head of the Biology Department 112 Science Place University of Saskatchewan Saskatoon, SK. S7N 5E2 Canada College of Graduate and Postdoctoral Studies Room 116 Thorvaldson Building 110 Science Place Saskatoon, SK. S7N 5C9 Canada i Abstract The ground-nesting activities of a sweat bee, Halictus rubicundus [Christ], and data about its commonly associated mite, now tentatively identified as Anoetus halictonida (Woodring, 1973), were investigated at two sites on the University of Saskatchewan campus in Saskatoon during 2014 and 2015, thereby representing the first such study of this relationship in western Canada. Plaster of Paris casting was utilized to identify and excavate 78 subterranean nests of H. rubicundus throughout the spring- summer of 2015, to reveal nest architecture, phenology of the bee’s life stages, potential social interactions among bees, plus the types and proportions of pollen that contribute to the larval diet of this polylectic bee species. Microscopic examination of bees and brood cells revealed various life stages (eg. Tritonymphs; gravid females) of A. halictonida, but only deutonymphs resided on adult bees, in specific body locations according to host sex. Mite loads on adult females (96.3%) predominated on the lower surfaces of hind wings in a symmetric fashion, but also dorsally at the mesosomal-metasomal junction. Phoretic loads of deutonymphs on adult males (57.1%) averaged 1/3 that of females and instead were concentrated ventrally on the thorax and lower head. Mites residing on pre-adults (pupae and pharate bees), however, were surprisingly scattered and equal among host sexes, suggesting an eventual net mite transfer from adult male to female bees, possibly at copulation. Even the largest load of deutonymphs (167) was considered negligible (<0.5% the body weight of an adult female bee). Scanning electron microscopy revealed new information about the flexibility and microstructure of the caudal suckerplate and legs of deutonymphs of A. halictonida, allowing attachment to H. rubicundus. A brief comparison to other halictid-anoetid interactions involving H. confusus and Sphecodes in the same study area and the possibility of interspecific transfer is discussed. ii Acknowledgements I am grateful to my supervisor Dr. Art Davis, an invaluable and unwaveringly supportive mentor. Thank you to my committee members, Drs. Neil Chilton and Cedric Gillott, for their advice which was sorely needed. Special thanks for the technical assistance provided by several very patient individuals on the University of Saskatchewan campus. Within the Biology Department Guosheng Liu provided assistance with the department SEM, whereas Marlynn Mierau, and Marlene Mahoney helped with photography. Tom Bonli of the Geology Department and Eiko Kawamura of the Western College of Veterinary Medicine assisted with the use of their departments’ respective SEMs. Clint Berschiminsky of Facilities Management Division helped arrange permission to excavate on campus, and trusted me not to dig up the sprinkler system. Identification of unknown species was provided by Drs. Sabine Banniza (University of Saskatchewan), Heather Proctor (University of Alberta), Pavel Klimov (University of Michigan), and Barry OConnor (University of Michigan). Thanks to my labmates in the Davis lab, especially Daniel Wiens, the resident ant expert at the time. This project owes its funding to an NSERC USRA, a Graduate Teaching Fellowship (2014-2015 academic year), and an NSERC Discovery Grant to A.R. Davis which provided part of the stipend and the general lab supplies necessary for this project. Funding was also supplied by a Margaret MacKay Scholarship. Lastly, thanks to my Mom and Dad, my sister, and my family for their love and support. iii Table of Contents Permission to Use………………………………...………………………………………..……………….i Abstract…………………………………………….……………………………………..………………..ii Acknowledgments………………………………….……………………………………..………………iii Table of Contents…………………………………...…...………………………………………………..iv List of Tables……………………………………………...…………………………………………..…viii List of Figures……………………………………………..…………………………………………...…ix Chapter 1-Introduction………………………………………………………………………………...…1 1.1 Symbiotic relationships………………………………….…………………………………................1 1.1.1 Parasitism……………………………………………………………………….……………1 1.1.2 Exploitative symbiotic relationships excluding parasitism…………………………………..2 1.1.3 Commensalism…………………………………………………………………….…………3 1.1.3.1 Definitions of phoresy…………………………………………………..…………3 1.1.3.2 Aspects of phoresy………………………………………………………...………6 1.1.3.2.1 Reasons for phoresy……………………………………….……………7 1.1.3.2.2 Life cycle stages participating in phoresy………………………………7 1.1.3.2.3 Finding a host…………………………………………………….……..8 1.1.3.2.4 Structures of attachment………………………………………………10 1.1.3.3 Known halictid bee-mite associations…………………………………………...12 1.1.4 Objectives……………………………………………………………………………….….22 Chapter 2 – Life history of the sweat bee, Halictus rubicundus [Christ](Hymenoptera: Halictidae)………………………………………………………………………………………………...23 2.1 Introduction………………………………………………………………………..………………....23 2.1.1 Bee phylogeny and the family Halictidae…………………………………………..………23 iv 2.1.2 Designation of solitary and social behaviour among bees…………………………...……..24 2.1.3 Foraging behaviour and pollination biology………………………………………...……...29 2.2 Materials and Methods……………………………………………………………………………....30 2.2.1 Nesting sites of Halictus rubicundus……………………………………………...………..31 2.2.2 Nest architecture and excavation of nest contents…………………………………….……35 2.2.3 Other bees nesting and reproducing at the sites………………………………………….…37 2.2.4 Light and scanning electron microscopy of bees…………………………………………...37 2.2.5 Mass of adult bees…………………………………………………………………………..38 2.2.6 Microscopy and determination of average weight of pollen provisions……………………38 2.3 Results……………………………………………………………………………………...………....38 2.3.1 Nest architecture……………………………………………………………………..……..38 2.3.2 Immature stages of Halictus rubicundus and nest phenology…………………………...…39 2.3.3 Notes on behaviour of adult Halictus rubicundus……………………………………….…47 2.3.4 Mass of adult bees…………………………………………………………………………..47 2.3.5 Mass of pollen provisions from excavated nests of Halictus rubicundus……………….…48 2.3.6 Identification of pollen grains comprising larval provisions of Halictus rubicundus……...49 2.4 Discussion………………………………………………………………………………………..……59 2.4.1 Characteristics of nesting biology of Halictus rubicundus…………………………………59 2.4.2 Pollen provisions within nests of Halictus rubicundus……………………………………..63 Chapter 3 - The histiostomatid mite, Anoetus halictonida [Woodring] (Sarcoptiformes: Histiostomatidae)………………………………………………………………………………………….66 3.1 Introduction………………………………………………………………………………..…………66 3.2 Materials and Methods…………………………………………………………………….………...74 3.2.1 Mite distribution within excavated nests and on inhabitants…………………………….…74 v 3.2.1.1 Mites on adult bees………………………………………………………………74 3.2.1.2 Mites on immatures………………………………………………………………75 3.2.1.3 Mites within brood cells……………………………………………………….…75 3.2.2 Mite location on bees…………………………………………………………………….…75 3.2.2.1 Mite distribution on adult female bees…………………………………………...75 3.2.2.2 Mite distribution on adult male bees…………………………………………..…76 3.2.2.3 Mite distribution on immature bees……………………………………………...76 3.2.2.4 Method of attachment……………………………………………………………77 3.2.3 Mite stages and their morphology………………………………………………………..…78 3.2.4 Mite weights and phoretic loads……………………………………………………………78 3.2.5 Transfer of mites……………………………………………………………………………79 3.2.5.1 Incidence of mite transfer to flowers………………………………………….…79 3.2.5.2 Carbon dioxide anaesthetization…………………………………………………79 3.2.5.3 Collection of deceased bees…………………………………………………...…81 3.2.6 Comparison to other mites found on halictids and local bees………………………...……81 3.3 Results………………………………………………………………………………………...………81 3.3.1 Mite distribution on adult bees…………………………………………………………..…81 3.3.2 Mite distribution on immature bees……………………………………………………...…85 3.3.3 Localized mite distribution on bees……………………………………………………...…90 3.3.3.1 Mite distribution