THE CAUSES AND CONSEQUENCES OF REPRODUCTIVE INTERFERENCE IN THE LYGAEIDAE Emily Rose Burdfield­Steel A Thesis Submitted for the Degree of PhD at the University of St Andrews 2014 Full metadata for this item is available in Research@StAndrews:FullText at: http://research-repository.st-andrews.ac.uk/ Please use this identifier to cite or link to this item: http://hdl.handle.net/10023/6549 This item is protected by original copyright The causes and consequences of reproductive interference in the Lygaeidae Emily Rose Burdfield-Steel This thesis is submitted in partial fulfilment for the degree of PhD at the University of St Andrews 23rd May 2014 1 Table of Contents Declarations ........................................ … ....................................................................................... 5 Candidate’s declarations ......................... ................................................................................................... 5 Supervisor’s declarations ............................................................................................................................ 5 Permission for electronic publications ....................................................................................................... 5 Acknowledgements......................................................................................................................... 6 Co-authorship statement ................................................................................................................ 7 Abstract .......................................................................................................................................... 8 Chapter 1 – Introduction ................................................................................................................. 9 1. Introduction to reproductive interference ...........................................................................................10 1.1 Types of reproductive interference ..................................................................................................10 1.2 Ecological and evolutionary consequences of RI ..............................................................................15 1.3 Relationship between RI and sexual conflict ....................................................................................16 1.4 Hybridisation .....................................................................................................................................17 1.5 Occurrence of RI ................................................................................................................................19 2. Study system: The Lygaeidae ................................................................................................................21 2.1 Introduction ......................................................................................................................................21 2.2 Phylogenetic status and basic biology ..............................................................................................22 2.2.1 Sexual systems..............................................................................................................................23 2.2.2 Oviposition ...................................................................................................................................23 2.2.3 Development ................................................................................................................................28 2.2.4 Diapause .......................................................................................................................................31 2.2.5 Feeding biology and economic impact .........................................................................................31 2.2.6 Endosymbionts .............................................................................................................................35 2.2.7 Social Interactions ........................................................................................................................37 2.2.8 Predators and parasites ...............................................................................................................40 2.3 Common study systems: a brief introduction ...................................................................................40 2.4 Aposematism, predator defence and life history effects..................................................................42 2.5 Pheromones in Lygaeidae – aggregation and communication .........................................................48 2.6 Population structure and ecology – Migration, diapause and genetic structuring ..........................52 2.7 Mating systems – Promiscuity, sperm competition and harassment ...............................................55 2.8 Reproductive interference – ecological and evolutionary consequences ........................................63 3. Conclusion .............................................................................................................................................64 Chapter 2 – General Husbandry and development time in four species of Lygaeidae ....................... 67 1. General Husbandry ...............................................................................................................................68 2. Development times in the laboratory ...................................................................................................69 2.1 Introduction ......................................................................................................................................69 2.2 Methods ............................................................................................................................................70 2.3 Results ...............................................................................................................................................71 2.4 Discussion ..........................................................................................................................................72 2 Chapter 3 – Reproductive interference between Lygaeus equestris and four Lygaeidae species ...... 79 1. Introduction ..........................................................................................................................................80 2. Methods ................................................................................................................................................82 2.1 Experiment 1 .....................................................................................................................................82 2.2 Experiment 2 .....................................................................................................................................84 3. Results ...................................................................................................................................................85 3.1 Experiment 1 .....................................................................................................................................85 3.2 Experiment 2 .....................................................................................................................................89 4. Discussion ..............................................................................................................................................89 Chapter 4 – Cuticular hydrocarbons and the potential for sex- and species- discrimination in five species of Lygaeidae...................................................................................................................... 93 1. Introduction ..........................................................................................................................................94 2. Methods ................................................................................................................................................96 2.1 CHC characterisation .........................................................................................................................96 2.2 Species and sex differences ..............................................................................................................97 2.3 Species and age differences ..............................................................................................................98 2.4 CHC removal ......................................................................................................................................99 3. Results ...................................................................................................................................................99 3.1 CHC characterisation and species and sex differences .....................................................................99 3.2 Species, sex and age differences .....................................................................................................100 3.3 CHC removal ....................................................................................................................................101 4. Discussion ............................................................................................................................................104 Chapter 5 – Variation in social and sexual behaviour in four species of aposematic seed bugs: the role of toxic and non-toxic food ...................................................................................................