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Assessing the sustainability of anticoagulant-based rodent control for wildlife conservation in New Zealand A thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Conservation Biology at Massey University, Palmerston North, New Zealand SUMAN PREET KAUR SRAN 2019 1 I dedicate this thesis to My Grandmother, Baljinder Kaur Sran who has loved and supported me unconditionally 2 Table of Contents Acknowledgements ....................................................................................................................... 7 Abstract ......................................................................................................................................... 9 Glossary of Key Terms related to Anticoagulant Resistance ...................................................... 11 CHAPTER 1 Introduction ............................................................................................................. 13 Rodents in New Zealand ......................................................................................................... 14 Rattus rattus ........................................................................................................................... 14 Mus musculus .......................................................................................................................... 15 Anticoagulant rodenticides ..................................................................................................... 15 Mode of action of anticoagulant rodenticides ....................................................................... 17 Anticoagulant use in New Zealand ......................................................................................... 18 Brodifacoum as rodenticide .................................................................................................... 19 Clinical signs of brodifacoum poisoning.................................................................................. 21 Non-target poisoning .............................................................................................................. 22 Pathways of resistance to anticoagulants .............................................................................. 23 Pleiotropic effects of resistance .............................................................................................. 28 Methods to detect anticoagulant resitance in rodents .......................................................... 29 Aims and objectives .................................................................................................................... 35 CHAPTER 2 Evaluating an effective dose of brodifacoum for ship rat (Rattus rattus) in New Zealand forests ............................................................................................................................ 39 2.1 Introduction ...................................................................................................................... 40 Anticoagulant resistance ......................................................................................................... 40 Lethal feeding period test ................................................................................................... 42 Blood-clotting response test ............................................................................................... 43 International normalised ratio ............................................................................................ 44 Gap of knowledge ............................................................................................................... 45 2.2 Materials and methods ..................................................................................................... 46 Study site ............................................................................................................................. 46 Trapping .............................................................................................................................. 50 Maintenance of captive rats ............................................................................................... 50 Brodifacoum dose-preparation ........................................................................................... 51 Experimental design ............................................................................................................ 52 Tissue conservation ............................................................................................................. 53 Statistical analysis ............................................................................................................... 53 3 2.3 Results ............................................................................................................................... 54 Trapping ............................................................................................................................... 54 BCR test ............................................................................................................................... 54 Estimation of effective dose ................................................................................................ 57 2.4 Discussion .......................................................................................................................... 57 CHAPTER 3 Comparison of blood-clotting responses to brodifacoum between ship rat (Rattus rattus) populations captured from areas of low, medium and high brodifacoum use ............... 65 3.1 Introduction ....................................................................................................................... 66 3.2 Material and methods ....................................................................................................... 69 Study Sites ........................................................................................................................... 69 Trapping ............................................................................................................................... 70 Maintenance of captive rats ................................................................................................ 72 Brodifacoum dose-preparation ........................................................................................... 72 Experimental Design ............................................................................................................ 73 Tissue conservation ............................................................................................................. 74 Statistical Analysis ............................................................................................................... 74 3.3 Results ............................................................................................................................... 74 Trapping ............................................................................................................................... 74 BCR test ............................................................................................................................... 75 3.4 Discussion .......................................................................................................................... 78 BCR test ............................................................................................................................... 78 Male vs Female Responses to Brodifacoum ........................................................................ 78 Technical vs Practical resistance .......................................................................................... 79 Impact on current rodent pest management in New Zealand ............................................ 80 Cause of resistance .............................................................................................................. 81 Conclusion ........................................................................................................................... 82 CHAPTER 4 Comparison of blood-clotting responses to brodifacoum between house mice (Mus musculus) populations captured from areas of low, medium and high brodifacoum use ......... 85 4.1 Introduction ................................................................................................................. 86 4.2 Material and methods ....................................................................................................... 89 Study Sites ........................................................................................................................... 89 Trapping ............................................................................................................................... 90 Maintenance of captive mice .............................................................................................. 90 Experimental Design ............................................................................................................ 93 4 Laboratory methods............................................................................................................ 93 Tissue conservation ............................................................................................................