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Yang J, Zhou Z, Li G, Dong Z, Li Q, Fu K, Liu H, Zhong Z, Fu H, Ren Z, Gu W, Peng G. Oral immunocontraceptive vaccines: A novel approach for fertility control in wildlife. Am J Reprod Immunol 2023; 89:e13653. [PMID: 36373212 DOI: 10.1111/aji.13653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 10/29/2022] [Accepted: 11/08/2022] [Indexed: 11/16/2022] Open
Abstract
The overabundant populations of wildlife have caused many negative impacts, such as human-wildlife conflicts and ecological degradation. The existing approaches like injectable immunocontraceptive vaccines and lethal methods have limitations in many aspects, which has prompted the advancement of oral immunocontraceptive vaccine. There is growing interest in oral immunocontraceptive vaccines for reasons including high immunization coverage, easier administration, frequent boosting, the ability to induce systemic and mucosal immune responses, and cost-effectiveness. Delivery systems have been developed to protect oral antigens and enhance the immunogenicity, including live vectors, microparticles and nanoparticles, bacterial ghosts, and mucosal adjuvants. However, currently, no effective oral immunocontraceptive vaccine is available for field trials because of the enormous development challenges, including biological and physicochemical barriers of the gastrointestinal tract, mucosal tolerance, pre-existing immunity, antigen residence time in the small intestine, species specificity and other safety issues. To overcome these challenges, this article summarizes achievements in delivery systems and contraceptive antigens in oral immunocontraceptive vaccines and explores the potential barriers for future vaccine design and application.
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Affiliation(s)
- Jinpeng Yang
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Ziyao Zhou
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Gangshi Li
- Chengdu Ruipeng Changjiang Road Pet Hospital, Chengdu, Sichuan, China
| | - Zhiyou Dong
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Qianlan Li
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Keyi Fu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Haifeng Liu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Zhijun Zhong
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Hualin Fu
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Zhihua Ren
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
| | - Wuyang Gu
- Chengdu Ruipeng Changjiang Road Pet Hospital, Chengdu, Sichuan, China
| | - Guangneng Peng
- Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China
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Benka VA, Boone JD, Miller PS, Briggs JR, Anderson AM, Slootmaker C, Slater M, Levy JK, Nutter FB, Zawistowski S. Guidance for management of free-roaming community cats: a bioeconomic analysis. J Feline Med Surg 2022; 24:975-985. [PMID: 34842477 PMCID: PMC9511502 DOI: 10.1177/1098612x211055685] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES This study used computer simulation modeling to estimate and compare costs of different free-roaming cat (FRC) management options (lethal and non-lethal removal, trap-neuter-return, combinations of these options and no action) and their ability to reduce FRC population abundance in open demographic settings. The findings provide a resource for selecting management approaches that are well matched for specific communities, goals and timelines, and they represent use of best available science to address FRC issues. METHODS Multiple FRC management approaches were simulated at varying intensities using a stochastic individual-based model in the software package Vortex. Itemized costs were obtained from published literature and expert feedback. Metrics generated to evaluate and compare management scenarios included final population size, total cost and a cost efficiency index, which was the ratio between total cost and population size reduction. RESULTS Simulations suggested that cost-effective reduction of FRC numbers required sufficient management intensity, regardless of management approach, and greatly improved when cat abandonment was minimized. Removal yielded the fastest initial reduction in cat abundance, but trap-neuter-return was a viable and potentially more cost-effective approach if performed at higher intensities over a sufficient duration. Of five management scenarios that reduced the final population size by approximately 45%, the three scenarios that relied exclusively on removal were considerably more expensive than the two scenarios that relied exclusively or primarily on sterilization. CONCLUSIONS AND RELEVANCE FRCs present a challenge in many municipalities, and stakeholders representing different perspectives may promote varying and sometimes incompatible population management policies and strategies. Although scientific research is often used to identify FRC impacts, its use to identify viable, cost-effective management solutions has been inadequate. The data provided by simulating different interventions, combined with community-specific goals, priorities and ethics, provide a framework for better-informed FRC policy and management outcomes.
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Affiliation(s)
- Valerie A Benka
- Alliance for Contraception in Cats and Dogs, Portland, OR, USA
| | | | - Philip S Miller
- IUCN/SSC Conservation Planning Specialist Group, Apple Valley, MN, USA
| | - Joyce R Briggs
- Alliance for Contraception in Cats and Dogs, Portland, OR, USA
| | | | | | - Margaret Slater
- Strategy and Research Department, American Society for the Prevention of Cruelty to Animals, New York, NY, USA
| | - Julie K Levy
- Maddie’s Shelter Medicine Program, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, USA
| | - Felicia B Nutter
- Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, USA
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Cottingham E, Johnstone T, Hartley CA, Devlin JM. Use of feline herpesvirus as a vaccine vector offers alternative applications for feline health. Vet Microbiol 2021; 261:109210. [PMID: 34416538 DOI: 10.1016/j.vetmic.2021.109210] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/15/2021] [Indexed: 12/26/2022]
Abstract
Herpesviruses are attractive vaccine vector candidates due to their large double stranded DNA genome and latency characteristics. Within the scope of veterinary vaccines, herpesvirus-vectored vaccines have been well studied and commercially available vectored vaccines are used to help prevent diseases in different animal species. Felid alphaherpesvirus 1 (FHV-1) has been characterised as a vector candidate to protect against a range of feline pathogens. In this review we highlight the methods used to construct FHV-1 based vaccines and their outcomes, while also proposing alternative uses for FHV-1 as a viral vector.
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Affiliation(s)
- Ellen Cottingham
- The Asia Pacific Centre for Animal Health, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia.
| | - Thurid Johnstone
- U-Vet Animal Hospital, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Werribee, Victoria, 3030, Australia
| | - Carol A Hartley
- The Asia Pacific Centre for Animal Health, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
| | - Joanne M Devlin
- The Asia Pacific Centre for Animal Health, Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, 3010, Australia
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Pepin KM, Davis AJ, Cunningham FL, VerCauteren KC, Eckery DC. Potential effects of incorporating fertility control into typical culling regimes in wild pig populations. PLoS One 2017; 12:e0183441. [PMID: 28837610 PMCID: PMC5570275 DOI: 10.1371/journal.pone.0183441] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 08/03/2017] [Indexed: 11/18/2022] Open
Abstract
Effective management of widespread invasive species such as wild pigs (Sus scrofa) is limited by resources available to devote to the effort. Better insight of the effectiveness of different management strategies on population dynamics is important for guiding decisions of resource allocation over space and time. Using a dynamic population model, we quantified effects of culling intensities and time between culling events on population dynamics of wild pigs in the USA using empirical culling patterns and data-based demographic parameters. In simulated populations closed to immigration, substantial population declines (50-100%) occurred within 4 years when 20-60% of the population was culled annually, but when immigration from surrounding areas occurred, there was a maximum of 50% reduction, even with the maximum culling intensity of 60%. Incorporating hypothetical levels of fertility control with realistic culling intensities was most effective in reducing populations when they were closed to immigration and when intrinsic population growth rate was too high (> = 1.78) to be controlled by culling alone. However, substantial benefits from fertility control used in conjunction with culling may only occur over a narrow range of net population growth rates (i.e., where net is the result of intrinsic growth rates and culling) that varies depending on intrinsic population growth rate. The management implications are that the decision to use fertility control in conjunction with culling should rely on concurrent consideration of achievable culling intensity, underlying demographic parameters, and costs of culling and fertility control. The addition of fertility control reduced abundance substantially more than culling alone, however the effects of fertility control were weaker than in populations without immigration. Because these populations were not being reduced substantially by culling alone, fertility control could be an especially helpful enhancement to culling for reducing abundance to target levels in areas where immigration can't be prevented.
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Affiliation(s)
- Kim M. Pepin
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Fort Collins, Colorado, United States of America
- * E-mail:
| | - Amy J. Davis
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Fort Collins, Colorado, United States of America
| | - Fred L. Cunningham
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Mississippi State, United States of America
| | - Kurt C. VerCauteren
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Fort Collins, Colorado, United States of America
| | - Doug C. Eckery
- National Wildlife Research Center, USDA, APHIS, Wildlife Services, Fort Collins, Colorado, United States of America
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Wolff JN, Gemmell NJ, Tompkins DM, Dowling DK. Introduction of a male-harming mitochondrial haplotype via 'Trojan Females' achieves population suppression in fruit flies. eLife 2017; 6:e23551. [PMID: 28467301 PMCID: PMC5441865 DOI: 10.7554/elife.23551] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 04/27/2017] [Indexed: 01/05/2023] Open
Abstract
Pests are a global threat to biodiversity, ecosystem function, and human health. Pest control approaches are thus numerous, but their implementation costly, damaging to non-target species, and ineffective at low population densities. The Trojan Female Technique (TFT) is a prospective self-perpetuating control technique that is species-specific and predicted to be effective at low densities. The goal of the TFT is to harness naturally occurring mutations in the mitochondrial genome that impair male fertility while having no effect on females. Here, we provide proof-of-concept for the TFT, by showing that introduction of a male fertility-impairing mtDNA haplotype into replicated populations of Drosophila melanogaster causes numerical population suppression, with the magnitude of effect positively correlated with its frequency at trial inception. Further development of the TFT could lead to establishing a control strategy that overcomes limitations of conventional approaches, with broad applicability to invertebrate and vertebrate species, to control environmental and economic pests.
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Affiliation(s)
| | - Neil J Gemmell
- Department of Anatomy, University of Otago, Dunedin, New Zealand
| | | | - Damian K Dowling
- School of Biological Sciences, Monash University, Victoria, Australia
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Dowling DK, Tompkins DM, Gemmell NJ. The Trojan Female Technique for pest control: a candidate mitochondrial mutation confers low male fertility across diverse nuclear backgrounds in Drosophila melanogaster. Evol Appl 2015; 8:871-80. [PMID: 26495040 PMCID: PMC4610384 DOI: 10.1111/eva.12297] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 06/29/2015] [Indexed: 01/27/2023] Open
Abstract
Pest species represent a major ongoing threat to global biodiversity. Effective management approaches are required that regulate pest numbers, while minimizing collateral damage to nontarget species. The Trojan Female Technique (TFT) was recently proposed as a prospective approach to biological pest control. The TFT draws on the evolutionary hypothesis that maternally inherited mitochondrial genomes are prone to the accumulation of male, but not female, harming mutations. These mutations could be harnessed to provide trans-generational fertility-based control of pest species. A candidate TFT mutation was recently described in the fruit fly, Drosophila melanogaster, which confers male-only sterility in the specific isogenic nuclear background in which it is maintained. However, applicability of the TFT relies on mitochondrial mutations whose male-sterilizing effects are general across nuclear genomic contexts. We test this assumption, expressing the candidate TFT-mutation bearing haplotype alongside a range of nuclear backgrounds and comparing its fertility in males, relative to that of control haplotypes. We document consistently lower fertility for males harbouring the TFT mutation, in both competitive and noncompetitive mating contexts, across all nuclear backgrounds screened. This indicates that TFT mutations conferring reduced male fertility can segregate within populations and could be harnessed to facilitate this novel form of pest control.
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Affiliation(s)
- Damian K Dowling
- School of Biological Sciences, Monash University Clayton, Vic., Australia
| | | | - Neil J Gemmell
- Allan Wilson Centre for Molecular Ecology and Evolution, Department of Anatomy, University of Otago Dunedin, New Zealand
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Miller PS, Boone JD, Briggs JR, Lawler DF, Levy JK, Nutter FB, Slater M, Zawistowski S. Simulating free-roaming cat population management options in open demographic environments. PLoS One 2014; 9:e113553. [PMID: 25426960 PMCID: PMC4245120 DOI: 10.1371/journal.pone.0113553] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 10/28/2014] [Indexed: 11/19/2022] Open
Abstract
Large populations of free-roaming cats (FRCs) generate ongoing concerns for welfare of both individual animals and populations, for human public health, for viability of native wildlife populations, and for local ecological damage. Managing FRC populations is a complex task, without universal agreement on best practices. Previous analyses that use simulation modeling tools to evaluate alternative management methods have focused on relative efficacy of removal (or trap-return, TR), typically involving euthanasia, and sterilization (or trap-neuter-return, TNR) in demographically isolated populations. We used a stochastic demographic simulation approach to evaluate removal, permanent sterilization, and two postulated methods of temporary contraception for FRC population management. Our models include demographic connectivity to neighboring untreated cat populations through natural dispersal in a metapopulation context across urban and rural landscapes, and also feature abandonment of owned animals. Within population type, a given implementation rate of the TR strategy results in the most rapid rate of population decline and (when populations are isolated) the highest probability of population elimination, followed in order of decreasing efficacy by equivalent rates of implementation of TNR and temporary contraception. Even low levels of demographic connectivity significantly reduce the effectiveness of any management intervention, and continued abandonment is similarly problematic. This is the first demographic simulation analysis to consider the use of temporary contraception and account for the realities of FRC dispersal and owned cat abandonment.
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Affiliation(s)
- Philip S. Miller
- Conservation Breeding Specialist Group, Species Survival Commission, International Union for Conservation of Nature, Apple Valley, Minnesota, United States of America
- * E-mail:
| | - John D. Boone
- Great Basin Bird Observatory, Reno, Nevada, United States of America
| | - Joyce R. Briggs
- Alliance for Contraception in Cats and Dogs, Portland, Oregon, United States of America
| | - Dennis F. Lawler
- Illinois State Museum, Springfield, Illinois, United States of America
| | - Julie K. Levy
- Maddie's Shelter Medicine Program, Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States of America
| | - Felicia B. Nutter
- Department of Infectious Disease and Global Health, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Massachusetts, United States of America
| | - Margaret Slater
- Shelter Research and Development, American Society for the Prevention of Cruelty to Animals, Florence, Massachusetts, United States of America
| | - Stephen Zawistowski
- American Society for the Prevention of Cruelty to Animals, New York, New York, United States of America
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Massei G, Cowan D. Fertility control to mitigate human–wildlife conflicts: a review. WILDLIFE RESEARCH 2014. [DOI: 10.1071/wr13141] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
As human populations grow, conflicts with wildlife increase. Concurrently, concerns about the welfare, safety and environmental impacts of conventional lethal methods of wildlife management restrict the options available for conflict mitigation. In parallel, there is increasing interest in using fertility control to manage wildlife. The present review aimed at analysing trends in research on fertility control for wildlife, illustrating developments in fertility-control technologies and delivery methods of fertility-control agents, summarising the conclusions of empirical and theoretical studies of fertility control applied at the population level and offering criteria to guide decisions regarding the suitability of fertility control to mitigate human–wildlife conflicts. The review highlighted a growing interest in fertility control for wildlife, underpinned by increasing numbers of scientific studies. Most current practical applications of fertility control for wild mammals use injectable single-dose immunocontraceptive vaccines mainly aimed at sterilising females, although many of these vaccines are not yet commercially available. One oral avian contraceptive, nicarbazin, is commercially available in some countries. Potential new methods of remote contraceptive delivery include bacterial ghosts, virus-like particles and genetically modified transmissible and non-transmissible organisms, although none of these have yet progressed to field testing. In parallel, new species-specific delivery systems have been developed. The results of population-level studies of fertility control indicated that this approach may increase survival and affect social and spatial behaviour of treated animals, although the effects are species- and context-specific. The present studies suggested that a substantial initial effort is generally required to reduce population growth if fertility control is the sole wildlife management method. However, several empirical and field studies have demonstrated that fertility control, particularly of isolated populations, can be successfully used to limit population growth and reduce human–wildlife conflicts. In parallel, there is growing recognition of the possible synergy between fertility control and disease vaccination to optimise the maintenance of herd immunity in the management of wildlife diseases. The review provides a decision tree that can be used to determine whether fertility control should be employed to resolve specific human–wildlife conflicts. These criteria encompass public consultation, considerations about animal welfare and feasibility, evaluation of population responses, costs and sustainability.
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Prasad B, Banerjee M, Srinivasu P. Dynamics of additional food provided predator–prey system with mutually interfering predators. Math Biosci 2013; 246:176-90. [DOI: 10.1016/j.mbs.2013.08.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 08/16/2013] [Accepted: 08/23/2013] [Indexed: 10/26/2022]
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Gemmell NJ, Jalilzadeh A, Didham RK, Soboleva T, Tompkins DM. The Trojan female technique: a novel, effective and humane approach for pest population control. Proc Biol Sci 2013; 280:20132549. [PMID: 24174117 DOI: 10.1098/rspb.2013.2549] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Humankind's ongoing battle with pest species spans millennia. Pests cause or carry disease, damage or consume food crops and other resources, and drive global environmental change. Conventional approaches to pest management usually involve lethal control, but such approaches are costly, of varying efficiency and often have ethical issues. Thus, pest management via control of reproductive output is increasingly considered an optimal solution. One of the most successful such 'fertility control' strategies developed to date is the sterile male technique (SMT), in which large numbers of sterile males are released into a population each generation. However, this approach is time-consuming, labour-intensive and costly. We use mathematical models to test a new twist on the SMT, using maternally inherited mitochondrial (mtDNA) mutations that affect male, but not female reproductive fitness. 'Trojan females' carrying such mutations, and their female descendants, produce 'sterile-male'-equivalents under natural conditions over multiple generations. We find that the Trojan female technique (TFT) has the potential to be a novel humane approach for pest control. Single large releases and relatively few small repeat releases of Trojan females both provided effective and persistent control within relatively few generations. Although greatest efficacy was predicted for high-turnover species, the additive nature of multiple releases made the TFT applicable to the full range of life histories modelled. The extensive conservation of mtDNA among eukaryotes suggests this approach could have broad utility for pest control.
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Affiliation(s)
- Neil J Gemmell
- Centre for Reproduction and Genomics and Allan Wilson Centre for Molecular Ecology and Evolution, Department of Anatomy, University of Otago, , Dunedin, New Zealand, Department of Mathematics and Statistics, University of Otago, , Dunedin, New Zealand, School of Animal Biology, University of Western Australia and CSIRO Ecosystem Sciences, , Perth, Western Australia 6009, Australia, Science and Risk Assessment Directorate, Ministry for Primary Industries, , PO Box 2526, Wellington, New Zealand, Landcare Research, , Private Bag 1930, Dunedin, New Zealand
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Double impact of sterilizing pathogens: added value of increased life expectancy on pest control effectiveness. J Math Biol 2011; 64:1281-311. [DOI: 10.1007/s00285-011-0449-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 05/23/2011] [Indexed: 10/18/2022]
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Gunther I, Finkler H, Terkel J. Demographic differences between urban feeding groups of neutered and sexually intact free-roaming cats following a trap-neuter-return procedure. J Am Vet Med Assoc 2011; 238:1134-40. [PMID: 21529235 DOI: 10.2460/javma.238.9.1134] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To examine demographic differences during a 1-year observational period between urban feeding groups of neutered and unneutered free-roaming cats following a trap-neuter-return procedure. DESIGN Natural-setting trial. Animals-Free-roaming adult cats (n = 184) and kittens (76) living in 4 feeding groups in an urban region of Israel. PROCEDURES Cats in 2 feeding groups were subjected to a trap-neuter-return (TNR) procedure. Cats in 2 other feeding groups were untreated. Data were collected on a weekly basis before and during feeding time over a 1-year period. Following individual cat identification, presence of adults and kittens was recorded throughout the year. Rates of immigration, emigration, and kitten survival were compared between neutered and unneutered groups. RESULTS The number of adult cats in the 2 neutered groups increased significantly during the study period because of higher immigration and lower emigration rates than in the unneutered groups, in which the number decreased. In the neutered groups, annual presence of neutered cats was significantly higher than that of sexually intact cats. Kitten survival in the neutered groups was significantly higher than in the unneutered groups. CONCLUSIONS AND CLINICAL RELEVANCE Targeting the TNR method mainly at feeding groups in urban residential neighbourhoods may result in increased group size, as a consequence of 2 major changes in group dynamics: sexually intact cats immigrate into the neutered groups more readily and neutered cats reduce their emigration rates, possibly because of a reduction in reproductive and competitive pressures. To maintain a high proportion of neutered cats in such cat groups, persistent TNR campaigns are therefore necessary.
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Affiliation(s)
- Idit Gunther
- Zoology Department, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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Carroll MJ, Singer A, Smith GC, Cowan DP, Massei G. The use of immunocontraception to improve rabies eradication in urban dog populations. WILDLIFE RESEARCH 2010. [DOI: 10.1071/wr10027] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
ContextRabies causes ~55 000 human deaths each year, primarily as a result of bites from dogs, which are the major rabies reservoir in the developing world. Current rabies control strategies include vaccination, culling and surgical sterilisation of dogs. However, recently developed immunocontraceptives could be used alongside vaccination to apply fertility control to more animals. AimsWe used a modelling approach to explore (1) whether adding single-dose contraceptives to rabies vaccination would improve effectiveness of rabies eradication, (2) how sensitive control methods are to variation in population parameters and (3) the effects of applying control continuously or in pulses on rabies eradication. MethodsA continuous time, compartmental model was created to describe canine rabies epidemiology. Parameters were derived from the literature. The following three control methods were applied at varying rates and durations: vaccination, vaccination plus fertility control (v + fc) and culling. Outcomes were classified into the following three categories: rabies persistence, rabies eradication and population extinction. Key resultsWhen control was applied continuously for up to 24 months, vaccination was least effective; the effort required to eradicate rabies was about twice that required with culling or v + fc. At realistic control rates, only v + fc consistently resulted in rabies eradication. Increasing population growth rate and city size made rabies eradication harder; for vaccination, considerably greater control rates and durations were required, whereas culling and v + fc showed only minor decreases in effectiveness. When control was applied for 1 or 2 months (for one month every 12 months or every 6 months) per year for up to 20 years, vaccination became less effective because of population turnover between control periods; v + fc lost little effectiveness, as decreased birth rates reduced the input of susceptible animals. ConclusionsUsing immunocontraception alongside vaccination could improve rabies control campaigns by reducing the proportion of the population that must be treated, or reducing the necessary duration of the campaign. It could also make control effective under larger population growths, in larger cities and when control is pulsed. ImplicationsImmunocontraceptives could become a useful tool in canine rabies control by allowing fertility control to be applied on a large scale. Further work is required to improve understanding of dog ecology and parameterise location-specific models, which could be used to inform management plans.
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Arthur AD, Krebs CJ, Pech RP, Farroway LN, Singleton GR. The transmission rate of MCMV in house mice in pens: implications for virally vectored immunocontraception. WILDLIFE RESEARCH 2009. [DOI: 10.1071/wr09006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pest mammals have severe economic, environmental and social impacts throughout the world. Fertility control could reduce these impacts. Murine cytomegalovirus (MCMV) is being considered as an immunocontraceptive vector to control outbreaks of house mice (Mus domesticus) in Australian grain-growing regions. For successful control, a modified MCMV must transmit at a sufficient rate to keep populations of house mice below acceptable economic thresholds. We used disease models developed previously by using observations of free-ranging wild-mouse populations to assess the transmission rate of two laboratory strains of MCMV (N1 and G4) collected in a previous experiment. Mice contained in pens were deliberately infected with the N1 strain only, or with the N1 strain followed by the G4 strain. If we assume density-dependent transmission, which is the more likely mode of transmission, we found the N1 strain of MCMV transmitted at a rate ~1/300 of the rate of field strains, and hence too slowly for successful virally vectored immunocontraception (VVIC). If transmission was frequency-dependent, the rate of transmission was ~1/3 of the rate of field strains, and hence may allow successful VVIC. The G4 strain transmitted at least as slowly as the N1 strain, and possibly much more slowly; however, we could not determine whether this was an inherent property of the G4 strain or whether it was caused by competition with the N1 strain. Given the reliance of successful VVIC on rapid transmission, we recommend that future work in any VVIC system explicitly quantifies the transmission rate of recombinant viruses relative to field strains, both in the presence and absence of competing strains.
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Bradford JB, Hobbs NT. Regulating overabundant ungulate populations: an example for elk in Rocky Mountain National Park, Colorado. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2008; 86:520-8. [PMID: 17276577 DOI: 10.1016/j.jenvman.2006.12.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 09/19/2006] [Accepted: 12/08/2006] [Indexed: 05/05/2023]
Abstract
In many areas of the world, populations of native ungulates have become so abundant that they are believed to be harming vegetation and disrupting ecosystem function. Methods for controlling overabundance populations include culling animals from the population and controlling fertility using contraceptives. However, understanding the feasibility these alternatives requires insight into their long-term effects on populations. We constructed a simulation model to evaluate options for regulating elk populations in and around Rocky Mountain National Park and used the model to compare different treatment options. Methods were evaulated with respect to the time required to reduce the population to a target level, the number of animals treated and/or culled and the risk of extinction. We contrasted culling with lifetime-effect contraceptives and yearlong contraceptives. Lifetime contraceptives required treating the fewest animals to maintain the population at desired targets. However, this approach also causes the greatest population variability and potential risk of extinction. Yearlong contraceptives required treatment of dramatically more animals but had essentially no extinction risk whereas culling produced intermediate levels of both extinction risk and number of animals treated. These results characterize the risks and benefits of alternative control strategies for overabundant wildlife. They emerge from a modeling approach that can be broadly useful in helping managers in choose between alternatives for regulating overabundant wildlife.
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Affiliation(s)
- John B Bradford
- USDA Forest Service, Northern Research Station, 1831 Hwy 169 E., Grand Rapids, MN 55744, USA.
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Are non-sexual models appropriate for predicting the impact of virus-vectored immunocontraception? J Theor Biol 2008; 250:281-90. [DOI: 10.1016/j.jtbi.2007.09.037] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 09/18/2007] [Accepted: 09/26/2007] [Indexed: 11/19/2022]
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ARTHUR ANTHONYD, PECH ROGERP, SINGLETON GRANTR. Cross-strain protection reduces effectiveness of virally vectored fertility control: results from individual-based multistrain models. J Appl Ecol 2007. [DOI: 10.1111/j.1365-2664.2007.01334.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Affiliation(s)
- Irene Rochlitz
- Animal Welfare and Human-animal Interactions Group, Department of Veterinary Medicine, University of Cambridge, Madingley Road, CB3 0ES Cambridge, UK
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Hardy CM, Hinds LA, Kerr PJ, Lloyd ML, Redwood AJ, Shellam GR, Strive T. Biological control of vertebrate pests using virally vectored immunocontraception. J Reprod Immunol 2006; 71:102-11. [PMID: 16870262 DOI: 10.1016/j.jri.2006.04.006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2006] [Accepted: 04/20/2006] [Indexed: 10/24/2022]
Abstract
Species-specific viruses are being genetically engineered to produce contraceptive biological controls for pest animals such as mice, rabbits and foxes. The virus vaccines are intended to trigger an autoimmune response in the target animals that interferes with their fertility in a process termed virally vectored immunocontraception. Laboratory experiments have shown that high levels of infertility can be induced in mice infected with recombinant murine cytomegalovirus and ectromelia virus expressing reproductive antigens as well as in rabbits using myxoma virus vectors. The strategies used to produce and deliver species-specific immunocontraceptive vaccines to free-living wildlife are presented in this review. Discussion includes coverage of the likely safety of the proposed vaccines as well as the implications of the approach for fertility control in other species.
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Affiliation(s)
- C M Hardy
- Division of Entomology, Commonwealth Industrial and Scientific Research Organisation, GPO Box 1700, Canberra, ACT, Australia.
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Hilker FM, Langlais M, Petrovskii SV, Malchow H. A diffusive SI model with Allee effect and application to FIV. Math Biosci 2006; 206:61-80. [PMID: 16387332 DOI: 10.1016/j.mbs.2005.10.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2004] [Revised: 08/09/2005] [Accepted: 10/04/2005] [Indexed: 10/25/2022]
Abstract
A minimal reaction-diffusion model for the spatiotemporal spread of an infectious disease is considered. The model is motivated by the Feline Immunodeficiency Virus (FIV) which causes AIDS in cat populations. Because the infected period is long compared with the lifespan, the model incorporates the host population growth. Two different types are considered: logistic growth and growth with a strong Allee effect. In the model with logistic growth, the introduced disease propagates in form of a travelling infection wave with a constant asymptotic rate of spread. In the model with Allee effect the spatiotemporal dynamics are more complicated and the disease has considerable impact on the host population spread. Most importantly, there are waves of extinction, which arise when the disease is introduced in the wake of the invading host population. These waves of extinction destabilize locally stable endemic coexistence states. Moreover, spatially restricted epidemics are possible as well as travelling infection pulses that correspond either to fatal epidemics with succeeding host population extinction or to epidemics with recovery of the host population. Generally, the Allee effect induces minimum viable population sizes and critical spatial lengths of the initial distribution. The local stability analysis yields bistability and the phenomenon of transient epidemics within the regime of disease-induced extinction. Sustained oscillations do not exist.
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Affiliation(s)
- Frank M Hilker
- Institute of Environmental Systems Research, Department of Mathematics and Computer Science, University of Osnabrück, 49069 Osnabrück, Germany.
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Arthur AD, Pech RP, Singleton GR. Predicting the effect of immunocontraceptive recombinant murine cytomegalovirus on population outbreaks of house mice (Mus musculus domesticus) in mallee wheatlands. WILDLIFE RESEARCH 2005. [DOI: 10.1071/wr05003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Virally vectored immunocontraception using a modified murine cytomegalovirus (MCMV) is being developed for the control of house mice in Australia. In this paper, we develop disease–host models using a combination of laboratory and field data. We then combine these models with a model of a previous mouse population outbreak to explore the likely effectiveness of modified MCMV for controlling mice. Models of homogeneous mixing with and without vertical/pseudovertical transmission provided reasonable fits to field serological data collected during the onset and development of a mouse population outbreak in south-eastern Australia. Both models include the high transmission rate of MCMV suggested by the data. We found no strong support for non-linear contact rates or heterogeneous mixing. When applied to a past outbreak of mice both models gave similar results and suggested that immunocontraceptive MCMV could be effective at reducing agricultural damage to acceptable levels. Successful control was still possible when lags in the development of infertility of up to 10 weeks were added to the model, provided high levels of infertility were achieved. These lags were added because mice can become pregnant just before becoming infertile – the resultant litter would not emerge for 6–7 weeks. Trade-offs between two parameters that could be altered by engineering strains of MCMV – the level of infertility in infected mice and the virus transmission rate – were explored and suggest that a variety of parameter combinations could produce successful control. Our results are encouraging for the future development of virally vectored immunocontraception control of house mice, but future work will need to consider some of the assumptions of these single-strain models.
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Courchamp F, Chapuis JL, Pascal M. Mammal invaders on islands: impact, control and control impact. Biol Rev Camb Philos Soc 2003; 78:347-83. [PMID: 14558589 DOI: 10.1017/s1464793102006061] [Citation(s) in RCA: 495] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The invasion of ecosystems by exotic species is currently viewed as one of the most important sources of biodiversity loss. The largest part of this loss occurs on islands, where indigenous species have often evolved in the absence of strong competition, herbivory, parasitism or predation. As a result, introduced species thrive in those optimal insular ecosystems affecting their plant food, competitors or animal prey. As islands are characterised by a high rate of endemism, the impacted populations often correspond to local subspecies or even unique species. One of the most important taxa concerning biological invasions on islands is mammals. A small number of mammal species is responsible for most of the damage to invaded insular ecosystems: rats, cats, goats, rabbits, pigs and a few others. The effect of alien invasive species may be simple or very complex, especially since a large array of invasive species, mammals and others, can be present simultaneously and interact among themselves as well as with the indigenous species. In most cases, introduced species generally have a strong impact and they often are responsible for the impoverishment of the local flora and fauna. The best response to these effects is almost always to control the alien population, either by regularly reducing their numbers, or better still, by eradicating the population as a whole from the island. Several types of methods are currently used: physical (trapping, shooting), chemical (poisoning) and biological (e.g. directed use of diseases). Each has its own set of advantages and disadvantages, depending on the mammal species targeted. The best strategy is almost always to combine several methods. Whatever the strategy used, its long-term success is critically dependent on solid support from several different areas, including financial support, staff commitment, and public support, to name only a few. In many cases, the elimination of the alien invasive species is followed by a rapid and often spectacular recovery of the impacted local populations. However, in other cases, the removal of the alien is not sufficient for the damaged ecosystem to revert to its former state, and complementary actions, such as species re-introduction, are required. A third situation may be widespread: the sudden removal of the alien species may generate a further disequilibrium, resulting in further or greater damage to the ecosystem. Given the numerous and complex population interactions among island species, it is difficult to predict the outcome of the removal of key species, such as a top predator. This justifies careful pre-control study and preparation prior to initiating the eradication of an alien species, in order to avoid an ecological catastrophe. In addition, long-term monitoring ofthe post-eradication ecosystem is crucial to assess success and prevent reinvasion.
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Abstract
European wild rabbits originated in southwestern Europe but have been introduced into many other countries world-wide, becoming serious pests in many instances. As a consequence of rabbits being regarded so differently, applied research for their management often has opposing goals, namely their conservation or their control. Furthermore, modern gene technology has led to the concept of using genetically modified myxoma viruses for rabbit management, again with quite contrary aims in mind. In this paper we explain the possible ecological and economic consequences of using these genetically modified viruses inappropriately and we consider whether national and international regulations are sufficient to prevent improper use. If international regulations are inadequate, molecular biologists and ecologists must consider the consequences of their research and advice beyond their own country to avoid unwanted impacts.
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Affiliation(s)
- E Angulo
- Estación Biológica de Doñana, Apdo 1056, E-41080 Sevilla, Spain.
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Ji W, Clout MN, Sarre SD. Responses of male brushtail possums to sterile females: implications for biological control. J Appl Ecol 2000. [DOI: 10.1046/j.1365-2664.2000.00546.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hood G, Chesson P, Pech R. Biological control using sterilizing viruses: host suppression and competition between viruses in non-spatial models. J Appl Ecol 2000. [DOI: 10.1046/j.1365-2664.2000.00544.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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