Predicting the efficacy of virally-vectored immunocontraception for managing rabbits

Models were developed to examine the efficacy of immunocontraception as an alternative control method for pest rabbits. The models simulated the dynamics of rabbit populations structured by age and sex, and helped identify the benefits of an integrated pest management strategy that includes immunocontraception and lethal control. Virally vectored immunocontraception (VVIC) using a sterilising myxoma virus reduced the long-term density of rabbits. However, our models indicated that the efficacy of VVIC is much less than using lethal methods of management currently available (e.g. poison baiting). Nevertheless, in areas where lethal control cannot be used, a sterilising strain of myxoma may be a useful tool for rabbit management, but competition between sterilising and non-sterilising strains will reduce the overall efficacy of VVIC. Regardless of how effective poisoning is at reducing rabbit numbers, the benefits in terms of increased pasture availability and wool growth may not outweigh the costs incurred by a poisoning campaign. In our analysis the most cost-effective control remains natural epizootics of myxomatosis since they do not incur a cost to the landholder. There is likely to be some small additional benefit to releasing a sterilising strain of myxoma, and landholders may need to supplement this with baiting under some circumstances (e.g. above average breeding season or areas where myxomatosis occur infrequently).