Building an eDNA surveillance toolkit for invasive rodents on islands: can we detect wild-type and gene drive Mus musculus?

Background: Invasive management strategies range from preventing new invasive species incursions to eliminating established populations, with all requiring effective monitoring to guide action. The use of DNA sampled from the environment (eDNA) is one such tool that provides the ability to surveille and monitor target invasive species through passive sampling. Technology being developed to eliminate invasive species includes genetic biocontrol in the form of gene drive. This approach would drive a trait through a population and could be used to eliminate or modify a target population. Once a gene drive organism is released into a population then monitoring changes in density of the target species and the spread of the drive in the population would be critical. Results: In this paper, we use invasive Mus musculus as a model for development of an eDNA assay that detects wild-type M. musculus and gene drive M. musculus. We demonstrate successful development of an assay where environmental samples could be used to detect wild-type invasive M. musculus and the relative density of wild-type to gene drive M. musculus. Conclusions: The development of a method that detects both wild-type M. musculus and a gene drive M. musculus (t_CRISPR) from environmental samples expands the utility of environmental DNA. This method provides a tool that can immediately be deployed for invasive wild M. musculus management across the world. This is a proof-of-concept that a genetic biocontrol construct could be monitored using environmental samples.