Starting from the experience of the COVID-19 pandemic, our aim is to quantify the value of biodiversity as a device for the prevention of zoonoses in order to understand how the preservation of biodiversity should enter the policy mix to be implemented to prevent and mitigate epidemics. We propose to assess the probability of emergence of an infectious disease as a function of biodiversity. We then propose to incorporate this function in a macroeconomic model to compute the optimal trade-off between biodiversity preservation and economic growth. From this modeling, we evaluate the insurance value of biodiversity against epidemics outbreaks. Our work aim to understand how this value depends on public policy parameters such as risk aversion and aversion to fluctuations but also on ethical parameters.