Cost-effective portfolio allocation across quarantine, surveillance and eradication using info-gap theory

Biosecurity activities primarily include pre-border and border quarantine,
post-border surveillance and post-border eradication. Budget allocated to
quarantine and surveillance activities ultimately influence the
expenditure and success rate of eradication campaigns. Optimal portfolio
allocation examined in previous research is susceptible to potential
severe uncertainties existing in ecology and in the behaviour of invasive
species itself. These uncertainties, together with a limited budget, make
it difficult for decision makers to allocate the total management budget
to each biosecurity activity in a robust manner. Info-gap decision theory
is applied to model the severe uncertainty in invasive species management,
and robust optimize the total management cost. This research shows that
using a combination of pre-border and border quarantine (to reduce the
incursion probability) and post-border surveillance (to enable early
detection and rapid response), enables decision makers to be more robust
to potential uncertainty. Further, it is reported that investment in
quarantine that is more cost-effective should outweigh that in
surveillance, in line with precautionary principle. Increasing the
estimated population threshold for surveillance detection also gains more
robustness. Synthesis and applications: Portfolio allocation options
developed in this research provide decision makers with a way to manage
the invasive species spatially, cost-effectively, and confidently by
allocating the total management budget in a robust manner. The methods
outlined in this research can not only be applied to invasive species, but
also the conservation of endangered species that are constrained by severe
uncertainty in ecological modelling and limited resources.