Biological invasions and their potential economic costs in Morocco.

Biological invasions pose substantial economic threats globally, yet detailed cost assessments for many Global South nations, especially in Africa, remain scarce. This study presents the first comprehensive breakdown of the potential economic costs of biological invasions in Morocco. We identified 343 invasive alien species, comprising approximately 1.11% of the country's biodiversity. Using the InvaCost database, we retrieved cost estimates for 137 species with available records. We calculated the mean annual cost per species, adjusted these values both socio-economically (using World Bank Purchasing Power Parity) and climatically (via Köppen climatic regions), and extrapolated them based on species prevalence in Morocco. This yielded an estimated annual economic impact ranging from US$1.14 billion (conservative adjusted value) to US$5.13 billion (maximum scenario). Across all estimations, damage costs consistently exceeded management costs by one or two orders of magnitude. Plant feeding insects such as Phenacoccus madeirensi, Bemisia tabacci, and Cydia pomonella emerged among the costliest species, threatening agriculture and food security. High-impact animals included the Asian tiger mosquito (Aedes albopictus) and the brown rat (Rattus norvegicus), both affecting public health and social welfare. In freshwater systems the common carp (Cyprinus carpio) imposed substantial fisheries losses. Invasive plants, particularly Euphorbia and Cenchrus species, were also widespread and contributed heavily to projected costs. Despite challenges in extrapolating cost data from other regions, this study underscores the urgent need for more research and for targeted management and policy interventions to minimize the spread of invasive species and reduce their economic toll. Proactive measures in Morocco, coupled with international collaboration, will be critical to mitigating this socio-ecological crisis and ensuring long-term sustainability.