Biosecurity impacts biodiversity: Reinforcing an ecologically sustainable response to New World screwworm management to safeguard dung beetles in US rangelands

Within livestock systems, the balance between effective biosecurity and the preservation of biodiversity requires understanding managed rangelands as resilient, productive ecosystems that can naturally regulate pests and pathogens. However, this is often challenged by forecasted loss from regional outbreaks of pests that can cause significant economic damage by compromising animal health. This commentary presents the need for a proactive, landscape-level management response to the recent reintroduction of the New World screwworm (NWS) in the United States that integrates environmentally sustainable, effective suppression strategies. Specifically, we highlight the conservation and role of dung beetle communities as economically significant to livestock production and essential contributors to pasture health. Rapid interventions, specifically chemical control measures, are often necessary to contain emerging threats but can unintentionally impact beneficial insect species and indirectly increase secondary pests. Insecticide and pharmaceutical products used to prevent or treat NWS in livestock systems are excreted in faeces, often as unmetabolized parent compounds, and residual concentrations can cause lethal and sub-lethal effects to dung beetles for weeks to months post-application. We advocate for selective use of chemical-intensive interventions within different frameworks and discuss the risks of landscape-level preventative, herd-level chemical application. Moreover, we emphasize that long-term biosecurity must balance livestock health, environmental integrity and economic stability.