Tick Biocontrol Strategy in Dairy Cattle: Drone-Applied <i>Metarhizium anisopliae</i> Fungus as an Alternative to Conventional Acaricides for Reducing Pesticide Residues in Milk

The Brazilian dairy industry faces significant challenges from Rhipicephalus (Boophilu) microplus infestations, which affect cattle health and milk quality. While chemical acaricides are widely used, concerns about resistance, environmental contamination, and milk residues drive the need for safer alternatives. This study assessed the efficacy and safety of drone-applied Metarhizium anisopliae powder compared to conventional chemical acaricides in a 63-day field trial. The fungal biological control (FMT) achieved tick reduction comparable to chemical methods (CCT), with ISO/IEC 17025-certified residue analysis showing critical differences: FMT milk samples (n = 126) contained no detectable residues, while CCT milk contained chlorpyrifos (210–5 ng mL–1), cypermethrin (225–10 ng mL–1), and piperonyl butoxide (107–1 ng mL–1) within 7 days after application. These findings support M. anisopliae as a residue-free and environmentally sustainable biocontrol alternative, providing efficacy comparable to that of chemical methods while reducing food safety risks. This approach holds promise for integration into sustainable pest management strategies in dairy production systems.