Essential oils are environment-friendly natural ingredients that can be used as biopesticides. Biopesticide formulation using nutmeg seed oil (Myristica fragrans Houtt) and its application as an inhibitor of lichen growth on rocks. This study aimed to synthesize biopesticides and determine their inhibitory activity on lichen growth on rocks. The biopesticide was synthesized by adding AgNO3 powder directly to the nutmeg seed oil, Tween 80 surfactant, and PEG 400 co-surfactant. The synthesized biopesticide had a dark brown color, indicating that the reduction process was successful, as shown by the formation of absorption at a wavelength of 437 nm. The results of the PSA and SEM-EDX analyses showed that the biopesticide had a particle size of 454.8 nm and was spherical in shape with Ag, C and O contents of 59.07%, 28.94% and 11.99% respectively. The addition of Tween 80 and PEG 400 surfactants resulted in particle sizes of 235 nm and 406.2 nm respectively, and a round and non-uniform shape. Tween 80 affects the synthesis of nutmeg oil biopesticide, that is, it is more stable. The synthetic biopesticide is effective as an anti-lichen on stone surfaces.

Keywords: Nutmeg oil, Silver nanoparticles, Biopesticide, Anti-lichen activity