Abstract
The tomato leaf miner (Tuta absoluta) is recognized as a highly destructive pest affecting members of the Solanaceae family, particularly tomato crops, where infestations may cause total crop loss. Its rapid spread and increasing resistance to chemical insecticides underscore the urgent need for innovative, environmentally compatible control strategies. In this context, the present study investigates the bioactivity of surface extracts derived from four Salvia species (S. buchananii, S. corrugata, S. discolor, and S. namaensis) against T. absoluta larvae, focusing on their insecticidal and feeding-deterrent effects. Chemical characterization through LC–MS analysis demonstrated that these Salvia species contain diverse secondary metabolites, including diterpenoids, triterpenoids, and flavonoids. Initial screening using a leaf-dip bioassay at a concentration of 2.50 mg/mL showed that S. discolor was particularly effective among the Salvia extracts tested. Subsequent dose–response assays with S. discolor extracts (0.16–5.00 mg/mL) confirmed strong larvicidal and feeding inhibitory effects, with LC50 and FI50 values of 0.12 and 0.13 mg/mL, respectively. Additionally, weak inhibition of acetylcholinesterase (AChE) was observed, suggesting a minor contribution of neurotoxic effects to the overall activity of the extract. The findings suggest that S. discolor extracts may be useful for managing T. absoluta infestations, pending evaluation of their effects on non-target organisms.