The tomato leaf miner, Tuta absoluta, is a major threat to solanaceous crops, particularly tomatoes, and can cause yield losses of up to 100%. The rapid spread of the pest and increasing resistance to conventional insecticides highlight the need for alternative control methods [1,2]. Considering these challenges, we evaluated the insecticidal and antifeedant activities of dichloromethane surface ex- tracts from four Salvia species (S. buchanani, S. corrugata, S. discolor, and S. namaensis) against T. absoluta larvae using a leaf-dip bioassay protocol (IRAC susceptibility test method) with few modifi- cations. LC-MS analysis revealed that the extracts were rich in abietane-type diterpenes and highly methoxylated flavonoids, which are known for their bioactive properties. Preliminary screening at a concentration of 2.5 mg/mL revealed S. discolor to be the most effective, demonstrating statistically higher larval mortality than the commercial insecticide Spinosad. Encouraged by these findings, we further evaluated the effects of the species at varying concentrations (0.16, 0.31, 0.62, 1.25, and 5.0 mg/mL). S. discolor demonstrated remarkable potency, with an LC50 of 0.013 mg/mL. Additionally S. discolor consistently induced strong feeding inhibition across all tested concentrations, suggesting its potential as a possible natural alternative to synthetic insecticides. Future studies will be carried out to investigate the compounds responsible for these effects.
Potential of Salvia extracts as natural insecticides against the tomato leaf miner, Tuta absoluta
Devi P;Bisio A
2025-01-01
Abstract
The tomato leaf miner, Tuta absoluta, is a major threat to solanaceous crops, particularly tomatoes, and can cause yield losses of up to 100%. The rapid spread of the pest and increasing resistance to conventional insecticides highlight the need for alternative control methods [1,2]. Considering these challenges, we evaluated the insecticidal and antifeedant activities of dichloromethane surface ex- tracts from four Salvia species (S. buchanani, S. corrugata, S. discolor, and S. namaensis) against T. absoluta larvae using a leaf-dip bioassay protocol (IRAC susceptibility test method) with few modifi- cations. LC-MS analysis revealed that the extracts were rich in abietane-type diterpenes and highly methoxylated flavonoids, which are known for their bioactive properties. Preliminary screening at a concentration of 2.5 mg/mL revealed S. discolor to be the most effective, demonstrating statistically higher larval mortality than the commercial insecticide Spinosad. Encouraged by these findings, we further evaluated the effects of the species at varying concentrations (0.16, 0.31, 0.62, 1.25, and 5.0 mg/mL). S. discolor demonstrated remarkable potency, with an LC50 of 0.013 mg/mL. Additionally S. discolor consistently induced strong feeding inhibition across all tested concentrations, suggesting its potential as a possible natural alternative to synthetic insecticides. Future studies will be carried out to investigate the compounds responsible for these effects.
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