Efficacy of Salvia hydrangea, DC. ex Benth essential oil and extract against Phthorimaea operculella (Lepidoptera: Gelechiidae) across multiple life stages

Background: Phthorimaea operculella (potato tuber moth) is among the most destructive pests of Solanaceous crops. Excessive use of chemical pesticides poses environmental and health concerns. Plant-derived materials offer environmentally friendly alternatives with lower ecological risk. Objective: In this research, the insecticidal toxicity of Salvia hydrangea DC. ex Benth essential oil and extract was evaluated on multiple life stages of P. operculella. Additionally, larval penetration and adults’ oviposition preferences were assessed. Methods: Bioassays were conducted at 25 ± 2 °C, 65 ± 5 % relative humidity (RH), and a photoperiod of 8:16 (L:D) in a completely randomized design with five replications per treatment. Probit analysis was used to estimate lethal concentrations (LC50). Results: Adults were the most sensitive to S. hydrangea essential oil (LC50 = 0.33 µl/L air). The plant extract was more toxic to adults (LC50 = 219.72 mg/L) than to eggs (LC50 = 490.24 mg/L). Both the essential oil and the extract reduced larval penetration rates and significantly affected oviposition preferences of adult P. operculella. In addition, among homeopathic preparations tested, Silicea 30 C showed the greatest effect on potato growth parameters. Conclusion: Salvia hydrangea essential oil and extract exhibit substantial activity against P. operculella and can contribute to protecting stored potatoes from infestation. When used in combination with Silicea 30 C, these plant-derived products may be integrated into broader pest management programs. Further studies should evaluate field efficacy, non-target effects, and compatibility with compatible storage practices.