The insecticidal activities of two Elsholtzia species plant EOs

Insect infestation is a common issue in stored products. Recently, the use of plant-derived essential oils (EOs) has garnered increasing attention as an eco-friendly alternative to conventional chemical pesticides. In this study, the insecticidal and repellent activities of EOs extracted from different parts (inflorescence and leaf) of Elsholtzia densa Benth. and Elsholtzia ciliata (Thunb.) Hyl. were evaluated against two stored-product pests: Tribolium castaneum and Liposcelis bostrychophila. The EOs were extracted by hydrodistillation and analyzed using gas chromatography-mass spectrometry (GC-MS). Concentration-mortality data were submitted to Probit analysis to estimate the LC50 and LC90 (lethal concentration for 50% and 90% of the insects, respectively). The results of the bioassay showed that ECFI EO had the strongest fumigant toxicity (LC50 values of 6.12 mg/L air and 0.35 mg/L air for T. castaneum and L. bostrychophila, respectively) and repellent effects. In contact toxicity, EDDI EO was most effective against T. castaneum (LD50 = 0.89 μg/adult), while ECFI EO showed highest toxicity to L. bostrychophila (LD50 = 25.48 μg/cm2). These findings emphasized the potential of Elsholtzia species plant EOs as green and efficient alternatives for the control of storage pests.