Fumigant and repellent properties of sesquiterpene-rich essential oil from Teucrium polium subsp capitatum (L.)

Objective: To test fumigant and repellent properties of sesquiterpene-rich essential oil from Teucrium polium subsp. capitatum (L.). Methods: The fumigant toxicity test was performed at (27 +/- 1) degrees C, (65 +/- 5)% relative humidity, and under darkness condition and 24 h exposure time. The chemical composition of the isolated oils was examined by gas chromatography-mass spectrometry. Results: The major compounds were alpha -cadinol (46.2%), caryophyllene oxide (25.9%), alpha muurolol epi (8.1%), cadalene (3.7%) and longiverbenone (2.9%). In all cases, considerable differences in mortality of insect to essential oil vapor were observed in different concentrations and exposure times. Callosobruchus maculatus (C. maculates) (LC50=148.9 mu L/L air) was more susceptible to the tested plant product than Teucrium castaneum (T. castaneum) (LC50=360.2 mu L/L air) based on LC50 values. In the present investigation, the concentration of 3 mu L/mL acetone showed 60% and 52% repellency against T. casteneum and C. maculates adults, respectively. Conclusions: The results suggests that sesquiterpene rich essential oils from the tested plant could be used as a potential control agent for stored-product insects.