Evaluation of fumigant activities of some lamiaceae species essential oils against German cockroach (Blattella germanica L.)

The aim of this thesis was to evaluate the fumigant activity of essential oils obtained from aerial parts of three Lamiaceae plants [Mentha longifolia L. subsp. typhoides (Brig.) Harley, Dorystoechas hastata Boiss. & Heldr. ex Bentham (endemic) and Origanum minutiflorum O. Schwarz et. H. Davis (endemic)], naturally grown in the Antalya region, were evaluated on 10-15 days-old (2nd or 3th instar) nymphs of German cockroach (Blattella germanica L.). Fumigant activity was evaluated by exposing the nymphs to the vapors emitted by 25-500 µL/L of essential oil in a closed area. In addition, the essential oils used in this thesis were extracted by Clevenger-type hydrodistillation and the chemical composition of the essential oils were analyzed by gas chromatography-mass spectrometry (GC: MS). While the major compounds found in D. hastata essential oil were 1,8-cineole, borneol and camphor, the main constituent of the O. minutiflorum essential oil was carvacrol, and major components in the essential oil of M. longifolia subsp. typhoides were cis-piperitone epoxide and piperitenone oxide. When all the essential oils were compared on the basis of fumigant toxicity, D. hastata essential oil is more statistically significant fumigant than the other two essential oils at 100, 200 and 300 µL/L concentrations. There is no statistical significant difference at these concentrations between M. longifolia and O. minutiflorum essential oils. Moreover, at the application concentrations of 400 and 500 µL/L, the most toxic essential oil was found D. hastata. This essential oil was followed M. longifolia and O. minutiflorum essential oils, respectively. Dorystoechas hastata essential oil resulted in about 85% mortality at the concentrations of ?200 µL/L. O. minutiflorum essential oil exhibited a very low level of fumigant toxicity (?14.4%) against the German cockroach. The highest toxic effects of M. longifolia essential oil were seen at the concentrations of 400 and 500 µL/L (30.0%). In conclusion, of the three essential oils tested, D. hastata essential oil was the most effective against B. germanica nymphs at this study. More studies are needed to show the insecticidal activity of the essential oils obtained from different plant species against cockroaches. In future, it is hoped that environmentally friendly new insecticides can be developed from essential oils.