Chemical composition of Rosmarinus and Lavandula essential oils and their insecticidal effects on Orgyia trigotephras (Lepidoptera, Lymantriidae)

Objective: To evaluate toxic activities of essential oils obtained from Rosmarinus officinalis and Lavandula stoechas against the fourth larval instars of Orgyia trigotephras. Methods: A total of 1 200 larvae were divided into three groups I, Group I was to investigate the effect of extracted essential oils from these aromatic plants as gastric disturbance. Bacillus thuringiensis and ethanol were used as control group. Group 11 was used as contact action and Group [if was used as fumigant action. Decis and ethanol were used as control group. During the three experiments, the effect of essential oils on larvae was assessed. Results: The chemical composition of essential oils from two medicinal plants was determined and, their insecticidal effects on the fourth larval state of Orgyia trigotephras were assessed. The two simples presented an insecticidal activity, nevertheless Rosnzarinus officinalis essential oil was less efficient compared to Lavandula stoechas one are discussed. Conclusions: The relationship between the chemical composition and the biological activities is confirmed by the present findings. Therefore the potential uses of these essential oils as bioinsecticides can be considered as an alternative to the use of synthetic products