Synthetic Pyrethroids: Toxicity and Metabolism

Abstract

The compositions of 12 essential oils (EOs) obtained by hydrodistillation of edible fruits and herbs were analyzed by gas chromatography/mass spectroscopy (GC/MS). The insecticidal activity of each oil against the house fly Musca domestica was evaluated by placing flies in a glass jar with a screw cap that held a piece of EO-treated cotton yarn. The dose necessary to kill 50% of flies (LC50) in 30 min was determined at 26 ± 1°C Twelve EOs and 17 individual terpenes were assayed against M. domestica, showing LC 50 values ranging from 3.9 to 85.2 and from 3.3 to >100 mg/dm 3, respectively. EO from Citrus sinensis was the most potent insecticide (LC50 =3.9 mg/dm3), followed by EOs from C. aurantium (LC50 = 4.8 mg/dm3) and Eucalyptus cinerea (LC50 = 5.5 mg/dm3). According to GC/MS analysis, limonene (92.47%), linalool (1.43%), and β-myrcene (0.88%)) were the principal components of C. sinensis EO. Limonene was also the principal constituent (94.07%) of C. aurantium, while 1,8-cineole (56.86%) was the major constituent of E. cinerea EO. 1,8-Cineole was most active against M. domestica (LC 50=3.3 mg/dm3), while (4R)(+)-limonene, was moderately active (LC50 = 6.2 mg/dm3). Dimethyl 2,2-dichlorovinyl phosphate (DDVP) selected as a positive control, showed an LC50 of 0.5 mg/dm3. EOs from C. sinensis, C. aurantium, and E. cinerea show promise as natural insecticides against houseflies. Musca domestica;. natural insecticide;. essential oils;. Citrus sinensis;. Eucalyptus cinerea.