Evaluation of contact toxicity and persistence of essential oils from Foeniculum vulgare Mill., Teucrium polium Boiss. and Satureja hortensis L. against Callosobruchus maculatus L. adults (Coleoptera: Bruchidae)

Contact toxicity and persistence of essential oils from Foeniculum vulgare Mill. (Apiaceae)، Teucrium polium Boiss. (Lamiaceae) and Satureja hortensis L. (Lamiaceae) were investigated against the adults of cowpea seed beetle، Callosobrochus maculates at 28±2 °C and 60±5% R. H. under dark condition. Essential oils were obtained by hydro-distillation using a clevenger-type apparatus. Contact toxicity was studied against one-day-old adult of C. maculatus with six concentrations at 24hours exposure time. The persistence of insecticidal activity of essential oils was examined for a period of 30 h at the LC99 level. The results of contact toxicities showed that the mortality of adults increased with oil concentration. Males were more susceptible to essential oils than females. The essential oil of F. vulgare proved to be most toxicant with the LC50 values of 390. 38 and 513. 46 µl m-2 against males and females، respectively. The LC50 values of S. hortensis oil were 535. 69 and 640. 99 µl m-2 and the counterpart values of T. polium oil were 1263. 09 and 1469. 72 µl m-2 against males and females، respectively. The results of persistence test of oils revealed that essential oil of S. hortensis was the most persistent and essential oil of T. polium was the least persistent. The persistence of S. hortensis oil could be attributed to its high proportion of oxygenated compounds compared to other oils. The present study demonstrated that these essential oils could be used as appropriate alternatives to control cowpea seed beetle.