Comparing oral toxicity of Apium graveolens and Falcaria vulgaris extracts with Bt against Phthorimaea operculella

In this study, toxicity of hexane, ethyl acetate and methanol extracts of Apium graveolens and Falcaria vulgaris were compared with the microbial insecticide Bt against 1st instars of Phthorimaea operculella. The aerial parts of plants dried in shadow, and were extracted using the above mentioned solvents via maceration method. The results revealed that after 24 hours’ exposure, ethyl acetate extracts of both plants were significantly more toxic than other extracts with LC50 values of 0.21 and 0.38 mg/l respectively. These extracts in addition with hexane extracts also were more toxic than Bt after 48 and 72 hours. The dose-response line slopes of methanol extracts of both plants were more than other agents otherwise less toxic than them. The best relative potency calculated as 69.76 fold in comparing toxicity of Bt with ethyl acetate extract of A. graveolens which indicates the toxicant potential of this extract against PTM larvae. According to the results, Ethyl acetate extracts of both plants showed more AchE inhibitory activity in comparing with other extracts and 60-70% inhibition recorded by LC70 concentration of these extracts. Adults emergence reduced by 68-80% in LC70 concentration of ethyl acetate extracts of both plants. Life span of PTM larvae which treated with methanol and ethyl acetate extract of both plants, increased by 8 days in comparing with controls.