Biological Activity Of Extracts From Castor Or Angelica On Vegetable Pests And The Insecticidal Mechanisms

This paper conducted bioactivity experiments of ethanol and water extracts of Castor and Angelica as well as ricinine and ricin on vegetable noctuids and Brevicoryne brassicae L., and assayed the synergistic effect of several synergists on the main insecticidal activity ingredient (ricinine) as well as the effects of ricinine on phosphatase, glutathione S-transferase and acetylcholinesterase in Spodoptera exigua our results is as follows:The toxic efficacy (adjusted mortalities were all above95%) of ethanol extracts of Castor cake on S. exigua, Spotoptera litura Fab. and B. brassicae is excellent; the adjusted mortalities of S. exigua and B. brassicae led to by action of the whole-root Angelica are both above90%, which toxic efficacy isn’t well to S. litura. Meanwhile, the water extracts of Castor cake, the whole-root Angelica, the head-part Angelica and the root-hair Angelica all have excellent toxic efficacy on B. brassicae, which adjusted mortalities were all above90%; however, these four kinds of water extracts all have poorer toxic efficacy on S. litura, and the supreme adjusted mortality is lower than60%; the order of toxic efficacy of the four water extracts on S. exigua is between B. brassicae and S. litura.Toxicity experiment of the main insecticidal activity ingredient of Castor indicated that the adjusted mortalities of ricinine on S. exigua and B. brassicae are up to97%which is far higher that of ricin (lower that60%). The LC50of ricinine to S. exigua and B. brassicae were0.4and0.3respectively,which were lower that of ricin-190.6and60.2respectively, this indicated that the main insecticidal activity ingredient of Castor is ricinine which has better contacting death and antifeeding action but poorer growth inhibition and stomach poisoning action on S. exigua The result of stomach toxicity experiment indicated that the adjusted mortalities after24h and48h were both lower than20%, and that the growth inhibition rates of the ricinine at the supreme concentration of3.8g/L to S. exigua after24h and48h are24.17%and43.10%respectively.The results of enzyme activity assay of S. exigua indicated that the activities of phosphatase, glutathione S-transferase and acetylcholinesterase in S. exigua decreased gradually with the increase of concentration of ricinine. The values of alkaline phosphatase, acid monophosphoesterase, glutathione S-transferase and acetylcholinesterase were0.160U/gprot,0.0062U/gprot,2.98U/gprot and29.14U/mgprot respectively at24hours after0.24g/L ricinine treatment, and deduced to0.135U/gprot,0.00302U/gprot,1.97U/gprot and13.95U/mgprot respectively at24hours after0.38g/L ricinine treatment; the same tendencies that the values of enzyme activity gradually decreased with the increase of concentrations of ricinine, were detected at48and72hours after ricinine treatment. After getting the toxic efficacy of five kinds of synergists (Silok-organosilicon2230, Silok-organosilicon X2, Silok-organosilicon2235, Silok-organosilicon X4and Silok-organosilicon B220) to S. exigua, we screened out the Silok-organosilicon X2and Silok-organosilicon X4which have the poorest toxic efficacy to be the two synergists. When Silok-organosilicon X2were added into ricinine, the toxic efficacies of the compounds to S. exigua and B. brassicae were significantly enhanced, which synerpispic ratios are all higher than1(mostly up to68.19), whereas Silok-organosilicon X4were added into ricinine, the toxic efficacies of the compounds to S. exigua and B. brassicae were also significantly enhanced, which synerpispic ratios are all higher than1(mostly up to16.00).