| Through the experiment, these anhydrous alcohol extracts, respectively from Cinnamomum camphora, Pterocarya stenoptera, Parthenocissus tricuspidata and Artemisia argyi, were tested against the tea plant insect pest, Ectropis oblique Prout, for contact toxicity, stomach toxicity, antifeedant activity and ovicidal activity. Ovicidal activity of essential oil from Cinnamomum camphora was also tested. Moreover, the respective influences of these anhydrous alcohol extracts on PPO and POD activities of tea leaves were assessed. The results are as followed.1.The significant ovicidal activities against the eggs of Ectropis oblique Prout were provided by these alcohol extracts respectively from4kinds of plants and the essential oil from Camphor trees, compared to the control group(P<0.01).2.The survivals of2nd instar larvae and4th instar larvae of Ectropis oblique Prout,exposed to the alcohol extract of camphor tree’s branches, were significantly reduced compared to the control group, with the corrected mortality percentage of26.7%(P<0.05) and38.1%(P<0.01), respectively. However, no significant contact toxicity of three other alcohol extracts were detected. Growth of the survivals of2nd instar larvae weren’t significantly suppressed by these alcohol extracts, but slightly suppressed by the alcohol extracts of Parthenocissus tricuspidata. The average increased weight of the survivals of2nd instar larvae, exposed to the alcohol extract from Parthenocissus tricuspidata, was0.4500g,less than0.5410g of the control group. The alcohol extract of camphor tree’s branches showed obvious negative effect on the survivals of4th instar larvae of Ectropis oblique Prout. The average increased weight of the survivals was0.0441g, the average weight of leaf consumption was0.1451g, and the average weight of excretion was0.0880g. The three indexes were respectively smaller than0.0753g,0.2493g and0.1897g of the control group.The inhibition rate of larvae’s weight gain, larvae’s leaf consumption and the weight of larvae’s excretion were respectively41.4%,41.8%and53.6%.3.Both of the alcohol extracts from Parthenocissus tricuspidata and Artemisia argyi showed antifeedant activity against the2nd instar larvae of Ectropis oblique Prout,but only the alcohol extract from Artemisia argyi showed significant antifeedant activity(P<0.05).The calibrated antifeedant rate in the Artemisia argyi group and in the was Parthenocissus tricuspidata group were respectively14.9%and10.5%.4.No significant reduction of the larvae,feed on the tea leaves digged in these alcohol extracts,was found. However, the increased weight of each larvae in the Cinnamomum camphora group was significantly less than in the control group (P<0.05), and the inhibition rate of the larvae’s weight gain in the Cinnamomum camphora group was25.9%.Another difference between the increased weight of the larvae in the Pterocarya stenoptera group and in the control group was found, with24.4%of the inhibition rate of the larvae’s weight gain, but the one was not significant.The average increased weight of the larvae in the Cinnamomum camphora group, the Pterocarya stenoptera group and the control group was respectively0.0294g,0.0307g and0.0397g.5.12hours after spraying the four alcohol extracts over the tea leaves, the activities of polyphenol oxidase in these tea leaves reached their highest values. Among the four alcohol extracts, the extract of Pterocarya stenoptera significantly raised polyphenol oxidase activities in tea leaves(P<0.01), and the average of their highest values was45.14U/g.min-1, higher than40.91U/g.min-1of the control group. The tea leaves, treated with the extract of Pterocarya stenoptera, showed2peak value of polyphenol oxidase activity, respectively at12h and36h. Only one peak value, at12h, was detected in the tea leaves treated with three other alcohol extracts. Except the experimental group of Pterocarya stenoptera, all of the other experimental groups’polyphenol oxidase activities were decreased first and then increased, and the lowest values of the three groups were all at36h. However, polyphenol oxidase activities of tea leaves in the Pterocarya stenoptera group were decreased first, then increased, and decreased last. The highest values of peroxidase activities in the Artemisia argyi group, Pterocarya stenoptera group, Parthenocissus tricuspidata group, Cinnamomum camphora group and the control group were290.4U/g.min-1,256.1U/g.min-1,243.6U/g.min-1,174U/g.min-1and214.6U/g.min-1, respectively. The highest value of peroxidase activity in the Artemisia argyi group was significantly higher than in the Cinnamomum camphora group(P<0.01) and in the control group(P<0.05). Peroxidase activity in the Pterocarya stenoptera group was decreased first, then increased, and decreased last, but were all increased first and then decreased in three other treatment groups. The highest values in the Artemisia argyi group, Parthenocissus tricuspidata group, Cinnamomum camphora group, and Pterocarya stenoptera group occurred at48h,48h,24h and12h.6. In conclusion, the alcohol extracts respectively from4kinds of plants and the essential oil from Cinnamomum camphora showed significant ovicidal activity(P<0.01); significant contact toxicity and growth-inhibiting activity against Ectropis oblique Prout were found in the alcohol extract from Cinnamomum camphora(P<0.05); the alcohol extracts from Artemisia argyi and Parthenocissus tricuspidata showed stronger antifeedant activities against Ectropis oblique Prout than three other alcohol extracts,and the antifeedant activity of the extracts from Parthenoeissus tricuspidata was significantly higher than the control group (P<0.05); Spraying the alcohol extracts from Artemisia argyi and Pterocarya stenoptera over tea leaves could significantly increase peroxidase activity and polyphenol oxidase activity, respectively. |
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