| Vitex negundo Linn. belongs to Vitex Linn.Verbenaceae. It distributes widely in China, and is abundant in the natural resources of Mount Tai. Tested with Plutella xylostella L. and Pieris rapae L.that two are main insect pests on the crucifer vegetable crops, the method of extracting insecticidal active material from Vitex negundo, and the action mode of the extracting material to the pests were studied systematically. The action mechanism of the extracting material to the pests was researched tentatively also. The study provides the basis for the development and utilization of this insecticidal plant in the future, and it has theoretical and practical meaning for the IPM. The main results are as follows:1. Confirming the condition and method of extracting insecticidal active material from Vitex negundo Linn. The cold-dip method was used to extract the active material in the seeds and leaves of Vitex negundo Linn by using some organic solvents with different polarity, such as dichlorome thane, acetone, petroleum ether, carbinol and alcohol. The creams pure material was obtained from the extract liquor by percolation, purification and concentration. The proper substituted solvent and emulsification were selected. The insecticidal active deternination to Plutella xylostella showed that the activity of dichlorome thane seed extract was the highest, followed by dichlorome thane leaves extract, then by the petroleum ether and carbinol extracts, and the acetone and alcohol extracts were the lowest. The proper temperature of distilling was 25℃. Comprehensive analysis showed that Vitex negundo seeds are the best raw materials of insecticidal activity ingredient.2. The extract had the high toxic to diamondback moth (Plutella xylostella), cabbage white (Pieris rapae), English green aphid(Sitobion avenae)and green peach aphid (Myzus persicae),but was safe to the natural enemy, multicolored ladybeetle (Harmonia axyridis). The 3rd instars of Plutella xylostella, 4th instars of Pieris rapae, wingless adult of Sitobion avenae and Myzus persicae were treated at 4mg/ml dosage with dichlorome thane seeds extract. After 24 hours, the results were that their rectified mortality were 78.3%,91.7%,79.6% and 75.7% respectively.With the same dosage treating Harmonia axyridis adults and 4th instars, it's mortality was 0% and 15% respectively. So it's very safe to adults and had little effect on survival of its larvae.3. Contact toxicity of extracts from Vitex negundo to the different instar larvae of Plutella xylostella and Pieris rapae were researched. LC50 of dichlorome thane seed extract to the 1st, 2nd, 3rd, and 4th instar larvae of Plutella xylostella were 0.474 mg/ml, 0.835 mg/m, 1.707mg/g and 1.832 mg/ml respectively, and it's LC50 to the 2nd and 4th instar larvae of Pieris rapae were 0.641 mg/ml and 1.328mg/g, respectively. There was different toxicity among the different instars, and it's toxicity to the 1st instar larvae of Plutella xylostella was 3.86 time higher than to that of the 4th larvae, and it's toxicity to the 2nd instar larvae of Pieris rapae was 2.07 time higher than to that of the 4th instar larvae. 4. The extracts had evident oviposition deterrence to the adults of Plutella xylostella. The results showed that the oviposition deterrence of carbinol leave extract and dichlorome thane seeds extract were the highest and at 4mg/ml dosage, the oviposition deterrence ratioes were 61.56% and 55.40%, and they had high residual efficacy duration. Treated after 108 hours, the oviposition deterrence of the two extracts were above 40%. The oviposition deterrence ratio of alcohol leave extract was 49.6% in 24 hours. The oviposition deterrence ratio of carbinol seed extract, petroleum ether extracts and alcohol seed extract, were very low.5. The dichlorome thane seed extract from Vitex negundo, had no evident effect on the eggs of Plutella xylostella and Pieris rapae.,at 4mg/ml dosage. The extracts had no stomachic action to the larvae of Plutella xylostella and Pieris rapae.6. The extracts from Vitex ne...
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