| Vitex negundo Linn belongs to Vitex Linn.. verbenaceae. It distributes widely in China, and is abundant in the natural resources of Mountain Tai. The best method of extraction and the best extraction solvent of Vitex negundo Linn's insecticital activity materials were studied systematically with aphid (the primary sucking insects).The bioactivity of Vitex negundo dichlorome thane seeds extract to three kinds of aphids was also studied. Furthermore, the extracting of total alkaloid from Vitex negundo and the bioactivity to Aphis gossypii was studied tentatively. The study provide a basis for development and utilization of this insecticidal plant in the future, it has theoretical and practical meaning for the IPM. The main results were as follows:1.Making clear the best extraction solvent and method of the insecticidal activity materials in Vitex negundo Linn. Three kinds of extract technology was used to extract the activity materials in seeds and leaves of Vitex negundo Linn, such as organic solvent extraction, supercritical carbon dioxide extraction and steam distillation. The insecticidal activity experimentation to Aphis gossypii showed that the activity of dichlorome thane seeds extract and leaf essential oils obtained throμgh the steam distillation were the highest, the mortality rates were 86.98% and 85.27% after treated by 250 times dilution for 24h, respectively. Followed by supercritical carbon dioxide extract, methanol extract and petroleum ether extract of leaf and seed, the mortality rates were 74.69%,73.04%,65.01%,54.42%,59.63%,33.82%, respectively. Comprehensive analysis showed that Vitex negundo dichlorome thane seeds extract was optimal method for the extraction.2.The bioactivity of Vitex negundo dichlorome thane seeds extract and four kinds of insecticides to three kinds of aphids were studied. Making clear that the Vitex negundo dichlorome thane seeds extract was highly toxic and deterrent to aphid. The toxicity of five kinds of insecticides to three kinds of aphids was determined with impregnation method in the laboratory conditions. The result showed that the toxicity of the Vitex negundo dichlorome thane seeds to Aphis citricola , Aphis gossypii and Myzus persicae were 0.11, 0.11 and 0.05 times of omethodate , respectively. The results indicated that Vitex negundo dichlorome thane seeds extract was highly toxic to Aphis citricola , Aphis gossypii and was lower to Myzus persicae. Among four kinds of incecticides, the toxicity of imidacloprid to Myzus persicae, Aphis gossypii and Aphis citricola was the highest, and toxicity of imidacloprid showed times of 129.56, 94.47, 144.44 from omethodate, which had the lowest toxicity to three kinds of aphids, toxicity of imidacloprid Thiamethoxam and acetamiprid were between that of imidacloprid and omethodate. toxicity of imidacloprid Thiamethoxam and acetamiprid were between that of imidacloprid and omethodate. The Vitex negundo dichlorome thane seeds extract had a high deterrent effect on Myzus persicae which was only lower than imidacloprid, Deterrent rates of Vitex negundo dichlorome thane seeds extract on Myzus persicae after treated for 24 and 48 hours were 55.75% and 39.44%, for imidacloprid was 69.89% and 65.43%, Deterrent rate of other three kinds of insecticides on Myzus persicae were lower.3.Making clear that Vitex negundo dichlorome thane seeds extract showed synergism to imidacloprid. Toxicity of the mixtures of Vitex negundo dichlorome thane seeds extract and imidacloprid against Aphis gossypii were tested by topical application of capillary tube. The results indicated that the co-toxicity coefficient was 177.45 as the mixtures in 1000:1, and the co-toxicity coefficient was 109.84 as the mixtures in 125:1, It indicated that they have an synergism .4.Toxic effects of total alkaloid extracted from seeds of Vitex negundo Linn to Aphis gossypii were studtied. Total alkaloid was extracted from seeds of Vitex negundo Linn with acid extraetion method. The content of total alkaloid of methanol extract was more than dichlorome thane extract. Total alkaloid from Vitex negundo Linn was highly toxic to Aphis gossypii, LD50 was 0.4231μg/larva, LD50 of Vitex negundo dichlorome thane seeds extract to Aphis gossypii was 0.5076μg/larva, the results indicated that total alkaloid from Vitex negundo Linn was an important active component of Vitex negundo dichlorome thane seeds extract. Total alkaloid from Vitex negundo exhibited the definite antifeedant activities to the Aphis gossypii, the antifeeding rates were 58.33%and 45.28% after treated with concentration of 40mg/ml for 12 hour and 24 hour, the antifeeding rate was reduced to 30.43% after treated for 48 hour, respectively.5.The effect of sublethal dose of total alkaloid from Vitex negundo on the life, reproduction, honeydew and development of Aphis gossypii showed that total alkaloid from Vitex negundo had sustainable and significant inhibition to Aphis gossypii population. Survival rates, honeydew weight of Aphis gossypii and their progeny could be availably reduced treaed with LD30 dosage, and the developmental periods of their progeny was prolonged. fecundity per female of Aphis gossypii of treatment group was 6.66 larves after treated with total alkaloid from Vitex negundo in nine days, but control group was 15.73 larves per female. Aphis gossypii of treatment group were all dead till the tenth day, while the survival rates of Aphis gossypii of control group was still 70%. Total alkaloid from Vitex negundo had no obvious effect on weight of each drop honeydew of alive Aphis gossypii, while had a significant effect on the honeydew excretion frequency of the Aphis gossypii, the honeydew excretion frequency of the treatment group was 13.70drop/larve, control group was 15.78 drop/larve. The instar stage of 1st instar and 4th instar of treament were significantly prolonged, while instar stage of 2nd instar and 3rd instar were similar. The 1st instar mortality rate of treatment were 20%, and the control group was 18%, the average weight of Aphis gossypii were 142μg/larve after treated for 5 days, and control group was 150μg/ larve, weight was obviously decreased.
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