The frequency of the infective larvae of Toxocara canis, the common parasite of the dog was assessed in brain portions of male Albino mice ingested two doses： 200 mg/Kg and 400 mg/Kg of potassium dichromate-hexavale...The frequency of the infective larvae of Toxocara canis, the common parasite of the dog was assessed in brain portions of male Albino mice ingested two doses： 200 mg/Kg and 400 mg/Kg of potassium dichromate-hexavalent （VI） as an indicator. Only 2,000 ova of the parasite were inoculated orally to twenty seven healthy young male mice. Frequency of the parasite was tested 13 weeks post-inoculation. Using bio-statistical analysis （one way analysis of variance） the frequency of detected larvae of both doses in the brain portions of the experimental animals showed an insignificant difference （P〉 0.05） in comparison with control. The results indicate the safety of small and mild intoxication doses of the potassium dichromate on distribution of Toxocara canis in brain portions of mice.展开更多
The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual fi...The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual film method. The resistance to two insecticides in the field populations of C. plutellae was not stable under insecticide-free conditions in the insectarium. Compared with susceptible F11 progeny of C. plutellae in the insectarium, the resistance ratios （RR） in F0 parents were 18.4 for fenvalerate and 11.4 for cypermethrin based on LC50 at 9 hours, and 32.8 for fenvalerate and 28.5 for cypermethrin based on LC50 at 24 hours when the parasitoids were left in contact with the insecticides for 1 hour and mortalities were recorded at 9 and 24 hours, respectively. However, the RR in a field population of C. plutellae were 9.2 for fenvalerate and 12.7 for cypermethrin, if the parasitoids were left in contact with the insecticides for 24 hours. The resistances to the two pyrethroids in other field populations collected from Jianxin and Shangjie from November 2000 and July 2004 were also determined. Significant seasonal variations of resistance to the two insecticides in the field populations of C. plutellae were found. The RR were 3.0-18.4 for fenvalerate and 4.8-20.6 for cypermethrin in Jianxin populations from November 2000 to April 2002 based on LC50 at 9 h, and 2.3-13.6 for fenvalerate and 3.6-16.0 for cypermethrin in Shangjie populations from May 2002 to July 2004 based on LC50 at 24 hours. The resistance levels were high in spring and autumn and decreased sharply in summer. In addition, significant recovery from the knocked-down caused by the insecticides was found in the F0 and field populations of C. plutellae which were resistant to fenvalerate and cypermethrin if the parasitoids were left in contact with the pyrethroids for 1 hour. However, no recovery was found in susceptible F11 progeny.展开更多
文摘The frequency of the infective larvae of Toxocara canis, the common parasite of the dog was assessed in brain portions of male Albino mice ingested two doses： 200 mg/Kg and 400 mg/Kg of potassium dichromate-hexavalent （VI） as an indicator. Only 2,000 ova of the parasite were inoculated orally to twenty seven healthy young male mice. Frequency of the parasite was tested 13 weeks post-inoculation. Using bio-statistical analysis （one way analysis of variance） the frequency of detected larvae of both doses in the brain portions of the experimental animals showed an insignificant difference （P〉 0.05） in comparison with control. The results indicate the safety of small and mild intoxication doses of the potassium dichromate on distribution of Toxocara canis in brain portions of mice.
基金Acknowledgments This work was supported by the Natural Science Foundation of Fujian, China （No. B0410016） and China-Japan Cooperation Program by Science and Technique Bureau of Fujian Province, China （20051002）. This work was also supported in part by Grants-in-Aid from the Japan Society for the Promotion of Science （Nos. （A） 11356002 and （C） 14606001） and China-Japan Cooperated Program by JSPS.
文摘The seasonal changes of insecticide resistance and stability in hymenopteran Cotesia plutellae, collected from Jianxin, Fuzhou-City, and Shangjie, Minhou-County, Fujian, China, were assessed by using a dry residual film method. The resistance to two insecticides in the field populations of C. plutellae was not stable under insecticide-free conditions in the insectarium. Compared with susceptible F11 progeny of C. plutellae in the insectarium, the resistance ratios （RR） in F0 parents were 18.4 for fenvalerate and 11.4 for cypermethrin based on LC50 at 9 hours, and 32.8 for fenvalerate and 28.5 for cypermethrin based on LC50 at 24 hours when the parasitoids were left in contact with the insecticides for 1 hour and mortalities were recorded at 9 and 24 hours, respectively. However, the RR in a field population of C. plutellae were 9.2 for fenvalerate and 12.7 for cypermethrin, if the parasitoids were left in contact with the insecticides for 24 hours. The resistances to the two pyrethroids in other field populations collected from Jianxin and Shangjie from November 2000 and July 2004 were also determined. Significant seasonal variations of resistance to the two insecticides in the field populations of C. plutellae were found. The RR were 3.0-18.4 for fenvalerate and 4.8-20.6 for cypermethrin in Jianxin populations from November 2000 to April 2002 based on LC50 at 9 h, and 2.3-13.6 for fenvalerate and 3.6-16.0 for cypermethrin in Shangjie populations from May 2002 to July 2004 based on LC50 at 24 hours. The resistance levels were high in spring and autumn and decreased sharply in summer. In addition, significant recovery from the knocked-down caused by the insecticides was found in the F0 and field populations of C. plutellae which were resistant to fenvalerate and cypermethrin if the parasitoids were left in contact with the pyrethroids for 1 hour. However, no recovery was found in susceptible F11 progeny.
