Objective:To determine the larvicidal and adult emergence inhibition activities of castor （Ricinus communis） seed extract against three potential mosquito vectors Anopheles stephensi（An. slephensi）,Culex quinquefa...Objective:To determine the larvicidal and adult emergence inhibition activities of castor （Ricinus communis） seed extract against three potential mosquito vectors Anopheles stephensi（An. slephensi）,Culex quinquefasciatus（Cx.quinquefasciatus） and Aedes albopictus（Ae.albopictus） in India.Methods:The R.communis seed extract was tested,employing WHO procedure,against fourth larval instars of the three mosquito species for 24 h and larval mortalities were recorded at various concentrations（2-64μg/mL）:the 24 h LC<sub>50</sub> values of the R.communis seed extract were determined following Probit analysis.The larval killing,antipupation and adult emergence inhibition rates of the test extract,using a single concentration of 2μLC<sub>50</sub>,were studied at different time periods（24-72 h）:the extract toxicity was tested against a fish.Oreochromis niloticus（O.niloticus）.Results:The R.communis seed extract exhibited larvicidal effects with 100%killing activities at concentrations 32-64μg/mL,and with LC<sub>50</sub> values 7.10.11.64 and 16.84μg/mL for Cx.quinquefasciatus,An.stephensi and Ae.albopictus larvae,respectively. When the larvae were treated with the extract at a single concentration of 2×LC<sub>50</sub>,significant differences were observed,compared to control groups,in rate of pupation（P【0.001） as well as in adult formation（P【0.001）.Conclusions:The present findings suggest that the R.communis seed extract provided an excellent potential for controlling An.stephensi,Cx.quinquefasciatus and Ae. albopictus mosquito vectors.展开更多
Purchasing agricultural insurance and joining agricultural cooperatives are two prevalent instruments used by farmers in China for dealing with agricultural risks. Data from 443 swine farmers in Jiangsu and Henan prov...Purchasing agricultural insurance and joining agricultural cooperatives are two prevalent instruments used by farmers in China for dealing with agricultural risks. Data from 443 swine farmers in Jiangsu and Henan provinces of China were collected. Factors affecting the farmers’ decision to purchase agricultural insurance and join agricultural cooperatives were assessed. The possibility of simultaneous use of both instruments and the potential correlation between these two decisions was considered as well. Results showed that the farmers’ decision to use agricultural insurance and cooperatives was positively correlated, indicating that farmers who purchased agricultural insurance which mainly used to mitigate production risks were more likely to join agricultural cooperatives which more used to share market risks, and vice versa. Farmers’ knowledge of swine insurance and trust in the local government positively impacted the purchase of agricultural insurance, while education, years involved in swine production and scale of swine production positively impacted farmers joining agricultural cooperatives.展开更多
文摘Objective:To determine the larvicidal and adult emergence inhibition activities of castor （Ricinus communis） seed extract against three potential mosquito vectors Anopheles stephensi（An. slephensi）,Culex quinquefasciatus（Cx.quinquefasciatus） and Aedes albopictus（Ae.albopictus） in India.Methods:The R.communis seed extract was tested,employing WHO procedure,against fourth larval instars of the three mosquito species for 24 h and larval mortalities were recorded at various concentrations（2-64μg/mL）:the 24 h LC<sub>50</sub> values of the R.communis seed extract were determined following Probit analysis.The larval killing,antipupation and adult emergence inhibition rates of the test extract,using a single concentration of 2μLC<sub>50</sub>,were studied at different time periods（24-72 h）:the extract toxicity was tested against a fish.Oreochromis niloticus（O.niloticus）.Results:The R.communis seed extract exhibited larvicidal effects with 100%killing activities at concentrations 32-64μg/mL,and with LC<sub>50</sub> values 7.10.11.64 and 16.84μg/mL for Cx.quinquefasciatus,An.stephensi and Ae.albopictus larvae,respectively. When the larvae were treated with the extract at a single concentration of 2×LC<sub>50</sub>,significant differences were observed,compared to control groups,in rate of pupation（P【0.001） as well as in adult formation（P【0.001）.Conclusions:The present findings suggest that the R.communis seed extract provided an excellent potential for controlling An.stephensi,Cx.quinquefasciatus and Ae. albopictus mosquito vectors.
基金supported by the National Natural Science Foundation of China (71673139)the Humanities and Social Science Youth Foundation of the Ministry of Education of China (19YJC790186)the Project of Philosophy and Social Science in the Colleges and Universities of the Jiangsu Province, China (2018SJA0133)
文摘Purchasing agricultural insurance and joining agricultural cooperatives are two prevalent instruments used by farmers in China for dealing with agricultural risks. Data from 443 swine farmers in Jiangsu and Henan provinces of China were collected. Factors affecting the farmers’ decision to purchase agricultural insurance and join agricultural cooperatives were assessed. The possibility of simultaneous use of both instruments and the potential correlation between these two decisions was considered as well. Results showed that the farmers’ decision to use agricultural insurance and cooperatives was positively correlated, indicating that farmers who purchased agricultural insurance which mainly used to mitigate production risks were more likely to join agricultural cooperatives which more used to share market risks, and vice versa. Farmers’ knowledge of swine insurance and trust in the local government positively impacted the purchase of agricultural insurance, while education, years involved in swine production and scale of swine production positively impacted farmers joining agricultural cooperatives.
