[Objective] The aim of this study was to detect the acute toxicity of clethodim, cypermethrin and 2,4-D-butylate. [Method] Chironomus sinicus larvae were exposed to different concentrations of clethodim, cypermethrin ...[Objective] The aim of this study was to detect the acute toxicity of clethodim, cypermethrin and 2,4-D-butylate. [Method] Chironomus sinicus larvae were exposed to different concentrations of clethodim, cypermethrin and 2,4-D-butylate. Survival rate, lethal concentration 50 （LC50） and superoxide dismutase （SOD） activity in the homogenate of the larvae were monitored to detect the toxicity of the pesti- cides. [Result] The survival rates of C. sinicus larvae exposed to cypermethrin and 2,4-D-butylate for 12 h were almost unchanged at different concentrations, but de- creased with concentration increasing 48 h later. For each pesticide, the differences in survival rates of C. sinicus larvae at 48 h were significant. The 48 h LC50 of clethodim, cypermethrin and 2,4-D-butylate to C. sinicus larvae were 1.842, 0.150 and 1.999 mg/L, respectively. The acute toxicity of cypermethrin was the highest a- mong the three pesticides and that of 2,4-D-butylate was the lowest. Clethodim sig- nificantly reduced the SOD content in a dose-dependent manner. 2,4-D-butylate also reduced SOD content in C. sinicus larvae, but the reduction was not significantly re- lated to its dosage. However, cypermethrin showed no significant effect on SOD ac- tivity in C. sinicus larvae.展开更多
Objective:To investigate the acute toxicity of cadmium and lead on larvae of two tropical Chironomid species,Chironomus kiiensis(C.kiiensis) Tokunaga and Chironomus javanus(C. javanus) Kieffer.Methods:Different larval...Objective:To investigate the acute toxicity of cadmium and lead on larvae of two tropical Chironomid species,Chironomus kiiensis(C.kiiensis) Tokunaga and Chironomus javanus(C. javanus) Kieffer.Methods:Different larval instars(first-fourth) were exposed using a sialic non-replacement testing procedures to various concentrations of cadmium and lead.Results: In general,younger larvae(first and second instars) of both species were more sensitive to both metals than older larvae(third and forth instars).The toxic effects of the metals on C.kiiensis and C. javanus were influenced by the age of the larvae(first to fourth instars),types of metals(cadmium or lead) and duration of larval exposure(24,48,72 and 96 h) to the metals.Conclusions:Cadmium was more toxic to the chironomids than lead and C.javanus was significantly more sensitive to both metals than C.kiiensis(P<0.05).展开更多
Objective:To synthesize silver nanoparticles with Colocasia esculenta as a reducing agent and to evaluate their effect against Culex quinquefasciatus and Chironomus sp.Methods:The aqueous extract of Colocasia esculent...Objective:To synthesize silver nanoparticles with Colocasia esculenta as a reducing agent and to evaluate their effect against Culex quinquefasciatus and Chironomus sp.Methods:The aqueous extract of Colocasia esculenta stem was used for nanosynthesis.The synthesized nanoparticles were characterized by UV-Vis spectrophotometry,Fourier-transform infrared spectroscopy,scanning electron microscope,transmission electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and Zeta potential studies.The toxicity of Colocasia esculenta stem extract and the synthesized silver nanoparticles was evaluated against the larval stages of target human filarial vector Culex quinquefasciatus and non-target Chironomus sp.Results:Scanning electron microscopy and transmission electron microscopy studies revealed almost spherical shape of the synthesized silver nanoparticles with size ranging from 13-50 nm.After 24 hours of exposure,the LC50 and LC90 of the plant extract against 4th instars larvae of Culex quinquefasciatus were 745.56 mg/L and 1258.28 mg/L,respectively,which were higher than those of synthesized silver nanoparticles(5.17 mg/L and 17.32 mg/L after 24 h;1.58 mg/L and 13.01 mg/L after 48 h).In addition,the LC50 and LC90 of silver nanoparticles against Chironomus sp.were 9.71 mg/L and 23.15 mg/L after 24 h as well as 2.38 mg/L and 19.49 mg/L after 48 h,respectively.Conclusions:The aqueous stem extract of Colocasia esculenta is a good agent for synthesis of silver nanoparticles,which are almost spherical with size less than 30 nm.The synthesized nanoparticles show good larvicidal activity without any harmful effect on non-target species.展开更多
Bamboo stumps can be a congenial breeding habitat of the mosquitoes. In view of this, a preliminary assessment of the dipteran immatures inhabiting the stumps of bamboo groves in the Darjeeling Himalayas was carded ou...Bamboo stumps can be a congenial breeding habitat of the mosquitoes. In view of this, a preliminary assessment of the dipteran immatures inhabiting the stumps of bamboo groves in the Darjeeling Himalayas was carded out at a spatial scale. Of the 104 stumps of Dendrocalamus hamiltoni surveyed, 70 were found to host immatures of three dipteran species, the mosquitoes Aedes aegypti and Culex quinquefasciatus and the midges Chironomus sp. in varying densities. Though the stumps varied in diameter, in each stump on average 12. 1 immatures were found. The abundance of the immatures was positively correlated with the diameter of the stumps （r = ＋0.382; P 〈 0.001） but negatively with the pH of the water present in the stumps （r = -0.336; P 〈 0.01）. The coefficient of association was found to be ＋8.4 for the Ae. aegypti and Chironomus immatures, while in the rest of the species pair the association seemed to be independent. Thus it can be concluded that the stumps in the bamboo groves of Darjeeling Himalayas provides a favourable habitat for the mosquito and chironomid immatures.展开更多
基金Supported by Fundamental Research Funds for the Central Universities(2572014EA0703)Innovation Experiment Program for University Students from Northeast Forestry University(201310225108)~~
文摘[Objective] The aim of this study was to detect the acute toxicity of clethodim, cypermethrin and 2,4-D-butylate. [Method] Chironomus sinicus larvae were exposed to different concentrations of clethodim, cypermethrin and 2,4-D-butylate. Survival rate, lethal concentration 50 （LC50） and superoxide dismutase （SOD） activity in the homogenate of the larvae were monitored to detect the toxicity of the pesti- cides. [Result] The survival rates of C. sinicus larvae exposed to cypermethrin and 2,4-D-butylate for 12 h were almost unchanged at different concentrations, but de- creased with concentration increasing 48 h later. For each pesticide, the differences in survival rates of C. sinicus larvae at 48 h were significant. The 48 h LC50 of clethodim, cypermethrin and 2,4-D-butylate to C. sinicus larvae were 1.842, 0.150 and 1.999 mg/L, respectively. The acute toxicity of cypermethrin was the highest a- mong the three pesticides and that of 2,4-D-butylate was the lowest. Clethodim sig- nificantly reduced the SOD content in a dose-dependent manner. 2,4-D-butylate also reduced SOD content in C. sinicus larvae, but the reduction was not significantly re- lated to its dosage. However, cypermethrin showed no significant effect on SOD ac- tivity in C. sinicus larvae.
基金funded by Ministry of Science,Technology and Innovation(MOSTI) under the National Science Fellowship(2006-2008)
文摘Objective:To investigate the acute toxicity of cadmium and lead on larvae of two tropical Chironomid species,Chironomus kiiensis(C.kiiensis) Tokunaga and Chironomus javanus(C. javanus) Kieffer.Methods:Different larval instars(first-fourth) were exposed using a sialic non-replacement testing procedures to various concentrations of cadmium and lead.Results: In general,younger larvae(first and second instars) of both species were more sensitive to both metals than older larvae(third and forth instars).The toxic effects of the metals on C.kiiensis and C. javanus were influenced by the age of the larvae(first to fourth instars),types of metals(cadmium or lead) and duration of larval exposure(24,48,72 and 96 h) to the metals.Conclusions:Cadmium was more toxic to the chironomids than lead and C.javanus was significantly more sensitive to both metals than C.kiiensis(P<0.05).
基金supported by WBDST Memo No:126[Sanc.]/ST/P/S&T/15G-10/2015.
文摘Objective:To synthesize silver nanoparticles with Colocasia esculenta as a reducing agent and to evaluate their effect against Culex quinquefasciatus and Chironomus sp.Methods:The aqueous extract of Colocasia esculenta stem was used for nanosynthesis.The synthesized nanoparticles were characterized by UV-Vis spectrophotometry,Fourier-transform infrared spectroscopy,scanning electron microscope,transmission electron microscopy,energy-dispersive X-ray spectroscopy,X-ray diffraction and Zeta potential studies.The toxicity of Colocasia esculenta stem extract and the synthesized silver nanoparticles was evaluated against the larval stages of target human filarial vector Culex quinquefasciatus and non-target Chironomus sp.Results:Scanning electron microscopy and transmission electron microscopy studies revealed almost spherical shape of the synthesized silver nanoparticles with size ranging from 13-50 nm.After 24 hours of exposure,the LC50 and LC90 of the plant extract against 4th instars larvae of Culex quinquefasciatus were 745.56 mg/L and 1258.28 mg/L,respectively,which were higher than those of synthesized silver nanoparticles(5.17 mg/L and 17.32 mg/L after 24 h;1.58 mg/L and 13.01 mg/L after 48 h).In addition,the LC50 and LC90 of silver nanoparticles against Chironomus sp.were 9.71 mg/L and 23.15 mg/L after 24 h as well as 2.38 mg/L and 19.49 mg/L after 48 h,respectively.Conclusions:The aqueous stem extract of Colocasia esculenta is a good agent for synthesis of silver nanoparticles,which are almost spherical with size less than 30 nm.The synthesized nanoparticles show good larvicidal activity without any harmful effect on non-target species.
文摘Bamboo stumps can be a congenial breeding habitat of the mosquitoes. In view of this, a preliminary assessment of the dipteran immatures inhabiting the stumps of bamboo groves in the Darjeeling Himalayas was carded out at a spatial scale. Of the 104 stumps of Dendrocalamus hamiltoni surveyed, 70 were found to host immatures of three dipteran species, the mosquitoes Aedes aegypti and Culex quinquefasciatus and the midges Chironomus sp. in varying densities. Though the stumps varied in diameter, in each stump on average 12. 1 immatures were found. The abundance of the immatures was positively correlated with the diameter of the stumps （r = ＋0.382; P 〈 0.001） but negatively with the pH of the water present in the stumps （r = -0.336; P 〈 0.01）. The coefficient of association was found to be ＋8.4 for the Ae. aegypti and Chironomus immatures, while in the rest of the species pair the association seemed to be independent. Thus it can be concluded that the stumps in the bamboo groves of Darjeeling Himalayas provides a favourable habitat for the mosquito and chironomid immatures.
