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
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
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.
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.
