Triazophos (TAP) removal in horizontal subsurface flow constructed wetlands (HSCWs) and its accumulation in plants and substrates
SCIENTIFIC REPORTS
Authors: Wu, Juan; Li, Zhu; Wu, Liang; Zhong, Fei; Cui, Naxin; Dai, Yanran; Cheng, Shuiping
Abstract
Triazophos (TAP) is a widely used phosphorus pesticide in China that possesses a potential risk for water pollution. We have studied the removal efficiency of TAP using pilot-scale horizontal subsurface flow constructed wetlands (HSCWs) as well as the contribution of plants, substrates and other pathways to its removal. For TAP concentrations of 0.12 +/- 0.04 mg L-1, 0.79 +/- 0.29 mg L-1 and 3.96 +/- 1.17 mg L-1, the removal efficiencies were 94.2 +/- 3.7%, 97.8 +/- 2.9% and 84.0 +/- 13.5%, respectively, at a hydraulic loading rate (HLR) of 100 mm d(-1); at an HLR of 200 mm d-1, the removal efficiencies were 96.7 +/- 1.3%, 96.2 +/- 1.7% and 61.7 +/- 11.1%, respectively. The isopleth maps of TAP along the direction of flow indicate that most of the TAP removal occurred in the front and middle regions, while the major removal region would move forward with increasing influent TAP. Plant and substrate accumulation accounted for 0.035 +/- 0.034% and 4.33 +/- 0.43% of the total removal, respectively, indicating that over 95% of the TAP removal was achieved through other mechanisms. Thus, these results suggest HSCWs can be an effective approach with which to treat TAP contaminated water. Furthermore, the longitudinal scale and hydraulic conditions, as well as the roles of plants, substrates and microbes and their interactions, should be further considered in the design and application of CWs for pesticide pollution control.
Physiology of insecticide-induced stimulation of reproduction in the rice brown planthopper (Nilaparvata lugens (Stal)): dynamics of protein in fat body and ovary
INTERNATIONAL JOURNAL OF PEST MANAGEMENT
Authors: Hu, Jun-Huan; Wu, Jin-Cai; Yin, Jian-Li; Gu, Hai-Nan
Abstract
This study concerns elucidating the physiology of insecticide-induced stimulation reproduction in Nilaparvata lugens (Stal) (Homoptera : Delphacidae). In insects, vitellogenesis involves the synthesis of the yolk protein precursor in the fat body and its deposition in the oocytes. Our investigations were specifically targeted at the dynamics of the protein content of both the fat body and ovary of adult females developed from the nymphs on rice plants treated with imidacloprid, triazophos and deltamethrin. The results show that the protein contents of the fat body and the ovary increased significantly in insects from rice plants which were subjected to insecticide foliar sprays at both tillering and yellow maturation stages, as compared to the controls from untreated plants. However, the amount of increase varied with insecticide, treatment concentrations and adult age. In general, the percent increase induced by triazophos and deltamethrin was generally greater than that induced by imidacloprid, and the higher concentration induced a greater increase than did the lower concentration. Protein contents of both fat body and ovary increased linearly with adult age.