ABSTRACT
Dermal exposure is regarded as a potentially significant but understudied route for pesticides uptake in terrestrial reptiles. In this study, a native Chinese lizard was exposed to control, diflubenzuron or flufenoxuron contaminated soil (1.5â¯mgâ¯kg-1) for 35â¯days. Tissue distribution, liver lesions, thyroid hormone levels and transcription of most target genes were examined. The half-lives of diflubenzuron and flufenoxuron in the soil were 118.9 and 231.8â¯days, respectively. The accumulation of flufenoxuron in the liver, brain, kidney, heart, plasma and skin (1.4-35.4â¯mgâ¯kg-1) were higher than that of diflubenzuron (0-1.7â¯mgâ¯kg-1) at all time points. The skin permeability factor of flufenoxuron was more than 20-fold greater than that of diflubenzuron at the end of exposure. However, the liver was more vulnerable in the diflubenzuron exposure group. The alterations of triiodothyronine (T3) and thyroxine (T4) level after diflubenzuron or flufenoxuron exposure were accompanied with the changes in the transcription of target genes involved not only in hypothalamus-pituitary-thyroid (HPT) axis (sult, dio2, trα and udp) but also in metabolism system (cyp1a and ahr). These results indicated that flufenoxuron produced greater body burdens to lizards through dermal exposure, whereas both diflubenzuron and flufenoxuron have the potential to disturb metabolism and thyroid endocrine system.
Subject(s)
Diflubenzuron/toxicity , Lizards/metabolism , Pesticides/toxicity , Phenylurea Compounds/toxicity , Soil Pollutants/toxicity , Animals , Body Burden , Brain/metabolism , Diflubenzuron/blood , Diflubenzuron/pharmacokinetics , Kidney/metabolism , Liver/drug effects , Liver/metabolism , Liver/pathology , Male , Myocardium/metabolism , Pesticides/blood , Pesticides/pharmacokinetics , Phenylurea Compounds/blood , Phenylurea Compounds/pharmacokinetics , Soil Pollutants/blood , Soil Pollutants/pharmacokinetics , Thyroxine/blood , Triiodothyronine/bloodABSTRACT
Three rodent feed-through studies were conducted to evaluate the efficacy of insecticides to control Phlebotomus argentipes (Diptera: Psychodidae). The initial test evaluated diflubenzuron, eprinomectin, fipronil and ivermectin as feed-through treatments in Rattus rattus (Rodentia: Muridae). In the preliminary trial, all four insecticides yielded 100% mortality of P. argentipes larvae within 20 days of exposure to treated rodent faeces. Based upon the initial results, fipronil was evaluated further as a feed-through utilizing Bandicota bengalensis (Rodentia: Muridae). The B. bengalensis trial evaluated fipronil against both adult and larval sandflies at 250 p.p.m., 100 p.p.m. and 50 p.p.m. The results showed the fipronil treatment to have 100% efficacy against larvae up to 20 days post-treatment and over 74% efficacy against adult sandflies presented with B. bengalensis faeces up to 10 days post-treatment at all three dosage levels. The results of the three studies suggest that all four insecticides may be useful tools with which to control Leishmania vector populations.
Subject(s)
Animal Feed/analysis , Diflubenzuron/pharmacology , Insect Control/methods , Insecticides/pharmacology , Ivermectin/pharmacology , Phlebotomus/drug effects , Pyrazoles/pharmacology , Administration, Oral , Animals , Diflubenzuron/blood , Feces/chemistry , Feeding Behavior/drug effects , Female , Insecticides/blood , Ivermectin/analogs & derivatives , Ivermectin/blood , Larva/drug effects , Male , Murinae/metabolism , Phlebotomus/growth & development , Pyrazoles/blood , Rats/metabolism , Time FactorsABSTRACT
A selective and specific high-pressure liquid chromatographic (HPLC) method for the simultaneous assay of Clanfenur and its metabolites in biological fluids of interest has been developed which is suitable for routine analysis, using micro volumes (0.1 ml) of plasma samples only. After protein precipitation the extract is analysed by reversed-phase HPLC with UV detection. Excellent recovery, linearity, accuracy and precision (less than 5% for plasma) are achieved by the assay which is able to quantify Clanfenur and its metabolites in plasma at concentrations between 0.025 and 5.0 mg l-1.
