Biochemical and histopathological studies to assess chronic toxicity of triazophos in blood, liver and brain tissue of rats

Triazophos, O,O-diethyl-1-H-1,2,4-triazol-3-yl phosphorothioate, (TZ) is an organophosphorus pesticide which is extensively used in agriculture for controlling insect pests. Except a FAO/WHO report no study has investigated its short-term toxicity with respect to its potential to cause biochemical and histopathological alterations. The present study was designed to identify the effect of TZ at different doses (1.64, 3.2 and 8.2 mg/kg) on the oxidative stress parameters in blood as well as organs involved in xenobiotic metabolism (liver and brain) following chronic exposure for 90 days. Moreover, the study also delineates the effect of TZ on the histo-architecture of these organs. The results indicated a dose dependent induction (p < 0.001) of oxidative stress, as evident by increased malondialdehyde (MDA) level and compromised antioxidant defense including glutathione S transferase (GST) activity, glutathione (GSH) content and ferric reducing ability of plasma (FRAP) in blood, and increased MDA level with concomitantly decreased GSH content in tissues, following chronic exposure to TZ. The ratio of MDA: FRAP in blood was found to be increased following chronic exposure to TZ and may serve as a suitable indicator of severity of oxidative damage. Onset of such biochemical alterations is one of the early adaptive responses to TZ exposure which leads to histopathological alterations in terms of diffuse fatty changes expanding from mid-zonal area to whole lobule in liver. However, increased oxidative stress did not bring any morphological alteration in brain. The present study concludes that induction of oxidative stress, leading to subsequent histopathological alterations in liver, is an important mechanism underlying the TZ induced chronic toxicity.     

有机磷农药三唑磷人工抗原合成及鉴定

[目的]合成并鉴定有机磷农药三唑磷人工抗原。[方法]采用活泼酯法将三唑磷半抗原（TZPM-Hap）与牛血清蛋白（BSA）和卵血清蛋白（OVA）偶联,制备出免疫抗原（TZPM-A-BSA）和包被抗原（TZPM-A-OVA）,并通过紫外扫描和动物免疫试验对其进行了鉴定。[结果]紫外扫描和动物免疫试验结果表明人工抗原合成成功。[结论]为制备单抗及开发快速、简便的三唑磷ELISA试剂盒奠定了基础。     

20 %三唑磷乳油在荔枝上的残留消解动态及环境安全性评价

采用气相色谱（GC-NPD）分析测定三唑磷在广西、广东两试验点荔枝及荔枝园土壤中的残留及消解动态.2003、2004年两年试验表明,20 %三唑磷EC 500倍喷施1次,荔枝果肉、果皮及全果中的原始沉积量分别为0.0395～0.0718 mg/ kg、4.0502～4.7655 mg/ kg及1.2578～1.9041 mg/ kg,半衰期平均分别为6.8、8.2及9.5 d;在荔枝园土壤中的原始沉积量为0.1358～0.1824 mg/ kg,半衰期为7.4 d.20 %三唑磷500倍对荔枝施药3次,距末次施药后14 d采样测定全果中的残留量为0.7246～0.8254 mg/ kg,低于英国制订的三唑磷在香蕉中的MRL值1 mg/ kg.     

一株三唑磷降解菌mp-4的分离鉴定及降解特性的研究

从长期经有机磷农药污染的土壤中分离到一株能高效降解三唑磷的菌株mp 4,通过生理生化实验和16 S rDNA同源性序列分析将该菌鉴定为苍白杆菌属(Ochrobactrum sp.)。mp 4菌能以三唑磷为唯一碳源生长,对三唑磷的降解率为98. 3%。在25~37℃、pH值为6.6时生长较好,27~32℃、pH7 5~8 8时有较好的降解性能。在水稻大田试验中,米壳的三唑磷残留去除率为91 9%,糙米的三唑磷残留去除率为100%。     

枸杞木虱各虫期对三唑磷的敏感性及其与羧酸酯酶活力关系的研究

用浸渍法和药膜法分别测定了枸杞木虱若虫和成虫对三唑磷的敏感性，并测定了枸杞木虱各虫期羧酸酯酶的活性及三唑磷对其羧酸酯酶的抑制率。枸杞木虱各虫期对三唑磷的LC50随着龄期的增加而增加，各龄期的羧酸酯酶活性也随着龄期的增加而增加。三唑磷对各虫期羧酸酯酶的抑制率除3龄以外，也随着龄期的增加而增加，3龄期的抑制中浓度IC50较其他虫期为高。枸杞木虱羧酸酯酶活性越高，对农药的敏感性越低。     

稻米中三唑磷残留免疫亲合色谱-高效液相色谱分析

【目的】提高三唑磷残留的监测效率。【方法】采用碳酰二咪唑（CDI）将Sepharose CL-4B活化并与纯化的抗三唑磷多克隆抗体共价偶联，合成免疫亲合色谱（IAC）吸附剂并制备对三唑磷具有特异性亲合力的IAC柱。对IAC条件进行了优化，选择0.02 mol·L-1 pH 7.2磷酸盐缓冲液作吸附与平衡介质，60%（体积分数）甲醇水作洗脱剂。【结果】在试验条件下，IAC柱对三唑磷的动态柱容量达1.91 ?g·ml-1床体积，当标样溶液中三唑磷含量为2 ng·ml-1时，经IAC柱富集的效率近250倍。稻米中添加三唑磷0.1 ?g·g-1，提取液以IAC柱分离富集，洗脱液采用高效液相色谱（HPLC）法测定，5次重复测定的平均回收率为102.5%，相对标准偏差4.44%。【结论】成功建立了三唑磷IAC-HPLC分析技术并用于稻米中三唑磷残留的测定。     

Effects of triazophos on biochemical substances of transgenic Bt rice and its nontarget pest Nilaparvata lugens Stål under elevated CO2

The brown planthopper (BPH), Nilaparvata lugens Stål, is a serious rice pest throughout Asia. Recent outbreaks of N. lugens populations were mainly associated with the overuse of pesticides and resistance to insecticides. Warmer global temperatures that are associated with anthropogenic climate change are likely to have marked ecological effects on terrestrial ecosystems. However, the effects of elevated CO₂ concentrations on the biochemical, physiological and nutrient quality of transgenic Bt rice that has been treated with pesticides and on the control efficacy of the pesticides are not understood. The present study investigated changes in soluble sugar content, free amino acid levels, oxalic acid levels, flavonoids levels, and triazophos residues in transgenic Bt rice (TT51) and the control efficacy of triazophos for N. lugens following triazophos foliar spray under conditions of elevated CO₂ (eCO₂). Our findings showed that the soluble sugar content of TT51 treated with triazophos under eCO₂ was significantly higher than that under ambient CO₂ (aCO₂) and also higher than that of the non-transgenic parent (MH63) under aCO₂. However, the results for free amino acid levels were the opposite of those for soluble sugar levels. The oxalic acid and flavonoid contents of rice plants significantly decreased with increases in triazophos concentration, CO₂ concentration, and days after treatment (DAT). The oxalic acid and flavonoid contents of TT51 treated with triazophos under eCO₂ were significantly lower than those under aCO₂ and also lower than those of MH63 under aCO₂. The residue concentration of triazophos varied with CO₂ concentration, rice variety, and DAT. The residues in TT51 treated with 80 ppm of trizaopos under eCO₂ were significantly lower than those under aCO₂ and those in MH63 under aCO₂. The survival rate of nymphs N. lugens in TT51 under eCO₂ was significantly higher than that under aCO₂ and that in MH63 under aCO₂ at 1 DAT or 15 DAT after the release of 2nd instars nymphs. These findings indicated that (1) for TT51, triazophos reduced the resistance of rice plants to N. lugens with an elevated CO₂ concentration, as N. lugens consumed more phloem sap on TT51 plants; (2) triazophos dissipation in TT51 under eCO₂ was significantly faster than that under aCO₂ and that in MH63 under aCO₂; (3) the control efficacy of triazophos for N. lugens significantly decreased under eCO₂. The present findings provide important information for integrated pest management among transgenic varieties.     

两种防治大豆高隆象药剂防效及其对大豆的氧化胁迫效应

在复合种植模式下大豆高隆象的发生率远高于其它害虫,成为造成大豆产量损失的重要因素。本研究用防治大豆高隆象的两种药剂处理大豆,检测大豆氧化胁迫损伤,并调查了间作和净作模式下的虫害发生率和药剂防效。结果表明:药剂处理组中,大豆的生长发育受阻,活性氧(ROS)累积量上升,膜脂通透性增加,抗氧化酶活力增强;药剂处理对大豆叶片均造成了氧化胁迫损伤。喷施三唑磷氧化胁迫损伤效应显著低于喷施氯虫苯甲酰胺和复配;间作模式下大豆高隆象的发生率远低于净作,两种模式下,三唑磷对大豆高隆象的防效均比氯虫苯甲酰胺以及两种药剂复配的效果更好。优选三唑磷作为大豆高隆象成虫的防治药剂。     

25%毒·唑磷乳油防治稻纵卷叶螟药效试验

为探索常规杀虫剂防治稻纵卷叶螟效果下降的替代农药,采用25%毒.唑磷乳油进行了田间药效试验。结果表明,25%毒.唑磷乳油防治稻纵卷叶螟虽然速效性不够理想,但具有持效期长、对2~3龄幼虫防治效果较好的特点,在稻纵卷叶螟偏重发生时,可达到理想的防治效果。未发现25%毒.唑磷乳油对水稻产生毒副作用,因此,是防治稻纵卷叶螟较理想的药剂。