甲拌磷在甘蔗及土壤中的残留动态分析

为了对甲拌磷在甘蔗田施用后的环境安全性进行量化评估及制定安全使用标准,采用田间试验方法,研究了5%甲拌磷颗粒剂在土壤中的消解动态,并对其在甘蔗上使用的安全性作出了评价。采用直接测定甲拌磷及其代谢物和用高锰酸钾作为氧化剂两种方法,用气相色谱火焰光度检测器测定了甲拌磷在甘蔗中的最终残留量和土壤中的消解动态及最终残留量。结果表明甲拌磷在土壤中的半衰期为11~12.3d,在正常使用条件下,不会造成甘蔗残毒污染和土壤的残留积累。     

甲拌磷在小麦植株、籽粒及土壤中的分析方法

本文确立了小麦籽粒、植株和土壤中甲拌磷的分析方法。样本用丙酮提取,加二氯甲烷萃取．通过中性氧化铝和活性炭混合柱层析净化,然后上气相色谱用NPD检测。在小麦籽粒、植株和土壤中的平均回收率分别为85．5％～96．8％,82．7％-88．5％和84．3％-99．4％：变异系数分别为3．93％～7．31％,4．57％～9．15％和5．99％-10．5％;最低检测浓度分别为0．00125．0．005和0．00125mg／kg。     

甲拌磷人工抗原的合成及多克隆抗体制备

以五硫化二磷与无水乙醇为原料,首先制得硫化物中间体,再添加甲醛和2-巯基乙醇进行反应,得到甲拌磷半抗原.在DMAP作为催化剂的条件下,甲拌磷半抗原与丁二酸酐反应,得到甲拌磷半抗原的衍生物.通过碳二亚胺法将甲拌磷半抗原衍生物分别与牛血清白蛋白(BSA)和鸡卵清白蛋白(OVA)共价偶联,得到免疫抗原和包被抗原.用免疫抗原免疫兔子获得了高效价的多克隆抗体,抗血清效价达到了1∶50 000.通过试验确立甲拌磷标准曲线,检测限为6.383μg/L,检测线性范围为6.383～10 000μg/L.     

超声波萃取-气相色谱法对甘蔗中有机磷残留量的测定

[目的]为建立一套快速、简单、准确的有机磷残留量检测方法。[方法]建立了使用超声波强化萃取-氢火焰离子化检测器气相色谱法（FID／GC）检测甘蔗中甲拌磷、特丁硫磷残留量的方法。[结果]当甲拌磷的浓度为0．80～3．20μg／ml，特丁硫磷的浓度为0．96～3．20μg／ml时，它们的浓度与峰面积呈良好的线性关系；样品加标平均回收率为81．58％～84．77％，相对标准偏差（RSD）为4．69％～6．68％。[结论]FID／GC方法操作简便，能满足农药残留量的分析要求：     

Impact of phorate on malate dehydrogenases, lactate dehydrogenase and proteins of epigeic, anecic and endogeic earthworms

The effects of an organophosphate pesticide phorate on cytoplasmic malate dehydrogenase (cMDH), mitochondrial malate dehydrogenase (mMDH), lactate dehydrogenase (LDH), supernatant and mitochondrial proteins of an epigeic (Perionyx sansibaricus), anecic (Lampito mauritii) and endogeic (Metaphire posthuma) earthworms were studied. The treatment of different concentrations (20, 40, 80 and 160 ppm) of phorate for 16 days gradually decreased the specific activities of cMDH, mMDH and LDH as well as cytoplasmic and mitochondrial protein contents. This showed the inhibitory effect of phorate on metabolic enzymes and proteins in tropical earthworms. The inhibition was dose- and time-dependent. The inhibitory response in mitochondrial enzyme (mMDH) and protein was somewhat earlier and more as compared to the inhibitory effect of phorate on cytoplasmic enzymes (cMDH, LDH) and protein. This indicates a greater interference of phorate in cellular respiration of earthworms. The phorate related decreases in enzyme and protein profiles were about 60% and 58% in P. sansibaricus, 54% and 49% in L. mauritii and 47% and 42% in M. posthuma, respectively. It reflects phorate-induced substantial decline in protein synthesis and aerobic and anaerobic capacity of earthworms. The maximum effect of phorate was on epigeic earthworm followed by anecic and endogeic species. The present findings suggest the differential sensitivity of different earthworm species in enzymatic and protein responses to phorate and the sensitivity was associated with the ecophysiological categories of earthworms.     

Management of the root-knot nematode Meloidogyne graminicola infesting rice in the nursery and crop field by integrating seed priming and soil application treatments of pesticides

The study evaluates the effects of seed priming (5 g or ml kg⁻¹ seed) and soil application (2 kg or l ha⁻¹) of eight organophosphate pesticides on rice root-knot disease caused by Meloidogyne graminicola. Seed priming (SP) or soil application (SA) of phorate, carbofuran and chlorpyriphos (1000 J₂ of M. graminicola kg⁻¹ soil) suppressed galling in the rice nursery by 92 and 99%, 80 and 88% and 76 and 80%, respectively, over control. Relatively similar decreases in the galling were recorded when this nursery was grown for four months in the sterilized soils in earthen pots. Rice cv. PS-5 grown in naturally infested soil in earthen pots (1000 J₂ kg⁻¹ soil) became stunted, showing chlorotic foliage, and terminal galls developed on the roots. The treatment of SP + SA 15 + 30 days after planting (DAP) with phorate, carbosulfan, and chlorpyriphos significantly suppressed the root-knot development and improved the plant growth of rice over the controls (P ≤ 0.05). The overall effect of the SP + SA 15 DAP treatments was marginally weaker than the SP + SA 15 + 30 DAP treatments but statistically on par. Under field conditions, the greatest decrease in the galling occurred due to SP + SA 15 + 30 DAP of phorate (69−71%) and SP + SA 15 DAP (65−67%) followed by carbosulfan and chlorpyriphos. The yield of rice plants was also highest with phorate (32−36% and 29−34%) over the control during the two years of the study. The soil population of M. graminicola decreased by 58–84% over four months due to the phorate treatments. The study demonstrates that seed priming with phorate effectively controls nematode infections in the nursery and that soil application at 15 DAP (2 kg ai ha⁻¹) prevents root-knot development in an infested field under irrigated conditions. Use of SP + SA 15 DAP may enable to avoid one soil application of phorate in the field.     

Enzyme activity in soils showing enhanced degradation of organophosphate insecticides

Summary Studies were conducted to determine whether soils that showed enhanced biodegradation of organophosphate insecticides had significantly different enzyme activities from those in the same soils with no previous exposure to the insecticides. Twenty-one pairs of soils were collected from farms in the Midwest where chlorpyrifos, terbufos, fonofos, or phorate had failed to protect corn (Zea mays L) from corn rootworm (Diabrotica sp). Each soil was analyzed for acid and alkaline phosphatase, phosphodiesterase, phosphotriesterase, and dehydrogenase activities. Over 40% of the insecticide-treated soils had higher acid phosphatase activity than the fence row soils which had no previous exposure to the insecticide. Over twothirds of the soils treated with fonofos had higher acid phosphatase and phosphotriesterase activity than the fence row soils. If these enzymes are not directly involved in the biodegradation of the insecticitde, they may be indicative of enhanced biodegradation and may be used to predict which soils may be prone to insecticide failure.Contribution from the Soil-Microbial Systems Laboratory, Natural Resources Institute, USDA-ARS, Beltsville, MD 20705, USA     

甲拌磷在甘蔗及土壤中的残留动态分析

为了对甲拌磷在甘蔗田施用后的环境安全性进行量化评估及制定安全使用标准,采用田间试验方法,研究了5%甲拌磷颗粒剂在土壤中的消解动态,并对其在甘蔗上使用的安全性作出了评价。采用直接测定甲拌磷及其代谢物和用高锰酸钾作为氧化剂两种方法,用气相色谱火焰光度检测器测定了甲拌磷在甘蔗中的最终残留量和土壤中的消解动态及最终残留量。结果表明甲拌磷在土壤中的半衰期为11～12.3d,在正常使用条件下,不会造成甘蔗残毒污染和土壤的残留积累。     

The basis for the safening of clomazone by phorate insecticide in cotton and inhibitors of cytochrome P450s

Clomazone may be safely used in cotton to manage weeds when applied following treatments of the organophosphate insecticides phorate or disulfoton. The loss of chlorophyll and carotenoids with 6 days of 100 nM clomazone treatment of cotton seedlings was partially prevented with phorate in hydroponic solution in a rate-dependent manner. In a study to examine the timing of safening from a one-day clomazone (100 nM) treatment, maximum safening was achieved when phorate (50 μM) was applied the same day as clomazone. Phorate decreased metabolism of ¹⁴C-clomazone to polar metabolites in excised cotton shoots and shoots of intact cotton plants. Microsomal studies of corn shoots showed an NADPH-dependent/cytochrome P450 reaction was inhibited by phorate. Additional studies with corn microsomes, corn seedlings and cotton seedlings supported the basis of clomazone safening is the inhibition of toxic clomazone metabolism by P450 inhibitors.