间接竞争ELISA方法测定水中2，4-D的研究

以2,4-D-BSA为包被抗原,采用自行制备的2,4-D单克隆特异性抗体6D11建立了水中2,4-D的间接竞争 ELISA检测方法．本研究比较了包被抗原2,4-D-BSA浓度分别为240ng·mL-1、120ng·mL-1和60ng·mL-1的反应体系和竞争反应时间为60min和15min的间接竞争ELISA剂量-反应曲线,确定了当包被抗原浓度为60 ng·mL-1、竞争反应时间为15min时,剂量-反应曲线的IC50值较低．采用上述实验条件分别测定了由PBS缓冲溶液、饮用水、清华大学地下水和圆明园福海地表水配制的2,4-D标准溶液的剂量．反应曲线,发现实际水样的基质效应对检测结果的影响较大;采用实际水样和PBS缓冲溶液配水在含有5％乙醇的PBS缓冲体系中反应的方法,基本上消除了基质效应对检测结果的干扰．采用上述优化试验条件,测定2,4-D浓度分别为0．5mg·L-1、0．125mg·L-1和0．03mg·L-1的加标样品,测定数据的准确度符合痕量有机污染物定量检测对准确度的要求,但是平行样品测定数据之间的变异系数较大,需要进一步改进检测方法,用于实际水样的检测．     

低质量浓度除草剂2，4滴丁酯处理对土壤动物群落结构的影响

土壤动物是土壤污染的敏感指示生物,对土壤环境变化表现出比较灵敏的反映,为了解低质量浓度除草剂对土壤生态系统的影响,进一步推动除草剂使用的安全性评价研究,采用除草剂2,4滴丁酯对土壤动物群落进行室内染毒模拟试验,参照农田施用常规参考质量浓度,设置4个质量浓度梯度和一个不喷施除草剂的对照质量浓度,质量浓度最高限于参考喷施质量浓度的3~4倍,一次染毒后分别于12、24、48和72 h后对土壤动物进行分离并对群落结构特征进行分析。试验共获得土壤动物18655个,隶属于2门,4纲,12目,群落结构分析结果表明低质量浓度2,4滴丁酯导致土壤动物个体数和类群数有所减少,但减少的程度并不大。个体数量变化与质量浓度增高之间呈现较明显负相关（r=-0.856,P〈0.05）,种类数变化与质量浓度之间不具有明显的相关性,土壤动物种类数的减少主要取决于稀有类群和极稀有类群,数量的变化则主要是优势类群和常见类群的增减。2,4滴丁酯的施加使得土壤动物群落多样性指数和优势度指数降低,均匀度指数增高。土壤动物个体数量和类群数量变化与染毒后经历的时间之间并未表现出明显的规律性,染毒后不同时间土壤动物优势度指数相差较大,而多样性指数和均匀度指数在不同历时时间段内相差不大。综合各分析结果能够看出,低质量浓度2,4滴丁酯处理会对土壤动物群落造成一定影响,但影响程度并不大。     

Effect of 2,4-dichlorophenoxyacetic acid on growth, protein and chlorophyll-a content of Chlorella vulgaris and Spirulina platensis cells

In this study, effect of different 2,4 -dichlorophenoxyacetic acid (2,4-D) concentrations (0.0, 9.10(-5), 9.10(-4), 9.10(-3) and 9.10(-2) mM) on growth rate, content of protein and chlorophyll-a in Chlorella vulgaris and Spirulina platensis cells was investigated. The most stimulatory effect on growth rate, protein and pigment ratio of C. vulgaris and S. platensis was observed at 9.10(-4) mM concentrations of 2,4-D. The results show that low concentrations of 2,4-D have hormonal effect due to being a synthetic auxin. Cell number protein and pigment rates were inhibited at 9.10(-2) mM concentration in C. vulgaris. Such parameters were inhibited in S. platensis, both at 9.10(-3) and 9.10(-2) mM 2,4-D concentrations. This is due to herbicidal effect of high concentrations of 2,4-D. S. platensis was found to be more sensitive than S. vulgaris to 2,4-D applications. The use of algae as bio-indicators in herbicide contaminated fresh water habitats, was discussed.     

Production of puerarin and isoflavones in cell suspension cultures of Pueraria lobata (Willd.): effects of medium supplementation with casein hydrolysate and coconut milk

Callus induced from leaf explants of Pueraria lobata seedlings were suspended in Gamborg B5 medium supplemented with 1 mg l(-1) 2,4-dichlorophenoxyacetic acid, 1 mg l(-1) naphthalene acetic acid, 0.5 mg l(-1) kinetin and 30 g l(-1) sucrose. The effects of coconut milk and casein hydrolysate (CH) on cell growth and yields of puerarin and isoflavones in cells suspension were studied. The contents of total isoflavones and puerarin in suspension cultures were determined by spectrophotometry and HPLC. Coconut milk (10%, filter sterilized) decreased the growth of cell cultures and the accumulation of total isoflavones, while 0.2% CH promoted the growth of cell cultures and the accumulation and release of puerarin and total isoflavones. The total yield of puerarin and isoflavones were 34% and 40.8% higher than in the control, respectively. The optimum medium for cell cultures of leaves of P. lobata seedlings was B5 liquid medium supplemented with 2% sucrose, 1.0 mg l(-1) 2,4-D, 1.0 mg l(-1) NAA, 0.5 mg l(-1) kinetin and 20 mg l(-1) CH. The procedure use is a potentially useful for the production of isoflavones.     

除草剂2，4-D在土壤中吸附常数的测定

介绍除草剂２,４－Ｄ在４种不同有机碳含量、不同ｐＨ值的土壤中吸附常数的测定．结果表明,４种土壤对２,４－Ｄ的吸附等温线均符合非线形的Ｆｒｅｕｎｄｌｉｃｈ吸附等温式,其有机碳吸附常数的平均值为２３９．６．２,４－Ｄ的吸附常数与土壤有机碳含量呈正相关,土壤的ｐＨ值对２,４－Ｄ的吸附也有一定的影响．     

典型酚类化合物对土壤跳虫的慢性毒性

以跳虫Folsomia candida为受试物种,基于其28 d繁殖试验评价了12种典型酚类化合物的慢性毒性效应。结果表明,在所设浓度范围内,除间苯二酚外的其他酚类对跳虫繁殖均存在不同程度的抑制效应。氯酚类对跳虫慢性毒性最大,2,4-二氯酚、2-氯酚、2,4,6-三氯酚对跳虫繁殖毒性的EC50分别为5.94、10.2、19.7 mg·kg-1;其次为烷基酚类,2,4-二甲基酚、3-甲基酚、壬基酚对跳虫繁殖毒性的EC50分别为21.7、35.1、50.5 mg·kg-1。苯酚的毒性较上述烷基酚低,EC50值为71.7 mg·kg-1。其他取代酚—包括2-萘酚、4-硝基酚、邻苯二酚对跳虫繁殖的EC50分别为95.4、133、306 mg·kg-1。双酚A仅在最高浓度(500 mg·kg-1)处理下对跳虫繁殖有显著影响。     

土壤外源Sb(Ⅲ)的老化对其形态和跳虫(Folsomia candida)毒性的影响

老化是影响土壤重金属生物可利用性和毒性的重要因素。为了解老化对土壤Sb形态和毒性的影响,结合化学分析和生物测试,以模式生物跳虫(Folsomia candida)为受试生物,研究了北京潮土中外源Sb(Ⅲ)分别老化7 d、60 d后价态、水溶态和急性/慢性毒性的变化。结果表明,老化仅7 d后,土壤较低浓度的Sb主要以Sb(Ⅴ)存在,而浓度较高(1 600、2 400、4 800 mg·kg-1)时Sb(Ⅴ)分别仅占47.4%、27.5%和2.2%,但老化长达60 d后,浓度最高(4 800 mg·kg-1)的土壤中Sb(Ⅴ)的比重上升到38.1%,其他浓度处理的土壤中,均以Sb(Ⅴ)为主。随着老化时间的延长,土壤中水溶态Sb含量占总Sb的比例显著降低。与土壤老化过程中毒性较大的Sb(Ⅲ)向毒性较小的Sb(Ⅴ)转化与水溶态Sb含量下降相一致,Sb对跳虫的毒性随老化时间的延长明显减弱:7 d老化后土壤Sb对跳虫急性存活的半数致死浓度(LC50)为2 105 mg·kg-1,对跳虫慢性存活的LC50为683 mg·kg-1,对跳虫繁殖的半数效应浓度(EC50)为307 mg·kg-1;老化60 d后土壤Sb对跳虫急性存活、慢性存活的LC50均大于设置的最高浓度,对跳虫繁殖的EC50为1 419 mg·kg-1。因此,对于Sb这种变价金属而言,当进行土壤Sb生态毒性评价时,为避免高估其生态风险,考虑老化作用显得尤为重要。     

6种硝基苯化合物对海洋生物的急性毒性研究（Study on the Acute Toxicity of Six Nitrobenzenes to Marine Organisms）

为研究硝基苯化合物对海洋生物的毒性,选择了6种代表性硝基苯化合物对小球藻(Chlorella vulgaris)、黑鲷(Sparus macrocep)幼鱼和螠蛏(Siliqua minima)幼体进行了急性毒性实验,获得了这些化合物对这些生物体的急性毒性数据及环境安全浓度.实验结果表明:2,4-二硝基甲苯、2,4-二硝基氯苯、2,4-二氯硝基苯和邻二硝基苯对小球藻48h半数抑制浓度(EC50)分别为0.50、0.21、2.44和0.10mg·L-1,毒性顺序为邻二硝基苯(剧毒)>2,4-二硝基氯苯(剧毒)>2,4-二硝基甲苯(剧毒)>2,4-二氯硝基苯(高毒).2,4-二硝基氯苯、邻二硝基苯、2,4-二硝基甲苯、2,4-二氯硝基苯、对硝基苯胺和硝基苯对黑鲷幼鱼的96h半数致死浓度(LC50)分别为0.14、0.15、4.45、1.37、11.52和5.71mg·L-1,其安全浓度分别为:0.001、0.002、0.04、0.01、0.12、0.06mg·L-1,毒性顺序为2,4-二硝基氯苯(剧毒)>邻二硝基苯(剧毒)>2,4-二氯硝基苯(高毒)>2,4-二硝基甲苯(高毒)>硝基苯(高毒)>对硝基苯胺(中毒).2,4-二硝基氯苯、2,4-二硝基甲苯、2,4-二氯硝基苯、邻二硝基苯、硝基苯和对硝基苯胺对幼蛏的96h LC50分别为0.39、13.20、3.45、15.56、86.90和148.87mg·L-1,安全浓度分别为:0.004、0.13、0.03、0.16、0.87、1.49mg·L-1,毒性顺序为2,4-二硝基氯苯(剧毒)>2,4-二氯硝基苯(高毒)>2,4-二硝基甲苯(中毒)>邻二硝基苯(中毒)>硝基苯(中毒)>对硝基苯胺(低毒).     

除草剂对优质小麦品质和旗叶保护酶的调控效应

通过田间试验研究了4种除草剂在正常剂量下对2个优质小麦品种品质性状、蛋白质组分和旗叶保护酶系的影响.结果表明,整个籽粒灌浆过程中,2,4-D丁酯处理使籽粒蛋白质含量一直较高,世玛处理在灌浆前中期籽粒蛋白质含量较高,但灌浆末期籽粒蛋白质含量最低,巨星和骠马处理影响较小.2,4-D丁酯处理使收获时籽粒蛋白质含量及组分最高,湿面筋含量、沉降值、吸水率、稳定时间和评价值等加工品质最好,世玛处理则使营养品质和加工品质最差,巨星和骠马处理影响相对较小.籽粒灌浆期间,2,4-D丁酯处理使旗叶SOD、CAT和POD活性一直较低,尤其是籽粒灌浆末期活性最低;其它除草剂使旗叶SOD、CAT和POD活性在不同灌浆时期存在差异:灌浆前中期,骠马处理使3种保护酶活性最高;灌浆后期,世玛处理使旗叶中保护酶活性下降缓慢,且活性最高.籽粒灌浆期前期,4种除草剂对旗叶中MDA含量的影响是:世玛＞骠马＞CK＞巨星＞2,4-D丁酯,灌浆中后期,2,4-D丁酯和巨星处理使MDA含量快速提高,世玛和骠马处理使MDA含量升高相对较慢,到灌浆末期,2,4-D丁酯使MDA含量最高,世玛处理最低.图5表2参22     

A pulsed switching peroxi-coagulation process to control hydroxyl radical production and to enhance 2,4-Dichlorophenoxyacetic acid degradation

• A new pulsed switching peroxi-coagulation (PSPC) system was developed. • The EC_T for 2,4-D removal in the PSPC was lower than that in the EF. • The iron consumption for 2,4-D removal in the PSPC was lower than that in the PC. The aim of this study was to develop a new pulsed switching peroxi-coagulation system to control hydroxyl radical (?OH) production and to enhance 2,4-Dichlorophenoxyacetic acid (2,4-D) degradation. The system was constructed with a sacrifice iron anode, a Pt anode, and a gas diffusion cathode. Production of H₂O₂ and Fe²⁺ was controlled separately by time delayers with different pulsed switching frequencies. Under current densities of 5.0 mA/cm² (H₂O₂) and 0.5 mA/cm² (Fe²⁺), the ?OH production was optimized with the pulsed switching frequency of 1.0 s (H₂O₂):0.3 s (Fe²⁺) and the ratio of H₂O₂ to Fe²⁺ molar concentrations of 6.6. Under the optimal condition, 2,4-D with an initial concentration of 500 mg/L was completely removed in the system within 240 min. The energy consumption for the 2,4-D removal in the system was much lower than that in the electro-Fenton process (68±6 vs. 136±10 kWh/kg TOC). The iron consumption in the system was ~20 times as low as that in the peroxi-coagulation process (196±20 vs. 3940±400 mg/L) within 240 min. The system should be a promising peroxi-coagulation method for organic pollutants removal in wastewater.     

8种常见农药对海胆胚胎各发育期的急性毒性

为初步探讨农药对海胆胚胎的急性毒性效应,以虾夷马粪海胆(Strongylocentyotus internedius)为实验材料,研究了8种常见农药--草甘膦(Glyphosate)、百草枯(Paraquat)、异菌脲(Iprodione)、代森锰锌(Mancozeb)、三唑醇(Triadimenol)、霜霉威(Propamocarb)、百菌清(Chlorothalonil)和速克灵(Procymidone)对海胆胚胎各发育期(二细胞期、四细胞期、上浮囊胚期、原肠期、棱柱幼体期、四腕幼虫期)的半数效应浓度(EC50),并分析了正辛醇/水分配系数(LogP)与EC50的关系.结果显示:1)8种农药对海胆胚胎各发育期均具有一定的急性毒性,以四腕幼虫期为例,8种农药的EC50值分别为草甘膦(3.99mg·L-1)>百草枯(10.38mg·L-1)>代森锰锌(20.77mg·L-1)>速克灵(55.42mg·L-1)>霜霉威(56.09mg·L-1)>异菌脲(86.29mg·L-1)>三唑醇(273.20mg·L-1)>百菌清(647.38mg·L-1).2)LogP与EC50呈现一定的正相关性,即随着LogP的增加,各农药对海胆胚胎的抑制率逐渐降低.     

Degradation of benzo[a]pyrene in soil with arbuscular mycorrhizal alfalfa

Mycorrhizal and non-mycorrhizal alfalfa (Medicago sativa) was grown in pots containing soil artificially contaminated with various levels of benzo[a]pyrene (B[a]P) (0, 1, 10 and 100 mg kg(-1)). Soil and plants were sampled after 30, 40, 50, 60 and 90 days and compared with unlanted pots. The percentage of mycorrhizal root length colonized by Glomus caledoniun was not significantly affected by the addition of B[a]P up to 10 mg kg(-1) but was significantly lower at 100 mg kg(-1)B[a]P compared with low concentrations (p < 0.05). There was no difference in soil polyphenol oxidase and dehydrogenase activity among the controls and applications of 1 and 10 mg kg(-1) of B[a]P. However, enzyme activities were significantly higher at 100 mg kg(-1) B[a]P compared with the other three treatments, and there was no mycorrhizal effect. Over a period of 90 days the concentration of B[a]P in soil in which alfalfa was grown was significantly lower than in unplanted soil (p < 0.05). Degradation rates of B[a]P added at 1, 10 and 100 mg kg(-1) without G. caledonium were 76, 78 and 53%, and with mycorrhizal inoculation were 86, 87 and 57%. The degradation rate in unplanted soil was significantly lower than in planted soil, and was significantly higher in medium- and low-B[a]P treatments than in the high B[a]P concentration tested. There is a possibility of enhancement phytoremediation of PAHs in rhizosphere soil with arbuscular mycorrhizal fungi.     

Effects of copper (I) oxide on growth and biochemical compositions of two marine microalgae

In copper based antifouling (AF) paints Cu (I) oxide was largely used as booster biocide. In this study effect of Cu (I) oxide on two marine microalgae, Tetraselmis suecica and Dunaliella tertiolecta was demonstrated. EC50 (96 hr) concentrations estimated for T. suecica and D. tertiolecta were 1.3 mg l(-1) and 1.34 mg l(-1), respectively. Copper (I) oxide induced changes in growth, chlorophyll, carbohydrate and protein contents were observed in T. suecica and D. tertiolecta. At low concentration of 0.0625 mg l(-1), 3-26% and 1-16% growth stimulation was observed in T. suecica and T. tertiolecta respectively. Increasing Cu (I) oxide concentrations proportionately decreased the carbohydrate and protein contents. This study clearly indicates the toxicity of excessive Cu (I) oxide on growth and biochemical compositions of T. suecica and D. tertiolecta.     

22种常用除草剂对蚯蚓(Eisenia fetida)的急性毒性

为评价农药对土壤动物的影响,采用滤纸法和人工土壤法测定了22种常用除草剂对赤子爱胜蚓(Eisenia fetida)的急性毒性.滤纸法染毒48 h,特丁净、丙草胺、精异丙甲草胺、乙草胺和莎稗磷对蚯蚓为中等毒性,其LC50值为10.32(8310～12.23)～34.69(29.16～43.99) μg·cm-2;其次为...     

西红柿镍毒害的土壤主控因子和预测模型研究

选取我国有代表性的17种土壤,运用生态毒理学方法研究了土壤中外源镍(Ni)对西红柿的毒性,结果发现土壤中外源Ni对西红柿的生长毒性主要受土壤pH值、有机碳含量的影响.在供试淋洗(使用模拟的人工雨水滤洗定量的土壤样品)和非淋洗土壤中,Ni对西红柿生物量50%抑制的毒性阈值(EC50)范围分别从11mg·kg-1到932mg·kg-1和从7mg·kg-1到2055mg·kg-1,其最大值和最小值比例分别达到了85和294倍.土壤pH值是土壤中Ni对西红柿生长毒性的主控因子,进一步引入土壤有机碳因子时,淋洗和非淋洗土壤理化性质和EC50之间回归方程的决定系数R2由0.853和0.743分别提高到了0.925和0.824.利用土壤性状(土壤pH值、有机碳含量)可以较好地预测土壤中外源Ni对西红柿生长的毒性阈值.     

三种表面活性剂对高浓度DDTs污染土壤的洗脱作用

以高浓度滴滴涕(DDTs)污染场地土壤为研究对象,采用表面活性剂洗脱试验,比较研究了聚氧乙烯山梨糖醇酐单硬脂酸酯(Tween60)、辛基酚聚氧乙烯醚(TritonX 100)、十二烷基硫酸钠(SDS)对污染土壤中DDTs的洗脱效率.试验结果表明,三种表面活性剂对污染土壤中DDTs均具有一定的洗脱作用,去离子水对DDTs几乎没有洗脱效果.随着洗脱液中Tween60和SDS质量浓度的逐渐升高,土壤中DDTs的总洗脱效率逐渐增大,一次性洗脱时最大洗脱效率分别为43.60%和34.62%.随着洗脱液中TritonX 100质量浓度的逐渐升高,土壤中DDTs的总洗脱效率出现先增大后降低再升高的变化现象,最大为15.46%.土壤中六种DDT组分的洗脱效率不完全一样,其中Tween60对2,4'-DDD的洗脱效率可达55.12%,对4,4'-DDD的洗脱效率为54.09%;SDS对2,4'-DDD的洗脱效率为59.99%,对4,4'-DDD的洗脱效率为57.10%.试验结果可为筛选适宜的表面活性剂及质量浓度,研发高浓度DDTs污染场地土壤表面活性剂洗脱修复技术的工程应用提供理论依据.     

麻疯树胚乳愈伤组织诱导及其污染消除

经过比较分析各种消毒方法,获得了较为理想的麻疯树(Jatrophacurcas)胚乳愈伤组织,并动态观察其类型、形态特征、增殖速率和形态发生能力,为麻疯树胚乳植株再生及愈伤组织和细胞培养生产药用成分奠定了基础.以麻疯树成熟胚乳为外植体进行愈伤组织的诱导,测试0.4mg/L的分裂素(BA、KT与TDZ)与2.0mg/L的生长素(IAA、IBA、NAA与2,4D)搭配组合的诱导效果.结果表明,对胚乳愈伤诱导效果而言,2.0mg/L的2,4D效果最好,NAA的效果次之,IBA又次之,IAA的效果最差.BA和KT诱导效果差异不显著,TDZ的添加可促进胚乳愈伤组织的诱导.选择适宜的消毒剂(种类、浓度)和消毒(处理)时间对胚乳外植体的接种成功具有至关重要的作用.在本试验所采取的灭菌方式中,用70%酒精处理30s,然后用10%NaClO处理25min,灭菌效果最佳,同时对胚乳外植体的生长影响最小.图3表1参23     

EDTA and citric acid mediated phytoextraction of Zn, Cu, Pb and Cd through marigold (Tagetes erecta)

Phytoextraction is an emerging cost-effective solution for remediation of contaminated soils which involves the removal of toxins, especially heavy metals and metalloids, by the roots of the plants with subsequent transport to aerial plant organs. The aim of the present investigation is to study the effects of EDTA and citric acid on accumulation potential of marigold (Tagetes erecta) to Zn, Cu, Pb, and Cd and also to evaluate the impacts of these chelators (EDTA and citric acid) in combination with all the four heavy metals on the growth of marigold. The plants were grown in pots and treated with Zn (7.3 mg l(-1)), Cu (7.5 mg I(-1)), Pb (3.7 mg l(-1)) and Cd (0.2 mg l(-1)) alone and in combination with different doses of EDTA i.e., 10, 20 and 30 mg l(-1). All the three doses of EDTA i.e., 10, 20 and 30 mg l(-1) significantly increased the accumulation of Zn, Cu, Pb and Cd by roots, stems and leaves as compared to control treatments. The 30 mg l(-1) concentration of citric acid showed reduced accumulation of these metals by root, stem and leaves as compared to lower doses i.e., 10 and 20 mg l(-1). Among the four heavy metals, Zn accumulated in the great amount (526.34 mg kg(-1) DW) followed by Cu (443.14 mg kg(-1) DW), Pb (393.16 mg kg(-1) DW) and Cd (333.62 mg kg(-1) DW) in leaves with 30 mg l(-1) EDTA treatment. The highest concentration of EDTA and citric acid (30 mg l(-1)) caused significant reduction in growth of marigold in terms of plant height, fresh weight of plant, total chlorophyll, carbohydrate content and protein content. Thus EDTA and citric acid efficiently increased the phytoextractability of marigold which can be used to remediate the soil contaminated with these metals.     

多效唑对水生生物的急性毒性评价研究

本文以斜生栅藻、大型水蚤和草鱼为试验生物,研究植物生长调节剂多效唑对水生生物的急性毒性效应。多效唑对斜生栅藻EC_(50)-96h为20.62mg/l;对大型水蚤LC_(50)-48h为21.86mg/h;对草鱼苗静态生物检测结果为LC_(50)—120h 16.33mg/l,流水生物检测结果为LC_(50)-96h 14.36mg/l,LC_(50)-120h 9.13mg/l。经多效唑处理后,藻的细胞形态也发生明显改变。根据农药的实验室毒性评价划分标准,多效唑对三种生物的毒性均属低毒;田间安全性预评价的结果也表明其毒性为低毒,故认为多效唑是一种对水生生物危害较小的农药。但其慢性毒性及长期积累效应,尚有待进一步研究。     

2,4-D二甲胺盐对莲草直胸跳甲生存和繁殖的影响

为探究除草剂在防治喜旱莲子草(Alternanthera philoxeroides)的过程中对其天敌昆虫的影响,采用不同浓度的2,4-D二甲胺盐浸叶处理的喜旱莲子草饲喂莲草直胸跳甲,连续饲喂7d后,考察了莲草直胸跳甲的繁殖、存活和发育情况。结果表明,2,4-D二甲胺盐可显著降低莲草直胸跳甲成虫的取食量,且抑制作用随药剂浓度升高和取食时间延长而显著增强;较高浓度(1.72～3.44g·L~(-1))的2,4-D二甲胺盐还会导致莲草直胸跳甲雌成虫存活率和产卵量的明显降低,卵孵化率、幼虫存活率和蛹羽化率也显著降低。可见,高浓度(1.72～3.44g·L~(-1))的2,4-D二甲胺盐对莲草直胸跳甲的生长发育和繁殖有显著不利影响,在防治喜旱莲子草时,应将2,4-D二甲胺盐的施用浓度控制在0.22～0.86g·L~(-1)内。