茚虫威在红火蚁工蚁间的横向接触传导效应

[背景]红火蚁是我国重要的外来入侵害虫。利用其相互清洁和交哺行为等社会性昆虫特有的生活习性,使杀虫剂在巢群内传导,可以达到全巢药剂控制的目的。然而,有关茚虫威在红火蚁巢群内的传导效应尚未见有详细报道。[方法]采用供药蚁/受药蚁模型,研究了药剂剂量、供药蚁—受药蚁比例、处理时间对茚虫威在红火蚁工蚁间横向传毒的影响。[结果]剂量越高,受药蚁的死亡率越高,25 ng·头-1处理组受药蚁死亡率为14.1%～70.0%,而50 ng·头-1处理组的受药蚁死亡率最高可达100%;供药蚁—受药蚁比例显著影响茚虫威的传毒,比例为1∶1时,50、100、250、500 ng·头-1处理组受药蚁死亡率可达100%;随着时间延长,受药蚁的死亡率升高,但在12 h后,供药蚁死亡率最高仅为8.0%,表明茚虫威具缓效特性。[结论与意义]本研究明确了在红火蚁工蚁间茚虫威横向传毒的剂量、时间和供药蚁—受药蚁比例的效应,为应用该药剂提供了依据。     

茚虫威在红火蚁工蚁间的横向接触传导效应

【背景】红火蚁是我国重要的外来入侵害虫。利用其相互清洁和交哺行为等社会性昆虫特有的生活习性,使杀虫剂在巢群内传导,可以达到全巢药剂控制的目的。然而,有关茚虫威在红火蚁巢群内的传导效应尚未见有详细报道。【方法】采用供药蚁/受药蚁模型,研究了药剂剂量、供药蚁—受药蚁比例、处理时间对茚虫威在红火蚁工蚁间横向传毒的影响。【结果】剂量越高,受药蚁的死亡率越高,25 ng·头-1处理组受药蚁死亡率为14.1%~70.0%,而50 ng·头-1处理组的受药蚁死亡率最高可达100%;供药蚁—受药蚁比例显著影响茚虫威的传毒,比例为1∶1时,50、100、250、500 ng·头-1处理组受药蚁死亡率可达100%;随着时间延长,受药蚁的死亡率升高,但在12 h后,供药蚁死亡率最高仅为8.0%,表明茚虫威具缓效特性。【结论与意义】本研究明确了在红火蚁工蚁间茚虫威横向传毒的剂量、时间和供药蚁—受药蚁比例的效应,为应用该药剂提供了依据。     

茚虫威对意大利蜜蜂毒性研究

通过单次饲喂高浓度茚虫威药液以及连续饲喂亚致死浓度茚虫威药液进行染毒,记录和分析急性慢性经口毒性试验中,意大利蜜蜂的中毒症状和死亡情况;测定慢性毒性试验中意大利蜜蜂每天药液消耗量,并计算危害商值进行初步风险评价。结果表明,98%茚虫威原药对意大利蜜蜂的半致死剂量48 h-LD_(50)为0.399μg a.i./bee,每日半数致死剂量240 h-LDD_(50)为0.0233μg a.i./bee/day,其中慢性毒性试验中1.66 mg a.i./L处理组的意大利蜜蜂死亡率在144 h之后呈现显著性的增加,240 h达到70%,且该处理组意大利蜜蜂的摄食量为17.6μL,少于对照组和其他处理组。此外,茚虫威根据目前推荐使用剂量计算出的危害商值基本大于50。茚虫威对意大利蜜蜂急性毒性(48 h)是高毒,存在较高的风险;亚致死浓度在144 h后会对意大利蜜蜂造成较大的威胁。     

不同浓度茚虫威对红火蚁的防治效果

为探索适合防治红火蚁的茚虫威浓度,利用丙酮溶解茚虫威原药,使用雾化手段与载体和配方其他试剂充分混合,干燥后保存,进行野外试验测定其防治红火蚁的药效。结果表明,研制的0.025%茚虫威饵剂综合防治效果达85.30%,0.05%茚虫威饵剂达100%,0.1%茚虫威饵剂达100%。3个浓度的茚虫威饵剂拥有良好的防治红火蚁药效,0.05%浓度最适合研制红火蚁饵剂。     

茚虫威对玫瑰三节叶蜂叶绿素和类胡萝卜素含量的影响

【背景】研究昆虫体色不仅在昆虫系统学中,而且在生物学、生态学和害虫防治等中都具有重要意义。有些取食植物叶片的幼虫体色表现为绿色,该绿色是由类胡萝卜素与蓝色四吡咯色素结合所形成,叶绿素又属于四吡咯化合物。但目前尚未见昆虫体内含叶绿素的报道。【方法】在田间套笼饲养玫瑰三节叶蜂幼虫,饲养至5和6龄时,借鉴植物叶绿素测定方法,分别测定其叶绿素含量,并在6龄时用杀虫剂茚虫威处理,观测对其叶绿素含量的影响。【结果】5和6龄玫瑰三节叶蜂幼虫均含有叶绿素,且5龄幼虫含量高于6龄幼虫。其中,5龄幼虫叶绿素a含量为1.6780 mg·g-1,叶绿素b为0.6847 mg·g-1,类胡萝卜素为0.4797 mg·g-1;6龄幼虫叶绿素a含量为1.2726 mg·g-1,叶绿素b为0.5187 mg·g-1,类胡萝卜素为0.4863 mg·g-1。剔除幼虫消化道后,5龄幼虫叶绿素a含量为0.4008 mg·g-1,叶绿素b为0.2618 mg·g-1,类胡萝卜素为0.2444 mg·g-1;6龄幼虫叶绿素a含量为0.4299 mg·g-1,叶绿素b为0.3826 mg·g-1,类胡萝卜素为0.2859 mg·g-1。用茚虫威处理后,6龄幼虫体内叶绿素和类胡萝卜素含量（含消化道）显著下降,其中,叶绿素a下降约48%,叶绿素b下降约34%,类胡萝卜素下降约37%;而对于剔除消化系统的6龄幼虫,茚虫威处理后,其叶绿素和类胡萝卜素含量下降幅度较小。【结论与意义】玫瑰三节叶蜂幼虫含有叶绿素和类胡萝卜素,杀虫剂能降低其叶绿素和类胡萝卜素含量,且其体色可能与叶绿素有着密切的关系。     

生境类型影响了茚虫威饵剂对红火蚁的防治效果

本文在3个类型生境中使用同一剂量茚虫威饵剂处理3个密度红火蚁区域,评价了该饵剂对红火蚁活蚁巢、工蚁的防治效果。结果显示,不同生境中随着处理时间的延长,茚虫威饵剂对低密度、中等密度、高密度红火蚁的防效总体变化动态趋势相近,均为由低到高,并趋于稳定;生境植被越茂盛,该饵剂对红火蚁的防效越低,由低到高以依次为浅草草坪、深草草坪、荒草地;蚁巢密度越大,同一剂量饵剂对蚁巢防效越低,由高到低依次为1-3个/100 m~2、4-7个/100 m~2、8个/100 m~2。研究结果表明,生境植被、红火蚁密度会对毒饵剂的防效产生明显影响。     

茚虫威亚致死浓度对茚虫威敏感性降低的棉铃虫生物学参数及解毒酶活性的影响

【目的】本研究旨在明确茚虫威亚致死浓度对茚虫威敏感性降低的棉铃虫Helicoverpa armigera生物学参数及解毒酶活性的影响,以科学有效防治这一害虫,避免其对茚虫威的抗性快速发展。【方法】采用浸叶法测定了茚虫威对棉铃虫茚虫威抗性汰选种群(TP)及其同源对照种群(CP)3龄幼虫的毒力;用两性生命表分析LC₂₀浓度茚虫威对TP种群当代(F₀)生命表参数的影响,并测定了LC₂₀浓度茚虫威处理48 h后CP和TP种群棉铃虫3龄幼虫体内解毒酶［多功能氧化酶(MFO)、羧酸酯酶(CarE)和谷胱甘肽-S-转移酶(GST)］及乙酰胆碱酯酶(AChE)的活性。【结果】茚虫威对棉铃虫CP种群和TP种群3龄幼虫的LC₂₀分别为2.27和9.91 mg/L。LC₂₀茚虫威处理TP种群后,48 h的生长量、化蛹率、羽化率和成虫畸形率均显著低于未用药对照,而特定年龄生命期望值e_xj高于未用药对照;TP种群棉铃虫3龄幼虫体内GST和MFO活性与CP种群相比显著升高,CarE活性显著降低。【结论】本研究结果表明棉铃虫TP种群在LC₂₀浓度茚虫威胁迫下存在明显的生长与繁殖不利性,同时对其也产生了适应能力。LC₂₀浓度茚虫威处理后,棉铃虫TP种群的GST和MFO活性被显著诱导,说明这两种酶可能与棉铃虫对茚虫威产生抗药性密切相关;而CarE活性被显著抑制,说明该酶可能参与了茚虫威转化成N-脱甲氧羰基代谢物(DCJW)的活化过程。     

茚虫威对不同抗药性品系小菜蛾呼吸代谢的影响

以小菜蛾Plutella xylostella(L.)敏感品系(S)、田间品系(F)及茚虫威汰选抗性品系(T17)幼虫为供试虫源,采用便携式光合作用测定仪测定小菜蛾3～4龄幼虫在受药前后或不同受药剂量等条件下呼吸速率的变化,从能量代谢的角度研究抗药性机制。结果表明,汰选抗性品系、田间品系与敏感品系同龄期小菜蛾幼虫在未受药条件下的呼吸速率差异不显著,表明抗药性的产生并未影响小菜蛾本底的呼吸速率。以各个品系的茚虫威LC20和LC50剂量处理幼虫后,3个品系的呼吸速率均明显提高,汰选抗性品系呼吸速率提高幅度明显大于其他2个品系。在LC20剂量下3个品系呼吸速率峰值均出现在2h前后,10h后恢复到正常水平;在LC50剂量下敏感品系没有明显差异;而田间品系和汰选抗性品系分别在药剂处理后4h和6h达到呼吸高峰,汰选抗性品系保持高水平呼吸速率时间长达9h,分别于药后15h和24h恢复到正常水平。这表明用药后抗性品系呼吸速率的提高幅度与小菜蛾的解毒代谢能力有关,这也揭示了昆虫幼虫中毒后能量消耗会随着抗性水平的提高而增加。     

农药助剂对茚虫威防治番茄潜叶蛾的减量增效作用

为评价农药助剂对15%茚虫威悬浮剂防治番茄潜叶蛾Tuta absoluta(Meyrick)的减量增效作用,分别向减量10%、20%、30%的15%茚虫威悬浮剂药液中添加500 ppm的有机硅silwet 408、矿物油、芦荟精油助剂,测定其对番茄潜叶蛾的田间防效。结果显示：相同浓度下,添加农药助剂后的防效均显著高于15%茚虫威悬浮剂的防效,相对常规用量通过添加有机硅Silwet 408、矿物油或芦荟精油可使农药减量10%～20%。田间应用将15%茚虫威悬浮剂按照常规用量减量10%～20%,通过添加有机硅Silwet 408、矿物油或芦荟精油可有效防治番茄潜叶蛾。     

茚虫威和高效氯氰菊酯对小菜蛾的亚致死效应

【目的】通过研究茚虫威和高效氯氰菊酯两种杀虫剂对小菜蛾Plutella xylostella (L.)的亚致死效应, 进一步了解农药的杀虫机制, 同时为合理使用农药、 减少农药给环境和农业生产带来的一系列不良影响提供理论依据。【方法】浸叶法测定茚虫威和高效氯氰菊酯对小菜蛾2龄幼虫的毒力; 选择茚虫威的3个实验浓度（TI-LC₁₅, TI-LC₃₀和TI-LC₅₀）和高效氯氰菊酯的3个实验浓度（TB-LC₁₅, TB-LC₃₀和TB-LC₅₀）分别处理小菜蛾2龄幼虫48 h, 记录各虫态存活率和发育历期, 3龄、 4龄幼虫及蛹的重量, 并记录单雌产卵量和成虫寿命; 应用特征年龄 龄期及两性生命表方法, 研究不同处理组小菜蛾后代的生长发育、 存活率以及种群增长。【结果】TI-LC₃₀, TI-LC₅₀, TB-LC₁₅, TB-LC₃₀和TB-LC₅₀处理组各虫态发育历期比对照组显著延长（P<0.05）, 3龄、 4龄幼虫和蛹的重量以及单雌产卵量均显著低于对照组（P<0.05）, 但TI-LC₁₅组小菜蛾3龄和4龄幼虫发育历期均显著低于对照组（P<0.05）。TI-LC₃₀, TI-LC₅₀, TB-LC₃₀和TB LC50组小菜蛾后代的总产卵期显著短于相应对照组（P<0.05）, 产卵量也都显著降低（P<0.05）; TI和TB实验组小菜蛾后代种群内禀增长率r_m、 周限增长率λ、 净生殖率R₀以及总生殖率GRR都比对照显著降低（P<0.05）。【结论】低剂量的茚虫威和高效氯氰菊酯能显著抑制处理当代小菜蛾的生长发育和生殖, 并对其下一代的生长发育及种群增长也有明显的抑制。     

水胺硫磷在香蕉及土壤中的残留动态

通过田间试验,采用气相色谱法检测水胺硫磷在香蕉及其土壤中的残留消解动态。结果表明,水胺硫磷在香蕉中的原始沉积量及残留量与施药剂量密切相关,施用加倍剂量处理的原始沉积量为推荐剂量的148%。水胺硫磷在香蕉及土壤中的消解规律符合一级动力学关系,在香蕉中的相关系数︱r︱= 0.9465～0.9490(P＜0.01),消解系数(︱k︱) = 0.1606±0.0035,半衰期(T1/2)为4.3～4.5 d,消解99%所需要时间(T0.99)为28.1～29.4 d;在土壤上︱r︱= 0.9552(P＜0.01),︱k︱= 0.2107,T1/2为3.3 d、T0.99为21.9 d。距末次施药后58~65d,在香蕉最终产品及蕉园土壤均未检出水胺硫磷残留。     

氰戊菊酯在香蕉及蕉园土壤中的残留动态与安全性评价

采用气相色谱(GC-ECD)及田间试验方法,研究氰戊菊酯在香蕉及蕉园土壤中的残留降解动态。结果表明,氰戊菊酯在香蕉上的原始残留沉积量因不同施药处理有所差异,香蕉及蕉园土壤上的降解速度较缓慢,降解规律符合“C＝C₀·^e-kt”一级动力学关系。在香蕉上,相关系数r = 0.9722～0.9980(P＜0.01),降解系数k = 0.0703～0.0767,半衰期T_1/2 = 9.1～9.9 d,降解99%所需要时间T_0.99 = 60.1～65.6 d;在土壤中,k = 0.0821,T_1/2 = 8.5 d,T_0.99 = 56.1 d。距第2次施药后62～68 d,最终香蕉的残留量＜0.01 mg·kg^-1,土壤中为0.015～0.020 mg·kg^-1。在福建蕉区,氰戊菊酯的常规施药方法是间隔期7 d连续2次施用有效剂量112.50 g·hm^-2,采样前安全间隔期可推荐为＞13.6 d,产品质量最终可符合GB/T 2763-2012、NY/T 750-2011的要求。     

Enantioselective Determination of the Insecticide Indoxacarb in Cucumber and Tomato by Chiral Liquid Chromatography–Tandem Mass Spectrometry

A convenient and precise chiral method was developed and validated for measuring indoxacarb enantiomers in cucumber and tomato using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) with a reversed‐phase Chiralpak AD‐RH column. The target analytes were extracted by acetonitrile and then purified by solid phase extraction (SPE) using NH₂/Carb combined‐cartridge. Parameters including the matrix effect, linearity, precision, accuracy, and stability were used. Then the proposed method was successfully applied to investigate the possible enantioselective degradation of rac‐indoxacarb in cucumber and tomato under open conditions. The results indicated that the degradation of indoxacarb enantiomers followed first‐order kinetics in cucumber and tomato. The half‐lives of (+)‐S‐indoxacarb in cucumber and tomato were 3.0 and 5.9 days, respectively; while the (–)‐R‐indoxacarb were 7.3 and 12.2 days, respectively. The data of the half‐lives showed that (+)‐S‐indoxacarb was preferentially degraded in cucumber and tomato. Moreover, indoxacarb degraded faster in cucumber than in tomato. Chirality 25:350–354:, 2013. © 2013 Wiley Periodicals, Inc.     

Enantioselective Degradation of Indoxacarb From Different Commercial Formulations Applied to Tea

The stereoselective degradation of indoxacarb enriched with (+)‐S‐indoxacarb (S/R:70/30) was investigated in three typical green teas. A convenient and precise chiral method was developed and validated for measuring indoxacarb enantiomers in green tea. The developed method was based on high‐performance liquid chromatography coupled with tandem mass spectrometry using a Chiralpak IC column. The stereoselective degradation of indoxacarb enantiomers showed that the (+)‐S‐enantiomer dissipated faster than the (?)‐R‐enantiomer in all three typical tea farms. However, no enantiomerization was observed after applying pure (+)‐S‐indoxacarb. Residues on tea plant of the active ingredient (+)‐S‐indoxacarb from suspension concentrate (SC) was more persistent than that from emulsifiable concentrate (EC). Chirality 27:262–267, 2015. © 2015 Wiley Periodicals, Inc.     

氯氰菊酯在香蕉、土壤上的残留动态及安全性评价

采用气相色谱法及田间试验法研究氯氰菊酯在香蕉及蕉园土壤上的残留降解动态。结果表明,氯氰菊酯在香蕉上的原始沉积量较低,不同施药剂量有明显的差异。氯氰菊酯在香蕉及蕉园土壤上降解速度较缓慢,残留降解规律均符合一级动力学关系,在香蕉上两种施药剂量的降解速率相接近,半衰（T1/2）为12.1～12.8 d、降解99%需时（T0.99）为80.3～85.1 d;在蕉园土壤上T1/2、T0.99分别为8.0 d、52.9 d。在香蕉上距第2次施药后62～70 d最终产品残留量＜0.01 mg/kg。在福建蕉区氯氰菊酯按常规施药方法,间隔期7 d连续施用有效剂量56.25 g/hm2两次,施药安全间隔期可推荐为＞7 d,最终产品质量符合NY/T 750-2011规定的MRL要求。     

Dynamics of Meloidogyne incognita Virulence to Resistance Genes Rk and Rk2 in Cowpea

The virulence index of three Meloidogyne incognita field isolates to the resistance gene Rk in cowpea was 0%, 75%, and 120%, with the index measured as reproduction on resistant plants as a percentage of the reproduction on susceptible plants. Continuous culture of the 75% virulent isolate on susceptible tomato for more than 5 years (about 25 generations) resulted in virulence decline to about 4%. The rate of the decline in virulence was described by exponential decay, indicating the progressive loss of virulence on a susceptible host. The 120% virulent isolate declined to 90% virulence during five generations on susceptible cowpea. Following virulence decline, the two isolates were compared over 5 years in inoculated field microplots both separately and as a mixture on susceptible, gene Rk, and gene Rk² cowpea plants. At infestation of the plots, the two isolates were 1.2% and 92.0% virulent, respectively, to gene Rk and 0.2% and 8.1% virulent, respectively, to gene Rk². Virulence to gene Rk in the two isolates and in mixture increased under 5 years of continuous Rk cowpea plants to 129% to 172% and under Rk² cowpea plants to 113% to 139 % by year 5. Virulence to gene Rk² increased during continuous cropping with Rk cowpea plants to 42% to 47% and with Rk² cowpea plants to 22% to 48% by year 5. Selection of Rk²-virulence was slower in the isolate with low itt-virulence. The virulence to both genes Rk and Rk² in the mixed population was not different from that in the highly virulent isolate by year 5 of all cropping combinations. Selection of Rk²-virulence on plants with Rk, and vice versa, indicated at least partial overlap of gene specificity between Rk and Rk² with respect to selection of nematode virulence. This observation should be considered when resistance is used in cowpea rotations.     

Cowpea Root Rot Severity and Metabolic Changes in Relation to Manganese Application

Severity of root rot (Rhizoctonia solani and Rhizoctonia bataticola) of cowpea (Vigna unguiculata L.) was reduced by 42.7 and 42.0%, respectively over control following the application of 10 μg/g Mn as manganese sulphate. Reduction in disease incidence was associated with increased levels of polyphenol oxidase (PPO), peroxidase (PO) and total phenols. PO activity was several times more as compared with PPO‐specific activity and increased markedly after infection either with R. solani or R. bataticola. Contrary to PPO and PO, the specific activity of catalase declined sharply. Infection also caused an increase in the content of reducing sugars, Cu, Zn and Mn but a decrease in o‐dihydric phenols, flavanols, total soluble sugars, non‐reducing sugars and Fe contents. It is suggested that Mn at the rate of 10 μg/g soil can be used to manage the root rot of cowpea.     

Enantioselective degradation of indoxacarb in cabbage and soil under field conditions

The enantioselective degradation of indoxacarb in cabbage and soil has been investigated in Beijing and Anhui under open conditions. Indoxacarb enantiomers in samples were extracted with acetonitrile, cleaned up by florisil SPE column, separated on high performance liquid chromatography with a cellulose-tris-(3, 5-dimethylphenylcarbamate)-based chiral stationary phase (CDMPC-CSP), and determined by a photodiode array detector. The validation of the developed method by fortification rac-indoxcarb in cabbage and soil showed good accuracy and precision. The results of field trials indicated that the dissipation of indoxacarb enantiomers followed pseudo-first-order kinetics or first-order kinetics in cabbage and soil at two locations. The half-lives of two enantiomers in cabbage ranged from 2.8 to 4.6 d which were shorter than those in soil ranging from 23 to 35 d. The changes of enantiomeric fraction values proved that enantioselective degradation of indoxacarb happened in cabbage and soil. The (-)-indoxacarb showed faster degradation in the Beijing cabbage, whereas in the Anhui cabbage, (+)-indoxacarb preferentially degraded. In soil, preferential degradation of (+)-indoxacarb was observed at two locations.     

Comparison of in vivo and in vitro translation of Cowpea Mosaic Virus RNAs

The translation products from Cowpea Mosaic Virus (CPMV) RNAs obtained in two different cell-free systems were compared with the viral polypeptides synthesized in CPMV-infected cowpea protoplasts. It was shown that in both the wheat germ system and the rabbit reticulocyte lysate CPMV M component RNA was translated into two polypeptides of 105,000 and 95,000 dalton, which were not detected in CPMV-infected protoplasts. B component RNA however, gave different products depending on the system used. In the reticulocyte system this RNA was translated into a 200,000 dalton polypeptide which was further cleaved to give 170,000 and 32,000 dalton polypeptides. In the wheat germ system this processing step was lacking as only the 200,000 dalton product was formed. Since the 170,000 and 32,000 dalton polypeptides were also found in CPMV-infected protoplasts the two in vitro systems used apparently represent different stages of the expression of the B component RNA, thus providing a tool to study the mechanism of CPMV gene expression in vivo.     

Somatic Embryogenesis and Plant Regeneration from Protoplasts of Cowpea (Vigna sinensis)

Immature cotyledons of cowpea (Vigna sinensis Endlo) were used for protoplast isolation. Enzyme solution for protoplast isolation contained 40% cellulase Onozuka R-10,0.30% Macerozyme R-10 and 2% hemicellulase. The purified protoplasts were cultured in Bs,MS or KM8p liquid medium in dark (25℃) at a density of 1 × 105–5 × 105/ml. The protoplasts started cell division in 3–5 days . Sustained cell divisions resulted ill formation of cell clusters and small calli,with cell division frequency reaching 23%–28% in MS medium . Calli of 2 mm in size were transferred onto MSB (MS salts+B5 vitamins) medium with 2 mg/L 2,4-D, 0. 5mg /L BA forfurther growth. Embryogenic calli appeared on this medium. After passage to fresh medium with the same composition, the embryogenic calli were transferred into MSB liquid medium to establish suspension culture. When the suspended calli were transferred back onto MSB agar medium with 0. 1 mg /L IAA, 0.5mg/L KT, 5% mannitol (cultured in light,2000 lx,12h/d), a lot of adventitious roots formed in 7–10 days, and then somatic embryos formed from the protoplast derived calli. But only a few embryoids developed further into the cotyledonary stage ,and the others died at globular, heart-shaped, or torpeto stage . Finally, some cotyledonary embryoids germinated and developed into plantlets or shoots with leaves.