Dynamics of residues from a novel nano-imidacloprid formulation in soyabean fields

Imidacloprid has been widely used to control vegetable pests in China. This research was conducted to establish a method for preparing a novel imidacloprid nano-formulation and develop a simple and efficient method for determination of residues of the novel imidacloprid formulation in soyabean fields. Imidacloprid micro-crystals were directly encapsulated with chitosan and sodium alginate through layer-by-layer self-assembly. The coated colloids and photocatalysts were characterized using confocal laser scanning microscopy and scanning electron microscopy. Residues of the novel imidacloprid were determined by HPLC equipped with a UV detector. The results showed that imidacloprid micro-crystals were obtained by association and had a mean length of 7 μm and a zeta potential of −37.5 mV. The pesticide loading and encapsulation efficiency were 56.2 ± 0.96% and 81.6 ± 0.96%, respectively. Degradation of the nano-imidacloprid and the suspension concentrate imidacloprid formulations in soil coincided with C = 0.227e^−0.152t and C = 0.544e^−0.177t with half lives of about 2.8 d and 6.2 d, respectively. Degradation of the two imidacloprid formulations in soyabean plants coincided with C = 6.644e^−0.475t and C = 8.585e^−0.573t with half lives of about 1.9 d and 4.5 d, respectively. Thus, in soil, the degradation rate of the nano formulation was faster than that of the suspension concentrate, but the degradation rates were vice versa in the plant. The final residue of the nano imidacloprid formulation after 35 days was below the limit of detection but in the soyabean plant, the final residue was 0.003 mg kg⁻¹, much lower than the USA Environment Protection Agency’s Maximum Residue Level. Therefore, a dosage of 900 ml hm⁻² is suggested for the nano-imidacloprid concentrate, which could be considered as safe to fields.     

吡虫啉种衣剂对甜菜生长性状的影响及对中华豆芫菁的防治效果

本论文以吡虫啉600 g a.i./L悬浮种衣剂为研究药剂,以甜菜为研究材料,研究了不同剂量吡虫啉悬浮种衣剂对甜菜种子包衣后,对甜菜生长性状的影响及对中华芫菁的防治效果.结果表明,吡虫啉600 g a.i./L悬浮种衣剂分别以200ml/100kg、400ml/100kg、800ml/100kg种子制剂用量包衣后,能显著提高幼苗的出苗率,其中以800ml/100kg种子出苗率最高,为90.7％;对甜菜幼苗生长性状也有明显的影响,与清水对照和常规用药剂相比,处理药剂对株高、根长、地上重量都有显著的促进作用,对地下重量的影响与对照和常规药剂没有显著差异.试验用药剂各个处理对中华芫菁成虫均有一定的防治效果,且用药量越大,防治效果越好,播种后53d,Gauch0 600FS 400、800ml/100kg种子对中华豆芫菁的防效都在75％以上.     

吡虫啉在枸杞中的残留动态

为了评价吡虫啉在枸杞上使用后的残留动态,在宁夏、内蒙古和甘肃同时进行残留动态试验。结果表明,吡虫啉在枸杞中的残留消解完全符合一级反应动力学方程式,在枸杞鲜果上的半衰期为3.0～3.4d,在枸杞干果上的半衰期为2.9～5.0d;按推荐剂量施用的情况下,在枸杞中的残留为0.004 2～0.403mg/kg。吡虫啉在枸杞中最高残留限量(MRL值)推荐值为1mg/kg。     

绿色威雷·吡虫啉和噻虫啉对枯死木松褐天牛成虫的防治效果

[目的]筛选枯死木内松褐天牛成虫防治效果较好的药剂。[方法]采用绿色威雷、吡虫啉、噻虫啉和清水处理林间枯死木,测定其对松褐天牛成虫的致死力及对松褐天牛成虫取食量的影响。[结果]绿色威雷对松褐天牛成虫的致死力最大,且对成虫取食量的抑制作用也最强,其次是噻虫啉和吡虫啉,清水效果最差,成虫的取食量也最大,但这4种处理间无显著差异。[结论]试验结果为有效防控林间枯死木内松褐天牛成虫提供了理论依据。     

吡虫啉拌种量对小麦蚜虫的防治效果及其在小麦籽粒中的残留研究

不同小麦种植区、不同种植习惯以及不同播种期决定了小麦播种量差异较大。以小麦品种冀5265为试材,采用田间小区试验的方法,分别在小麦播种量为180、225和300 kg/hm2条件下,研究了吡虫啉不同拌种剂量对小麦出苗率、小麦蚜虫的防治效果以及小麦籽粒中残留的影响。结果表明：在3组播种量处理下,吡虫啉不同拌种剂量对小麦出苗率均没有影响;吡虫啉拌种防治小麦蚜虫具有较好的防治效果和较长的持效期,在整个麦蚜发生期无需施药。在小麦播种量相同的前提下,对小麦蚜虫的防治效果随拌种剂量的提高而上升,持效期延长;在拌种剂量相同的前提下,随着播种量的加大,前中期防效无显著差异,后期防效提高,持效期延长。在试验剂量下,小麦籽粒中吡虫啉残留量均低于美国规定的小麦籽粒中吡虫啉的最高限量标准,不同的播种量对小麦籽粒中吡虫啉残留量没有显著影响。吡虫啉拌种防治麦蚜技术在试验剂量下对作物安全,可高效控制麦蚜为害,在产品中残留也低于国际最高限量标准。     

康福多在水稻和土壤中的残留分析

残留试验表明,用２０％康福多浓可溶剂６００ｍｌ／ｈｍ＾２喷施防治稻飞虱,在田水中原始沉积量为０．１１～０．２５ｍｇ／ｋｇ,半衰期为５．９～７．９ｄ;在土壤中原始沉积量为０．０８～０．１６ｍｇ／ｋｇ,半衰期为５．３～２４．６ｄ;在茎叶上原始沉积量２．８２～６．９９ｍｇ／ｋｇ,半衰期为６．５～６．８ｄ。最终残留量试验,表明在水稻卷叶螟、稻飞虱发生期喷药２次,施药剂量为３００～６００ｍｌ／ｈｍ＾２,最后一次施药距收获期为７ｄ,在糙米中残留量均低于０．０５ｍｇ／ｋｇ,在土壤和茎叶中的最终残留量分别小于０．０８３ｍｇ／ｋｇ和０．８２２ｍｇ／ｋｇ。     

吡虫啉对家蚕的毒性

吡虫啉对蚕的毒性试验表明 :4龄起蚕致死中浓度 (LC50 )为 2 71mg/L ,致死中量 (LD50 )为0 0 3 4 μg/头。 4龄起蚕连续添食吡虫啉水溶液试验表明 :0 0 0 71mg/mL( 1 4× 1 0 4 倍稀释液 )浓度吡虫啉连续添毒对蚕有明显的毒性 ,茧的经济性状也有显著地下降。 0 0 1 2 5mg/mL( 8× 1 0 4 倍稀释液 )吡虫啉连续添毒 1 2h的蚕 ,上蔟率为 86%,死笼茧率为 3 9%,鲜茧茧层率为 2 1 2 %,比对照区低 0 3 %,而持续添毒则表现为全部死亡。此外 ,吡虫啉对家蚕具有触杀和熏蒸毒性     

同翅目害虫对吡虫啉抗性研究进展

吡虫啉是第一个新烟碱类杀虫剂,于1991年面市。吡虫啉对防治同翅目害虫（蚜虫、粉虱、飞虱）和部分鞘翅目害虫（甲虫）及其抗性种群有特效。但随着吡虫啉的大量应用,很多害虫产生了抗药性问题。就同翅目害虫对吡虫啉的抗性发生概况、交互抗性、抗性机理以及抗性治理的研究进展作了综述。     

吡虫啉防治小麦穗蚜最佳用量研究

为了寻找防治小麦穗蚜高效安全的替代药剂,达到小麦高产优质的目的,对吡虫啉防治穗蚜的效果和最佳用量进行了研究。结果表明:10 %吡虫啉可湿性粉剂对小麦穗蚜的防效与4 0 %氧化乐果乳油和2 6 %杀杀死乳油相当,持效期长,但速效性稍差;田间最佳用量为2 2 5～30 0 g/hm2 。