Regional susceptibilities to 12 insecticides of melon and cotton aphid,Aphis gossypii (Hemiptera: Aphididae) and a point mutation associated with imidacloprid resistance

The melon and cotton aphid Aphis gossypii Glover (Hemiptera; Aphididae) is one of the most serious pests worldwide. We surveyed insecticide susceptibility in A. gossypii field populations to 12 insecticides (6 neonicotinoids, 3 pyrethroids and 3 others) to examine resistance ratios. The levels of insecticide resistance were extremely high, especially to neonicotinoids, such as acetamiprid, clothianidin, thiacloprid and imidacloprid. To identify the neonicotinoid resistance mechanisms, we used an imidacloprid-resistant (IMI-R) strain as a model strain. IMI-R showed an extremely high resistance ratio and also cross-resistance to all the test neonicotinoids. However, there was little or no cross-resistance to the other insecticides, including sulfoxaflor. Synergist tests and enzyme activity assays suggested the absence of resistance mechanisms based on enhanced detoxification enzymes, such as cytochrome P450, esterase and glutathione S-transferase. One point mutation was found in the beta1 subunit loop D region of the nicotinic acetylcholine receptor (nAChR) of the IMI-R strain. This R81T point mutation was also found in field populations collected from 5 regions. Therefore, the R81T point mutation was identified as an important mechanism of imidacloprid resistance in A. gossypii.     

15%吡·多悬浮种衣剂的研制

采用湿式超微粉碎法加工工艺对15%吡.多悬浮种衣剂进行了研究。对润湿分散剂、增稠剂、成膜剂、防冻剂进行了筛选试验,确定了最优配方。经低温和热贮稳定性试验,制剂外观无明显分层,水中分散性良好,各项指标均符合悬浮种衣剂相关标准。     

吡虫啉与高效氯氰菊酯增效混配制剂对温室白粉虱的防治效果

采用玻片浸蘸法对吡虫啉与高效氯氰菊酯混配对温室白粉虱的联合毒力,测定共毒系数CTC为119.03～215.70,表现增效和相加作用。据此确定最佳配比,配制成增效混剂4.5%微乳剂进行防治温室白粉虱的田间试验,结果表明药效良好,其用量12～18ga.i./hm2的效果达75%～99%,优于对照药4.5%高效氯氰菊酯EC。该增效混剂防治温室白粉虱的速效性和持效性皆佳,且对作物安全。     

14%吡虫啉·敌敌畏注干液剂防治柳树天牛技术研究

利用14%吡虫啉.敌敌畏注干液剂、4.15%吡虫啉.阿维菌素注干液剂、4.5%吡虫啉注干液剂、10%啶虫脒注干液剂和30%敌畏.氧乐注干液剂等5种药剂进行了树干注射防治危害柳树的光肩星天牛(Anop lophora g labrip enn is(M otschu lsky))试验,并研究了14%吡虫啉.敌敌畏注干液剂田间防治光肩星天牛的使用技术。结果表明,供试的5种注干药剂对光肩星天牛幼虫均有一定的防治作用,其中14%吡虫啉.敌敌畏注干液剂防效最好。14%吡虫啉.敌敌畏注干液剂以1.0 mL/cm树干胸径注药量对天牛幼虫的防效可达90.7%,优于对照药剂30%敌畏.氧乐注干液剂。利用14%吡虫啉.敌敌畏注干液剂林间防治天牛时,当幼虫虫口密度低于1.15头/株时,1年注药1次;虫口密度约为5头/株时,1年注药2次;虫口密度约为12头/株时,两年注药3次,可将虫口密度控制到0.15头/株以下,有效控制天牛的危害。     

丁硫克百威与吡虫啉不同配比对苹果黄蚜的室内毒力测定

室内毒力测定表明 ,丁硫克百威与吡虫啉不同配比的混合物对苹果黄蚜均有一定的增效作用 ,其中 2∶1混配物的增效作用幅度最大。     

吡虫啉在海南豇豆及土壤中的消解动态研究

建立了豇豆、土壤中吡虫啉测定高效液相色谱法,并研究吡虫啉在海南豇豆和其种植土壤中的消解动态以及在豇豆中的最终残留。结果表明:方法回收率为78%~89%,在0.05~5μg/mL线性关系良好,相对标准偏差(RSD)7%,最低定量限0.01μg/mL,方法满足检测工作要求。吡虫啉在豇豆和土壤中的半衰期分别为2.9、5.1 d。以1.5倍推荐剂量一次喷施农药2.5 d后吡虫啉残留量小于0.5μg/g。吡虫啉在土壤中半衰期较短,属于易降解农药;分别以1.5、2倍推荐剂量3次施药,每次施药间隔2d,自然降解4、6d后残留量均低于0.5μg/g。     

玉米中吡虫啉的残留检测方法的研究

介绍了高效液相色谱法测定玉米中吡虫啉农药残留量的方法,样品经甲醇超声提取,固相萃取小柱快速净化提取物,经紫外检测器分离测定,方法的检出限为0.05 mg/kg,回收率大于80%,相对标准偏差小于7%。     

芒果套袋前后喷施吡虫啉·噻嗪酮农药的消解动态研究

建立喷施清水的对照、套袋前喷药、套袋后喷药、不套袋喷药4种处理方法,喷施38％吡虫啉和噻嗪酮混合悬浮剂,建立芒果中吡虫啉、噻嗪酮残留的高效液相色谱(HPLC)检测方法.结果表明,在0.05～0.5 mg/kg添加水平下,吡虫啉和噻嗪酮的平均回收率分别为82.6 ～93.8％、101.4～104.2％,相对偏差(RSD)分别为1.9-4.5％、9.3-15.6％.芒果中吡虫啉、噻嗪酮的最小检出量均为0.01 mg/kg.吡虫啉套袋前施药、套袋后施药、不套袋施药3种处理方式下的半衰期分别是16.74、6.38、8.10 d.噻嗪酮在套袋前施药、不套袋施药2种处理方式下的半衰期分别是9.72、9.23 d.套袋后施药的噻嗪酮的残留量低,第3天已经低于检出限.套袋处理降低了2种农药在芒果上的消解速率,吡虫啉在芒果上有较强的内吸性.     

A novel photodegradable insecticide: Preparation, characterization and properties evaluation of nano-Imidacloprid

Imidacloprid (IMI) microcrystals were directly encapsulated with nature polysaccharides chitosan (CHI) and sodium alginate (ALG) through layer-by-layer (LbL) self-assembly. The coated colloids were characterized using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The in vitro controlled release pattern of IMI through the PE diffusion barrier was studied using a diffusion cell assembly at physiological pH of 7.4. Photocatalysts were characterized by Brunauer-Emmett-Teller (BET) surface area and SEM. The adsorption and photocatalytic activities of photocatalysts were evaluated by isothermal adsorption and IMI degradation under UV light and natural light illumination. The toxicity of the photodegradable insecticide was evaluated against the adult stage of Martianus dermestoides. The results showed that thermodynamically stable IMI microcrystals were obtained by association and had a mean length of 7 μm and a ζ-potential of −37.5. The drug loading and encapsulation efficiency were 56.15 ± 0.96% and 81.57 ± 0.96%, respectively. The polysaccharide capsules prolonged the release time of the encapsulated IMI crystals. Among the photocatalysts, SDS/Ag/TiO₂ had the highest photocatalytic activity. Toxicity of the novel 50% nano-SDS/Ag/TiO₂-IMI was higher in the adult stage compared to the 95% IMI as indicated by the lower LC₅₀ value.