斜纹夜蛾对茚虫威的抗药性汰选及交互抗性测定

为评估茚虫威抗性风险,在室内进行了斜纹夜蛾对茚虫威的抗性选育和交互抗性测定。经过10代6次室内抗性选育,获得了斜纹夜蛾对茚虫威抗性种群,与选育前相比,斜纹夜蛾对茚虫威的敏感性降低了15.63倍。抗性风险评估结果表明,斜纹夜蛾具有对茚虫威产生高水平抗性的风险。交互抗性测定发现,辛硫磷、高效氯氰菊酯和氟虫腈对茚虫威抗性种群的LC50值分别是同源对照种群的1.53、2.42和1.53倍,溴虫腈和灭多威对茚虫威抗性种群的LC50值分别是同源对照种群的0.78和0.96倍,表明茚虫威抗性种群对这几种杀虫剂未产生交互抗性。     

主要农业害虫对茚虫威的抗性现状及其治理策略

茚虫威属于噁二嗪类杀虫剂,与大多数杀虫剂不同的是其进入害虫体内需要经活化代谢转变成N-去甲氧羰基代谢物（decarbomethoxylated metabolite,DCJW）后不可逆地阻断钠通道,进而发挥杀虫活性。茚虫威由于其作用机制不同于常见的使钠离子通道延迟关闭的菊酯类药剂而被广泛用于鳞翅目和一些同翅目、鞘翅目害虫的防治。抗药性是任何杀虫药剂使用后面临的问题,茚虫威也不例外,许多害虫对其产生了不同程度的抗性。昆虫对茚虫威产生抗性的机制包括酯酶活性、谷胱甘肽S-转移酶（glutathione S-transferase,GST）和P450活性的增加以及分子靶标F1845Y、V1848I、L1014P的突变,这些对茚虫威抗性机制的研究基本都是基于抗性种群和敏感种群开展的,需要进一步验证其对抗性研究的贡献度。针对我国田间害虫种群对茚虫威的抗性现状,及时实施对茚虫威有效的抗性治理是迫切的。对于茚虫威的抗性治理除了传统的杀虫药剂轮用、混用外,需要利用其作用机制特点开展抗性治理策略研究。一是充分利用其活化代谢的特点,开展组合药剂的研究应用;二是菊酯类药剂和茚虫威的作用机制均与钠离子通道有关,但是前者是使钠离子通道关闭延迟,而后者是阻断钠离子通道,开展相关基础研究,使菊酯类药剂与茚虫威合理地用于抗性治理中。本文综述了茚虫威的抗性现状、抗性机制与交互抗性、茚虫威的抗性风险评价,针对茚虫威的抗性特点提出了抗性治理策略。     

茚虫威对草地贪夜蛾的毒力及解毒酶的诱导作用

茚虫威对鳞翅目害虫幼虫具有卓越的杀虫活性,是替代传统杀虫剂及治理抗药性害虫的理想药剂。为了明确茚虫威对草地贪夜蛾的生物活性及对其主要解毒酶活性的影响,为使用茚虫威科学防治草地贪夜蛾提供参考,本研究采用浸叶法测定了广西南宁草地贪夜蛾种群3龄幼虫对茚虫威敏感性及增效醚(PBO)、磷酸三苯酯(TPP)、顺丁烯二酸二乙酯(DEM)对茚虫威的增效作用;并测定了亚致死浓度(LC_(20))茚虫威对草地贪夜蛾体内MFO、GSTs和CarE酶的诱导作用。结果表明,茚虫威对草地贪夜蛾的LC_(20)、LC_(50)和LC_(90)分别为8.95、20.62 mg/L和73.57 mg/L。DEM、PBO和TPP对茚虫威的增效倍数依次为2.24、2.05和0.50倍。亚致死浓度(LC_(20))茚虫威处理后对3龄幼虫体内GSTs的活性和MFO含量与无药剂处理(CK)相比显著升高(P0.05),而CarE活性无显著变化(P0.05)。本文结果显示,广西草地贪夜蛾仍可以用推荐剂量80 mg/L茚虫威防治,而代谢抑制剂PBO和DEM对茚虫威有明显的增效作用,且GSTs活性和MFO含量在茚虫威诱导后显著升高,初步推测这两种解毒酶可能影响将来草地贪夜蛾对茚虫威的抗药性发展。     

防治山东省特色小宗作物金银花尺蠖试验研究

为明确1%甲氨基阿维菌素苯甲酸盐微乳剂和15%茚虫威悬浮剂用于防治金银花尺蠖的有效性和安全性，本研究采用浸渍法、喷雾法分别测定了2种药剂对金银花尺蠖的室内活性、田间防效以及对金银花的安全性。室内活性试验结果表明，甲氨基阿维菌素苯甲酸盐和茚虫威对金银花尺蠖均具有较高活性，LC₅₀值(48h)分别为0.276 5、9.288 3 mg/L,且较高于对照药剂高效氯氟氰菊酯(LC₅₀值11.370 3mg/L)的活性。安全性试验结果表明，1%甲氨基阿维菌素苯甲酸盐微乳剂和15%茚虫威悬浮剂对金银花植株安全，安全系数分别为4.0。田间药效验结果表明，1%甲氨基阿维菌素苯甲酸盐微乳剂和15%茚虫威悬浮剂试验剂量下药后3～14d防效>80%。研究表明，1%甲氨基阿维菌素苯甲酸盐微乳剂和15%茚虫威悬浮剂对金银花尺蠖具有较好的防治效果，可推荐作为田间防治金银花尺蠖的药剂。     

茚虫威在金银花中的残留动态研究及安全性评价

为了探明茚虫威在金银花中的残留特性和安全性,对茚虫威在金银花中的消解动态及最终残留进行了研究。样品经乙腈提取,超高效液相色谱-串联质谱(UPLC-MS/MS)检测,外标法定量。运用所建立的方法对茚虫威在山东泰安、河北邢台、浙江杭州、湖南邵阳、广东湛江和重庆九龙坡6个试验点的金银花中的残留消解动态和最终残留进行了研究。试验结果表明:茚虫威残留量在金银花中随时间延长而递减,符合一级反应动力学方程,消解速度较快,半衰期为1.5～2.2 d,属易消解型农药。参照中国制定的茶叶中茚虫威的最大残留限量(MRL)5 mg/kg,15%茚虫威悬浮剂按推荐使用剂量90 g/hm~2,施药1次,施药后7 d,所采收的金银花中的茚虫威残留量低于5 mg/kg。研究结果可为茚虫威在金银花上的合理使用及其最大残留限量制定提供参考。     

施用茚虫威饵剂后红火蚁的蚁巢迁移及弃尸行为

红火蚁Solenopsis invicta是典型的社会性昆虫, 在防控过程中容易引起红火蚁巢体迁移和弃尸等现象, 影响防控效果。本研究对标记好的蚁巢施用茚虫威饵剂, 然后定时观察新增加的蚁巢数量和工蚁弃尸量。结果表明, 施用0.08%和0.1%茚虫威饵剂后, 所有处理均有新蚁巢出现, 施药后5~10 d, 新蚁巢大量出现, 随后蚁群趋向稳定, 新增蚁巢减少, 至处理后25~30 d, 再次出现新蚁巢。0.1%茚虫威饵剂15 g/巢处理在施药后5 d出现8个新蚁巢, 药后10 d和30 d分别又新增5个蚁巢, 其他时间新增蚁巢数较少。按处理剂量, 药后30 d, 2种药剂15 g/巢处理出现的新巢数量均显著高于25 g/巢处理。0.1%茚虫威15 g/巢处理, 校正蚁巢累计增加率高达124.98%, 0.08%茚虫威饵剂15 g/巢处理为89.05%; 0.08%和0.1%茚虫威饵剂25 g/巢处理, 校正蚁巢累计增加率分别为12.00%和51.34%。施用15 g/巢饵剂后2 d开始有大量工蚁尸体被丢弃, 至药后4 d弃尸量达最大值, 0.08%和0.1%茚虫威饵剂处理弃尸量分别为330.5头/巢和300.2头/巢, 随后呈逐步下降趋势, 至14 d, 弃尸量降至最低。施药后8 d内弃尸量达总弃尸量75.26%以上, 至药后10 d, 已达总弃尸量的90.08%以上。施用0.08%和0.1%茚虫威饵剂25 g/巢的处理新蚁巢出现较少, 表明施用相对低剂量的饵剂, 更容易引起蚁巢迁移。红火蚁的弃尸行为主要发生在饵剂施用后的前8 d。     

基于叶绿素评价茚虫威和氯虫苯甲酰胺对烟草幼苗生态安全性

在温室中培育烟苗幼苗,至9叶一心时,在第9叶片上用微量注射器处理上不同浓度的杀虫剂茚虫威和氯虫苯甲酰胺100μL,24h后测定烟草幼苗叶绿素和类胡萝卜素的含量。结果表明,氯虫苯甲酰胺和茚虫威对烟草幼苗具有生态安全性。     

甲维·茚虫威对稻纵卷叶螟的田间防效

以5%甲维盐乳油和15%茚虫威悬浮剂两种单剂作为对照药剂,研究了复配剂15%甲维·茚虫威悬浮剂8、11、16g/667m2共3个制剂用量处理对稻纵卷叶螟的田间防效。调查发现,单次施药19 d后,15%甲维·茚虫威悬浮剂较高用量(16 g/667m2)处理的防效为89.35%,显著高于其他处理;该复配剂中等用量(11 g/667m2)处理的防效与15%茚虫威悬浮剂处理接近,略高于5%甲维盐乳油;较低用量(8 g/667m2)处理的防效与5%甲维盐乳油接近,显著低于其他施药处理。15%甲维·茚虫威悬浮剂对稻纵卷叶螟的总体防效较高,具有较好的速效性与持效性,并对水稻生长安全。     

30%茚虫威悬浮剂防治稻纵卷叶螟效果

每667 m~2用30%茚虫威悬浮剂15 g、30%茚虫威悬浮剂15 g+1.8%阿维菌素乳油20 g、15%多杀·茚虫威悬浮剂15 g防治稻纵卷叶螟,在稻纵卷叶螟第四代卵孵化高峰期施药,对稻纵卷叶螟的防治效果较好。     

超高效液相色谱法测定水稻中茚虫威的残留

建立了一种超高效液相色谱法(UPLC)测定水稻基质中茚虫威残留量的方法。稻田水用二氯甲烷直接萃取;稻田土、糙米和稻壳经甲醇溶液提取,旋蒸除去甲醇,浓缩液经二氯甲烷液液分配;稻秆经乙腈溶液提取,旋蒸除去乙腈,浓缩液经二氯甲烷液液分配;采用UPLC-PDA检测残留的茚虫威,在7min中内实现了茚虫威的完全分离。结果表明:茚虫威的质量浓度范围为0.05~5.18μg/mL时,峰面积与质量浓度具有良好的线性关系,相关系数为0.999 9,仪器的最小检出量为0.52ng,最低检测浓度为1.25×10-3mg/kg,茚虫威的平均回收率为79.77%~99.91%,相对标准偏差(RSD)为1.21%~9.25%。该方法适合于水稻基质中茚虫威含量的快速准确测定。     

Genetics and evidence for an esterase-associated mechanism of resistance to indoxacarb in a field population of diamondback moth (Lepidoptera: Plutellidae)

Bioassays (at generation G2) with a newly collected field population (designated CH3) of Plutella xylostella L. from farmers' fields in the Cameron Highlands, Malaysia, indicated resistance ratios of 813-, 79-, 171-, 498- and 1285-fold for indoxacarb, fipronil, spinosad, deltamethrin and Bacillus thuringiensis toxin Cry1Ac respectively compared with a laboratory susceptible population (Lab-UK). At G2 the field-derived population was divided into two subpopulations: one was selected (G2 to G7) with indoxacarb (indoxa-SEL), while the second was left unselected (UNSEL). A significant reduction in the resistance ratio for each compound was observed in UNSEL at G8. For indoxa-SEL, bioassays at G8 found that selection with indoxacarb gave a resistance ratio of 2594 compared with Lab-UK and of 90 compared with UNSEL. The toxicity of fipronil, spinosad and deltamethrin was not significantly different in indoxa-SEL at G8 compared with G2 but was significantly greater than UNSEL at G8. The toxicity of Cry1Ac was significantly reduced in indoxa-SEL at G8 compared with G2 but was also significantly greater than UNSEL at G8. This suggests that indoxacarb selection maintained resistance to these compounds in the indoxa-SEL population. Synergist studies indicated that resistance to indoxacarb in indoxa-SEL was esterase associated. Logit regression analysis of F1 reciprocal crosses between indoxa-SEL and Lab-UK indicated that resistance to indoxacarb was inherited as an autosomal, incompletely recessive (D(LC) = 0.35) trait. Tests of monogenic inheritance suggested that resistance to indoxacarb was controlled by a single locus.     

Resistance selection and mechanisms of oriental tobacco budworm (Helicoverpa assulta Guenee) to indoxacarb

The oriental tobacco budworm, Helicoverpa assulta, is one of the most destructive pests for numerous commercial crops, and these organisms are responsible for enormous economic losses in Chinese agriculture. Insect larvae often feed within host plant fruits, providing protection from many currently used insecticides and making field control of H. assulta very difficult. Owing to its novel mode of action, high insecticidal activity, and low mammalian toxicity, the nonsystemic insecticide indoxacarb has been considered a promising alternative for the control of lepidopterous pests of agricultural significance. Indoxacarb evidences an elevated insecticidal activity against H. assulta. After 13 generations of selection with indoxacarb and bifenthrin insecticides under laboratory conditions, the LC₅₀ of these compounds for H. assulta increased by 4.19-fold and 10.67-fold, respectively. The synergists diethyl maleate (DEM) and triphenyl phosphate (TPP) increased indoxacarb toxicity by 2.76-fold and 4.10-fold in resistant strains and, comparatively, 1.58-fold and 1.75-fold in susceptible strains, suggesting that carboxylesterase (CarE) and glutathione-S-transferases (GSTs) may be involved in the development of indoxacarb resistance in H. assulta. Activity and kinetic parameters observed in detoxification enzymes further demonstrated that the enhanced activity of CarE and GSTs may be critical in development of indoxacarb resistance in H. assulta. The data provides a foundation for further study of the indoxacarb resistance mechanism observed in H. assulta and the rational use of indoxacarb as a rotation insecticide with other insecticide classes for the control of H. assulta.     

昆虫对双酰胺类杀虫剂抗性机制研究进展

双酰胺类杀虫剂是以昆虫鱼尼丁受体为作用靶标的新型杀虫剂,由于其作用机制独特,对多种鳞翅目害虫具有良好的防治效果而得到广泛应用。但已经有多种害虫的田间种群对该类药剂产生了抗性,甚至导致田间防治失败。本文在综述昆虫对双酰胺类杀虫剂抗性现状的基础上,重点总结了抗性机制方面的最新研究进展,并对今后的研究方向进行了展望,以期为进一步深入研究双酰胺类杀虫剂的抗性机制提供借鉴。     

Lack of cross-resistance to indoxacarb in insecticide-resistant Spodoptera frugiperda (Lepidoptera: Noctuidae) and Plutella xylostella (Lepidoptera: Yponomeutidae)

Two field strains of the fall armyworm, Spodoptera frugiperda (JE Smith), collected from corn in north Florida showed high resistance to carbaryl (626- and 1159-fold) and moderate resistance to parathion-methyl (30- and 39-fold) as compared with a laboratory susceptible strain. A field strain of the diamondback moth, Plutella xylostella (L.) collected from cabbage in north Florida and selected for 20 generations with permethrin showed high resistance to permethrin (987-fold) as compared with a susceptible strain. However, in all instances, no cross-resistance to indoxacarb, a novel oxidiazine insecticide, was observed in these two species. Biochemical studies revealed that, in S. frugiperda, activities of detoxification enzymes (microsomal oxidase, glutathione S-transferase and general esterase) were significantly higher in the field strains than in the susceptible strain, indicating that these detoxification enzymes were not actively involved in the resistance to indoxacarb. The lack of cross-resistance between indoxacarb and permethrin in P. xylostella further supports the notion that the mode of action of these insecticides on the insect sodium channel is different.     

Toxicity of a formulation of the insecticide indoxacarb to the tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae), and the big-eyed bug, Geocoris punctipes (Hemiptera: Lygaeidae)

Indoxacarb is a new oxadiazine insecticide that has shown outstanding field insecticidal activity. The toxicity of a 145 g litre-1 indoxacarb SC formulation (Steward) was studied on the tarnished plant bug Lygus lineolaris and the big-eyed bug Geocoris punctipes. Both insect species responded very similarly to indoxacarb in topical, tarsal contact and plant feeding toxicity studies. The topical LD50 of the formulation was c 35 ng AI per insect for both species. Prolonged tarsal contact with dry indoxacarb residues did not result in mortality for either insect species. However, both species were susceptible to feeding through dried residues of indoxacarb after spraying on young cotton plants. Feeding on water-washed plants resulted in lower mortality than that observed with unwashed plants, and toxicity declined even more dramatically after a, detergent rinse, indicating that much of the indoxacarb probably resides on the cotton leaf surface or in the waxy cuticle. These results were corroborated by HPLC-mass spectrometry measurements of indoxacarb residues on the plants. Greater mortality for both species was observed in a higher relative humidity environment. Higher levels of accumulated indoxacarb and its active metabolite were detected in dead G punctipes than in L lineolaris after feeding on sprayed, unwashed plants. When female G punctipes ate indoxacarb-treated Heliothis zea eggs, there was significant toxicity. However, only c 15% of the females consumed indoxacarb-treated eggs, and the rest of the females showed a significant diminution of feeding in response to the insecticide. Cotton field studies have shown that indoxacarb treatments at labelled rates lead to a dramatic decline in L lineolaris, with negligible declines in beneficial populations. A major route of intoxication of L lineolaris in indoxacarb-treated cotton fields thus appears to be via oral, and not cuticular, uptake of residues from treated cotton plants. The mechanisms for selectivity/safety for G punctipes are currently under investigation and may be a combination of differential feeding behavior and diminution of feeding by females exposed to indoxacarb-treated eggs.     

Cross‐resistance,mode of inheritance and stability of resistance to emamectin in Spodoptera litura (Lepidoptera: Noctuidae)

BACKGROUND: Spodoptera litura (F.) is a cosmopolitan pest that has developed resistance to several insecticides. The aim of the present study was to establish whether an emamectin‐selected (Ema‐SEL) population could render cross‐resistance to other insecticides, and to investigate the genetics of resistance. RESULTS: Bioassays at G₁ gave resistance ratios (RRs) of 80‐, 2980‐, 3050‐ and 2800‐fold for emamectin, abamectin, indoxacarb and acetamiprid, respectively, compared with a laboratory susceptible population Lab‐PK. After three rounds of selection, resistance to emamectin in Ema‐SEL increased significantly, with RRs of 730‐fold and 13‐fold compared with the Lab‐PK and unselected (UNSEL) population respectively. Further studies revealed that three generations were required for a tenfold increase in resistance to emamectin. Resistance to abamectin, indoxacarb, acetamiprid and emamectin in UNSEL declined significantly compared with the field population at G₁. Furthermore, selection with emamectin reduced resistance to abamectin, indoxacarb and acetamiprid on a par with UNSEL. Crosses between Ema‐SEL and Lab‐PK indicated autosomal and incomplete dominance of resistance. A direct test of a monogenic model and Land's method suggested that resistance to emamectin was controlled by more than one locus. CONCLUSION: Instability of resistance and lack of cross‐resistance to other insecticides suggest that insecticides with different modes of action should be recommended to reduce emamectin selection pressure. Copyright © 2010 Society of Chemical Industry     

Indoxacarb resistance in the house fly, Musca domestica

Indoxacarb (DPX-MP062) is a recently introduced oxadiazine insecticide with activity against a wide range of pests, including house flies. It is metabolically decarbomethoxylated to DCJW. Selection of field collected house flies with indoxacarb produced a New York indoxacarb-resistant (NYINDR) strain with >118-fold resistance after three generations. Resistance in NYINDR could be partially overcome with the P450 inhibitor piperonyl butoxide (PBO), but the synergists diethyl maleate and S,S,S-tributyl phosphorothioate did not alter expression of the resistance, suggesting P450 monooxygenases, but not esterases or glutathione S-transferases are involved in the indoxacarb resistance. Conversely, the NYINDR strain showed only 3.2-fold resistance to DCJW, and this resistance could be suppressed with PBO. Only limited levels of cross-resistance were detected to pyrethroid, organophosphate, carbamate or chlorinated hydrocarbon insecticides in NYINDR. Indoxacarb resistance in the NYINDR strain was inherited primarily as a completely recessive trait. Analysis of the phenotypes vs. mortality data revealed that the major factor for indoxacarb resistance is located on autosome 4 with a minor factor on autosome 3. It appears these genes have not previously been associated with insecticide resistance.