常用杀虫剂对菜蛾绒茧蜂的影响及毒理机制研究

田间采集试虫室内测定结果表明,敌敌畏、灭多威和杀虫双对菜蛾绒茧蜂Apanteles plutellae高毒,乙酰甲胺磷对绒茧蜂毒性较低,而氰戊菊酯、氯氰菊酯、氟虫腈、阿维菌素、定虫隆和Bt则是低毒的。菜蛾绒茧蜂AChE的Km及Vmax值分别是小菜蛾的0.22和2.08倍,AChE对敌敌畏的敏感性(K/em>i值)分别是小菜蛾的10.37倍。100 mg/L的胡椒基丁醚(PB)或磷酸三苯酯(TPP)均可使氰戊菊酯明显增效,其中PB的增效作用显著高于TPP。体内抑制实验结果表明,PB和TPP对绒茧蜂AChE活力无显著影响,低浓度(100 mg/L)的PB即可显著抑制绒茧蜂的α-NA和β-NA CarE活力,且抑制率高于TPP,TPP仅在高浓度(1 000 mg/L)时对绒茧蜂的两种CarE活力有显著抑制作用。由此推断,与小菜蛾相比,菜蛾绒茧蜂对有机磷的高敏感性与其显著较高的AChE敏感性有关;此外,多功能氧化酶的解毒代谢在菜蛾绒茧蜂对氰戊菊酯的耐药性中具重要作用。     

增效剂对菜蚜茧蜂杀虫剂敏感性的影响

以田间菜蚜茧蜂为试虫,采用药膜法研究了增效剂胡椒基丁醚(PB)、磷酸三苯酯(TPP)和马来酸二乙酯(DEM)对6种杀虫剂的增效作用。结果表明,三种增效剂对6种杀虫剂均有显著增效作用,其大小依次为PB>DEM>TPP。PB对甲胺磷、阿维菌素、氟虫腈、氰戊菊酯、氯氰菊酯和吡虫啉的增效比达5.0～9.6倍。TPP和DEM对甲胺磷、DEM对氟虫腈的增效比达2.6～3.0倍,但TPP和DEM对阿维菌素、氰戊菊酯和氯氰菊酯、TPP对氟虫腈的增效比均在1.9倍以下。PB、TPP和DEM对吡虫啉的增效比分别高达9.6、6.8和8.2倍。体内抑制试验结果显示,PB、TPP和DEM对菜蚜茧蜂AChE活性无明显抑制作用,而PB和TPP对羧酸酯酶(CarE)、DEM对谷胱甘肽S转移酶(CST)活性有显著抑制作用。由此认为,菜蚜茧蜂对所用的6种杀虫剂的耐药性与多功能氧化酶(MFO)、CarE和GST的解毒作用有关。     

小菜蛾和绒茧蜂乙酰胆碱酯酶对甲胺磷和甲基异柳磷敏感性监测

对 ACh E的 K m、Vmax和 Ki值的研究结果表明 ,田间小菜蛾和绒茧蜂对甲胺磷和甲基异柳磷的抗性与 ACh E对杀虫剂的不敏感性有关。田间监测结果表明 ,每年 9月至次年 2月期间 ,由于田间杀虫剂选择压较高 ,小菜蛾 ACh E对有机磷较不敏感 ,而在每年的 6月至 8月期间 ,ACh E敏感性有所升高 ,达到全年的最高点。寄生于同一虫源的绒茧蜂 ACh E敏感性的变化也呈明显的相关性。绒茧蜂 ACh E的敏感性显著高于小菜蛾 ,尚未达到高度不敏感水平。当田间选择压极高时 ,可导致小菜蛾 ACh E呈高度不敏感 ,此时绒茧蜂 ACh E也表现出较高的不敏感性。     

田间小菜蛾抗药性监测及毒理机制研究

田间监测结果表明，福州地区小菜蛾Plutella xylostella(L.)已对生产上常用的各类杀虫剂产生不同程度的抗性，从9月至次年5年期间，田间小菜蛾表现出较高水平的抗性，而在8月份则表现出明显低的抗性水平，短期高温和长期低温的环境条件可明显抑制小菜蛾幼虫的AChE和CarE活性，但短期低温的环境条件对小菜蛾幼虫的AChE和CarE活性影响不大，饲养温度的变化不会影响小菜蛾幼虫AChE和Ki值，但在较高的酶与杀虫剂的反应温度下，有机磷对小菜蛾、菜青虫和黄曲条跳甲AChE的抑制作用显著增高，此外，探讨了田间影响小菜蛾抗性水平的环境因素及毒理学机制。     

江苏省水稻二化螟的抗药性测定及对甲胺磷的抗性机制

采用3龄幼虫点滴法测定了江苏省水稻二化螟对杀虫单和甲胺磷的抗性水平，并就二化螟对甲胺磷产生抗性的机制进行了研究，结果表明，高淳和徐州二化螟种群对杀虫单已达高抗水平，其它地区也表现为中等抗生，在所测定的6个种群中，苏州种群对甲胺磷处于低抗水平，其它种群为中抗种群，澌知体增效作用表明，氧化胡椒基丁醚（PBO）对甲胺磷有明显的增效作用，磷酸三苯酯（TPP）和顺丁烯酸二乙酸（DEM）的增效作用不明显，对离体解毒酶的研究表明，R种群幼虫多功能氧化酶（MFO）的O-脱甲基作用的活力比S幼虫高，R幼虫乙酰胆碱酯酶（AChE)的活力与S幼虫无显著差异。以甲胺磷为抑制剂的R幼虫I50是S幼虫的2.52倍，二化螟对甲胺磷的抗性机理可能与MFO的O-脱甲基作用活力增矿山和AChE的敏感性降低有关。     

温度对几种害虫和寄生蜂乙酰胆碱酯酶对杀虫剂敏感性的影响

田间菜蛾绒茧蜂Cotesia plutellae、颈双缘姬蜂Diadromus collaris和菜蚜茧蜂Diaeretiella rapae对敌敌畏的敏感度及AChE的Ki值远高于其寄主害虫小菜蛾Plutella xylostella和菜缢管蚜Lipaphis erysimi。与对照(25℃)相比,高反应温度(37℃)可显著增高敌敌畏对所测试的5种昆虫AChE的抑制率,而低反应温度(5℃)对5种昆虫AChE的抑制率影响不显著。研究结果还表明,高温对3种寄生蜂AChE的影响明显高于对2种寄主害虫AChE的影响。     

瓜-棉蚜对有机磷及氨基甲酸酯杀虫剂抗性机制研究

从1983年开始就北京及河北省廊坊、香河和涿鹿县四个地区瓜-棉蚜(Aphis gossypiiGlov.)对18种有机磷及2种氨基甲酸酯杀虫药剂进行了抗性系统监测,与苏联瓜蚜(A.gos-sypii Glov.)敏感系毒力值(LC_(50))进行比较,抗蚜威最高达7887.7倍,马拉硫磷357.8倍,乐果128.6倍,敌敌畏83.5倍,乙酰甲胺磷72.1倍;而对喹硫磷、甲基辛硫磷、呋喃丹及溴氯磷则相当敏感,LC_(50)值在45.2—186.0 ppm之间。其抗性谱大致呈交叉型交互抗性。酶系测定结果表明,瓜-棉蚜的乙酰胆碱酯酶(AChE)敏感性降低与抗药性关系最为密切,氧化乐果和抗蚜威对AChE的I_(50)值与其Log LC_(50)(ppm)呈显著相关(P<0.05)。四个地区的瓜-棉蚜AChE对底物(乙酰硫代胆碱ATCh)的米氏常数(Km)及最大反应速度(Vmax)值均无明显差异,但ATCh浓度超过10~(-2)mol/L时,对AChE还没有明显的抑制作用。瓜-棉蚜α-乙酸萘酯羧酸酯酶与对久效磷的抗性呈正相关,面与抗性较高的乐果则无相关性。多功能氧化酶活性的高低与抗药性水平有关,乐果加PB(1:1)也有一定增效作用。GSH-S-转移酶活性与瓜-棉蚜抗性不相关。     

小菜蛾抗性稳定性及抗性治理对策研究

试验表明，福州地区田间小菜蛾已对有机磷、氨基甲酸酯及拟除虫菊酯产 生高抗性。脱离选择压力3代后，小菜蛾的抗性水平迅速下降。Bt预处理可提高抗性和敏感小菜蛾幼虫 对有机磷的敏感性，尤其对抗性小菜蛾增效极显著，对敏感小菜蛾AChE的 Ki值则影响不 大。据此提出在抗性治理中，应轮用或换用不同毒理机制的杀虫剂，且其间隔至少为2～3代。     

寄主抗药性对菜蛾绒茧蜂寄生能力的影响

考察了在使用氰戊菊酯的条件下 ,小菜蛾抗药性对菜蛾绒茧蜂寄生能力的影响。在杀虫剂作用下 ,用抗性寄主饲养的菜蛾绒茧蜂RRC品系对抗性寄主RRP品系幼虫的寄生率达89% ,寄主幼虫死亡率仅 5% ,比RRC对小菜蛾敏感品系SSP幼虫寄生时、或用SSP饲养的菜蛾绒茧蜂SSC品系对SSP寄生时的寄生率显著要高 ,寄主死亡率显著要低。表明杀虫剂存在时 ,寄主抗药性使其具较高存活率而给寄生蜂提供更多的寄主 ,有利于寄生蜂的繁衍。方差分析结果显示 ,小菜蛾品系及蛾×蜂互作对供试小菜蛾幼虫的被寄生率及死亡率均有显著影响 ,表明小菜蛾抗性改变了其对菜蛾绒茧蜂的适合性     

小菜蛾对阿维菌素的抗性机制及交互抗性研究

用叶片药膜法研究了阿维菌素抗性小菜蛾 Plutella xylostella （L.）品系 对常用药剂的交互抗性谱以及增效醚（PB）和磷酸三苯酯（TPP）的增效作用。小菜蛾对阿 维菌素与高效氯氰菊酯、溴氰菊酯、氰戊菊酯和联苯菊酯等菊酯类药剂间具有比较低的交互 抗性，对后者抗性为3～20倍，对阿维菌素的抗性为575.6倍；对氟虫脲和氟啶脲没有交互抗 性。PB和TPP对阿维菌素分别增效8.2和5.5倍，说明小菜蛾对阿维菌素的抗性可能与多功能 氧化酶（MFO）和羧酸酯酶有关。通过差光谱技术测定了阿维菌素抗性和敏感小菜蛾细胞色 素P450的含量，抗性品系是敏感品系的1.38倍。     

Insecticide toxicity and synergism by enzyme inhibitors in 18 species of pest insect and natural enemies in crucifer vegetable crops

The toxicities of three enzyme inhibitors and their synergistic effects on four insecticides were studied by using the dry film method on field populations of 18 species of insects collected in Jianxin and Shanjie, China, from 2003 to 2005. Meanwhile, the inhibitory effects of these enzyme inhibitors on the activities of acetylcholinesterases (AChE), carboxyesterases (CarE) and glutathione-S-transferases (GST), in vivo, were also studied. In general, triphenyl phosphate (TPP) and diethyl maleate (DEM) showed low toxicities to six herbivorous pest insects, four ladybirds and eight parasitoids. Piperonyl butoxide (PB) exhibited low toxicities to the herbivorous pest insects and ladybirds, but high toxicities to the eight parasitoids. The tolerance to the insecticides in 11 pest insects and natural enemies was mainly associated with the tolerance to PB. PB showed the highest synergism on methamidophos, fenvalerate, fipronil and avermectin in nine species of pest insects and natural enemies. In general, TPP and DEM showed significant synergisms to these four insecticides in four parasitoid species. However, in contrast to their effects on the parasitoids, the synergistic effects of TPP and DEM on the four insecticides by TPP and DEM against four pest insects and one ladybird varied depending on the insect species and enzyme inhibitor. Activity of AChE, CarE or GST could be strongly inhibited, in vivo, by PB, TPP or DEM, depending on the insect species and enzyme inhibitors. From the results obtained in this study, mixed-function oxidase (MFO) was thought to play the most critical role in insect tolerances to the tested insecticides in the field. Low competition existed in the evolution of insecticide resistance in the field populations of parasitoids, as compared with herbivorous pest insects and ladybirds. Possible causes of the high synergistic effects of PB on the four classes of insecticides, based on multiattack on the activity of CarE, GST or AChE in the insect species, are also discussed.     

Insecticide susceptibility of surviving Cotesia plutellae (Hym: Braconidae) and Diaeretiella rapae (M'Intosh) (Hym: Aphidiidae) as affected by sublethal insecticide dosages on host insects

The effects of sublethal dosages of insecticides applied to Plutella xylostella L. (Lepidoptera: Yponomeutidae) and Lipaphis erysimi Kaltenbach (Homoptera: Aphidiidae) on the insecticide susceptibility of the surviving endoparasitoids, Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) and Diaeretiella rapae (M'Intosh) (Hymenoptera: Aphidiidae), were studied in Shangjie, Minhou, China. The susceptibility to methamidophos and the sensitivity of acetylcholinesterase (AChE) to methamidophos and dichlorvos in the adults of host insects were substantially lower than those in the two parasitoids. The host insects were treated with sublethal dosages of methamidophos in P. xylostella and of methamidophos and avermectin in L. erysimi. The cocoon formation in the two parasitoids decreased significantly, from 35.0% (control) to 13.0% (with methamidophos treatment) for C. plutellae; from 20.6% (control) to 9.0% (with methamidophos treatment) and from 24.3% (control) to 16.7% (with avermectin treatment) for D. rapae. The susceptibility to methamidophos of the resultant emerging adults of the two parasitoids was found to be significantly lower than that of the control when the parasitoids were left in contact with the same dosages of methamidophos. The average AChE activity inhibition by methamidophos and dichlorvos in 34-60 adults of the two parasitoids that emerged from the treatments (15.1% and 31.8% respectively for C. plutellae, and 21.1% and 26.9% for D. rapae) was also significantly lower than those of the controls (55.4% and 48.3% respectively for C. plutellae, and 42.9% and 51.7% for D. rapae). The bimolecular rate constant (k(i)) values of AChE to methamidophos and dichlorvos in the adults of parasitoids without the insecticide treatment were 1.78 and 1.56 times as high as those that emerged from the host insects treated with methamidophos for C. plutellae, and 1.91 and 1.66 times as high as those in the case of D. rapae. It is suggested that there is a difference in AChE sensitivity to insecticides between the resultant emerging parasitoids with and without insecticide pretreatment. Furthermore, the introduction of the insecticides to the host insects could be an important factor in the insecticide resistance development of the endoparasitoids. The natural selectivity would favour the parasitoids that had developed an insensitivity to the insecticide(s).     

Susceptibilities to methamidophos and enzymatic characteristics in 18 species of pest insects and their natural enemies in crucifer vegetable crops

The susceptibilities to methamidophos as well as the kinetic and inhibitory parameter of acetylcholinesterases (AChE) and the activities of carboxyestsrases (CarE) and glutathione-S-transferases (GST) were studied in 18 species field populations of insects collected in Fuzhou, China during April and May 2000 and 2001. The insect species included five hymenopteran endoparasitoids, one hymenopteran exoparasitoid, one hymenopteran hyperparasitoid, one dipteran predator, four coleopteran predator ladybirds, six herbivorous pest insects of lepidoptera, diptera, homoptera, and coleoptera, respectively. There existed significant correlations between the susceptibility to methamidophos and the k_i values of AChE to methamidophos, dichlorvos, and carbofuran and between the k_i and V_max values of AChE among 18 species of insects. The six herbivorous pests and four ladybirds showed significantly low k_i and V_max values of AChE compared to the seven parasitoids and predator Epistrophe balteate. It was difficult to correlate the susceptibility to methamidophos or the k_i values with the K_m values of AChE, or with the activity of CarE and GST. The activities of CarE and GST varied depending on the different insect species. Significant synergisms of piperonyl butoxide (PB), triphenyl phosphate (TPP), and diethyl maleate (DEM) with methamidophos were observed in 14 pest insects and their natural enemies. Synergisms of PB were found to be the greatest. Reduced k_i values suggested that insensitive AChE might play a critical role in the tolerance to methamidophos in the 18 insect species. The detoxification enzymes, mixed-function oxidase (MFO), CarE, and GST, were believed to be involved in the tolerance to methamidophos. MFO might play the most important role, and CarE or GST might be important in the tolerance in some insect species. Different models of tolerance to methamidophos and enzymatic potential were existed in parasitoids, predators, and herbivores based on the different selection of insecticide pressure (either directly by exposing to the spray in the field, or indirectly by the insecticides penetrated into the body of host insects) as well as different ecological and biological habitats.     

杀虫增效剂--酶抑制剂对蝶蛹金小蜂和颈双缘姬蜂的影响

采用药膜法测定了3种酶抑制剂对蝶蛹金小蜂和颈双缘姬蜂杀虫剂敏感性的影响。结果表明，胡椒基丁醚、磷酸三苯酯和马来酸二乙酯显著增大了蝶蛹金小蜂和颈双缘姬蜂对甲胺磷、氰戊菊酯、氯氰菊酯、氟虫腈和阿维菌素的敏感性，胡椒基丁醚的作用显著高于后两者，而后两者之间较为接近。2种寄生蜂对氰戊菊酯和氯氰菊酯的击倒作用具明显的恢复能力，而胡椒基丁醚、磷酸三苯酯和马来酸二乙酯可显著抑制这种击倒恢复能力。上述结果表明，2种寄生蜂对所测试杀虫剂的耐药性与多功能氧化酶、羧酸酯酶和谷胱甘肽-S-转移酶的解毒作用有关，其中多功能氧化酶的作用可能是最重要的。     

羧酸酯酶和乙酰胆碱酯酶在褐飞虱对甲胺磷抗性发展中的作用

室内抗药性筛选表明,褐飞虱对甲胺磷的抗性呈"快-慢-快"的发展趋势:第1到第4代抗性上升缓慢;第5代到第15代迅速上升,其中又呈现2个发展阶段,以第9代为拐点;第15代后抗性上升变慢。羧酸酯酶在抗药性上升中可能起到十分重要的作用,与LD50变化存在很高的相关性,达到极显著水平,相关系数为0.990 6。乙酰胆碱酯酶不敏感性在抗性发展后期变化很大,第8代到第16代间,与LD50变化存在极显著相关性,相关系数为0.970 1。由此可见,羧酸酯酶可能在褐飞虱对甲胺磷抗性的持续发展中起十分重要的作用,而乙酰胆碱酯酶不敏感性在抗性发展的后期阶段可能起到很重要作用。     

Present status and countermeasures of insecticide resistance in agricultural pests in China

Of the 23 species of agricultural pest known to resist insecticides in China, 4 are cotton pests, 4 rice pests and 5 are pests of brassicae. In the green rice leafhopper, malathion resistance is caused by increased carboxylesterase (CarE) activity, which plays a more important role in the resistance to dimethoate than the mixed-function oxidases (mfos). The in-vitro and in-vivo results are in agreement with studies of synergism of malathion and dimethoate by TPP and EBP. These synergists delay the development of resistance, and EBP when added to malathion has limited the development of resistance to malathion in the green rice leafhopper. In the cotton aphid, resistance to organophosphates involves several factors: acetylcholinesterase (AChE) insensitivity, high CarE activity, slight (× 2) increase in glutathione S-transferases (GSH-ases), mfo activity as well as reduced penetration. In vitro, the I₅₀ of the insensitive AChE is × 14 that of S aphids, and anaphthyl-acetate CarE hydrolysing activity is 70 times greater in R than in S aphids. Insecticide mixtures, alternation or rotation can delay build-up of resistance; resistance to malathion and trichlorfon was delayed in Culex pipiens pallens when the two insecticides were used together. Used singly each insecticide selected for high resistance within 25 generations. Mosaic rotation of dimethoate and fenvalerate delayed the onset of insecticide resistance in Lipaphis erysimi pseudobrassicae.