德国小蠊抗药性机理

德国小蠊(Blattella germanica)是一种重要的室内卫生害虫,化学防治是目前主要的防治手段,但抗药性已逐渐成为制约德国小蠊防治的关键因素。德国小蠊抗药性的产生存在多种机理,本文从行为抗性、表皮穿透性降低、代谢抗性、靶标抗性及微生物降解等方面对德国小蠊抗药性产生机理进行了综述,重点阐述了近年来德国小蠊抗药性机理最新的研究进展。     

害虫对氟虫腈的抗药性研究进展

氟虫腈是第一个商品化的苯基吡唑类杀虫剂,其作用机理是抑制γ-氨基丁酸(GABA)受体氯离子通道。氟虫腈为防治一些世界性的重大害虫包括对以前使用的杀虫剂具有严重抗性的害虫作出了重要贡献。然而,随着氟虫腈的大量使用,害虫对该药的抗药性问题受到日益关注。至今,重要的农业害虫如小菜蛾,烟粉虱、褐飞虱、白背飞虱,二化螟及斜纹夜蛾等已经对氟虫腈产生抗药性。文章就害虫对氟虫腈的抗药性发生概况、交互抗性及抗药性机理策略进行综述,以期为氟虫腈的合理使用提供理论基础。     

羧酸酯酶介导的小菜蛾对氟虫腈的抗性

【目的】羧酸酯酶（carboxylesterases, CarEs）是昆虫重要的解毒代谢酶之一,可以介导靶标昆虫对多种杀虫剂的代谢抗性。本研究检测了羧酸酯酶对小菜蛾Plutella xylostella 抗药性的介导功能,旨在阐明羧酸酯酶在小菜蛾代谢解毒中的生理生化和分子机理。【方法】采用点滴法测定氟虫腈对小菜蛾敏感种群和抗氟虫腈种群的毒力,以及羧酸酯酶抑制剂磷酸三苯酯（triphenyl phosphate, TPP）对氟虫腈的增效作用;以LC₃₀和LC₅₀浓度的氟虫腈处理抗性小菜蛾,测定药剂处理后CarEs酶活性的变化;利用qRT-PCR技术分析Pxae22和Pxae31两个基因在小菜蛾不同发育阶段、组织和种群的表达模式;利用dsRNA干扰Pxae22和Pxae31后观察基因的表达变化和小菜蛾3龄幼虫对药剂敏感性的变化。【结果】TPP可以削弱小菜蛾3龄幼虫对氟虫腈的抗性,增效倍数约为6倍;使用较低剂量（LC₃₀和LC₅₀）氟虫腈处理小菜蛾3龄幼虫后,处理组CarEs比活力明显高于对照,提示氟虫腈对小菜蛾CarEs活性具有诱导作用。对羧酸酯酶基因Pxae22和Pxae31在小菜蛾不同发育阶段、4龄幼虫不同组织和不同种群3龄幼虫中的表达模式分析发现,这两个基因在小菜蛾4龄幼虫中的表达量最高;在4龄幼虫中以中肠组织中的表达量较高,头、表皮、脂肪体中的表达量很低; 抗性种群中的表达量显著高于敏感种群。通过干扰 Pxae22和 Pxae31后的qRT-PCR验证,两个基因的表达量均显著降低,进一步的氟虫腈毒力测定发现,干扰P xae22和 Pxae31后的小菜蛾3龄幼虫对氟虫腈的敏感性分别增加了1.63倍和1.73倍。【结论】羧酸酯酶在小菜蛾对氟虫腈解毒代谢中具有重要作用;Pxae22和Pxae31是小菜蛾的两个抗性相关基因,其表达水平的变化直接影响小菜蛾对氟虫腈的敏感性。     

海南地区小菜蛾对氯虫苯甲酰胺和乙基多杀菌素的抗药性变化趋势

【目的】为了明确海南地区小菜蛾Plutella xylostella(L.)对氯虫苯甲酰胺和乙基多杀菌素的抗性现状和抗性发展趋势,为制定有效的化学防治措施及抗性治理策略提供参考。【方法】本文采用叶片浸渍法,测定了海南海口、三亚两个地区小菜蛾田间种群2011—2014年度对2种药剂的抗药性水平。【结果】结果表明:自2011年以来,海口地区小菜蛾种群对氯虫苯甲酰胺的抗性倍数从2011年的0.95倍,突然发展为2012年的303.18倍,2013年下降为61.37倍,2014年又上升为92.41倍,年度间波动较大;三亚地区的抗性倍数由2011年的1.16倍,逐年上升为2012年的44.00倍,2013年的51.22倍和2014年度的120.62倍,年度间抗性持续上升,达到高抗性水平。海口地区小菜蛾对乙基多杀菌素的抗性倍数从2012年的1.19倍,发展为2013年的29.35倍和2014年的30.25倍,达到中等抗性水平;三亚地区的抗性倍数由2012年的4.43倍,逐年上升为2013年的30.48倍和2014年度的54.96倍,年度间抗性持续上升。【结论】海南地区小菜蛾对乙基多杀菌素和氯虫苯甲酰胺均已产生中等水平或高水平的抗药性,抗药性呈现持续上升的趋势。这可能与两个地区的用药环境和用药习惯有关。田间防治时,应减少两种药剂的使用次数,注意轮换其它药剂。     

高效氟氯氰菊酯微胶囊悬浮剂对德国小蠊的防治效果

【目的】研究高效氟氯氰菊酯微胶囊悬浮剂对德国小蠊Blattella germanica的防治效果,为指导防治德国小蠊提供科学、合理的依据。【方法】参照国家标准GB/T 13917.1-2009《农药登记卫生用杀虫剂的室内药效试验及评价第1部分:喷射剂》的测试方法进行防治试验。【结果】0.8 m L/m2剂量的瓷砖和玻璃面板药效的持续时间分别为98 d、112 d;1.6 m L/m2剂量的瓷砖和玻璃面板药效的持续时间分别为112 d、119 d。【结论】相同剂量的瓷砖和玻璃面板相比较,玻璃面板的药效持续时间长,但稳定性低。     

海葵毒素Av3对德国小蠊的毒性及其作用机制

摘要: 【目的】Ⅲ型海葵毒素(Av3)对昆虫具有显著的选择性毒性,对其作用机制的研究对新型高选择性毒性杀虫剂的设计研究具有重要意义。【方法】反向高效液相色谱及电喷雾质谱用于鉴定化学合成的Av3野生型(Av3 wild type, Av3-WT)及其突变体的纯度和分子量;生物活性测定检测Av3-WT及其突变体对德国小蠊Blattella germanica成虫的毒力;双电极电压钳技术检测Av3-WT及其突变体对德国小蠊钠通道BgNav1-1a失活的抑制作用。构建基于BgNav1-1a与大鼠钠通道rNav1.2a的重组嵌合体,通过双电极电压钳技术确定BgNav1-1a上参与Av3-WT选择性毒性的关键区域。【结果】芳香族氨基酸Y7, W8和Y18分别突变后形成的Av3-WT突变体Y7A, W8A和Y18A对德国小蠊成虫的毒力显著降低,半数击倒剂量(KD50)与Av3-WT相比均增加了超过10倍;与Av3-WT对通道失活62%的抑制率相比,250 nmol/L的毒素突变体Y7A, W8A和Y18A对BgNav1-1a失活的抑制作用也显著降低,通道失活的抑制率分别降低到12%, 23%和8%;以rNav1.2a胞外环DI/SS5-S6替换BgNav1-1a的相应序列获得的重组嵌合体钠通道对Av3-WT毒素的敏感性几乎丧失,仅3.6%的通道在1 μmol/L Av3-WT作用下失活被抑制。BgNav1-1a胞外环 DI/SS2-S6上的His404突变为Tyr后几乎丧失对毒素的敏感性,仅6%的通道在1 μmol/L Av3-WT作用下失活被抑制。【结论】芳香族氨基酸Tyr7, Trp8和Tyr18参与到构成Av3-WT分子的生物活性表面;钠离子通道胞外环DI/SS2-S6是影响Av3-WT毒素发挥选择性的关键结合区域,BgNav1-1a的DI/SS2-S6上的His404则是影响Av3-WT选择性毒性的关键氨基酸。     

湖北省褐飞虱对吡虫啉、噻嗪酮及氟虫腈的抗药性监测

采用稻茎浸渍法监测湖北省武穴、天门、监利、通城、孝感、公安及枣阳七地褐飞虱Nilaparvata lugens(Sta1)田间种群对吡虫啉、噻嗪酮、氟虫腈的抗药性。结果表明:2006、2007和2008年3年7地褐飞虱种群对吡虫啉的抗性分别为98.89～389.19倍、69.00～153.33倍和56.32～116.89倍,达高水平至极高水平抗性,但3年期间总体抗性水平呈现一定程度的下降趋势;2007和2008年2年7地褐飞虱对噻嗪酮的抗性分别为13.39～41.06倍和6.94～20.44倍,达低水平至高水平抗性;2007和2008年2年7地褐飞虱对氟虫腈抗性分别为0.97～2.64倍和0.63～1.42倍,为敏感阶段。此外,还对褐飞虱的治理进行讨论。     

不同杀虫剂对西花蓟马的室内毒力及田间药效

【目的】西花蓟马是一种世界性的危险性入侵害虫,筛选防治西花蓟马的有效药剂可为生产中科学用药提供依据。【方法】通过室内毒力测定和田间药效试验,测定了2种化学药剂和8种生物药剂对西花蓟马成虫的致死中浓度(LC_(50))和药后不同时期的防治效果。【结果】室内毒力测定依据LC_(50)值将各药剂对西花蓟马的敏感性由高到低依次排序为乙基多杀菌素(0.1958 mg·L~(-1))、印楝素(0.9399 mg·L~(-1))、苦参碱(1.2483 mg·L~(-1))、阿维菌素(1.8096 mg·L~(-1))、高效氯氰菊酯(4.4458 mg·L~(-1))、藜芦碱(10.7628 mg·L~(-1))、鱼藤酮(18.1898 mg·L~(-1))、吡虫啉(46.3964 mg·L~(-1))、松脂酸钠(131.5214 mg·L~(-1))、苏云金杆菌(446.2318 mg·L~(-1));田间药效试验发现,乙基多杀菌素和吡虫啉防治西花蓟马均表现出较强的速效性和持效性,药后1～14 d的防效分别可达84%和73%以上;其次是藜芦碱,药后1～14 d的防效可达48.15%～61.37%;高效氯氰菊酯的防效较低,药后14 d的防效为46.22%;生物药剂阿维菌素、苏云金杆菌、苦参碱、印楝素的速效性均较低,但防效随施药后时间的延长而逐渐上升;鱼藤酮持效性最低。【结论】乙基多杀菌素和吡虫啉可推荐为生产中防治西花蓟马的首选药剂,植物源药剂藜芦碱和生物药剂阿维菌素可作为交替使用药剂。     

杀虫剂对稻纵卷叶螟的室内毒力及田间药效

分别测定了8种杀虫剂对稻纵卷叶螟的室内毒力及田间防效,结果表明:8种杀虫剂对稻纵卷叶螟的LC50为0.671-10171.07mg.L-1,毒力由高到低的顺序为:甲氨基阿维菌素苯甲酸盐>阿维菌素(B1)>氟虫腈>氟铃脲>丙溴磷>毒死蜱>三唑磷>杀虫单。甲氨基阿维菌素苯甲酸盐、阿维菌素(B1)、氟虫腈、氟铃脲对稻纵卷叶螟的毒力分别为杀虫单的15180.7、5619.3、1611.9、997.2倍。在推荐剂量下,氟虫腈、丙溴磷、毒死蜱对稻纵卷叶螟防治效果较好,防效分别达86.11%、84.73%、83.37%。     

几类杀虫剂对灰飞虱的相对毒力及田间种群的抗药性现状

采用浸苗法测定了6类11种杀虫剂对灰飞虱Laodelphax striatellus (Fallén)3龄若虫的毒力,并分析比较了江苏句容、通州、楚州、大丰、南京和苏州以及安徽庐江等7地灰飞虱种群对10种杀虫剂的抗药性水平。对云南种群而言,在所测杀虫剂中,以乙酰甲胺磷为标准药剂,氟虫腈的相对毒力最高;噻嗪酮、阿维菌素和噻虫嗪次之;高效氯氰菊酯、IPP（硝基亚甲基类化合物）、毒死蜱、敌敌畏和三唑磷间毒力处于同一数量级,低于阿维菌素等杀虫剂;吡虫啉的相对毒力最低。与云南种群相比,2007年采自苏、皖7个不同地区的灰飞虱种群对噻嗪酮产生了极高水平的抗性,其抗性倍数均超过200倍;对高效氯氰菊酯产生了中高水平的抗性,其抗性倍数为7.8～108.8;安徽庐江灰飞虱种群对三唑磷产生了7.7倍的抗性,对毒死蜱产生了12.0倍的抗性,江苏楚州、南京、大丰和句容灰飞虱种群对毒死蜱产生了5.7～12.6倍的抗性; 所有灰飞虱种群对敌敌畏仍然敏感,对氟虫腈、阿维菌素和新烟碱类杀虫剂吡虫啉、噻虫嗪和IPP等也比较敏感。     

Behavioral and physiological resistance of the German cockroach to gel baits (Blattodea: Blattellidae)

A gel bait-resistant German cockroach, Blattella germanica (L.), strain Cincy was collected in Cincinnati, OH. This strain exhibited a high level of behavioral resistance to Avert (0.05% abamectin) and Maxforce FC (0.01% fipronil) gel baits. Topical application assays indicated moderate levels of physiological resistance of the Cincy strain to abamectin and fipronil. Resistance ratios (based on LD50 values from topical applications) to abamectin and fipronil were 2.5 and 8.7, respectively. The Cincy strain of had a significantly lower LD50 value to abamectin than a nonaverse field strain (Dorie) and similar LD50 values to fipronil as the Dorie strain. The aversion behavior (avoidance of gel baits) was therefore caused by food ingredients in the gel baits. The Cincy strain showed avoidance of agar containing fructose, glucose, maltose, and sucrose, which are phagostimulants to the laboratory strain. Modifications of the inert ingredients in the Maxforce FC gel bait significantly improved the efficacy against the Cincy strain. The Cincy strain produced significantly smaller oothecae and lower numbers of eggs in each egg capsule than the nonaverse Jwax and Dorie strains of cockroaches, suggesting fitness costs are associated with resistance.     

Toxicity of fipronil to German and American cockroaches

Topical and oral toxicity of fipronil, compared to chlorpyrifos, was determined for the German cockroach, Blattella germanica (L.), and American cockroach, Periplaneta americana (L.). Fipronil and Combat bait matrices were evaluated for their attractancies to both species. In the topical toxicity tests, LD50's of fipronil, at 72 h after topical application, were 0.03 and 0.02 µg/g for adult B. germanica and P. americana, respectively. Fipronil was significantly more toxic than topically applied chlorpyrifos (LD50's were 0.06 and 0.16 µg/g for B. germanica and P. americana, respectively). The oral toxicity of fipronil and chlorpyrifos in Petri dish experiments, against both species, was affected by stage (for B. germanica), diet concentration, and feeding assay. Fipronil caused higher mortality of B. germanica than chlorpyrifos in two feeding assays (continuous and abbreviated). Both compounds were equally toxic to adult males of P. americana at all rates. Fipronil caused higher nymphal mortality than chlorpyrifos 48–72 h after exposure in both feeding assays. In large population chamber tests, fipronil bait was more effective and faster in killing P. americana than Raid and Combat. LT50's were 0.8, 2.4, and 7.6 d for fipronil, Raid (a.i. = chlorpyrifos), and Combat (a.i. = hydramethylnon) baits, respectively. Mortality reached 96.5, 93.4, and 84.6%, respectively, at the end of the 14 d test. In the bait attractancy tests, both strains of B. germanica were attracted similarly to fipronil and Combat bait matrices. P. americana were attracted more to fipronil than to Combat bait matrix or to other alternative foods.     

Genetic basis for resistance to gel baits, fipronil, and sugar-based attractants in German cockroaches (Dictyoptera: blattellidae)

A gel bait-resistant Blattella germanica (L.) strain (Cincy) was collected in Cincinnati, OH, in 2003. This strain exhibited strong behavioral resistance to Avert (0.05% abamectin), Maxforce FC (0.01% fipronil), and Pre-Empt (2.15% imidacloprid) gel baits. Reciprocal mass crosses and back crosses between the Cincy strain and a susceptible strain (Jwax) were made and tested for their inheritance of resistance to Avert, Maxforce FC, and Pre-Empt gel baits. Topical assays comparing the parental and reciprocal-heterozygous strains indicated the resistance to fipronil was incompletely recessive. LD50 and LD50 values of the Jwax male x Cincy female strain were not significantly different from he Jwax female x Cincy male strain, suggesting no sex linkage in physiological fipronil resistance. Feeding assays revealed that F1 reciprocal crosses were significantly less responsive to blank Avert and Maxforce FC baits (without active ingredients) than the susceptible strain. The Jwax female x Cincy male strain did not display significantly greater consumption of blank Avert and Maxforce FC baits relative to the Jwax male x Cincy female strain. In feeding assays with agar containing D-fructose, D-galactose, D-glucose, D-lactose, D-maltose, and D-sucrose, the crosses showed an intermediate feeding response to glucose compared with the Cincy and Jwax strains, and a similar response to other sugars compared with the Jwax strain. The Jwax male x Cincy female strain was significantly less responsive to glucose than the Jwax female x Cincy male strain. Mortality induced by Avert, Maxforce FC, and Pre-Empt gel baits against the F6 Jwax male x Cincy femaale strain was 44.2 +/- 6.8, 92.9 +/- 2.1, and 78.7 +/- 5.2%, respectively, indicating the resistance to Avert and Pre-Empt gel baits inherited by Cincy females was extremely stable. The F6 Jwax male x Cincy female strain was significantly more resistant to Avert, Maxforce FC, and Pre-Empt than the F6 Jwax female x Cincy male strain. These findings suggest that behavioral resistance to gel baits has weak sex-linkage, with a greater degree of the resistance trait being inherited by female cockroaches. Alternatively, physiological resistance to fipronil has no sex-linkage, but it is nonetheless important to the complete resistance phenotype.     

Origin and extent of resistance to fipronil in the German cockroach, Blattella germanica (L.) (Dictyoptera: Blattellidae)

Fipronil, a phenylpyrazole insecticide, was made available in 1999 in bait formulations for use against the German cockroach, Blattella germanica (L.). We have investigated resistance to fipronil in the descendants of cockroaches collected just before, or contemporaneously with, the introduction of fipronil baits. Cockroaches were obtained in two types of settings: homes that either had or had not been serviced by a pest management professional while occupied by their current residents. Thorough inspections by us turned up no evidence that fipronil had been used in any of the homes, and in addition, no residents claimed to have used baits containing fipronil. Resistance to fipronil was detected by topically dosing adult males with the LC99 of fipronil, the value of which was determined in a dose-response assay with males of an insecticide-susceptible strain. Fewer than 99 of 100 males of all field-collected strains died within 72 h of being treated. Moreover, substantial numbers of males survived doses three and 10-fold greater than the LC99. Regression analysis showed that 67% of the variation in the percentage of males that died after being treated with fipronil was explained by a linear relationship with the percentage that died after being treated with dieldrin. Therefore, it appears that resistance to fipronil in German cockroaches--whose ancestors had never been exposed to it--is attributable to enduring resistance to the cyclodienes, which were formerly used for cockroach control and have a similar mode of action as fipronil. Lastly, we found that insects resistant to topically administered fipronil were likewise resistant, and to a similar degree, to ingested fipronil.     

Synergism of chlorpyrifos against the German cockroach, Blattella germanica

Of fifteen compounds tested as synergists for chlorpyrifos against susceptible and resistant strains of Blattella germanica, the German cockroach, eleven were active against the resistant strain but only seven were synergistic against the susceptible strain. Overall, the most effective synergist was S,S,S-tributyl phosphorotrithioate (DEF) followed by phenyl saligenin cyclic phosphonate (PSCP) and two substituted N,N-dimethylcarbamates: SK-102 and SK-37. The most effective synergist for overcoming chlorpyrifos resistance was SK-37 which reduced the resistance ratio by 3.2-fold. Four other synergists which reduced chlorpyrifos resistance, in order of their effectiveness, were: SK-102 > PSCP > DEF > tridiphane. The potential usefulness of these synergists for German cockroach control is discussed.     

Cross-resistance between dieldrin and fipronil in German cockroach (Dictyoptera: Blattellidae)

The toxicity of fipronil and dieldrin was determined in one susceptible laboratory strain and seven insecticide-resistant field-collected strains of Blattella germanica (L). The Zo960302 and Ga021001 strains were 1,270- and 2,030-fold resistant to dieldrin and 15- and 14-fold resistant to fipronil. The Su960304 and Od010803 strains were 15- and 13-fold resistant to dieldrin and two- and four-fold resistant to fipronil. Three strains showed no or a low level of resistance to dieldrin and fipronil. Crosses were performed between the susceptible strain Danish Pest Infestation Laboratory (DPIL)-SUS and the resistant strains Zo960302 and Su960304 and resistance to dieldrin and fipronil were intermediate compared with the susceptible and the resistant strains. Backcrosses to both of the parental strains showed cosegregation of dieldrin and fipronil resistance. The toxicity of dieldrin and fipronil was correlated when compared at LD50, and 93% of the observed variation in LD50 of fipronil can be ascribed to variation among predictions based on the value of LD50 of dieldrin. The frequency of the A302S substitution in the resistance to dieldrin (Rdl) gene in the highly dieldrin- and fipronil-resistant strains Zo960302 and Ga021001 and the moderately resistant Su960304 was 0.97, 1.0, and 0.38, respectively. We consider the connection between the frequency of the Rdl mutation and dieldrin and fipronil resistance a causal connection and not merely a coincidence.     

Inheritance of malathion resistance in the German cockroach

Malathion resistance in the German cockroach has been examined with respect to its inheritance pattern and linkage relationship. A resistant strain was crossed reciprocally with an unmarked and two marked susceptible strains. The progeny from F1, F2 and backcrosses were tested for resistance to malathion by exposure to toxicant-impregnated filter paper, and were classified according to marker traits where appropriate. Malathion resistance (R-Mal) is inherited as a simple autosomal dominant trait. Linkage studies showed R-Mal to be independent of or in group IV, pld in group VI, and T(9, 10) Pw marking both groups III and VIII. A possible malathion-resistance mechanism for this insect is discussed.

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Résumé La résistance de la Blatte germanique au malathion est réputée se manifester à la fois dans les conditions naturelles et dans les lignées élevées en laboratoire. Dans le présent travail cette résistance est étudiée en vue de déterminer le mécanisme de sa transmission héréditaire et de commencer à établir la carte chromosomique de ce caractère. Une lignée présentant un haut niveau de résistance au malathion est croisée avec une lignée sensible non marquée et avec deux autres lignées sensibles possédant un gêne marqueur. Les descendants de F1, de F2 et des croisements de retour sont testés pour leur résístance au malathion en soumettant les larves à un contact avec du papier filtre imprégné de malathion; ils sont classés en se rapportant aux caractères marqueurs. Les gênes marqueurs utilisés sont or sur le groupe IV, pld sur le groupe VI, et T(9, 10) Pw, marquant à la fois les groupes III et VIII. Les résultats montrent que les descendants F1 provenant de croisements réciproques sont identiques et ressemblent au parent résistant. Cette donnée ajoutée aux résultats concernant F2 et les croisements de retour avec les parents R et S, indique que la résistance au malathion est transmise comme un caractère dominant, monofactoriel et porté sur un autosome, caractère désigné R-Mal. Les études relatives au linkage du caractère R-Mal aves les gênes marqueurs, ont montré l'indépendance de R-Mal. II est suggéré que le mécanisme le plus probable de la résistance au malathion résulte d'une activité accrue de la carboxyesterase.

     

Secondary transmission of toxic baits in German cockroach (Dictyoptera: Blattellidae)

The death rates of three toxic gel baits (fipronil bait, 0.05%; hydramethylnon, bait 2.15%; and abamectin B1 bait, 0.05%) were estimated in Blattella germanica (L.). After ingestion, all three baits killed similar proportions of cockroaches, but they died more rapidly after ingestion of fipronil bait than after ingestion of abamectin B1 bait or of hydramethylnon bait. Laboratory experiments evaluated the impact of secondary transmission of fipronil bait and hydramethylnon bait. Mortality rates caused by secondary transmission were higher for fipronil bait than for hydramethylnon bait. Under controlled laboratory conditions, secondary transmission occurred mainly through direct contact with, or ingestion of, traces of baits dispersed in the environment by contaminated cockroaches. These traces were either deposited by "trampling" in the environment or on dead contaminated cockroaches. Social interactions and cannibalism played a minor role in secondary transmission of these two baits.