不同药剂对甜菜夜蛾幼虫毒力和田间应用效果研究

利用浸渍法分别测定虫螨腈等不同药剂对甜菜夜蛾3龄及5龄幼虫的毒力，结果表明：不同药剂对甜菜夜蛾幼虫的毒力存在明显差异，一些特异杀虫剂对甜菜夜蛾幼虫的毒力普遍高于试验用常规化学杀虫剂的毒力；同一药剂对不同龄期幼虫毒力的差异程度也不同，如虫螨腈、氟啶脲、氟铃脲、甲胺基阿维菌素、阿维菌素、虫酰肼等药剂对甜菜夜蛾3龄及5龄幼虫毒力的差异程度明显低于顺式氯氰菊酯、丙溴磷、灭多威等化学药剂。同时，作者还对12种药剂分别稀释1000倍对甜菜夜蛾5龄幼虫不同时间的毒力进行了观察，除常规化学农药出现中毒现象较快外，虫螨腈、甲胺基阿维菌素也表现较快中毒症状，田间药效试验进一步验证防治甜菜夜蛾宜选用虫螨腈、氟啶脲、氟铃脲、甲胺基阿维菌素、阿维菌素、虫酰肼等药剂。     

松油烯-4-醇对家蝇超氧化物歧化酶、过氧化氢酶及过氧化物酶的影响

以杀虫植物砂地柏Sabina vulgaris Ant.精油中主要杀虫成分——松油烯-4-醇点滴处理家蝇成虫后,测定其兴奋期、痉挛期、麻痹期及复苏期等4个中毒阶段试虫的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)及过氧化物酶(POD)活性。结果表明:SOD被明显激活,各中毒阶段的酶比活力均较对照高,差异显著,且表现为先增高后下降的趋势;CAT先被抑制后被激活,在复苏期酶比活力为对照的1.19倍,其中兴奋期和复苏期酶比活力与对照差异显著,而痉挛期和麻痹期与对照无明显差异;POD被明显激活,各中毒阶段的酶比活力依次为对照的2.25、2.04、1.23和2.91倍,与对照差异极显著。上述结果表明,保护酶活性的变化与松油烯-4-醇的作用有密切关系,SOD活力增加可能是松油烯-4-醇的诱导反应,而中毒试虫的复苏可能与CAT和POD活力的变化有关。     

6种农药对瓜蚜的毒力测定及田间药效

为了筛选防治西瓜瓜蚜的有效药剂,用6种药剂进行了室内毒力测定和田间药效试验。结果表明,1.8%阿维菌素EC对瓜蚜的毒力最高,60g/L乙基多杀菌素SC毒力最低,48hLC50分别为0.38mg/L和2 225.63mg/L。6种药剂毒力大小依次为阿维菌素溴氰虫酰胺氟啶虫胺腈啶虫脒吡虫啉乙基多杀菌素。田间试验结果表明,1.8%阿维菌素EC 3 000倍、10%溴氰虫酰胺OD 2 000倍、22%氟啶虫胺腈SC 4 000倍对瓜蚜速效性及持效性均较好,3~14d防效均达到90%以上,防效差异不显著;20%啶虫脒WP 3 000倍和10%吡虫啉WP 3 000倍速效性及持效性均较差,1d防效分别为31.31%和6.66%,14d防效分别为57.39%和47.80%;60g/L乙基多杀菌素SC 1 000倍防效最差,药后14d的最高防效仅为34.70%。推荐田间轮换使用阿维菌素、溴氰虫酰胺、氟啶虫胺腈防治瓜蚜。     

松油烯-4-醇对家蝇体内几种酶系的影响

测定了松油烯-4-醇对家蝇成虫的毒杀活性及其体内几种酶系活性的影响.结果表明:松油烯-4-醇对家蝇具有较强的触杀作用,24h的LD50为23.91μg/虫;对家蝇的致毒症状可明显地分为兴奋、痉挛、麻痹、死亡或复苏等几个阶段;对Na ,K -ATPase具有较强的抑制作用,在兴奋期、痉挛期、麻痹期和复苏期,酶抑制率分别为23.2l%、20.27%、61.84%和58.35%;离体条件下,对Na ,K -ATPase的I50为0.8379×103μg·mL-1;对AChE有一定的抑制作用;可激活酯酶,在复苏期,酶比活力为对照的1.42倍.     

氟啶虫胺腈与其他药剂复配对苹果黄蚜的联合毒力及效果评价

针对苹果黄蚜防治药剂类型单一、药剂敏感性下降等问题,采用浸叶法开展几种药剂对苹果黄蚜室内毒力测定,并用共毒系数法进行联合毒力评价。结果显示,氟啶虫胺腈和阿维菌素在8∶1～1∶8、氟啶虫胺腈和吡虫啉1∶1、氟啶虫胺腈和高效氯氟氰菊酯在4∶1～1∶4配比范围对苹果黄蚜有增效作用,3种组合最佳增效比均为1∶1。田间应用结果显示,药后3～21 d,22%氟啶虫胺腈SC单剂对苹果黄蚜防效达94.77%～99.40%;22%氟啶虫胺腈SC分别与5%阿维菌素EC、70%吡虫啉WG和2.5%高效氯氟氰菊酯EW按有效成分1∶1混配后对苹果黄蚜防效达86.43%～97.00%,均显著高于相应单剂对照,持效期可达21 d。推荐采用氟啶虫胺腈单剂及氟啶虫胺腈与阿维菌素、吡虫啉或高效氯氟氰菊酯混配剂作为替代药剂防治苹果黄蚜。     

氟虫腈对二化螟生长发育的影响及对解毒酶的诱导效应

研究了氟虫腈对不同虫态二化螟Chilo suppressalis的作用特点、持续毒性及对解毒酶的诱导效应。结果表明:氟虫腈对二化螟幼虫具有很强的毒杀作用,且毒杀作用随幼虫龄期的增长而逐渐减弱;对二化螟蛹的羽化具有较低的抑制作用;对卵孵化无抑制作用。亚致死剂量氟虫腈能引起幼虫持续死亡,降低存活试虫体重增长率和蛹重。用亚致死剂量氟虫腈处理4龄幼虫后,对其体内羧酸酯酶活性具有明显的诱导效应和时间效应,对谷胱甘肽S--转移酶活性的诱导效应仅在药剂处理后3h内较为显著,对多功能氧化酶活性表现出较强的诱导效应,比活力约为对照的1.37倍。     

氟虫腈与斑马鱼GABA_A及果蝇RDL受体作用的差异性研究

采用同源建模的方法构建了斑马鱼γ-氨基丁酸A型(GABA A)受体和果蝇RDL(resistance to dieldrin)受体跨膜区的三维结构,研究了氟虫腈在两个受体中作用位点的差异;采用分子对接和分子动力学方法,探讨了氟虫腈与斑马鱼GABA A受体和果蝇RDL受体的结合模式,并比较了氟虫腈与两个受体作用的差异性。结果表明:斑马鱼GABA A受体和氟虫腈作用位点的结构与果蝇RDL受体和氟虫腈作用位点的结构存在一定的差异,果蝇RDL受体中的Ala301对应斑马鱼GABA A受体α1亚基中的Val284和γ2亚基中的Ser306,氨基酸构象的差异较大;氟虫腈与斑马鱼GABA A受体的结合位点靠近胞内区一端,而与果蝇RDL受体的结合位点则位于受体第二跨膜区的Ala301~Leu308区域内。复合物分子动力学模拟结果表明,在模拟过程中,两个受体与氟虫腈复合物体系的势能可很快达到平衡状态。斑马鱼GABA A受体与氟虫腈之间形成4个氢键,其中概率大于60%的氢键有2个;而尽管果蝇RDL受体与氟虫腈形成了6个氢键,但只有1个氢键的概率大于50%,其复合物结合的稳定性比前者低。     

昆明山海棠杀虫活性成分雷公藤定碱和雷公藤次碱的触杀作用及对Na+ -K+ -ATP酶活性的影响

为进一步探讨杀虫植物昆明山海棠根皮中分离出的雷公藤定碱和雷公藤次碱的杀虫作用机理,采用微量点滴法处理3龄粘虫前胸背板,观察发现试虫均在2 h左右表现出中毒麻醉,8 h后完全恢复,24 h后重新表现为中毒麻醉,48 h后部分死亡。进一步的触杀毒力测定结果表明,雷公藤定碱和雷公藤次碱对3龄粘虫幼虫的24 h麻醉中量分别为8.82 μg/头和 4.58 μg/头,对3龄小菜蛾幼虫的麻醉中量分别为4.71 μg/头和3.46 μg/头。离体和活体条件下测定了雷公藤定碱和雷公藤次碱对5龄粘虫幼虫头部Na+-K+-ATP酶活性的影响,结果表明,两种药剂对粘虫幼虫神经系统Na+-K+-ATP酶活性均有一定的抑制作用,且该抑制作用具有一定的浓度依赖性,推测Na+-K+-ATP酶可能是雷公藤定碱和雷公藤次碱的一个重要作用靶标。     

虫螨腈胁迫对甜菜夜蛾保护酶系和解毒酶系的诱导效应

为探明虫螨腈对甜菜夜蛾幼虫体内生化代谢的影响及酶抑制剂对虫螨腈的增效潜力,采用点滴法测定了虫螨腈对甜菜夜蛾3、4、5龄幼虫的毒力和顺丁烯二酸二乙酯(DEM)、增效醚(PBO)、磷酸三苯酯(TPP)对虫螨腈的增效作用,并采用生化分析法测定了LD₂₅和LD₅₀剂量虫螨腈对甜菜夜蛾体内保护酶系和解毒酶系的影响。结果表明,虫螨腈对甜菜夜蛾不同龄期幼虫的毒力差异不大,处理后24h和48h的LD₅₀基本相同。PBO对虫螨腈有拮抗作用,增效比为0.21,而DEM和TPP对虫螨腈无增效作用。虫螨腈对甜菜夜蛾幼虫体内超氧化物歧化酶具有激活作用,对过氧化氢酶、过氧化物歧化酶及羧酸酯酶具有先抑制后诱导的作用;虫螨腈处理后6~24h,谷胱甘肽-S-转移酶活性显著提高,最高为对照的1.85倍;处理6h后,甜菜夜蛾体内细胞色素P450含量明显下降,而12~24h后,又明显上升,最高时为对照的1.86倍。     

7种杀虫剂防治小菜蛾田间药效评价

测定了7种不同杀虫剂对小菜蛾的防效,并对其田间的应用效果进行评价。结果表明：虫螨腈100g／L悬浮剂、氯虫苯甲酰胺200g／L悬浮剂、阿维菌素18g／L乳油、乙基多杀菌素60g／L悬浮剂和三氟甲吡醚100g/L乳油速效性和持效性均较好,药后1d防效即达到78％vT,上,持效期lOd以上;氟啶脲5％乳油速效性较差,高效氯氰菊酯4．5％乳油持效期相对较短。虫螨腈100g／L悬浮剂、氯虫苯甲酰胺200g／L悬浮剂、阿维菌素18g／Lg乳油、乙基多杀菌素60g／L悬浮荆和三氟甲吡醚100舡乳油可快速有效地防治小菜蛾,对天敌等影响较小,对作物安全．可作为防治的首选药剂使用。     

小菜蛾对阿维菌素B_1抗药性选育及交互抗性

用阿维菌素B_1(abamectin)对小菜蛾敏感种群在室内进行抗性品系选育。经过25代连续汰选,获得抗性种群Laba-R,与选育前比较,抗性提高100倍。Laba-R种群在不接触任何药剂条件下饲养20代,抗性逐渐下降,很难恢复到选育前的敏感状态。抗性汰选前后分别测定10种药剂的剂量-死亡率毒力回归线,发现Laba-R抗性种群对乙酰甲胺磷、锐劲特、灭多威、敌敌畏不存在交互抗性;对溴氰菊酯、氯氰菊酯、杀虫双、巴丹和Bt的敏感性略有下降,但无明显交互抗性。活体增效剂试验表明,增效醚(PBO)和磷酸三苯酯(TPP)对阿维菌素B_1均有明显的增效作用,其中PBO的增效活性尤为显著,它能使对阿维菌素B_1产生100多倍抗药性的小菜蛾完全恢复其敏感性。说明多功能氧化酶解毒代谢增强可能是小菜蛾对阿维菌素B_1产生抗性的主导因素之一。     

氟虫腈与昆虫γ-氨基丁酸受体相互作用研究

利用荧光标记法及分子模拟法,研究了氟虫腈与昆虫γ-氨基丁酸(aminobutyric acid,GABA)受体的相互作用。荧光标记试验结果显示,氟虫腈与家蝇脑内GABA受体有较强的相互作用,其最大结合量[RT]值和亲和常数Kd值分别为(21.3±2.5) pmol/mg protein和(109±9) nmol/L。分子模拟结果显示:氟虫腈与果蝇RDL受体间形成3条氢键;两者之间的CDOCKER的相互作用能为-137.93 kJ/mol。试验和理论两方面均证实,氟虫腈对昆虫GABA受体的强亲和性是导致氟虫腈对昆虫产生高毒性的重要原因。     

The role of GABA and glutamate receptors in susceptibility and resistance to chloride channel blocker insecticides

Despite a point mutation in the pore-forming segment of the Rdl GABA receptor subunit that is widespread and persistent in insect populations and confers high levels of resistance to dieldrin and other polychlorocycloalkane (PCCA) insecticides, the phenylpyrazole insecticide fipronil, which binds at same site, has proven to be effective in controlling many insects, including dieldrin-resistant populations. Fipronil and its major sulfone metabolite are unique among chloride channel blocking insecticides in that they also potently block GluCls. We present here a patch clamp study of the action of fipronil sulfone on native GABA receptors and GluCl receptors from susceptible and dieldrin-resistant German cockroaches, to provide a better understanding of the effect of the Rdl mutation on the function and insecticide sensitivity of these two targets, and its role in resistance. Dieldrin blocked GABA currents with an IC₅₀ of 3 nM in wild-type cockroaches, and 383 nM in resistant insects, yielding a resistance ratio of 128. Fipronil sulfone blocked GABA currents with an IC₅₀ of 0.8 nM in susceptible insects and 12.1 nM, or 15-fold higher, in resistant insects. While both GluClD (desensitizing) and GluClN (non-desensitizing) receptors were found in German cockroach neurons, GluClN receptors were rare and could not be included in this study. GluClD receptors from resistant insects had reduced sensitivity to glutamate and a lower rate of desensitization than those from susceptible insects, but their sensitivity to block by fipronil sulfone was not significantly changed, with an IC₅₀ of 38.5 ± 2.4 nM (n = 8) in the susceptible strain and 40.3 ± 1.0 nM (n = 7) in the resistant strain. Fipronil sulfone also slowed the decay time course of GluClD currents. These results suggest that GluClD receptors contain the Rdl subunit, but their sensitivity to fipronil sulfone is not altered in resistant insects.     

Effect of abamectin on electrophysiological activity in the ventral nerve cord of Periplaneta americana L.: Correlation with symptoms of poisoning and levels of toxicant in vivo

Twenty-four hours after injection of adult male Periplaneta americana with 36 ng [5-³H]abamectin, when symptoms of poisoning were apparent in most individuals, similar levels of radioactivity were found in tissue samples from the ventral nerve cord, metathoracic muscle, fat body and testis of randomly-selected insects. When insects injected with [5-³H]abamectin (36 ng) were separated after 24 h into three groups showing varying symptoms, the level of radioactivity in the ventral nerve cord was found to be significantly greater in partially-paralysed and paralysed groups (4- and 7-fold respectively) than in a treated but non- paralysed group. The mean levels of abamectin in the nerve cords of unaffected, ‘partially-paralysed’ and ‘paralysed’ insects were estimated to be 4, 23 and 37 nM respectively. Extracellular studies of the in-vitro action of abamectin (10 nM and 1 μM) on the spontaneous activity of a picrotoxin-sensitive, partially desheathed, ventral nerve cord preparation of adult male P. americana found the mean response time to be relatively slow (77 and 38 min respectively). In sheathed nerve cords, the mean response time to abamectin (1 μM) was 117 min. In all cases, treatment with abamectin increased the stimulus voltage required to evoke a response. Spontaneous activity was found to be progressively reduced in ventral nerve cord preparations from ‘partially-paralysed’ and ‘paralysed’ insects compared with ‘non-paralysed’ and untreated insects following dissection 24 h after injection of P. americana with unlabelled or labelled abamectin (36 ng), while the stimulus required to evoke activity in the ventral nerve cord showed the reverse trend. These differences in electrophysiological activity could be correlated directly with varying levels of abamectin in the nerve cords of ‘paralysed’ and ‘partially-paralysed’ insects.     

Glutamate-activated chloride channels: Unique fipronil targets present in insects but not in mammals

Selectivity to insects over mammals is one of the important characteristics for a chemical to become a useful insecticide. Fipronil was found to block cockroach GABA receptors more potently than rat GABA_A receptors. Furthermore, glutamate-activated chloride channels (GluCls), which are present in cockroaches but not in mammals, were very sensitive to the blocking action of fipronil. The IC₅₀s of fipronil block were 30 nM in cockroach GABA receptors and 1600 nM in rat GABA_A receptors. Moreover, GluCls of cockroach neurons had low IC₅₀s for fipronil. Two types of glutamate-induced chloride current were observed: desensitizing and non-desensitizing, with fipronil IC₅₀s of 800 and 10 nM, respectively. We have developed methods to separately record these two types of GluCls. The non-desensitizing and desensitizing currents were selectively inhibited by trypsin and polyvinylpyrrolidone, respectively. In conclusion, in addition to GABA receptors, GluCls play a crucial role in selectivity of fipronil to insects over mammals. GluCls form the basis for development of selective and safe insecticides.     

甘蓝夜蛾核型多角体病毒等药剂对玉米草地贪夜蛾的田间防效初探

草地贪夜蛾是今年新侵入我国的世界性重大农业害虫,主要为害玉米等作物,给我国玉米等粮食作物生产安全带来巨大隐患。为筛选防治草地贪夜蛾的安全高效药剂,设计并开展此试验。试验结果表明15%甲维·茚虫威悬浮剂20mL/667m 2+激健助剂15mL/667m 2、15%甲维·茚虫威悬浮剂20mL/667m 2、6%氯虫苯甲酰胺·阿维菌素悬浮剂50mL/667m 2、10亿孢子/mL甘蓝夜蛾核型多角体病毒悬浮剂100mL/667m 2+3%甲维盐微乳剂25mL/667m 2、3%甲维盐微乳剂50、25mL/667m 2、3%甲维·虱螨脲悬浮剂100mL/667m 2、5%阿维菌素乳油50mL/667m 2、10亿孢子/mL甘蓝夜蛾核型多角体病毒悬浮剂150mL/667m 2均能较好防治玉米草地贪夜蛾,药后7d防效均在79.4%以上,药后14d防效均在80.59%以上,可作为防治玉米草地贪夜蛾的优选应急用药措施。     

玉米象各发育期对磷化氢的敏感性

结果表明,磷化氢对玉米象(Sitophilus zeamais Motschlscky)成虫有较强的毒力。玉米象各发育期对磷化氢的敏感性为:成虫>幼虫>卵>蛹,幼虫的耐药力与成虫接近,卵与蛹的耐药力几乎相同,卵、蛹的耐药力比成虫、幼虫约大2倍。因此,磷化氢熏蒸效果检查,不仅应对所有虫态检查,而且应保持储粮中较长时间没有活虫发生;在保持磷化氢有效浓度条件下,增加暴露时间能增效;CT值能全面检查磷化氢实仓熏蒸效果。未来用CT值代替剂量值,对进一步改善磷化氢熏蒸技术和提高药效,具有重要的现实意义。     

Tebufenozide resistance selected in Plutella xylostella and its cross-resistance and fitness cost

A susceptible strain of diamondback moth, Plutella xylostella (L.), was used to select for resistance to tebufenozide in the laboratory. After continuous selection with tebufenozide 17 times during 35 generations, a resistant strain was achieved with high resistance to tebufenozide (RR 93.8). Bioassay revealed that this strain showed high cross-resistance to abamectin (RR 35.7), methoxyfenozide (29.1) and JS118 (16.5), and a little to deltamethrin (3.9), but no obvious cross-resistance was found to cypermethrin (1.3), fipronil (1.3), trichlorfon (1.1), chlorfenapyr (1.0), phoxim (0.9) and acephate (0.8). The resistant and susceptible insects had similar development rates, but life table tests indicated that the resistant strain showed reproductive disadvantages, including decreased copulation rate, reproductivity and hatchability. When compared with the susceptible strain, the resistant insects had a relative fitness of only 0.3. This indicated that tebufenozide resistance selected under laboratory conditions had considerable fitness costs in this pest, and therefore rotational use of insecticides without cross-resistance is recommended to delay development of resistance.     

水稻二化螟抗药性监测及防控对策*

采用点滴法测定了2007-2009年采自浙江、江苏、湖北、四川等地水稻二化螟4龄幼虫对沙蚕毒素类的杀虫单、有机磷类的三唑磷、毒死蜱、苯基吡唑类的氟虫腈及微生物源的阿维菌素等杀虫剂的抗性。结果表明：上述二化螟种群对５种杀虫剂抗性分布具有明显的地区性,其中浙江、江苏大部分地区供试种群对杀虫单、三唑磷的抗性水平达40倍以上,已普遍产生高至极高水平抗性;对毒死蜱产生的抗性水平达22倍以上,已普遍产生中等水平至高水平抗性;对氟虫腈产生的抗性水平达6倍以上,已普遍产生低水平至中等水平抗性;对阿维菌素敏感至低水平抗性;湖北孝感、四川武胜种群对５种药剂尚未产生抗性或为低水平抗性。本文还对二化螟抗性防控对策进行了讨论。     

2002年江苏省二化螟抗药性检测及治理

20 0 2年应用点滴法普查了江苏常熟、锡山、武进、句容、姜堰、高邮、楚州、宿豫、灌云及连云港 10县 (市 ) 12个二化螟种群 4龄幼虫对 4种 (类 )杀虫剂的抗药性。结果表明 ,供试种群对沙蚕毒素类农药杀虫单已普遍产生抗性 ,且苏南种群的抗性水平高于苏北 ,常熟为最高 ( 16倍 ) ;对有机磷类农药三唑磷苏南地区种群为低水平抗性 ,其他地区均属敏感水平。目前二化螟供试种群对苯基吡唑类农药氟虫腈和抗生素类农药阿维菌素未产生抗药性。本文还对二化螟抗性治理对策进行了讨论。