三种杀虫剂对昆虫病原线虫侵染臭椿沟眶象幼虫能力的影响

昆虫病原线虫在20世纪初后已发展成为生物防治领域研究热点之一,作为生防制剂被广泛使用,且可与杀虫剂混用.臭椿沟眶象Eucryptorrhynchus brandti是重要的林木蛀干害虫,对宁夏农田防护林主要树种臭椿Ailanthus altissima造成严重危害.目前臭椿沟眶象的主要防治方法之一是化学防治,但效果不理想.为了降低对臭椿沟眶象幼虫的农药使用剂量并提高防治效果,须筛选与昆虫病原线虫混用适合的杀虫剂.本研究测试了4.5％氯氰菊酯乳油、10％吡虫啉可溶液剂、5％啶虫脒乳油对小卷蛾斯氏线虫Steinernema carpocapsae All、长尾斯氏线虫Steinernema longicaudum X-7存活以及侵染率的影响,以筛选对臭椿沟眶象3龄幼虫致死效果好、能与昆虫病原线虫混用的杀虫剂和混用配比.结果 表明,3种杀虫剂对2种线虫的存活均无亚致死作用;吡虫啉对2种线虫的致死率无明显影响;不同浓度的氯氰菊酯和啶虫脒对2种线虫的致死率存在显著差异,其中有效成分为88.97 μg/mL、17.79 μg/mL的氯氰菊酯和有效成分为307.89 μg/mL、61.58 μg/mL的啶虫脒对2种线虫的致死率均显著高于对照.3种药剂与X-7、All混用对臭椿沟眶象3龄幼虫均表现为增效或叠加作用,其中有效成分为8.89 μg/mL的氯氰菊酯和有效成分为7.67 μg/mL的吡虫啉与线虫X-7混用对臭椿沟眶象3龄幼虫表现出增效作用,致死率分别为41.67％、54.17％,其它浓度和其它药剂与2种线虫混用的各处理均表现为叠加作用.该结果为进一步利用昆虫病原线虫开展野外防治试验奠定了基础.     

昆虫病原线虫Heterorhabditis beicherriana LF品系与Bt HBF-18菌株混用对华北大黑鳃金龟幼虫的防治效果

【目的】明确昆虫病原线虫 Heterorhabditis beicherriana LF品系(LF)与苏云金芽孢杆菌 Bacillus thuringiensis HBF-18菌株(Bt HBF-18)混用后对华北大黑鳃金龟 Holotrichia oblita 幼虫的致病力的协同增效作用,为该害虫的防治提供新的技术措施。【方法】在室内测定了LF在不同使用剂量、不同环境温度及不同土壤湿度条件下对华北大黑鳃金龟7-10日龄幼虫的致病力;通过室内生测测定了Bt HBF-18对LF存活的影响,以及Bt HBF-18与LF两者混用后对7-10日龄华北大黑鳃金龟幼虫的防治效果;同时通过室外盆栽试验测定了两者混用对华北大黑鳃金龟幼虫的防治效果。【结果】华北大黑鳃金龟幼虫死亡率随LF施用剂量和处理时间的增加而升高,其中,侵染期线虫(infective juveniles, IJs)800 IJs/100 μL及以上剂量处理7 d后幼虫死亡率达到了100%;25℃为该线虫侵染的最适宜环境温度;适宜土壤湿度范围为14%~20%,湿度过低或过高都会显著影响其侵染效率。室内生测结果表明, Bt HBF-18处理9 d对华北大黑鳃金龟幼虫的致死中浓度(LC 50 )为 1.44× 10^8 CFU/g土,此浓度对LF的存活基本没有影响。另外,室内生测和室外盆栽试验结果均表明,将LF与Bt HBF-18混用能显著提高对华北大黑鳃金龟幼虫的防治效果,混用后具有不同程度的加成或协同增效作用。室内生测试验中LC 50 Bt+200 IJs/100 μL LF混用处理3 d后,较单独LF和Bt HBF-18处理幼虫死亡率分别提高了约43.07%和36.05%,具有显著的协同增效作用;室外盆栽试验中1/2 LC 50 Bt+1 000 IJs/mL LF, LC 50 Bt+1 000 IJs/mL LF和1/2 LC 50 Bt+1 500 IJs/mL LF均具有协同增效作用,其中1/2 LC 50 Bt+1 500 IJs/mL LF增效作用最佳,较单独LF和Bt HBF-18处理幼虫死亡率分别提高了约38.89%和80.55%。【结论】将昆虫病原线虫LF与Bt HBF-18混用对华北大黑鳃金龟幼虫的防治具有加成或协同增效作用。     

噻虫嗪对昆虫病原线虫侵染韭菜迟眼蕈蚊能力的影响

【目的】为提高昆虫病原线虫对韭菜迟眼蕈蚊Bradysia odoriphaga Yang et Zhang幼虫的防治效果,将昆虫病原线虫与环境友好型化学杀虫剂混用是一条有效途径。【方法】测定了噻虫嗪与6个昆虫病原线虫品系混用对韭菜迟眼蕈蚊的作用效果,以及温度和土壤含水量对作用效果的影响,并进行了田间验证。【结果】田间推荐浓度噻虫嗪(100 mg·L~(-1))对6种供试线虫存活无显著影响。处理后3 d,低浓度噻虫嗪(15 mg·L~(-1))分别与6品系线虫混合后处理韭菜迟眼蕈蚊幼虫,其死亡率明显高于线虫和噻虫嗪单用处理。小卷蛾斯氏线虫SF-SN+噻虫嗪、印度异小杆线虫LN2+噻虫嗪和小卷蛾斯氏线虫All+噻虫嗪3种组合发挥杀虫作用的最适温度范围分别为20~25℃、25~30℃和25~30℃,显著高于其他温度;最适土壤含水量范围为10%~18%,也显著高于其他湿度。大田条件下,施用后7 d,单用噻虫嗪、线虫+噻虫嗪组合处理对韭菜迟眼蕈蚊的防治效果显著高于单线虫,且以芫菁夜蛾斯氏线虫SF-SN+噻虫嗪的防治效果最高,达到93%以上。【结论】芫菁夜蛾斯氏线虫SF-SN品系与噻虫嗪组合联合防治韭菜迟眼蕈蚊效果最好。     

昆虫病原线虫对黄地老虎致病力的研究

为了探索应用昆虫病原线虫防治黄地老虎Agrotis segetum的可行性,室内生测比较了9个昆虫病原线虫品系对黄地老虎4龄幼虫的致病力。生测结果表明,9个不同昆虫病原线虫品系对黄地老虎4龄幼虫的致病力差别很大,其中格氏线虫Steinernema glaseri ib(Sgib)是对黄地老虎幼虫致病力最强的昆虫病原线虫品系,侵染24、36和72 h黄地老虎幼虫的校正死亡率均高于其他线虫品系。此外,还测定了不同温度、土壤湿度以及线虫剂量对格氏线虫Sgib致病力的影响,结果表明,在21℃-27℃、20%土壤湿度以及侵染期线虫与黄地老虎幼虫数量比不少于10∶1的条件下,格氏线虫Sgib对黄地老虎幼虫的致病效果最好。田间小区实验表明,格氏线虫Sgib对黄地老虎幼虫的防效达到96.67%。     

化学杀虫剂对昆虫病原线虫侵染韭菜迟眼蕈蚊能力的影响

【目的】为提高昆虫病原线虫对韭菜迟眼蕈蚊Bradysia odoriphaga的防治效果,将昆虫病原线虫与环境友好型化学杀虫剂混用是一条有效途径。【方法】本研究测试了70%吡虫啉水分散颗粒剂、40%毒死蜱乳油和4.5%高效氯氰菊酯乳油对昆虫病原线虫Heterorhabdits bacteriophora Taishan strain H06品系、Steinernema carpocapsae strain SF-SN和All品系存活及侵染率的影响,及低剂量化学杀虫剂与昆虫病原线虫混用对韭蛆3龄幼虫的作用效果。【结果】高效氯氰菊酯(含量为2.00、0.40、0.20和0.10μg·mL-1)和吡虫啉(25.00、5.00、2.50和1.25μg·mL-1)对H.bacteriophora H06和S.carpocapsae All的存活无显著影响,3品系线虫毒死蜱(8.00μg·mL-1)对3品系线虫的致死率均显著高于对照;不同浓度的毒死蜱对3品系线虫的致死率存在显著差异。3种药剂分别与3品系线虫混合后处理韭蛆,韭蛆的死亡率明显高于线虫和杀虫剂单用处理。药后3 d,SF-SN与毒死蜱(8.00μg·mL-1)、吡虫啉(25.00μg·mL-1)和高效氯氰菊酯(2.00μg·mL-1)混合处理韭蛆,分别比单用杀虫剂提高防效34.20%、21.18%、54.99%,优于另外两种线虫与3种药剂混用的效果。【结论】供试线虫中,SF-SN品系与上述杀虫剂联合防治韭蛆效果最好。     

寒区昆虫病原线虫对韭菜迟眼蕈蚊的防治研究

结合室内生测、温室盆栽和大棚内小区试验的方法,探讨了寒区昆虫病原线虫(entomopathogenic nematode,EPN)对我国北方越冬韭菜迟眼蕈蚊Bradysia odoriphaga Yang et Zhang的防治作用。室内生测的结果显示,在侵染剂量为400条侵染期线虫(IJs)每头3龄幼虫或蛹时,异小杆线虫Heterorhabditis bacteriophora ZT(HbZT,哈尔滨市植物园分离株)、H.bacteriophora LG(Hb-LG,辽宁分离株)、H.bacteriophora NJ(Hb-NJ,美国新泽西分离株)和斯氏线虫Steinernema carpocapsae All(Sc-All)对迟眼蕈蚊3龄幼虫的致死率于72 h后均达100%,而对蛹的寄生效果则是Hb-ZT线虫最高;Hb-ZT与Sc-All(1∶1)混用,对幼虫的室内寄生效果高于单独施用2个线虫的寄生效果;温室盆栽试验中喷施Hb-ZT与Sc-All(1∶1)的线虫混合液,施用剂量减半(50万IJs/m2),对韭蛆成虫羽化的控制效果稍高于单独施用2个线虫(100万IJs/m2)效果;不同时期防治韭蛆的试验结果表明,于韭菜棚内发现韭蛆成虫5¹0 d内喷施线虫的防治效果较好;韭菜大棚内喷施剂量为50万IJs/m2的Hb-ZT与Sc-All线虫混合液对韭蛆幼虫防效达100%,增产作用与常规化学药剂(辛硫磷)相当。     

几种药剂及施药方式对稻纵卷叶螟的防治效果

对稻纵卷叶螟Cnaphalocrocis medinalis Guen e高龄幼虫防治药剂31%氟虫腈.三唑磷ME和当地几种常用药剂及不同施药方法对防治效果影响进行试验。结果表明:(1)毒死蜱(48%乐斯本EC)有较好速效性,药后1 d可达理想防效,三唑磷与氟出腈、氟铃脲复配的药剂(31%氟虫腈.三唑磷ME、21%氟虫腈.三唑磷EC、15%氟铃脲.三唑磷EC)药后3d才能达到理想防效;(2)药后3d,各处理均达到理想防效,防效依次为31%氟虫腈.三唑磷ME1.5L/hm2>31%氟虫腈.三唑磷ME1.05L/hm2>21%氟虫腈.三唑磷EC1.5L/hm2>48%毒死蜱EC1.5L/hm2>15%氟虫腈.三唑磷EC1.5L/hm2>15%阿维菌素.毒死蜱EC1.5L/hm2;(3)分虫龄防效统计,药后3d供试药剂对1龄以下(施药时虫龄,后同)幼虫防效均在91%以上,对2~3龄幼虫,31%氟虫腈.三唑磷ME保持90%以上的防效,其它处理防效明显下降,对4龄以上高龄幼虫,31%氟虫腈.三唑磷1.5L/hm2细喷雾处理防效仍达95.6%,其它处理防效很低。(4)细喷雾可提高31%氟虫腈.三唑磷ME对稻纵卷叶螟的防治效果,尤其是对高龄幼虫,与工农16型1.8mm孔径喷片的常规喷雾相比,1.2mm孔径喷片细喷雾处理药后3 d防效提高5.5%,东方红18型弥雾处理防效提高7.8%,其中,弥雾处理对1~2龄幼虫防效提高4.7%,对4~5龄幼虫防效提高了20.8%。     

不同品系昆虫病原线虫对烟草小地老虎的致病力

小地老虎Agrotis ypsilon Rottemberg是烟田的一种重要的地下害虫。为了探明不同品系的昆虫线虫对烟田地下害虫小地老虎的致病力,在室内采用生测试验法,以滤纸为介质,测定了斯氏属线虫Steinernema carpocapsae和异小杆属线虫Heterorhabditis bacteriophora共5个品系对小地老虎3龄幼虫、5龄幼虫和蛹的致病力。结果表明,5个不同昆虫病原线虫品系均对小地老虎3龄幼虫具有致病力,其中斯氏线虫S.carpocapsae-A11(Sc-A11)对小地老虎的致死速度最快,侵染24 h、36 h和72 h后小地老虎校正死亡率分别为41.3%、69.7%和86.7%,均高于其它线虫品系,小地老虎的死亡率随着线虫侵染时间的增加而增加的,至96 h后校正死亡率达到100%,Sc-A11侵染5龄幼虫的校正死亡率均高于其它线虫品系,可见Sc-A11对小地老虎幼虫的致病力最强,为最敏感的昆虫病原线虫品系。Sc-All对小地老虎3龄幼虫、5龄幼虫的校正死亡率在72 h时分别为86.7%、43.3%,化蛹率为23.7%,Sc-All不侵染小地老虎蛹。盆栽烟草上线虫Sc-A11剂量为20头IJs/cm~2施用3次和线虫剂量为80头IJs/cm~2施用2次的处理的保苗效果最好,3 d后保苗效果分别为79.64%和76.85%,达到最佳的防治效果。     

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。     

六种昆虫生长调节剂对葱蝇生长发育和繁殖力的影响

用灭蝇胺、氟铃脲等6种昆虫生长调节剂和对比药剂辛硫磷LC_40-50浓度处理葱蝇1龄和3龄幼虫,观察对其生长发育和繁殖的影响;并且研究了葱蝇成虫取食药剂对其繁殖力的控制效应。结果表明：6种药剂中除虫酰肼外,其余都对葱蝇幼虫发育历期、化蛹率、成虫产卵前期、成虫寿命、产卵量有很大影响,对其生长发育和繁殖表现出显著不利性。其中灭蝇胺和氟铃脲处理1龄幼虫后,存活幼虫的历期和成虫产卵前期各延长3天,化蛹率降低26.7%～30.0％,成虫寿命缩短22.3～24.3天,产卵量降低35.5％～49.9％;处理3龄幼虫主要导致产生畸形蛹,且正常羽化的成虫寿命降低18.0～20.67天,产卵量降低45.7%～57.8％。成虫连续取食用牛奶稀释的２ 000倍的药液,能导致产卵前期延长、产卵量减少、卵孵化率降低,幼虫死亡率极高,达95%以上。结果提示,利用成虫补充营养的特性,将灭蝇胺和氟铃脲等混入牛奶或糖水中诱集成虫取食,可有效降低成虫的繁殖力,有助于实现对葱蝇的无公害治理。     

Laboratory and field evaluation of Korean entomopathogenic nematode isolates against the oriental beetle Exomala orientalis (Coleoptera: Scarabaeidae)

The oriental beetle Exomala (Anomala) orientalis (Waterhouse) is an important pest of turfgrass in Korean golf courses, and although a few chemical insecticides are registered for insect pest control, they are not very effective against scarab larvae. There is also a growing concern in Korea about the run-off of insecticides into sensitive habitats and the potential for groundwater contamination. A safe and environmentally sound alternative is needed to conventional insecticides. We therefore evaluated six Korean entomopathogenic nematode isolates: S. carpocapsae Pocheon, S. glaseri Dongrae, S. glaseri Mungyeong, S. longicaudum Gongju, S. longicaudum Nonsan, and Heterorhabditis sp. Gyeongsan for their potential as bioinsecticides for control of E. orientalis. In addition, we evaluated a reduced chemical insecticide approach that combined chlorpyrifos-methyl with nematodes. In laboratory tests Heterorhabditis sp. Gyeongsan was the most efficacious, causing 100% mortality of the second and 38% of the third instars. All other nematode isolates caused 50-80% mortality of the second and 15-30% of the third instars. E. orientalis pupae were highly susceptible to all the Korean entomopathogenic nematode isolates except S. carpocapsae. In artificially infested field plots, all Korean nematode isolates cause 50-70% mortality of the third instar. A combination of a one-half rate of Heterorhabditis sp. and a one-half rate chlorpyrifos-methyl was synergistic, causing 91% mortality compared with 69% for the full rate of Heterorhabditis sp. or 22% for the full rate of chlorpyrifos-methyl. In a second field trial, a natural infestation of preoverwintering third instar was treated. In this trial a one-half rate of S. longicaudum Nonsan plus a one-half rate of chlorpyrifos-methyl caused 96.8% mortality, much more than a full rate of S. longicaudum Nonsan (45.9% mortality) or a full rate of chlorpyrifos-methyl (28.7% mortality). The interactions of Heterorhabditis sp. and S. longicaudum Nonsan with chlorpyrifos-methyl in our field trials appear to be synergistic.     

Steinernema carpocapsae (Rhabditida: Steinernematidae) as a biological control agent against the fungus Gnat Bradysia agrestis (Diptera: Sciaridae) in propagation houses

A recently introduced fungus gnat, Bradysia agrestis, has caused serious problems in Korean propagation houses where vegetable seedlings are produced for transplant into the fields. Although chemical insecticides are available against this pest, alternate control measures are needed. A Korean isolate of the entomopathogenic nematode, Steinernema carpocapsae Pocheon strain, was tested against this insect in the laboratory and propagation house. In the laboratory, S. carpocapsae affected oviposition, with the untreated females laying an average of 121±25 eggs, whereas the treated females averaged 7±2 eggs. The infectivity of S. carpocapsae to the fungus gnat was affected by the developmental stage and temperature, with highest mortality observed with the third and fourth instars and pupal stage. Nematode mortality in the second instar fungus gnat ranged between 23 and 35%, but showed no significant differences among the temperatures tested. The egg and first instar were not infected by the nematode. In nematode dispersal studies, adult female fungus gnats alone dispersed S. carpocapsae from the nematode-treated area to the control area at a higher rate than male and female gnats or male gnats alone. In the propagation house experiments with watermelon seedlings, no significant difference was observed in fungus gnat larval reduction at S. carpocapsae concentrations of 5, 10, or 20 infective juveniles (IJs)/g of soil at 7, 14, and 21 days after treatment. In comparison with the control, the S. carpocapsae treatments significantly reduced B. agrestis larval numbers. When the watermelon seed was treated with S. carpocapsae at sowing, the larval density of B. agrestis was significantly reduced, that is, the number of B. agrestis larvae ranged from four to eight and from five to eight in the nematode-treated plots compared with 26 and 30 in the control plots on the 17th and 34th day post-treatment, respectively. In the chemical insecticide treatments, diflubenzuron and chlorpyrifos were significantly more effective than S. carpocapsae and diazinon in reducing larval populations of the fungus gnat. Our data show that, although some of the chemical insecticides were more effective than S. carpocapsae Pocheon strain, the nematode was still an effective tool for management of the fungus gnat larvae and in protecting seedlings from damage in propagation houses.     

Insecticidal resistance and cross-resistance in populations of Cydia pomonella (Lepidoptera: Tortricidae) in central Europe

Insecticide bioassays were used to investigate resistance of Cydia pomonella (L.) (Lepidoptera: Tortricidae) to insecticides with various types of active ingredients. The efficacy baselines of selected insect growth regulators (fenoxycarb), insect growth inhibitors (diflubenzuron and teflubenzuron), organophoshorous insecticides (phosalone), and neonicotinoids (thiacloprid) against the eggs and first and fifth instars of sensitive laboratory strains of codling moth were determined. According to concentration-mortality baseline, 50% lethality concentration values and 90% lethality concentration values were determined for all the tested insecticides. The lethal concentration ratio quantified the relation between the efficacy of selected insecticides against fifth instars found by topical application and against first instars found by diet-treated bioassay. No difference was detected when the efficacy of technical grade diflubenzuron diluted in tetrahydrofuran and diflubenzuron in the formulated product Dimilin 48 SC diluted in water was compared. However, just before the application of insecticide, the integument of larvae must be treated with acetone. Two bioassays were used to monitor the resistance of codling moths collected in 2003-2005 in two apple (Malus spp.) orchards with different intensities of chemical control. Resistance ratios (RRs) to the tested insecticides were determined for both field populations of codling moth. For the population of codling moth from a commercial apple orchard in Velké Bílovice, cross-resistance to fenoxycarb, teflubenzuron, and phosalone was detected after the topical application of insecticides to fifth instars. The population of codling moth from Prague-Ruzyne was slightly resistant to phosalone and teflubenzuron. No resistance to diflubenzuron was detected in either tested population.     

Differential ovicidal and larvicidal resistance to benzoylureas in the codling moth, Cydia pomonella

French populations of the codling moth Cydia pomonella (L.) (Lepidoptera, Tortricidae), a major pest in apple and pear orchards, have developed resistance to different classes of insecticides including the benzoylurea diflubenzuron, a chitin synthesis inhibitor. Ovicidal tests performed on two susceptible strains and one strain selected for its resistance to diflubenzuron revealed the same order of magnitude in resistance ratios to this compound (30-fold) and two other benzoylureas teflubenzuron and flufenoxuron (22- and 11-fold, respectively). Field rates of these three compounds induced a 45–55% decrease in hatching in the resistant strain, compared to over 90% in the susceptible insects. Despite a 52-fold ovicidal resistance ratio to the juvenile hormone analog fenoxycarb, this compound induced a 85% decrease in hatching in the resistant strain. Conversely the newly hatched larvae of the resistant strain exhibited a 45 000-, 33- and 2.1-fold resistance ratio to diflubenzuron, teflubenzuron and flufenoxuron, respectively. The latter value was not significant, and the field rate of flufenoxuron killed over 97% of the resistant larvae while diflubenzuron had no effect. This lack of relationship between ovicidal and larvicidal resistance may be due to different transport properties together with differential enzymatic metabolization. Our results may limit the validity of substitution instars, which approach is frequently used for resistance monitoring. More importantly for resistance management, the resistance of different target instars to each compound has to be considered when establishing control strategies.     

Synergies between biological and neonicotinoid insecticides for the curative control of the white grubs Amphimallon majale and Popillia japonica

Synergistic combinations of biological and chemical insecticides might yield promising alternatives for soil insect pest management. In turfgrass of the Northeast U.S., control of root-feeding scarab larvae is highly dependent on conventional insecticides. Studies on interactions between entomopathogenic nematodes and neonicotinoid insecticides, however, demonstrate the feasibility of synergies as an approach for reduced-risk curative control. To understand the breadth of potential synergies, we screened numerous combinations of biological control agents with sublethal doses of neonicotinoids against third instars. Interactions were characterized as synergistic, additive or antagonistic. The most promising combinations identified in laboratory bioassays were advanced to greenhouse pot studies and then to field trials featuring microplots with artificially infested populations. To reveal variation across scarab species, trials were conducted on Amphimallon majale and Popillia japonica. Synergies were consistent across trials and specific to white grub species. For A. majale, synergistic combinations of Heterorhabditis bacteriophora with imidacloprid and clothianidin were discernible in laboratory, greenhouse and field trials. For P. japonica, synergistic combinations of Beauveria bassiana and Metarhizium anisopliae with both neonicotinoids were discernible in the laboratory and greenhouse, but not in the field. For both species, antagonistic interactions were discernible between Bt-products and both neonicotinoids. While nematode-neonicotinoid synergies among scarab larvae have been examined before, fungi-neonicotinoid synergies are unreported. In the context of previous studies, however, no patterns emerge to explain variation across target species or control agent. Further study of non-additive interactions will guide how biological and chemical products could be combined to enhance soil insect pest management.     

A systematic review on the eco-safe management of mosquitoes with diflubenzuron: An effective growth regulatory agent

Mosquitoes serve as the major vector transmitting malaria, dengue, yellow fever and several other diseases of human concern. Rising in mosquito-borne diseases and consequent fatalities throughout the world has made the management of mosquitoes of paramount importance. With the use of various insecticidal agents and their indiscriminate application in the fields for vector control; other issues such as multiple insecticide resistance, lethality to non-specific targets and adverse effects on human and environmental health have emerged making the situation more critical. Hence, the focus of researchers has diverted to the use of Insect Growth Regulators (IGRs) that affect the growth and development of the insects without inducing any appreciable toxic effects. The paper comprehensively reviews various IGRs and their potential use against insect pests and mosquito vectors. A special emphasis has been laid on the utilization of diflubenzuron, its larvicidal potency and growth regulatory effects against mosquitoes. The paper also delivers a detailed discussion on various approaches governing with the application of diflubenzuron, a chitin synthesis inhibitor, for its potent effects over a wide range of other insect species, low toxicity to humans, safety to other non-target animals, negligible deleterious environmental impact along with the possible development of resistance in the mosquitoes, thereby providing insights and the direction for the future in terms of the innovative and technological perspective. Keeping in view the role of multifarious mechanisms in the development of resistance; use of various synergistic compounds, such as hydrolase inhibitors - profenofos and S,S,S-tributyl phosphorotrithioate; glutathione S-transferase inhibitor – diethylmaleate; and oxidase inhibitor - piperonyl butoxide (PBO); has been recommended in combination with IGRs to enhance their efficacy, and reduce or reverse the resistance in target mosquitoes. Another compound, verapamil, has been found extremely efficient in imparting synergistic effect to diflubenzuron by inhibiting P-glycoproteins, a transporter of the insecticides causing their efflux from the cell. Recommendations have been made for safe and effective mosquito control measures, adequate policies and increased awareness about the mosquito-borne diseases among the masses. In addition, regular surveillance of mosquitoes is endorsed for the formulation of an efficient mosquito management strategy.     

小地老虎及粘虫幼虫对灭幼脲表现自然耐药力的体壁结构和生化基础

小地老虎Agrotis ypsilon rottem.幼虫对灭幼脲具有一定的自然耐药力。本文以粘虫Mythimna separata(Walker)作为敏感性虫种与之进行比较,实验结果表明,灭幼脲对两种试虫的室内毒力相差4倍左右,引起差异的原因,在体壁结构方面主要在于:(1)小地老虎幼虫的表皮层较粘虫的厚4.2倍左右;(2)上表皮不是匀质结构,依靠少数蜡道与体表沟通;(3)几丁质片层内的孔道数较少,仅及粘虫的1/4。由此构成了表皮对疏水性的灭幼脲表现抗穿透的性能。小地老虎幼虫体壁还含有较强的生化防卫体系,灭幼脲对多功能氧化酶、芳基酰胺酶有明显激活效应,这两种酶都是灭幼脲的降解酶。由此认为,小地老虎幼虫对灭幼脲所表现的自然耐药力,是由体壁的抗穿透性能以及由灭幼脲所激活的适应酶所造成。     

Life stage variations in insecticidal susceptibility and detoxification capacity of the beet webworm, Pyrausta sticticalis L. (Lep., Pyralidae)

Abstract:  Adults and larvae of the beet webworm Pyrausta sticticalis (Lep., Pyralidae) are susceptible in varying degrees to insecticides of different chemical classes. Comparative toxicity tests as well as the synergistic effects of piperonyl butoxide, S,S,S-tributyl phosphorotrithioate and diethylmaleate showed that variation in toxicities of beet webworm developmental stages to organophosphorus compounds and carbaryl is partly due to the activities of detoxification enzymes. Specific activities of monooxygenases, esterases and glutathione S-transferase were higher in fifth instars than in adults. Studies of the post-treatment fate of ¹⁴C-labelled malathion and ³H- trans -permethrin after application indicated that both compounds had a rapid rate of cuticular penetration, internal accumulation and excretion of applied toxicants and their metabolites by larvae. Adults of beet webworm had a lower sensitivity of acetylcholine esterase to the inhibition of carbaryl than the larvae.     

斜纹夜蛾线粒体复合物ⅢFe-S蛋白基因克隆、序列分析及在不同发育阶段的表达特征

Fe-S蛋白(rieske iron-sulfur protein, RISP)是线粒体复合物Ⅲ的关键蛋白亚基之一, 在呼吸链电子传递中起着重要作用。本文利用RT-PCR技术和RACE方法获得了斜纹夜蛾Spodoptera litura (Fab.)线粒体复合物ⅢRISP基因, 该基因序列全长4 413 bp, 含有3个内含子; 开放阅读框长816 bp, 编码271个氨基酸。经氨基酸序列比对, 与鳞翅目家蚕Bombyx mori和小菜蛾Plutella xylostella的Fe-S蛋白一致性较高, 分别为83%和79%, 与其他目昆虫的RISP一致性较低。qRT-PCR分析结果表明, SlitRISP基因在斜纹夜蛾不同发育阶段的表达水平存在显著差异, 即幼虫期和成虫期的表达量显著高于卵期和蛹期, 其中幼虫期又以第4和5龄幼虫表达水平显著高于初孵幼虫以及第1, 2, 3和6龄幼虫。斜纹夜蛾SlitRISP基因的克隆成功为今后对其功能研究以及作为靶标设计新型高效杀虫剂提供了基础。