5种杀虫剂对入侵害虫椰子织蛾的室内毒力测定

椰子织蛾是一种外来新入侵害虫,对棕榈科植物造成了严重危害。采用叶片浸渍法测定了甲维盐等5种杀虫剂对入侵害虫椰子织蛾5～6龄幼虫的室内毒力。5种药剂处理72 h后的室内毒力大小顺序为甲维盐＞氯虫苯甲酰胺＞毒死蜱＞高效氯氟氰菊酯水乳剂＞烟碱;72 h 致死中浓度（ LC50）为5．2604、9．7126、24．8202、104．0584、643．1496 mg· L-1。选取同样毒力效果所需成本依次为毒死蜱＜甲维盐＜高效氯氟氰菊酯＜氯虫苯甲酰胺＜烟碱。本研究可用于指导椰子织蛾的应急化学防控。综合毒力和成本,建议在生产上采用毒死蜱和甲维盐等相关药剂防治椰子织蛾。     

3种药剂对广东地区草地贪夜蛾3龄幼虫室内毒力测定及其田间药效评价

为明确几种药剂对广东地区草地贪夜蛾Spodoptera frugiperda幼虫的室内毒杀作用及田间防治效果,合理使用化学农药对草地贪夜蛾进行科学防治提供理论依据.本研究采用浸叶法测定了氯虫苯甲酰胺、高效氯氟氰菊酯和甲氨基阿维菌素苯甲酸盐对草地贪夜蛾3龄幼虫的室内毒杀作用;采用茎叶喷雾法,测定了 200克/升氯虫苯甲酰胺悬浮剂、150克/升氯虫苯甲酰胺?高效氯氟氰菊酯微囊悬浮-悬浮剂、25克/升高效氯氟氰菊酯乳油和5％甲氨基阿维菌素苯甲酸盐水分散粒对田间玉米上草地贪夜蛾幼虫的防治效果.室内毒力测定试验结果表明:甲氨基阿维菌素苯甲酸和氯虫苯甲酰胺对草地贪夜蛾3龄幼虫都有较好的毒杀作用,LC50分别为0.037 mg/L和0.094 mg/L;而高效氯氟氰菊酯对草地贪夜蛾的毒杀作用较一般,LC50为5.336 mg/L.田间试验结果表明,供试的3种药剂对草地贪夜蛾幼虫速效性一般,药后1 d的防治效果为40.79％～59.67％;药后3 d的防治效果为67.27％～88.55％;药后7 d其防治效果为55.75％～90.97％.氯虫苯甲酰胺和甲氨基阿维菌素苯甲酸盐对草地贪夜蛾具有较好室内的毒杀作用和田间防治效果,是目前防治草地贪夜蛾的理想药剂;高效氯氟氰菊酯对草地贪夜蛾室内的毒杀作用和田间防治效果较差,不推荐用来防治草地贪夜蛾.     

北京地区西花蓟马田间种群的抗药性监测

采用叶管药膜法在室内测定了2009—2010年北京海淀地区和昌平地区西花蓟马Frankliniella occidentalis(Pergande)田间种群对12种杀虫剂敏感性的年度变化。结果表明,北京昌平和海淀地区的西花蓟马对多数的药剂仍处于敏感状态,但对氯氟氰菊酯已产生近40倍的抗性,昌平种群对多杀菌素具有产生低水平抗性的趋势(抗性倍数为4倍)。推荐药剂包括多杀菌素、阿维菌素、甲氨基阿维菌素苯甲酸盐(甲维盐)、毒死蜱和溴虫腈,应注意与其它药剂的轮换使用,灭多威对西花蓟马的毒力水平最低,不推荐使用。     

高效氯氟氰菊酯对大鳞副泥鳅急性毒性和生理毒性的影响

为了估测高效氯氟氰菊酯对水生生物毒性的大小,以大鳞副泥鳅作为受试动物,研究不同浓度的高效氯氟氰菊酯对其急性毒性和生理毒性的影响。结果表明:高效氯氟氰菊酯对大鳞副泥鳅24h、48h、96h的半数致死浓度(LC50)分别为25.93μg/L、17.28μg/L、14.11μg/L,安全浓度为2.30μg/L。低浓度高效氯氟氰菊酯对大鳞副泥鳅肝脏谷丙转氨酶(GPT)和谷草转氨酶(GOT)起诱导作用,高浓度对其起抑制作用,试验组与对照组存在显著或极显著差异。研究表明,高效氯氟氰菊酯对大鳞副泥鳅有较强的毒性。     

六种杀虫剂对棉铃虫的毒力效果比较

【目的】比较新型杀虫剂对棉铃虫Helicoverpa armigera田间种群的毒力效果,从中筛选出高效农药种类,为当前棉铃虫防治中合理用药提供参考。【方法】在室内采用点滴法,测定了甲氨基阿维菌素苯甲酸盐(甲维盐)、氯虫苯甲酰胺、溴氰虫酰胺、茚虫威、溴虫腈、甲维·茚虫威对4个地理种群棉铃虫3龄幼虫的毒力效果;并比较了甲维盐、氯虫苯甲酰胺对2-5龄幼虫的毒力作用。【结果】6种杀虫剂对3龄幼虫的毒力效果从高到低的顺序依次为:氯虫苯甲酰胺甲维盐甲维·茚虫威溴氰虫酰胺茚虫威溴虫腈;不同地理种群对茚虫威的敏感性差异最大,其次依次为甲维·茚虫威、氯虫苯甲酰胺、溴氰虫酰胺、甲维盐和溴虫腈。甲维盐、氯虫苯甲酰胺对2-4龄幼虫均具有较好毒杀效果,但氯虫苯甲酰胺对5龄幼虫的毒效明显优于甲维盐。【结论】氯虫苯甲酰胺和甲维盐是当前防治棉铃虫的首选农药,且氯虫苯甲酰胺对高龄幼虫毒杀效果较好。     

我国白纹伊蚊对三种拟除虫菊酯类杀虫剂抗性检测诊断剂量的建立

【目的】建立中国白纹伊蚊Aedes albopictus成蚊对溴氰菊酯、氯菊酯和高效氯氟氰菊酯杀虫剂抗性检测的诊断剂量。【方法】应用溴氰菊酯、氯菊酯和高效氯氟氰菊酯原药制作不同浓度的药膜滤纸,接触筒法测定白纹伊蚊实验室敏感品系成蚊对3种拟除虫菊酯类杀虫剂的敏感性,记录1 h的击倒数和24 h的死亡数。应用Excel 2007和SPSS20.0进行数据统计处理,并制作杀虫剂的毒力回归线,计算各自的LC_(50)和LC_(99)值。以2倍LC_(99)值作为区分抗性和敏感种群的诊断剂量,制作药膜滤纸,接触筒法生物测定海口市白纹伊蚊现场种群成蚊对杀虫剂的抗药性。【结果】溴氰菊酯、高效氯氟氰菊酯和氯菊酯杀虫剂对白纹伊蚊实验室敏感品系成蚊的LC_(50)值分别为0.00619%,0.01403%和0.05009%,LC_(99)值分别为0.05175%,0.11859%,和0.53165%,相对应的诊断剂量分别为0.1035%,0.2372%和1.0633%。应用上述溴氰菊酯、氯菊酯和高效氯氟氰菊酯诊断剂量测定的海口市白纹伊蚊现场种群的死亡率分别为22.58%,36.29%和40.83%,表明该种群对这3种菊酯类杀虫剂均已产生了抗性。【结论】本研究建立的白纹伊蚊对3种拟除虫菊酯类杀虫剂的诊断剂量可作为该蚊成蚊抗药性监测的参考。     

化学杀虫剂对草地贪夜蛾毒力的生物测定方法比较

【目的】明确评估不同类型化学杀虫剂对草地贪夜蛾幼虫毒力的重复性最好且最方便的生物测定方法。【方法】在室内分别采用点滴法、饲料混药法和叶片药膜法比较了不同类型的7种化学杀虫剂(氯虫苯甲酰胺、甲氨基阿维菌素苯甲酸盐、乙酰甲胺磷、高效氯氟氰菊酯、乙基多杀菌素、虫螨腈和虱螨脲)对草地贪夜蛾3龄幼虫的毒力。【结果】以点滴法进行测定,7种化学杀虫剂中对草地贪夜蛾3龄幼虫毒力最大的是甲维盐,处理后24 h的LD_(50)为0.375μg/g;毒力最小的是虱螨脲,处理后72 h的LD_(50)为261.107μg/g。以饲料混药法进行测定,乙基多杀菌素对草地贪夜蛾3龄幼虫毒力最大,乙酰甲胺磷的毒力最低,处理后24 h的LC_(50)分别为0.061和9 426.217μg/g。以叶片药膜法进行测定,毒力最大的是甲维盐,最小的是高效氯氟氰菊酯,处理后24 h的LC_(50)分别为0.062和471.343 mg/L。对3种生物测定方法的数据进行分析,点滴法的χ~2值最小,P值最大;同时,相比于饲料混药法,点滴法和叶片药膜法测定中草地贪夜蛾种群遗传一致性较好。【结论】除虱螨脲外,测定的其余6种杀虫剂(氯虫苯甲酰胺、甲氨基阿维菌素苯甲酸盐、乙酰甲胺磷、高效氯氟氰菊酯、乙基多杀菌素、虫螨腈)对草地贪夜蛾幼虫的最适用的生物测定方法是点滴法。相比于饲料混药法和叶片药膜法,点滴法不仅能较准确地反映种群整体在遗传学上的纯度,同时在生物测定结果的重复性上也是最好的。虱螨脲推荐使用的生物测定方法是以胃毒为主的饲料混药法和叶片药膜法。     

西花蓟马对吡虫啉的抗性机制及交互抗性研究

为了解西花蓟马Frankliniella occidentalis(Pergande)对吡虫啉的抗性风险,本文就吡虫啉的交互抗性和抗性机制(增效剂和酶活性)进行了研究。结果表明,经过35代筛选,西花蓟马对吡虫啉的抗性上升到21.26倍。西花蓟马对吡虫啉与阿维菌素和甲维盐存在中等水平交互抗性,与氯氟氰菊酯、灭多威和毒死蜱存在低水平交互抗性。增效剂试验表明,三丁基三硫磷酸酯(DEF)、磷酸三苯酯(TPP)和马来酸二乙酯(DEM)具有显著增效(SR50,DEF=6.38,SR50,TPP=5.52,SR50,DEM=1.60,P<0.05)。生化测定表明:抗吡虫啉品系西花蓟马的羧酸酯酶(5.06倍)和谷胱甘肽S-转移酶酶活性(1.63倍)均显著(P<0.05)高于敏感品系,表明羧酸酯酶和谷胱甘肽S-转移酶酶活性的提高是西花蓟马对吡虫啉产生抗药性的主要原因。     

6种复配杀虫剂对七星瓢虫的毒力测定及风险评估

采用药膜法分别测定了10％甲维盐·茚虫威悬浮剂、12％甲维盐·虫螨腈悬浮剂、12％虫螨腈·虱螨脲悬浮剂、14％呋虫胺·螺虫乙酯悬浮剂、22％吡虫啉·螺虫乙酯悬浮剂和6％吡虫啉·高效氯氟氰菊酯悬浮剂6种复配杀虫剂对七星瓢虫Coccinella septempunctata Linnaeus幼虫急性毒性,并进行了初级风险评估.结果 显示,6种药剂对七星瓢虫48 h的LR5o(半致死用量,Median lethal rate)分别为0.812、2.255、4.082、22.735、6.755和0.00467 g a.i/hm2.在农田内暴露场景下,6种复配杀虫剂对七星瓢虫风险均不可接受;在农田外暴露场景下,仅有14％呋虫胺·螺虫乙酯悬浮剂和22％吡虫啉·螺虫乙酯悬浮剂对七星瓢虫风险可接受,其它均不可接受.结果 表明在田间最大推荐用量下,6种药剂对七星瓢虫的初级风险评价均存在高风险.     

不同药剂对Q型烟粉虱的防治效果评价

研究不同药剂对Q型烟粉虱Bemisia tabaci(Gennadius)的防治效果,为该虫的化学药剂防治提供理论依据。以烟粉虱成虫为试材,采用浸叶法,进行10种药剂对烟粉虱的室内毒力测定实验;采用喷雾法,在大棚黄瓜田进行10种单剂和9种混剂对烟粉虱的防治效果试验。其中阿维菌素对烟粉虱成虫的毒力最高,其LC50为2.8609mg/L,精高效氯氟氰菊酯对烟粉虱成虫的毒力最低,其LC50为389.1049mg/L,乙基多杀菌素对烟粉虱成虫无杀虫效果。9种药剂对烟粉虱成虫的毒力大小顺序为:阿维菌素啶虫脒高效氯氟氰菊酯高效氯氰菊酯氟啶虫胺腈氟啶虫酰胺螺虫乙酯噻虫嗪精高效氯氟氰菊酯。10种药剂在田间对烟粉虱的防效依次为:噻虫嗪阿维菌素氟啶虫胺腈氟啶虫酰胺精高效氯氟氰菊酯啶虫脒螺虫乙酯高效氯氟氰菊酯高效氯氰菊酯乙基多杀菌素。9种混剂的防效试验表明,有6种混剂对烟粉虱的防治效果比单剂防治效果好,其中效果最好的是阿维菌素与三种新烟碱类药剂的混用。     

几种杀虫剂防治荔枝蝽的应用效果及其评价

为了筛选出对荔枝蝽Tessaratoma papillosa高效低毒低投入的药剂,在室内采用喷雾法初步测定了16种常用杀虫剂对荔枝蝽成虫的活性,进一步测定了辛硫磷、丁醚脲和氟啶虫胺腈等3种药剂对荔枝蝽成虫、1龄若虫和2龄若虫的室内毒力,并开展了3种杀虫剂对荔枝蝽的田间防效试验。室内毒力结果表明：甲氰菊酯、杀虫双、阿维菌素、甲氨基阿维菌素苯甲酸盐、哒螨灵、茚虫威、虫螨腈、多杀霉素、乙基多杀霉素、灭蝇胺、异丙威等11种药剂对荔枝蝽成虫活性较低,辛硫磷、丁醚脲和氟啶虫胺腈对荔枝蝽有较高的杀虫活性,3种药剂对成虫72 h后的LC50分别为102.32、226.88和207.59 mg/L,对1龄若虫分别为42.41、120.90和87.59 mg/L,对2龄若虫分别为62.65、180.20和148.75 mg/L。在田间防效试验中,辛硫磷对荔枝蝽成虫药后1 d的防效高达82.46%;氟啶虫胺腈对荔枝蝽成虫药后1 d防效达89.23%,药后7 d防效维持在85.03%;丁醚脲对荔枝蝽成虫的最高防效为71.63%,与高效氯氟氰菊酯的防效相当。辛硫磷、丁醚脲和氟啶虫胺腈的防效投入比分别为9.68、36.25和176.41。辛硫磷投入低、速效性好且光解快,可作为防治荔枝蝽的应急药剂使用,氟啶虫胺腈和丁醚脲防效较好,但投入高,可作为对荔枝蝽有重要潜在研究价值的药剂。     

6种杀虫剂对南美番茄潜叶蛾的毒力及田间防效

[目的]研究6种杀虫剂对南美番茄潜叶蛾卵、幼虫和成虫的毒力及其在温室番茄上的防治效果,为南美番茄潜叶蛾防治提供高效杀虫剂和施药技术。[方法]采用浸渍法和药膜法测定了6种杀虫剂对南美番茄潜叶蛾卵、幼虫和成虫的毒力,田间调查毒力较高杀虫剂对温室番茄上南美番茄潜叶蛾防效。[结果] 6种杀虫剂中的乙基多杀菌素、甲氨基阿维菌素苯甲酸盐和阿维菌素对南美番茄潜叶蛾卵有毒力作用,致死中浓度（LC₅₀）分别为1.415、13.588和23.194 mg·L^-1。6种杀虫剂对南美番茄潜叶蛾幼虫的LC₅₀分别为：阿维菌素0.026 mg·L^-1、四唑虫酰胺0.052 mg·L^-1、甲氨基阿维菌素苯甲酸盐0.057 mg·L^-1、乙基多杀菌素0.072 mg·L^-1、氯虫苯甲酰胺0.484 mg·L^-1和呋虫胺2.039 mg·L^-1。对于南美番茄潜叶蛾成虫,24 h时,仅甲氨基阿维菌素苯甲酸盐和四唑虫酰胺对成虫有较高毒力;72 h时,6种杀虫剂对成虫的LC₅₀分别为：甲氨基阿维菌素苯甲酸盐0.390 mg·L^-1、乙基多杀菌素1.646 mg·L^-1、四唑虫酰胺2.630 mg·L^-1、呋虫胺5.577 mg·L^-1、阿维菌素22.502 mg·L^-1和氯虫苯甲酰胺39.636 mg·L^-1。在成虫盛发期第4天施药,阿维菌素、四唑虫酰胺、甲氨基阿维菌素苯甲酸盐、乙基多杀菌素在南美番茄潜叶蛾危害严重的温室番茄上防效达80%以上。[结论]阿维菌素、四唑虫酰胺、甲氨基阿维菌素苯甲酸盐、乙基多杀菌素、氯虫苯甲酰胺和呋虫胺对南美番茄潜叶蛾卵、幼虫或成虫有较高毒力,其中阿维菌素、四唑虫酰胺、甲氨基阿维菌素苯甲酸盐和乙基多杀菌素田间防效较好。     

Efficacy of systemic insecticides for protection of loblolly pine against southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Cerambycidae)

We evaluated the efficacy of the systemic insecticides dinotefuran, emamectin benzoate, fipronil, and imidacloprid for preventing attacks and brood production of southern pine engraver beetles (Coleoptera: Curculionidae: Scolytinae) and wood borers (Coleoptera: Cerambycidae) on standing, stressed trees and bolt sections of loblolly pine, Pinus taeda L., in eastern Texas. Emamectin benzoate significantly reduced the colonization success of engraver beetles and associated wood borers in both stressed trees and pine bolt sections. Fipronil was nearly as effective as emamectin benzoate in reducing insect colonization of bolts 3 and 5 mo after injection but only moderately effective 1 mo after injection. Fipronil also significantly reduced bark beetle-caused mortality of stressed trees. Imidacloprid and dinotefuran were ineffective in preventing bark beetle and wood borer colonization of bolts or standing, stressed trees. The injected formulation of emamectin benzoate was found to cause long vertical lesions in the sapwood-phloem interface at each injection point.     

七种杀虫剂对小麦吸浆虫和麦蚜防治效果研究

【目的】明确25%吡蚜酮SC、3%甲氨基阿维菌素苯甲酸盐ME、25%噻虫嗪WG、14%氯虫·高氯氟ZC、15%高氯·毒死蜱EC、2.5%高效氯氟氰菊酯EW和40%毒死蜱EC 7种杀虫剂对小麦吸浆虫和蚜虫的防治效果,为科学、合理用药防治小麦害虫提供参考。【方法】采用喷雾法和剥穗调查法,研究它们对小麦吸浆虫成虫和麦蚜的防效,及防后对小麦吸浆虫幼虫危害损失的影响。【结果】参试药剂药后1 d对小麦吸浆虫成虫防效均高于90%,药后3~5 d防效为84.81%~93.93%,防后挽回损失76%以上;对麦蚜药后1、3、5 d防效分别高于75%、80%和85%。在供试的7种药剂中,15%高氯·毒死蜱EC药后3~5 d对两种害虫防效、挽回吸浆虫危害均超过90%,应用效果最好;其次为25%噻虫嗪WG和40%毒死蜱EC,药后3~5 d对吸浆虫防效高于90%、对麦蚜防效分别高于86%和90%,挽回吸浆虫危害损失88%以上。【结论】供试药剂对小麦吸浆虫和麦蚜防效存在显著差异,15%高氯·毒死蜱EC对两种害虫防治效果最好。     

Effects of contact, oral and persistent toxicity of selected pesticides on Cotesia plutellae (Hym., Braconidae), a potential parasitoid of Plutella xylostella (Lep., Plutellidae)

Cotesia plutellae (Kurd.) is an important larval parasitoid of Plutella xylostella (L.). Effects of contact, oral and persistent toxicity of field doses of selected pesticides on immature and mature stages of this useful wasp were determined in controlled conditions. Contact toxicity tests showed that cartap 75% SG, chlorfenapyr 10% F, emamectin benzoate 1% EC, permethrin 20% EC, chlorfluazuron 5% EC, flufenoxuron 10% EC, and teflubenzuron 5% EC were found to be selective against the cocoon stage. In contrast, contact toxicity of four insecticides viz., cartap 75% SG, chlorfenapyr 10% F, emamectin benzoate 1% EC, permethrin 20% EC were found to be moderately to extremely toxic (80% to 100% lethal) to wasp stage. Effects of oral toxicity of three IGRs on wasp stage were somewhat selective. However, beneficial performance of wasps seems to be adversely affected as host parasitism was recorded as being significantly different ( P  < 0.05) in comparison with control. A persistent toxic effect of insecticides via cabbage leaves discs against female wasps showed that cartap 75% SG was moderately persistent (16–30 days). While chlorfenapyr 10% F and emamectin benzoate 1% EC were recorded slightly to be persistent (5–10 days) and permethrin seems to be short lived (< 5 days). Implications of tested products in IPM of cabbage are discussed.     

三种药剂对早稻二化螟的防效及施药适期探讨

试验结果表明,氯虫苯甲酰胺、氯虫·噻虫嗪有对二化螟Chilo suppressalis(Walker)有较好的防效和较长的持效,一次施药可兼治多个峰次。20%氯虫苯甲酰胺150mL/hm2、40%氯虫·噻虫嗪120g/hm2和2.15%甲氨基阿维菌素苯甲酸盐750mL/hm2在二化螟2龄幼虫高峰期施药,药后8d对幼虫防效分别达94.7%、91.2%和91.0%;药后18d的防效依次为99.0%、98.0%、73.2%,氯虫苯甲酰胺、氯虫·噻虫嗪处理防效仍高于药后8d,但甲氨基阿维菌素苯甲酸盐处理防效明显下降;药后18d对主峰保苗效果(枯心)氯虫苯甲酰胺和氯虫·噻虫嗪分别为99.0%、98.0%,甲氨基阿维菌素苯甲酸盐处理偏低,为73.2%。对后峰保苗效果(枯鞘)氯虫苯甲酰胺为84.9%好于氯虫·噻虫嗪处理的69.3%,甲氨基阿维菌素苯甲酸盐的防效仅为7.1%。氯虫·噻虫嗪不同时期施药处理后,主峰卵孵高峰后14d考查,防治效果和保苗效果以卵孵高峰施药最好,其次为2龄幼虫高峰期施药;主峰卵孵高峰后24d考查,主峰卵孵高峰至3龄幼虫高峰施药对主峰均有较好的防效,但对后峰的防效,随着施药时间推迟而提高,但在螟虫重发地区施药过迟,前期的大量枯鞘会影响稻苗生长与分蘖。因此作者建议在二化螟发生量大、后峰数量多地区,采用主峰卵孵高峰和后峰卵孵高峰2次防治对策,在螟虫发生较轻、后峰数量较少或全代发生较为集中地区,可根据当地虫情发生情况,适当推迟施药,达到一次用药,解决全代螟害。甲氨基阿维菌素苯甲酸盐持效期较短,可根据螟虫发生峰次施用。     

西花蓟马与烟蓟马药剂敏感性的比较

采用浸叶法比较了外来入侵物种西花蓟马Frankliniella occidentalis(Pergande)与本地物种烟蓟马Thrips tabaci Lindeman对辛硫磷、毒死蜱、高效氯氰菊酯、多杀霉素、甲氨基阿维菌素苯甲酸盐和阿维菌素6种杀虫剂的敏感性。结果显示:西花蓟马对辛硫磷、毒死蜱和多杀霉素的敏感性均比烟蓟马明显要高,而高效氯氰菊酯和阿维菌素对烟蓟马则具有较高的毒力。多杀霉素对西花蓟马和烟蓟马的防治效果最好,在药剂浓度为0.5mg/L时,2种蓟马的校正死亡率均超过90%。     

Field trials in Norway with SLICE (0.2% emamectin benzoate) for the oral treatment of sea lice infestation in farmed Atlantic salmon Salmo salar

Four commercial salmon farms on the West coast of Norway were recruited to a programme of field trials in which the efficacy of SLICE (0.2% emamectin benzoate; Schering-Plough Animal Health) was compared with a commercially available product, EKTOBANN (teflubenzuron 2 g kg(-1); Skretting A/S) in treating natural sea lice Lepeophtheirus salmonis infections in Atlantic salmon Salmo salmar L. At each test site, 3 fish pens were treated with each product. In total, nearly 1.2 million first-year-class fish were included in the trial, of which approximately 561,000 received emamectin benzoate at a dosage of 50 microg kg(-1) body wt d(-1), while approximately 610,000 received teflubenzuron at a dosage of 10 mg kg(-1) body wt d(-1). Medicated feed was provided at 0.5% body wt d(-1) over 7 consecutive days. Feed containing emamectin benzoate was generally well accepted by the fish and no problems were encountered in feeding the medicated diet at the desired dose. Lice numbers were counted 2 d before and 1, 7, 14 and 21 d after commencement of treatment. While treatment with both substances rapidly reduced lice numbers, pens treated with emamectin benzoate were found to harbour significantly fewer lice 14 and 21 d post-treatment. Twenty-one days following treatment with emamectin benzoate the lice abundance was reduced on average by 94%. Limited sampling outside the main study period indicated that emamectin benzoate protects against sea-lice infestation over longer periods.     

Field evaluation of nucleopolyhedrosis virus and some biorational insecticides against Helicoverpa armigera Hubner (Noctuidae: Lepidoptera)

American bolloworm, Helicoverpa armigera Hubner (Noctuidae: Lepidoptera) is considered as a major pest of various crops all over the world. It is mainly controlled by indiscriminate use of synthetic insecticides in the world due to which this pest developed resistance to most of the available insecticides. Therefore, in the current study, the efficacy of virulent strain of HaNPV (0.5 × 10⁹ PIB/ml) alone and in combination with recommended doses of spintoram (20 g/100 L of water) and emamectin benzoate (200 ml/100 L of water) was tested in field. The combination of HaNPV with spintoram and emamectin benzoate 100% reduced the larval population as compared to emamectin benzoate and HaNPV alone. This suggested that the combination of spintoram and emamectin benzoate with HaNPV could be used in field to manage the infestation of H. armigera.