甘菊挥发油化学组成及其对烟草甲与赤拟谷盗的杀虫活性

本试验研究了甘菊挥发油的化学组成及其对烟草甲和赤拟谷盗两种常见仓储害虫成虫的熏蒸、触杀和驱避作用。采用水蒸气蒸馏法提取挥发油,GC/MS法分析挥发油的成分及其相对含量。结果表明,从甘菊挥发油中鉴定出了31种化合物,主要组分为樟脑(29.99%)、桉叶油醇(16.87%)、β-水芹烯(4.63%)、顺马鞭草烯醇(4.41%)和顺-β-松油醇(4.04%);生物活性测试结果显示,甘菊挥发油对烟草甲和赤拟谷盗具有一定的触杀活性(LD_(50)分别为24.09μg/头和49.95μg/头)和熏蒸活性(LC_(50)分别为28.67 mg/L和14.40 mg/L)。同时,甘菊挥发油对赤拟谷盗表现出显著的驱避活性,对烟草甲驱避效果不明显。本试验首次研究了我国菊科菊属植物甘菊的挥发油的化学组成和杀虫活性,结果提示该挥发油对烟草甲和赤拟谷盗具有一定杀虫、驱避活性和防治潜力。     

香茅精油对两种主要储粮害虫的控制作用

研究了香茅精油对玉米象、赤拟谷盗的控制作用.结果表明,香茅精油对玉米象和赤拟谷盗都有很强的驱避性,对赤拟谷盗的驱避性随着时间的延长有增强的趋势.对玉米象和赤拟谷盗的成虫都保持了较强的的熏蒸活性.对玉米象有较强的触杀活性,而对赤拟谷盗的触杀活性较弱.剂量为0.15%(v/w)的香茅精油的丙酮稀释液对玉米象成虫的种群抑制率在第6天达到100%,剂量为0.1%(v/w)的香茅精油的丙酮稀释液对赤拟谷盗成虫的种群抑制率在第6天也达到了100%.研究表明香茅精油具有作为储粮保护剂的开发潜力.     

两种低氧条件对赤拟谷盗不同虫态的抑制作用

研究了在28℃、75%RH的温湿度条件下,5%和2%低氧储藏条件对赤拟谷盗高龄幼虫、蛹和成虫的抑制作用。在5%和2%氧气条件下暴露15d后,赤拟谷盗高龄幼虫化蛹率分别为95.0%和3.7%,蛹羽化率分别为98.0%和0%,成虫死亡率分别为12.7%和100%。本研究结果为气调储粮防治害虫提供依据。     

一种防治贮粮甲虫的新型种子处理剂-ADAGE

Adage是美国Syngenta公司近年开发成功的一种新型杀虫剂。实验表明，用0.5ppm-4ppm的剂量处理玉米种子，对赤拟谷盗、玉米象和锯谷盗的防治效果因虫种、剂量、处理时间和处理温度而有差异。当处理浓度为4ppm、处理时间为1-6d时，玉米象成虫在22℃、27℃和32℃时的死亡率分别为79．3％－89．3％、91．2％－99．2％和97．5％－100％。而对于赤拟谷盗，处理时间比处理温度更重要，当处理浓度为4ppm、温度为27℃、处理时间为1、2、3、6d时，赤拟谷盗成虫死亡率分别为23.4%、40.1%、60.8%和100％。同样，Adage对锯谷盗的防治效果也明显受到处理时间的影响。当处理浓度为4ppm、温度为32℃、处理时间为1、2、3、6d时，锯谷盗成虫死亡率分别为66．0％、88．5％、96．7％和100％。     

赤拟谷盗章鱼胺受体3(TcOctβR3)cDNA克隆、表达及功能

【目的】章鱼胺信号系统在调节昆虫行为和生理过程中具有至关重要的作用。赤拟谷盗(Tribolium castaneum)作为一种模式昆虫,被广泛用于解析昆虫生长发育及生理等调控机制的研究工作。本研究以赤拟谷盗为对象,旨在明确章鱼胺受体在调节赤拟谷盗行为和生理方面的功能。【方法】根据Gen Bank登录的相关序列信息(XP_008198078),利用RT-PCR技术克隆赤拟谷盗章鱼胺受体基因Tc OctβR3的c DNA序列。利用在线生物信息学分析软件预测该基因的开放阅读框、编码的氨基酸序列以及跨膜结构域等信息,基于邻接法构建该基因与其他昆虫相关序列的系统发育树,明确系统进化关系。分别提取赤拟谷盗各发育阶段(卵、幼虫、蛹和成虫)、不同组织(中枢神经系统、脂肪体、中肠、后肠、马氏管、精巢和卵巢)以及饥饿胁迫后的RNA,以赤拟谷盗核糖体蛋白S3(Tc RPS3)为内参基因,采用实时定量PCR技术分析该基因在赤拟谷盗不同发育阶段、不同组织以及在饥饿胁迫下的表达模式。运用哺乳动物异源表达系统在人胚胎肾细胞HEK293中瞬时表达Tc OctβR3,进而利用第二信使c AMP含量测定技术分析Tc OctβR3与配体的结合能力。最后,通过体外合成赤拟谷盗Tc OctβR3的双链RNA,利用RNA干扰以及轨迹球行为分析等技术探究该基因的生理功能。【结果】序列分析结果表明,赤拟谷盗Tc OctβR3开放阅读框全长1 305 bp,编码434个氨基酸,序列中含有G蛋白偶联受体典型的7个跨膜结构域。基于邻接法构建的系统发育树表明,该基因编码的蛋白质与小蜂甲(Aethina tumida)的OctβR3亲缘关系最近。实时定量PCR分析结果表明,Tc OctβR3在赤拟谷盗各发育阶段均有表达,尤其在低龄幼虫期转录水平最高,而在其他发育阶段表达量无显著差异;在赤拟谷盗不同组织中,Tc OctβR3在中枢神经系统的表达量显著高于其他组织;赤拟谷盗幼虫在经饥饿处理24 h的过程中,Tc OctβR3的表达量呈先下降后上升的趋势,且在处理6 h的表达量最低,为对照的0.47倍,在16 h表达量最高,为对照的1.80倍,最后恢复到正常水平。通过HEK293细胞异源表达Tc OctβR3后,c AMP测定结果表明章鱼胺(OA)呈浓度依赖性地激活Tc OctβR3,其EC50为8.68×10-7 mol·L-1,萘甲唑啉(NA)的激动活性最高,其有效中浓度EC50为8.56×10-8 mol·L-1。4种供试生物胺激动剂活性强弱为:萘甲唑啉酪胺(TA)章鱼胺多巴胺(DA)。进一步采用RNA干扰技术的分析结果表明,注射ds RNA能有效抑制Tc OctβR3的表达,沉默效率高达61.5%,但干扰该基因表达后不会影响赤拟谷盗成虫的爬行速度和产卵量。【结论】Tc OctβR3在赤拟谷盗中枢神经系统可能发挥重要作用,能调节幼虫对饥饿胁迫的响应。明确了Tc OctβR3的分子生物学特性,可为将来以其为靶标筛选高效激动剂和抑制剂提供理论依据。     

拥挤度和光照条件对赤拟谷盗成虫逃逸行为的影响

【目的】研究赤拟谷盗成虫逃逸活动规律和赤拟谷盗种群控制方法。【方法】以赤拟谷盗成虫为研究对象,分析赤拟谷盗成虫逐日逃逸现象,研究拥挤度、光照条件对其逃逸行为的影响。【结果】全黑暗和自然光周期条件下,赤拟谷盗成虫的逐日逃逸数量与拥挤度呈正相关;拥挤度达到50头/皿以上时,赤拟谷盗成虫逃逸行为频繁,且黑暗条件下的逃逸数量显著小于光照条件。【结论】光照对赤拟谷盗成虫的逃逸行为具有刺激作用,拥挤度的增加,有助于成虫逃逸。     

Laboratory selection of resistance by the red flour beetle,tribolium castaneum (Herbst), to an atmosphere of low oxygen concentration

Adult populations of the red flour beetle,Tribolium castaneum (Herbst), were exposed for 40 generations to an atmosphere containing 99.5% N₂ and 0.5% O₂ at 95% RH, in order to select a strain resistant to the low oxygen concentration (LOC) atmosphere. Selection pressure was maintained at between 50% and 70% mortality. At the 40th generation comparison of sensitivity between the selected strain and the original non-selected strain indicated a resistance factor at the 50% mortality level (LT50) of x 5.2. However, throughout the selections, log-time against probit-mortality curves remained roughly parallel from generation to generation and the slope remained low. These findings indicate a multiplicity of genetic factors that at a high level of selection contribute together towards an adaptation of the insects to survival in the LOC atmosphere. Removal of selection pressure from a sub-population of the selected strain from the 13th to 21st generation revealed that resistance was partially retained with a decrease in resistance factor of 23%. Although the study revealed that the insects were able to develop a strain resistant to hypoxia, exposures were at 95% RH to minimize the desiccation effect. This does not reflect field situations, where ambient relative humidities are generally below 70%.     

Phosphine resistance, respiration rate and fitness consequences in stored-product insects

Resistance to fumigants has been frequently reported in insect pests of stored products and is one of the obstacles in controlling these pests. The authors studied phosphine resistance and its physiological basis in adult insects of 12 populations of Tribolium castaneum (Herbst) (Tenebrionidae), ten populations of Rhyzopertha dominica (F.) (Bostrichidae) and eight populations of Oryzaephilus surinamensis L. (Silvanidae) from Brazil, and the possible existence of fitness costs associated with phosphine resistance in the absence of this fumigant. The bioassays for the detection of phosphine resistance followed the FAO standard method. The production of carbon dioxide and the instantaneous rate of population increase (r(i)) of each population of each species were correlated with their resistance ratios at the LC(50). The resistance ratio at LC(50) in T. castaneum ranged from 1.0- to 186.2-fold, in R. dominica from 2.0- to 71.0-fold and in O. surinamensis from 1.9- to 32.2-fold. Ten populations of T. castaneum, nine populations of R. dominica and seven populations of O. surinamensis were resistant to phosphine. In all three species there was significant association (P < 0.05) between respiration rate and phosphine resistance. The populations with lower carbon dioxide production showed a higher resistance ratio, suggesting that the lower respiration rate is the physiological basis of phosphine resistance by reducing the fumigant uptake in the resistant insects. Conversely, populations with higher r(i) showed lower resistance ratios, which could indicate a lower rate of reproduction of the resistant populations compared with susceptible populations. Thus, management strategies based on the interruption of phosphine fumigation may result in reestablishment of susceptibility, and shows good potential for more effective management of phosphine-resistant populations.     

高浓度CO2气调防治谷蠹及杂拟谷盗的研究

将谷蠹Rhyzopertha dominica(Fab.）成虫及杂拟谷盗Tribolium confusum Jacquelin du val卵、幼虫、肾和成虫分别暴露于35％CO2和11％O2，35％CO2和21％O2，75％CO2和11％O2，75％CO2和21％O2四种气调环境中12、24、36、48、60、72、84、96、108、120小时，结果表明谷蠹成虫对四种气调环境都很敏感，其LT50分别为34.6、42.0、18.6、17.8小时。杂拟谷盗成虫较耐35％CO2、11％O2及35％CO2、21％O2气调环境，处理120小时后，成虫死亡率低于12％。卵及幼虫对四种气调环境较为敏感，蛹对35％CO2、11％O2的耐受性比35％CO2、21％O2强，前者LT50为2248.3小时，后者为124.5小时，杂拟谷盗卵、幼虫、蛹及成虫对四种气调环境敏感顺序为：卵＞幼虫＞蛹＞成虫。     

三种有机磷杀虫剂混配对赤拟谷盗的增效作用

在室内采用药膜法测定了辛硫磷、对硫磷和杀螟硫磷两两混配对赤拟谷盗成虫的毒力,据其LC50值及CTC值比较不同配比的增效作用。结果表明触杀效果较好的组合是杀螟硫磷与辛硫磷以4∶1混配,共毒系数为285.30;杀螟硫磷与对硫磷以8∶1混配,共毒系数是281.88,增效作用明显。