嗜卷书虱和嗜虫书虱酯酶性质的比较研究

对嗜卷书虱Liposcelis bostrychophila和嗜虫书虱L. entomophila羧酸酯酶及乙酰胆碱酯酶(AChE)的生物化学性质进行了初步研究。结果表明:嗜虫书虱的羧酸酯酶活性明显高于嗜卷书虱,嗜卷书虱和嗜虫书虱羧酸酯酶对底物α-NA的Km值分别为0.665 7、0.285 7 mmol/L,Vmax值分别为1.672 2和2.463 1 mmol·(mg·30 min)-1。嗜卷书虱和嗜虫书虱乙酰胆碱酯酶的活性差异不显著,嗜虫书虱略高于嗜卷书虱。通过聚丙烯酰胺凝胶电泳,检测出8条嗜卷书虱、7条嗜虫书虱酯酶同工酶谱带,嗜卷书虱的酶谱分布比嗜虫书虱广。     

磷化氢熏蒸处理对嗜卷书虱不同虫态的致死作用

实验室条件下系统研究了磷化氢(PH3)对储物害虫嗜卷书虱Liposcelis bostrychophila卵、各龄若虫和成虫的致死作用,并选用PH3间歇熏蒸以及PH3与气调交替处理等措施对嗜卷书虱进行处理,比较了不同处理措施对嗜卷书虱种群的控制效果。结果表明,PH3熏蒸处理对嗜卷书虱各虫态有不同的致死效果。对卵而言,24、72和120 h熏蒸处理的LC50分别为0.137、0.045和0.035 mg/L;而24 h熏蒸处理对若虫的LC50在4.285~7.364 μg/L之间,对成虫的LC50为20.404 μg/L;采用25 μg/L的PH3进行24 h熏蒸处理,间隔10 d后再分别进行第2次和第3次熏蒸处理,可以完全控制嗜卷书虱的发生。采用PH3 (12 μg/L)和气调(体积比例为35% CO2,1% O2,64% N2)交替处理能够延缓嗜卷书虱种群抗性的发展,交替处理3~5次可以完全控制嗜卷书虱的发生。     

几种杀虫剂对嗜虫书虱的触杀作用

采用滤纸药膜法比较了常用8种杀虫剂对嗜虫书虱Liposcelis entomophila的触杀作用,在药剂的推荐浓度下有机磷类杀虫剂对嗜虫书虱的急性触杀作用强于其它药剂。同时测定了杀螟硫磷、敌敌畏和溴氰菊酯(含增效醚)3种药剂对嗜虫书虱的触杀毒力,其24h内触杀作用的LC_(50)分别为9．3284、2．1440和7．5007μg/cm~2,但杀螟硫磷的LC_(95)为459．4949μg/cm~2,远高于敌敌畏的8．2453μg/cm~2和溴氰菊酯(含增效醚)的14．5274μg/cm~2。此外,48h内敌敌畏等有机磷杀虫剂对嗜虫书虱的毒杀速度较其它供试药剂快。     

温度、湿度对嗜虫书虱生长发育和繁殖的影响

嗜虫书虱以全麦粉及酵母粉作饲料时,其各期发育速率与温度呈逻辑斯蒂曲线关系,世代发育起点和有效积温分别为15.16℃,306.75日度。在20—35℃范围内,世代存活率、种群内禀增长率以及成虫产卵量较高,高低温区均呈下降趋势。理论上29.55℃时周限增长率(λ)最大,达1.0628倍/天。高湿有利于其生长发育和繁殖,湿度低于60％时,各虫态均不能发育存活。结果表明,嗜虫书虱生长发育、繁殖最适温区为28—30℃,最适相对湿度在80％左右。     

嗜卷书虱和嗜虫书虱体内磷酸酯酶的生化与毒理学特性比较研究

采用药膜法对嗜卷书虱和嗜虫书虱进行生物测定,从5种杀虫剂对两种书虱的LC50可以看出,嗜卷书虱对两种拟除虫菊酯类药剂较嗜虫书虱敏感,嗜虫书虱对丁硫克百威较为敏感,而对有机磷类药剂的作用两种书虱的敏感性相似。两种书虱体内酸性磷酸酯酶（ACP）和碱性磷酸酯酶（ALP）的活力比较结果表明：嗜卷书虱和嗜虫书虱体内ACP的比活力为分别14 μmol/mg&#8226;30 min和2.2 μmol/mg&#8226;30 min,ALP的比活力分别为0.092 μmol/mg&#8226;30 min和0.046 μmol/mg&#8226;30 min。经方差分析,两种书虱ACP和ALP的比活力之间均存在显著性差异(p<0.05)。动力学参数比较结果显示,两种书虱ACP的V _max值之间的差异达到显著水平,而ALP的K _m值之间存在显著性差异。离体试验结果表明,5种药剂对磷酸酯酶的作用各不相同,个别药剂在低浓度下表现诱导作用,说明磷酸酯酶在不同外源毒物的解毒代谢过程中所起的作用有所不同。     

嗜卷书虱和嗜虫书虱体内磷酸酯酶的生化与毒理学特性比较

采用药膜法对嗜卷书虱和嗜虫书虱进行生物测定,从5种杀虫剂对两种书虱的LC50可以看出,嗜卷书虱对两种拟除虫菊酯类药剂较嗜虫书虱敏感,嗜虫书虱对丁硫克百威较为敏感,而对有机磷类药剂的作用两种书虱的敏感性相似.两种书虱体内酸性磷酸酯酶(ACP)和碱性磷酸酯酶(ALP)的活力比较结果表明:嗜卷书虱和嗜虫书虱体内ACP的比活力为分别14μmol/mg·30 min和2.2 μmol/mg·30 min,ALP的比活力分别为0.092μmol/mg·30 min和0.046μmol/mg·30 min.经方差分析,两种书虱ACP和ALP的比活力之间均存在显著性差异(p<0.05).动力学参数比较结果显示,两种书虱ACP的Vmax值之间的差异达到显著水平,而ALP的Km值之间存在显著性差异.离体试验结果表明,5种药剂对磷酸酯酶的作用各不相同,个别药剂在低浓度下表现诱导作用,说明磷酸酯酶在不同外源毒物的解毒代谢过程中所起的作用有所不同.     

嗜卷书虱抗气性和抗药性品系选育及抗性风险分析

嗜卷书虱Liposcelis bostrychophila Badonnel是一种发生在储粮环境中的重要害虫，其抗性问题十分突出。在实验室条件下，采用高CO2（35％CO2、21％O2、44％N2）、低O2＋高CO2（35％C02、1％O2、64％N2）、DDVP和PH3等4种不同的处理，对嗜卷书虱连续处理20代，每代处理2次，每次处理保持对成虫死亡率35％的选择压力，得到了4个不同的抗性品系HCO2-R、HCLO-R、DDVP-R和PH3-R，抗性指数分别为3．3、5．2、10．2和4．5。经过对抗性发展趋势的分析，嗜卷书虱对这几种环境胁迫都有一定的抗性潜力。对抗性品系的现实遗传力（h^2）进行分析，其h^2分别为0．388、0．155、0．341和0．594。抗性风险评估结果表明，分别采用高CO2低O2＋高CO2、DDVP和PH，处理，在50％的选择压力下，抗性增加10倍所需的代数分别为62．30、44．17、26．46和38．48代；而在90％的选择压力下，抗性增加lO倍所需的代数分别为28．1l、20．08、11．98和17．39代。因此对于采用气调处理，嗜卷书虱对低O2＋高CO2处理的抗性风险比用高CO2处理大，而采用药剂处理，嗜卷书虱对DDVP的抗性风险要比PH3处理大。     

S-烯虫酯

S-烯虫酯属昆虫生长调节剂类杀虫剂。纯品为淡黄色透明液体带有果香味,沸点:320℃,闪点:177℃(闭杯),pH:5.6,饱和蒸气压:0. 4kPa/20℃, 1.08mPa/25℃,辛醇/水分配系数KowlogP 6.7,旋光度[α] 20D +5.7°(丙酮溶剂),折射率:1.462。在水中溶解:79. 1 PPb/20℃,溶解大多数有机溶剂(20±1℃,g/L ),丙酮和己烷〉500,甲醇>450。S-烯虫酯原药质量分数95.0%;外观为黄色至浅褐色液体。20%S-烯虫酯微囊悬浮剂,筛析(通过75μm试验筛)>98%;悬浮率≥85%;自动分散性≥70%。产品的冷、热贮存和常温2年贮存均稳定。     

8种植物精油对嗜卷书虱的杀虫活性及香青兰精油的GC-MS成分分析

为筛选新型环保植物源仓储害虫杀虫剂,采用水蒸汽蒸馏法提取8种植物精油,滤纸药膜法、密闭空气熏蒸法测定精油对嗜卷书虱成虫的触杀、熏蒸活性,筛选出高活性植物,并用气相质谱-色谱联用仪（GC-MS）对高活性植物精油进行化学成分的分析和鉴定。结果表明：香青兰、窃衣、啤酒花精油对嗜卷书虱具有较强的触杀活性,LD₅₀分别为157.43、349.34和633.07µg/cm²;香青兰、蒌蒿和窃衣精油对嗜卷书虱具有较好的熏蒸活性,LC₅₀分别为0.20、0.70和1.66 mg/L。香青兰精油经GC-MS分析,检测并鉴定到23个化学成分,相对含量占总含量的84.22%,其主要成分为乙酸香叶酯（16.26%）、丁香酚（13.90%）、香叶醛（13.20%）、草蒿脑（7.89%）、丙烯酸-2-乙基己酯（8.55%）以及橙花醛（7.60%）。研究结果表明香青兰精油对嗜卷书虱的生物活性较好,值得进一步研究。     

新型除草剂丙酯草醚的作用机理

采用常规的室内生测和生化方法,开展新型除草剂丙酯草醚的作用机理研究.试验结果表明:同时添加5mg/L浓度的三种支链氨基酸即缬氨酸、亮氨酸和异亮氨酸能完全恢复丙酯草醚对高粱茎的生长抑制作用,而添加相同浓度的单一支链氨基酸只能部分消除其抑制作用.离体条件下,丙酯草醚IC50＞100mg/L,而双草醚IC50值为10-5～10-4mg/L,说明丙酯草醚对离体ALS没有抑制作用;活体条件下,丙酯草醚对ALS有一定的抑制作用,且随着处理时间的延长,酶活力降低,对ALS的抑制作用增加.因此,丙酯草醚使植物体内必需的支链氨基酸合成受阻,仍然属于ALS抑制剂,但其作用方式不同于磺酰脲类和嘧啶水杨酸类除草剂等典型的ALS抑制剂,它类似于前体农药,即在植物体内通过代谢活化来发挥作用.     

Influence of concentration, temperature and humidity on the toxicity of phosphine to the strongly phosphine-resistant psocid Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

BACKGROUND: The psocid Liposcelis bostrychophila Badonnel, is a widespread, significant pest of stored commodities, has developed strong resistance to phosphine, the major grain disinfestant. The aim was to develop effective fumigation protocols to control this resistant pest. RESULTS: Time to population extinction of all life stages (TPE) in days was evaluated at a series of phosphine concentrations and temperatures at two relative humidities. Regression analysis showed that temperature, concentration and relative humidity all contributed significantly to describing TPE (P<0.001, R(2)=0.95), with temperature being the dominant variable, accounting for 74.4% of the variation. Irrespective of phosphine concentration, TPE was longer at lower temperatures and high humidity (70% RH) and shorter at higher temperatures and low humidity (55% RH). At any concentration of phosphine, a combination of higher temperature and lower humidity provides the shortest fumigation period to control resistant L. bostrychophila. For example, 19 and 11 days of fumigation are required at 15 degrees C and 70% RH at 0.1 and 1.0 mg L(-1) of phosphine respectively, whereas only 4 and 2 days are required at 35 degrees C and 55% RH for the same respective concentrations. CONCLUSIONS: The developed fumigation protocols will provide industry with flexibility in application of phosphine.     

Inhibition of egg development by phosphine in the cosmopolitan pest of stored products Liposcelis bostrychophila (Psocoptera: Liposcelididae)

Phosphine-induced delay in development of eggs was investigated as a mechanism of resistance to this fumigant in Liposcelis bostrychophila Badonnel. One-day-old eggs of a susceptible and a strongly resistant strain of L bostrychophila were exposed to a range of phosphine concentrations for 6days at 30 (+/- 1) degrees C and 70 (+/- 2)% RH. Delay in mean hatching period occurred in both susceptible and resistant eggs, although it was more pronounced in the latter. A maximum delay of 2.65 days was recorded for eggs of the susceptible strain at 0.01 mg litre(-1) (the highest concentration at which eggs survived) and 13.39 days for the resistant strain at 1 mg litre(-1) (the highest concentration tested). Delay in egg development time was positively correlated with increasing phosphine concentration. Our results reveal that the most successful strategy to control resistant L bostrychophila is to apply relatively low concentrations of phosphine for extended exposure times (eg 0.05 mg litre(-1) for 16 days) that allow all eggs to hatch to the much less tolerant nymph stage.     

关于鲍氏虱(虫齿)和地虱(虫齿)的再描述

除危害各种储藏物 ,虱属昆虫也可随活体植物、木材、木质包装、废纸、土壤等进行远距离传播。为便于口岸检疫人员及时、准确鉴定所截获的虱属昆虫 ,本文记述了该属 2种中国新记录 ,即鲍氏虱liposcelisbouilloniBadonnel和地虱L .edaphicaLienhard ,并对其进行了再描述     

两种世界性仓储虱的重新描述

仓储虱在我国口岸检疫中常有截获。本文针对两种世界性仓储虱 ,即中国新记录虚伪虱LiposcelismendaxPearman和红虱L .rufaBroadhead ,进行了重新描述。 2种虱均可危害室内储藏物 ,分别属ⅡC种团和ⅠB种团 ,世界分布较广 ,我国仅发现于河南省     

Toxicological and biochemical characterizations of AChE in Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae)

The toxicological and biochemical characteristics of acetylcholinesterases (AChE) in the resistant and susceptible strains (SS) of Liposcelis bostrychophila were investigated. The two resistant strains were the dichlorvos-resistant strain (DDVP-R) and the phosphine-resistant strain (PH₃-R) with resistance ratios of 22.36 and 4.51, respectively. Compared to their susceptible counterpart, the AChE activity per insect and the specific activity of AChE in DDVP-R and PH₃-R were significantly higher. There were also significant kinetic differences between DDVP-R and PH₃-R. The apparent Michaelis-Menten constant (K_m) for acetylthiocholine iodide (ATChI) was obviously lower in SS than that in PH₃-R, indicating a higher affinity to the substrate ATChI in the susceptible strains. The affinity for the substrate ATChI in DDVP-R and SS were not significantly different. The V_max value of the PH₃-R was significantly greater when compared to the V_max for the SS suggesting a possible over expression of AChE in this resistant strain. The inhibition of AChE to insecticide exposure in vitro revealed that all six insecticides were inhibitory for the extracted AChE’s. Based on the I₅₀ values, AChE of the SS were more sensitive to dichlorvos, paraoxon-ethyl, malaoxon and demeton-S-methyl than those of the two resistant strains. As for carbaryl and eserine, the PH₃-R suggested a significantly higher I₅₀s compared to the susceptible strain, while, no significant differences were found between SS and DDVP-R.     

Potential of piperonyl butoxide‐synergised pyrethrins against psocids (Psocoptera: Liposcelididae) for stored‐grain protection

BACKGROUND: Piperonyl butoxide (PB)‐synergised natural pyrethrins (pyrethrin:PB ratio 1:4) were evaluated both as a grain protectant and a disinfestant against four Liposcelidid psocids: Liposcelis bostrychophila Badonnel, L. entomophila (Enderlein), L. decolor (Pearman) and L. paeta Pearman. These are key storage pests in Australia that are difficult to control with the registered grain protectants and are increasingly being reported as pests of stored products in other countries. Firstly, mortality and reproduction of adults were determined in wheat freshly treated at 0.0, 0.75, 1.5, 3 and 6 mg kg^?1 of pyrethrins + PB (1:4) at 30 ± 1 °C and 70 ± 2% RH. Next, wheat treated at 0.0, 1.5, 3 and 6 mg kg^?1 of pyrethrins + PB (1:4) was stored at 30 ± 1 °C and 70 ± 2% RH and mortality and reproduction of psocids were assessed after 0, 1.5, 3 and 4.5 months of storage. Finally, the potential of synergised pyrethrins as a disinfestant was assessed by establishing time to endpoint mortality for adult psocids exposed to wheat treated at 3 and 6 mg kg^?1 of synergised pyrethrins after 0, 3, 6, 9 and 12 h of exposure. RESULTS: Synergised pyrethrins at 6 mg kg^?1 provided 3 months of protection against all four Liposcelis spp., and at this rate complete adult mortality of these psocids can be achieved within 6 h of exposure. CONCLUSION: Piperonyl butoxide‐synergised pyrethrins have excellent potential both as a grain protectant and as a disinfestant against Liposcelidid psocids. Copyright © State of Queensland, Department of Employment, Economic Development and Innovation, 2010. Published by John Wiley and Sons, Ltd.     

Long-term effectiveness of grain protectants and structural treatments against Liposcelis decolor (Pearman) (Psocoptera: Liposcelididae), a pest of stored products

Numerous strains of the psocid pest, Liposcelis decolor (Pearman) were collected from farms and central storages and interbred to form three representative strains from three major grain-growing states of Australia: Queensland, South Australia and New South Wales. These were tested against the grain protectants and structural treatments currently registered for use in Australia. Recently, L decolor has become an important pest of stored grain in Australia, particularly in the eastern and southern parts. There is no published information available on management of this pest and the current pest-management strategy, based predominantly on phosphine fumigation, has failed to control infestations of this pest in numerous grain storages in Australia. Alternative methods of control such as use of contact insecticides were explored in the present work to supplement phosphine fumigation to manage this new pest. From eight grain protectants tested as admixtures, only chlorpyrifos-methyl, bioresmethrin plus piperonyl butoxide, and fenitrothion were found to provide long term (3-9 months) protection against all three strains of L decolor. Chlorpyrifos-methyl gave the best protection, providing a minimum of 7.5 to a maximum of 9 months protection, depending on the strains tested. Three structural treatments, azamethiphos, azamethiphos plus carbaryl and permethrin provided long-term control (8-9 months) of all three strains of L decolor on galvanised steel surfaces, with permethrin delivering 9 months protection against all strains. However, all of these treatments failed to provide long-term control of any strains on concrete surfaces. We conclude that chlorpyrifos-methyl as a grain admixture can be incorporated into fumigation strategies to optimise the control of L decolor infestations. Structural treatments, such as permethrin can be used to support a fumigation strategy in storages made of galvanised steel.     

Purification and biochemical characterization of glutathione S-transferases from three strains of Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae): Implication of insecticide resistance

Glutathione S-transferases (GSTs) catalyzing the conjugation of reduced glutathione (GSH) to a vast range of xenobiotics including insecticides were investigated in the psocid Liposcelis bostrychophila Badonnel. GSTs from susceptible and two resistant strains (DDVP-R for dichlorvos-resistant strain and PH₃-R for phosphine-resistant strain) of L. bostrychophila were purified by glutathione-agarose affinity chromatography and characterized by their Michaelis-Menten kinetics towards artificial substrates, i.e., 1-chloro-2,4-dinitrobenzene (CDNB), in a photometric microplate assay. The specific activities of GSTs purified from two resistant strains were significantly higher than their susceptible counterpart. For the resistant strains, GSTs both showed a significantly higher affinity to the substrate GSH while a declined affinity to CDNB than those of susceptible strain. The inhibitory potential of ethacrynic acid was very effective with highest I₅₀ value (the concentration required to inhibit 50% of GSTs activity) of 1.21 μM recorded in DDVP-R. Carbosulfan also exhibited excellent inhibitory effects on purified GSTs. The N-terminus of the purified enzyme was sequenced by Edman degradation, and the alignment of first 13 amino acids of the N-terminal sequence with other insect GSTs suggested the purified protein was similar to those of Sigma class GSTs.     

Laboratory evaluation of the effects of Manilkara subsericea (Mart.) Dubard extracts and triterpenes on the development of Dysdercus peruvianus and Oncopeltus fasciatus

BACKGROUND: Studies were carried out to evaluate the effects of Manilkara subsericea extracts and triterpenes on the development of two species of agricultural pest insects, Oncopelus fasciatus and Dysdercus peruvianus. RESULTS: All treatments of insects with M. subsericea extracts induced mortality, delayed development and inhibited moulting. Some extracts assayed (FH, FB and FD in D. peruvianus, and FH, FB and FEA in O. fasciatus) also produced body deformities in the few adults that emerged. Other extracts (FH, FEA, FB, FD and LET in both insects), however, induced either permanent (overaged) or extranumerary nymphs, both of which were unable to achieve the adult stage and reproductive status. The insects were also treated with triterpenes (α‐ and β‐amyrin acetates) which showed high lethality at 30 days after treatment and delayed the intermoult period so that overaged nymphs were detected. CONCLUSION: The results indicate that extracts and triterpenes from Manilkara subsericea act as potent growth inhibitors of phytophagous hemipteran nymphs. It is also concluded that the mixture of several different molecules in the extracts used produces synergic effects that do not occur after using the triterpenes (PFT) alone. These secondary metabolites in the M. subsericea extracts can potentially be used in integrated control programmes against crop pests. Copyright © 2012 Society of Chemical Industry     

Comparison of acetylcholinesterase from three field populations of Liposcelis paeta Pearman (Psocoptera: Liposcelididae): Implications of insecticide resistance

The toxicological and biochemical characteristics of acetylcholinesterases (AChE) in Liposcelis paeta Pearman were investigated in three field populations collected from Nanyang city of Henan Province (NY), Wuzhou (WZ) and Hezhou (HZ) Cities of Guangxi Province, China. The result of bioassay showed that the LC_50s of the NY (281.4802 mg/m²) and the WZ (285.0655 mg/m²) to dichlorvos were 1.156-fold and 1.171-fold higher than that of the HZ (243.5197 mg/m²), respectively. Compared to NY population, the activity per insect and the specific activity of AChE in WZ and HZ populations were significantly higher, and significant kinetic differences among the three populations were also observed. The apparent Michaelis–Menten constant (K_m) for acetylthiocholine iodide (ATChI) was obviously lower in NY than that in WZ and HZ populations, indicating a higher affinity to the substrate ATChI in the NY population. The affinity to the substrate ATChI between WZ and HZ population was also significantly different. As for V_max, the values of WZ and HZ populations were significantly greater when compared to that for NY population, suggesting a possible over expression of AChE in the former two populations. The inhibition studies of AChE indicated that paraoxon-ethyl, demeton-S-methyl, carbaryl, and eserine all possessed some inhibitory effects on AChE in L. paeta. The results of I_50S suggested that when compared to the other two populations, while AChE from HZ population was less sensitive to paraoxon-ethyl and demeton-S-methyl. The contradiction with the result of the bioassay might be due to the different insecticides used in the bioassay. Although both carbaryl and eserine had excellent inhibitory effects, there was no significant difference among the three populations. The statistical analysis of the bimolecular rate constants (k_i) was consistent with the above situation that carbamates expressed remarkable inhibitory effects. It was noticeable that NY population was most sensitive to carbaryl while least to eserine. The differences in AChE among three populations may attribute to the difference in control practices for psocids between Henan and Guangxi Provinces.