小菜蛾有机磷护性季节性变化及毒理机制研究

1998～ 2 0 0 3年期间的田间监测结果显示 ,福州地区小菜蛾 Plutella xylostella对甲胺磷和敌敌畏的抗性水平呈季节性变化 ,每年春秋季的抗性水平显著高于夏季 7月期间的抗性水平。与 2 5℃ 2 d的饲养条件相比 ,35℃ 2 d和 5℃ 30 d可使小菜蛾羧酸酯酶 (Car E)和谷胱甘肽 - S-转移酶 (GST)活力显著抑制 ,35℃ 2 d还可使小菜蛾乙酰胆碱酯酶 (ACh E)活力显著抑制 ,但 5℃4 d对小菜蛾 ACh E、Car E和 GST活力影响差异不显著。当反应温度均为 2 5℃时 ,在 35℃ 2 d、2 5℃ 2 d和 5℃ 30 d下饲养的小菜蛾 ACh E对甲胺磷和克百威的敏感性 (K i值 )没有明显变化 ,但酶与杀虫剂在 37℃的反应温度下 ,甲胺磷、敌敌畏和克百威对在 2 5℃下饲养的小菜蛾 ACh E的抑制作用显著增高。上述结果表明环境温度会影响小菜蛾的解毒代谢及杀虫剂对 ACh E的抑制作用。探讨了环境温度的季节性变化对田间小菜蛾有机磷抗性水平影响的毒理学机制。     

不同地理种群小菜蛾对甲胺磷的抗药性

采用浸叶法研究了福州建新镇、福建农林大学校园内、闽侯县上街镇和闽侯县甘蔗镇等地田间小菜蛾种群对甲胺磷的抗性水平及抗性机制。结果表明,与敏感小菜蛾相比,上述4个田间小菜蛾种群已对甲胺磷产生了34-82倍的抗性水平。敏感小菜蛾乙酰胆碱酯酶(AChE)的Ki值是田间抗性小菜蛾AChE的Ki值的17.3-39.1倍。不同小菜蛾种群对甲胺磷的抗性水平也存在着差异,小菜蛾种群AChE对甲胺磷的敏感性大小与其对甲胺磷的抗性水平高低显著相关。     

菜蛾绒茧蜂和小菜蛾对杀虫剂的敏感性及酶学特性的比较研究

分别采用药膜法和浸叶法测定了菜蛾绒茧蜂Apanteles plutellae和小菜蛾Plutella xylostella对杀虫剂的敏感度。结果显示： 有机磷、氨基甲酸酯、拟除虫菊酯类杀虫剂、阿维菌素和锐劲特对菜蛾绒茧蜂高毒,而抑太保和Bt为低毒,然而,短时间(1 h)接触常规防治剂量的锐劲特、氰戊菊酯、氯氰菊酯和乙酰甲胺磷对菜蛾绒茧蜂低毒。增效剂胡椒基丁醚（PB）、磷酸三苯酯（TPP）和马来酸二乙酯（DEM）对菜蛾绒茧蜂的甲胺磷、克百威、氰戊菊酯、氯氰菊酯、阿维菌素和锐劲特敏感性增效显著,但对抑太保无增效作用。PB的增效作用显著高于TPP 和DEM。PB和TPP对菜蛾绒茧蜂羧酸酯酶(CarE),以及DEM对谷胱甘肽S转移酶(GST)具显著的活体抑制作用,但PB,TPP和 DEM对菜蛾绒茧蜂乙酰胆碱酯酶（AChE）无抑制作用。菜蛾绒茧蜂AChE的米氏常数(K_m)、最大反应速度(V_max)、CarE和GST活性分别为小菜蛾的0.22、2.08、4.60和0.45倍,甲胺磷、敌敌畏和克百威对菜蛾绒茧蜂AChE的双分子速度常数(Ki)分别为对小菜蛾的14.7、10.5 和26.0倍。酶与抑制剂反应温度增高将导致酶抑制率增高,尤其对菜蛾绒茧蜂AChE的抑制作用更为显著。上述结果表明,菜蛾绒茧蜂对有机磷和氨基甲酸酯类杀虫剂的高敏感性与其显著高的AChE敏感性有关,氧化代谢的解毒作用对菜蛾绒茧蜂耐药性的影响大于水解作用。此外,对小菜蛾和菜蛾绒茧蜂杀虫剂敏感性差异的毒理学原因进行了讨论。     

高温对田间小菜蛾种群及抗性水平的抑制

田间调查结果表明,6月期间,田间小菜蛾种群密度处于相对较高水平,但在7月初至8月初期间急剧下降,8月下旬开始逐渐升高,9月～11月期间,小菜蛾种群密度显著高于春季的6月及夏季的8月下旬。总体上看,与25°C处理相比,40°C预处理田间小菜蛾8h后,氰戊菊酯、甲胺磷和阿维菌素对田间小菜蛾的24h和48h毒力均显著增高。与25℃处理相比,33．5°C预处理24h、36°C预处理8h和36℃预处理24h均显著抑制田间小菜蛾多功能氧化酶活性,且随着高温处理时间延长,抑制率明显增大。上述结果表明,夏季高温可导致田间小菜蛾种群密度急剧下降,并会显著抑制田间小菜蛾对杀虫剂的抗性水平及多功能氧化酶活性。     

高温对田间小菜蛾DNA损伤及4种抗药性相关酶系活性的抑制

研究了高温对福州上街菜田小菜蛾成虫4种抗药性相关酶系活性的影响。与饲养在25℃下的小菜蛾相比,33．5~C或40℃处理72h导致小菜蛾基因组DNA出现DNA凋亡特征梯度化条带。33~C饲养小菜蛾4、8、12或24h对小菜蛾成虫乙酰胆碱酯酶（AChE）和羧酸酯酶（CarE）活性无显著影响,但33℃饲养小菜蛾12或24h导致小菜蛾成虫谷胱甘肽s转移酶（GSTs）酶活性和细胞色素P450含量显著下降。36℃、24h可导致AChE活性显著下降,36℃、12h和24h可导致CarE活性显著下降,36℃、4h,8h,12h和24h可导致GST活性和细胞色素P450含量显著下降。总体上,高温对CarE、GSTs和细胞色素P450的抑制作用大于对AChE的影响,此外,3CC对AChE、CarE、GSTs酶活性和细胞色素P450含量的抑制作用大于33℃的抑制作用。     

常用杀虫剂对麦长管蚜和禾谷缢管蚜羧酸酯酶活性的抑制及对高效氯氰菊酯的增效作用

【目的】有机磷和氨基甲酸酯类药剂对拟除虫菊酯的增效作用与其对羧酸酯酶(Car E)(EC3.1.1.1)活性的抑制有关。本研究旨在评价13种常用有机磷和氨基甲酸酯类药剂及4种增效剂在防治麦蚜中对高效氯氰菊酯的增效作用。【方法】利用离体活性抑制的方法测定了13种杀虫剂及两种Car E抑制剂对麦长管蚜Sitobion avenae和禾谷缢管蚜Rhopalosiphum padi无翅成蚜Car E活性的抑制中浓度(I50),利用玻璃管药膜法测定了8种杀虫剂及两种抑制剂分别与高效氯氰菊酯以3∶1混配后对两种麦蚜的毒力效果,采用共毒系数(co-toxicity coefficient,CTC)法评价其联合作用。【结果】除硫双灭多威外,测定的其他12种药剂对麦长管蚜Car E活性的抑制作用显著高于对禾谷缢管蚜Car E活性的抑制作用,其中敌敌畏对麦长管蚜和禾谷缢管蚜Car E活性的抑制作用最强,I50分别为(5.40±0.74)×10-8mol/L和(1.41±0.41)×10-5mol/L。抗蚜威、灭多威、丁硫克百威、西维因、三唑磷、丙溴磷、马拉硫磷、敌敌畏及两种增效剂DEF和TPP分别与高效氯氰菊酯联合毒力测定表明,除丙溴磷外,上述药剂均可显著增强高效氯氰菊酯对禾谷缢管蚜的毒力,其中与马拉硫磷混配增效作用最强(CTC=467.59);除灭多威、丙溴磷和马拉硫磷外,其余7种药剂均可显著增强高效氯氰菊酯对麦长管蚜毒力,CTC在146.87~626.30之间,其中与三唑磷混配的增效作用最强(CTC=626.30)。【结论】筛选出对两种麦蚜毒力效果较好的杀虫剂或增效剂与高效氯氰菊酯的组合,包括抗蚜威、丁硫克百威、三唑磷、敌敌畏、DEF和TPP,对小麦蚜虫的有效防治具有重要指导意义。     

苏云金杆菌预处理小菜蛾对有机磷和氨基甲酸酯杀虫剂的增效作用

研究了小菜蛾Plutella xylostella幼虫经苏云金杆菌Bacillus thuringiensis预处理后,对有机磷和氨基甲酸酯杀虫剂敏感性的变化以及预处理对小菜蛾幼虫体内乙酰胆碱酯酶、羧酸酯酶、谷胱甘肽S-转移酶和谷胱甘肽的含量的影响。结果表明：苏云金杆菌预处理抗性小菜蛾幼虫后,其对甲胺磷、水胺硫磷和克百威的敏感性分别为未处理组的6.74、8.83和8.50倍;处理敏感小菜蛾幼虫后则分别为未处理组的2.96、1.69和3.88倍。苏云金杆菌预处理抗性小菜蛾,未处理组乙酰胆碱酯酶的K_m和V_max值分别为预处理组的1.86和1.56倍,所使用的6种杀虫剂对乙酰胆碱酯酶的K_I值,处理组为未处理组的1.80～2.66倍,苏云金杆菌预处理抗性小菜蛾对羧酸酯酶的K_m、K_I影响不大,但能显著地抑制羧酸酯酶和谷胱甘肽S-转移酶的活性并导致谷胱甘肽含量下降(对照分别为处理的2.02、1.76和1.66倍)。苏云金杆菌预处理敏感小菜蛾,对乙酰胆碱酯酶的K_m、V_max、K_I值和羧酸酯酶的K_m、K_I值以及谷胱甘肽含量影响不大,但能显著地抑制羧酸酯酶和谷胱甘肽S-转移酶的活性(对照分别为处理的1.54和1.64倍)。     

广东小菜蛾对苏芸金杆菌的抗性研究

广东省深圳,东莞、惠阳及博罗等供香港(以下简称供港)菜区小菜蛾对有机化学农药的抗性与广州内销菜区相近或稍高,对Bt杀虫剂的抗性则是供港菜区明显高于广州内销菜区。几种酶抑制剂TPP、SVl及Pb对Bt制剂无明显增效作用,可见小菜蛾对Bt制剂的抗性与酯酶和多功能氧化酶(MFO)的关系不大。用Bt制剂Dipel(大宝)连代选育小菜蛾敏感品系,选育18代,小菜蛾的抗性较选育前提高35倍。该抗性品系小菜蛾对个别菌株Bt及巴丹、杀虫双、速灭杀丁、万灵、敌敌畏等无交互抗性,而对昆虫生长调节抑制剂有轻微交互抗性。相反,用巴丹和杀虫双选育出的小菜蛾抗性品系对npel仍表现敏感。抗性品系小菜蛾在无触毒条件下饲养,抗性会自然减退,但不同类杀虫剂的抗性减退速率不尽相同。     

有机磷对抗拟除虫菊酯家蝇的毒力

测定敏感、抗溴氰菊酯(Del-R)、抗氯菊酯(2Cl-R)的家蝇品系对有机磷杀虫剂敌敌畏、辛硫磷及马拉硫磷的LD₅₀,α-乙酸萘酯（α-NA）酯酶动力学,酯酶的活性和酯酶的抑制作用。Del-R和2Cl-R的家蝇品系对三种有机磷杀虫剂的抗性倍数为0.966～7.190倍,均为低抗水平。三个家蝇品系的羧酸酯酶活性水平与抑制中浓度存在正相关性,说明羧酸酯酶在抗拟除虫菊酯家蝇对有机磷杀虫剂的抗性中起一定的作用。     

菜蚜茧蜂对六种杀虫剂抗药性的季节性变化

采用药膜法研究了福州建新和闽侯上街菜蚜茧蜂Diaeretiella rapae对杀虫剂抗药性的季节性变化。田间菜蚜茧蜂种群在网室内脱离选择压力后对杀虫剂敏感性显著升高。与敏感的F₂₁子代的LC₅₀相比,2002年6月8日至2004年11月18日期间,建新菜区菜蚜茧蜂对甲胺磷、氟虫腈、阿维菌素、氰戊菊酯和吡虫啉的抗性倍数分别为11.8～31.2,9.3～14.7,9.3～35.7,7.0～16.6,和13.3～30.1倍;2003年6月5日至2004年12月17日期间,上街菜区菜蚜茧蜂对甲胺磷、氟虫腈、阿维菌素、氰戊菊酯和吡虫啉的抗性倍数分别为7.5～34.9,4.0～14.3,9.2～38.6,7.8～18.9和12.1～24.2倍。田间菜蚜茧蜂种群在5月份和6月初抗性水平最高,12月份较低,6月末最低,尤其在6月份期间20天内抗性水平急剧下降。研究结果表明,田间菜蚜茧蜂对6种杀虫剂的抗性水平在脱离选择压力后不稳定,且呈显著的季节性变化。表2参25     

Seasonal changes of methamidophos susceptibility and biochemical properties in Plutella xylostella (Lepidoptera: Yponomeutidae) and its parasitoid Cotesia plutellae (Hymenoptera: Braconidae)

Methamidophos resistance and acetylcholinesterase (AChE) insensitivity to methamidophos, dichlorvos, and carbofuran were determined in the field populations of Plutella xylostella (L.) (Lepidoptera: Yponomeutidae) and its parasitoid Cotesia plutellae Kurdjumov (Hymenoptera: Braconidae) collected from the corresponding hosts between October 1998 and December 2003 in Fuzhou and Minhou, Fijian, China. Resistance levels to methamidophos and AChE insensitivity to the three insecticides in the two species of insects were high during autumn and spring and low during summer. Resistance to methamidophos was 15.3- and 12.6-fold higher in resistant F0 parents of P. xylostella and C. plutellae than in their susceptible F11 progeny, respectively. The bimolecular rate constant (k(i)) values of AChE to methamidophos, dichlorvos, and carbofuran were 4.6-, 6.3-, and 7.7-fold higher in F11 progeny of P. xylostella, and 3.7-, 4.5-, and 3.7-fold higher in F11 progeny of C. plutellae than those in their F0 parents, respectively. Compared with susceptible F11 progeny, the resistance ratios for methamidophos were 4.2-29.8 and 3.8-13.1 in 21 field populations of P. xylostella and C. plutellae, respectively. The k(i) values of AChE to methamidophos, dichlorvos, and carbofuran were 2.0-21.6-, 3.6-9.5-, and 2.6-9.2-fold higher in F11 progeny of P. xylostella, and 1.8-7.6-, 1.9-4.6-, and 2.2-7.6-fold higher in F11 progeny of C. plutellae than those in 21 field populations, respectively. Significant correlative variations of methamidophos resistance as well as significant correlative variations of k(i) values of AChE to insecticides between the two species of insects also were found in space and time. The k(i) values of AChE to insecticides in C. plutellae were far higher than those in P. xylostella. There were no obvious differences in the Km and Vmax of AChE between F0 parents and F11 progeny of P. xylostella and C. plutellae, respectively. But carboxylesterase activity was 1.6-fold higher in F0 parents of C. plutellae than in F11 progeny, and glutathione S-transferase activity was 1.5-fold higher in F0 parents of P. xylostella than in F11 progeny. The results suggested that the AChE insensitivity to insecticides might play the most important role in methamidophos resistance in the two species of insects. From these results, a spatial and temporal correlative evolution of methamidophos resistance and insensitive AChE was found to exist between P. xylostella and C. plutellae.     

Monitoring insecticide resistance in Australian Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) detects fipronil and spinosad resistance

Abstract  Insecticide resistance monitoring using a Potter precision spray tower with discriminating concentration and log dose probability techniques underpins the Australian insecticide management strategy for Frankliniella occidentalis Pergande. Abamectin, acephate, chlorpyrifos, dichlorvos, dimethoate, endosulfan, fipronil, malathion, methamidophos methidathion, methiocarb, methomyl, pyrazophos and spinosad are recommended for use against F. occidentalis but abamectin, methiocarb and pyrazophos are the only chemicals where insecticide resistance has not been detected. Although not registered, chlorfenapyr was effective against F. occidentalis and should be pursued for that purpose. In contrast, chlorpyrifos, dichlorvos and malathion resistance were detected at low to moderate levels throughout the study period putting their sustainable use for F. occidentalis control in doubt . Although it appears that acephate, dimethoate, endosulfan, fipronil, methamidophos, methidathion and spinosad remain effective, some populations contained a small percentage of thrips that survived exposure to a concentration that killed 100% of the susceptible strain. Subsequent laboratory selection of one such population separately with fipronil and spinosad caused an increase in resistance to these insecticides. These products must now be considered at risk. This is the first report of fipronil or spinosad resistance in populations of F. occidentalis.     

Assessment of insecticide resistance in five insect pests attacking field and vegetable crops in Nicaragua

Field populations of Hypothenemus hampei (Ferrari), Plutella xylostella (L.), Spodoptera exigua (Hübner), Helicoverpa zea (Boddie) and Bemisia tabaci (Gennadius) were tested for resistance to several insecticides commonly used in Nicariagua. Assays were conducted to estimate the LD50s or LC50s and the corresponding resistance ratios. A diagnostic concentration was used to discriminate between susceptible and resistant strains of H. hampei. The tests with >6,000 H. hampei adults collected from six different sites indicate the absence of resistance to endosulfan. Resistance to cypermethrin, deltamethrin, chlorfluazuron, thiocyclam, and methamidophos was documented in six field populations of P. xylostella. High levels of resistance to cypermethrin and deltamethrin, but moderate levels of resistance to chlorpyriphos and methomyl, were also documented in two field populations of S. exigua. Moderate levels of resistance to cypermethrin, deltamethrin and chlorpyriphos were also documented in three field populations of H. zea. Moderate to high levels of resistance to bifenthrin, methamidophos and endosulfan were documented in four field populations of B. tabaci. The presence of significant correlations between LD50s or LC50s suggests the occurrence of cross-resistance or simultaneous selection for resistance by different insecticides with different modes of action. Our data could not differentiate between these two possibilities. Because insecticides will continue being used in Nicaragua, a resistance management program is urgently needed. The implementation of integrated pest management tactics must be accompanied by specific regulations for pesticide registration. In the future, pesticide registration regulations in Nicaragua should include periodic resistance monitoring. The mechanisms to cover the costs of resistance monitoring and resistance management should also be established.     

Positive correlation of methamidophos resistance between Lipaphis erysimi and Diaeretilla rapae and effects of methamidophos ingested by host insect on the parasitoid

Temporal and spatial correlated variations on the methamidophos resistance and biomolecular rate constant of acetylcholinesterase to insecticides were found between the turnip aphid, Lipaphis erysimi and its endoparasitoid, Diaeretilla rapae , collected from field colonies and an insecticide-free field insectarium in Fujian, China. Compared to the related susceptible insectarium population, L. erysimi and D. rapae displayed 7.4–29.2- and 2.6–9.2-fold resistance ratios, respectively. In addition, two populations of L. erysimi with different methamidophos resistance levels, that is, a field (with 5.8-fold resistance ratio) and an insectarium population, were used to study the effects of methamidophos ingested by the host insect on D. rapae development. The percentage of D. rapae cocoon formation decreased significantly when the parasitized L. erysimi were fed on cauliflower leaves treated with methamidophos at lethal concentration dosages 10 (LC₁₀) or LC₅₀. At LC₅₀ dosages the percentage of D. rapae cocoon formation and adult emergence decreased significantly. When the parasitized L. erysimi were fed on methamidophos at LC₉₀ dosage, no D. rapae cocoons were found. When the field or insectarium L. erysimi were treated with methamidophos at LC₁₀, the susceptibility to methamidophos in the adult D. rapae emerged from the treated host insect was similar to the control. However, the susceptibility to methamidophos in the adult D. rapae became lower than the control when the host insects were treated at LC₅₀ dosages. The data thus suggested that the methamidophos ingested by the host insect L. erysimi could be an important factor in the endoparasitoids' insecticide resistance development. The natural selectivity would favor the parasitoids that had developed an insensitivity to the insecticide(s).     

B型烟粉虱田间种群对毒死蜱和敌敌畏抗性的生化机制

通过增效剂生物测定和生化分析,探讨了采自福建省的B型烟粉虱Bemisia tabaci 6个田间种群对毒死蜱和敌敌畏抗性的生化机制。结果表明：与敏感品系SUD-S相比,6个田间种群对毒死蜱和敌敌畏分别具有54.53～78.43倍和6.23～11.25倍的抗性。TPP、PBO和DEM对毒死蜱的增效比分别为3.61～24.94倍、1.14～1.76倍和1.04倍,对敌敌畏的增效比分别为1.67～2.64倍、1.33～1.65倍和1.09倍,表明羧酸酯酶的解毒代谢在烟粉虱对毒死蜱的抗性中起着重要作用。烟粉虱抗性种群乙酰胆碱酯酶的K_m值是敏感品系的1.83～4.0倍,V _max值是敏感品系的0.34～0.62倍; 敏感品系乙酰胆碱酯酶的活性在底物浓度大于1.0 mmol/L时受抑制,抗性种群乙酰胆碱酯酶的活性在底物浓度大于16 mmol/L时受抑制;抗性种群乙酰胆碱酯酶对敌敌畏和毒死蜱的敏感度分别比敏感品系低119.92～161.33倍和10.11～14.24倍,表明烟粉虱田间抗性种群乙酰胆碱酯酶可能已发生了变构,由变构引起的乙酰胆碱酯酶不敏感是烟粉虱田间种群对毒死蜱和敌敌畏产生抗性的重要原因。结果提示,乙酰胆碱酯酶不敏感性和羧酸酯酶的解毒代谢在烟粉虱对毒死蜱的抗性中均起着重要作用,而乙酰胆碱酯酶不敏感性在对敌敌畏的抗性中起重要的作用,多功能氧化酶和谷胱甘肽S转移酶在烟粉虱对毒死蜱和敌敌畏抗性中所起的作用不大。     

Detection of insecticide resistance in Plutella xylostella (L.) (Lepidoptera: Plutellidae) populations in South Australian crucifer crops

In response to reports of failures of sprays to control Plutella xylostella infestations in vegetable-growing areas around Adelaide in 1991, the extent of resistance to six insecticides in several South Australian populations of P. xylostella was determined. Populations sampled from vegetable crops in the Adelaide region were five- to 200-fold resistant to organophosphates (chlorpyrifos, methamidophos and mevinphos), eight- to 400-fold resistant to pyrethroids (esfenvalerate and permethrin) and six-fold resistant to the carbamate methomyl compared with a susceptible strain. Mevinphos and esfenvalerate were the most effective of the tested insecticides. These, together with Bacillus thuringiensis products, have continued until 1998 to be used almost exclusively for the control of P. xylostella in South Australian vegetable crops in the absence of any resistance management strategy.     

Effect of synthetic pyrethroids and other compounds on the susceptibility and development of the egg stage of the predacious miteAmblyseius gossipi [Mesostigmata: Phytoseiidae]

Eggs from a laboratory culture ofAmblyseius gossipi El-Badry laid on cotton strands were placed on leaf discs and sprayed with various pesticides or water for 40 s. The eggs were allowed to dry and then transferred to new discs. Compounds tested were cypermethrin, flucythrinate, fenvalerate, cyfluthrin, pyridaphenthion, methamidophos, dichlorvos and dicofol. Only methamidophos was inactive on the egg stage. When sprayed at a level of 400 ppm, eggs were highly susceptible to flucythrinate, cyfluthrin, pyridaphenthion, and fenvalerate and were slightly susceptible to dichlorvos and dicofol. Viability of eggs decreased as the concentration of the effective compounds increased. Older eggs were more sensitive than younger ones. None of the larvae from eggs treated with flucythrinate and pyridaphenthion were able to develop beyond the larval stage.

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Résumé Les œufs d'un élevage de laboratoire d'Amblyseius gossipi El-Badry pondus sur des fibres de coton furent placés sur des disques de feuille et traités avec des produits phytosanitaires variés ou de l'eau durant 40 s. Les œufs une fois ressuyés furent transférés sur de nouveaux disques. Les composés testés furent la cypermethrine, le flucythrinate, le fenvalerate, le cyfluthrine, le pyridaphenthion, le metamidophos, le dichlorvos et le dicofol. Seul le methamidophos était inactif sur le stade œuf. Traités à la dose de 400 ppm, les œufs furent très sensibles au flucythrinate, au cyfluthrine, au pyridaphenthion et au fenvalerate et légèrement sensible au dichlorvos et au dicofol. La variabilité des œufs décroissait comme augmentait la concentration des composés efficaces. Des œufs agés furent plus sensibles que des œufs plus jeunes. Aucune des larves issues d'œufs traités au flucythrinate et au pyridaphenthion n'étaient capables de se développer au-delà du stade larvaire.

     

抑制剂存在下不同种群烟粉虱乙酰胆碱酯酶残余活性频率分布及其与抗药性的关系

为了探讨烟粉虱Bemisia tabaci不同种群个体乙酰胆碱酯酶敏感性差异及其与抗药性的关系, 我们选用室内饲养的烟粉虱SUD S敏感品系和6个田间抗性种群, 采用酶标板酶动力学法测定了各品系 (种群）乙酰胆碱酯酶对抑制剂的敏感性反应以及抑制剂存在时各抗性种群个体乙酰胆碱酯酶残余活性频率分布。结果表明: 在抑制剂浓度为300 μmol/L时, 敏感品系乙酰胆碱酯酶的活性基本上被完全抑制, 可以明显地区分敏感品系与田间抗性种群。在抑制剂浓度为2 000 μmol/L时, 各抗性种群个体乙酰胆碱酯酶残余活性频率分布差异明显, 其中ZZ-R种群和FZ-R种群的乙酰胆碱酯酶残余活性频率分布相似, 大部分个体的乙酰胆碱酯酶残余活性分布在1.00~1.80 mOD/min之间; SM-R种群和ND-R种群的乙酰胆碱酯酶残余活性频率分布也相似, 大部分个体的乙酰胆碱酯酶残余活性分布在0.40~1.00 mOD/min之间; LY-R和NP-R种群大部分个体的乙酰胆碱酯酶残余活性分别分布在1.00~1.60 mOD/min和0.80~1.20 mOD/min之间。各抗性种群乙酰胆碱酯酶高残余活性 (大于1.00 mOD/min）个体频率与对敌敌畏的抗性水平之间具有明显相关性, 相关系数为0.86 (P<0.05）。考虑到乙酰胆碱酯酶对抑制剂作用不敏感是一些昆虫对有机磷和氨基甲酸酯类杀虫剂抗性的重要机制之一, 建议可以将乙酰胆碱酯酶对敌敌畏的敏感性作为烟粉虱抗药性生化检测的一个参考指标。