七星瓢虫的抗药性选育及其生物学特性研究

为了明确七星瓢虫对吡虫啉的抗性发展动态,在室内选用吡虫啉逐代筛选,选育抗吡虫啉的七星瓢虫品系。发现七星瓢虫对吡虫啉的抗性整体呈上升趋势,但抗性不稳定,选育20代后抗性为63.1519倍。同时为了明确七星瓢虫对吡虫啉产生抗性后对其生物学特性的影响,将抗性选育13代的七星瓢虫品系与敏感七星瓢虫品系、野外七星瓢虫种群进行生物学特性的比较,结果表明,从幼虫的整个发育历期来观察,抗性品系幼虫的发育历期为12.36 d,野外种群为9.88 d,敏感品系为10.62 d,3者之间差异显著;蛹发育历期3者之间没有差异;4龄老熟幼虫、蛹、初羽化雌成虫、初羽化雄成虫平均体重3组间有一定的差异;七星瓢虫抗性品系、敏感品系、野外种群前期的卵孵化率分别为63.0%、62.4%和66.3%,中期的卵孵化率分别为64.8%、58.7%和75.6%,后期的卵孵化率分别为69.3%、57.4%和75.5%,3组之间无显著差异;抗性品系雌成虫的平均产卵量为1043.3粒,敏感品系为1100.2粒,野外种群雌成虫为1250.1粒,3者之间没有显著差异。综上所述,抗药性对七星瓢虫的生物适合度有一定程度的影响,但是,由于抗性倍数较低,影响尚不明显。     

朱砂叶螨阿维菌素抗性品系选育及适合度研究

为研究朱砂叶螨抗性适合度,在抗性选育基础上实验室组建了朱砂叶螨相对敏感品系、抗阿维菌素品系在豇豆和棉花上的生命表(26℃),比较了相对敏感品系和抗性品系在两种寄主上发育历期、繁殖力及种群参数的差异.结果表明:连续汰选42代,朱砂叶螨对阿维菌素(乳油制剂)产生约8.7倍抗性;与相对敏感品系相比,抗性品系在棉花上若螨期缩短0.55天、世代历期延长0.88天,平均产卵量无显著差异;在豇豆上卵期缩短1.71天,若螨期延长0.41天,世代历期缩短2.06天,平均产卵量减少84.29粒/雌.抗性品系在棉花和豇豆上的相对适合度分别为0.89和0.58,表明该螨产生抗药性后,存在适合度缺陷.     

小菜蛾不同抗性品系及其杂交F_1代的生物适合度

构建了小菜蛾抗阿维菌素(A)、抗高效氯氰菊酯(B)和抗杀虫双(D)3个抗性品系及其6个杂交F1代(抗性品系分别两两杂交)以及1个敏感品系(S)的种群生命表,并计算了相对生物适合度。结果表明:A、B和D 3个抗性品系的相对生物适合度均比敏感品系S(生物适合度为1.0)低,分别为0.60、0.77和0.53;6个杂交F1代A♀+B♂、A♂+B♀、A♀+D♂、A♂+D♀、B♂+D♀和B♀+D♂的生物适合度分别为0.67、0.53、0.67、0.74、0.73和0.80,也比敏感品系的低,但和抗性品系的适合度相近或高于抗性品系。     

高效氯氟氰菊酯不同抗性基因型甜菜夜蛾相对适合度研究

在室内相同条件下 ,构建了甜菜夜蛾高效氯氟氰菊酯抗性种群 (R)、敏感种群(S)、正交 F1代 (RS)、反交 F1代 (SR)和对照种群 (CK)的生命表 ,研究了各种群的产卵量、卵孵化率、幼虫和成虫发育历期和蛹重等主要生物学特性。抗高效氯氟氰菊酯基因型甜菜夜蛾在生活力和繁殖力上与其它基因型比较均存在一定程度的不利性 ,杂合子的大部分生物学特性与敏感基因型比较差异不显著。在经过一个完整世代后 ,R、S、RS、SR和 CK种群的净增殖率(R0 )分别为 117.8、624.7、589.1、642 .3、218.8。以敏感种群为参比 ,S、RS、SR、R和 CK种群的相对适合度分别为 1、0 .934、1.028、0.188和 0 .368。与敏感品系 S相比 ,SR和 RS品系的相对适合度无变化 ,抗高效氯氟氰菊酯种群适合度明显降低。     

小菜蛾抗多杀菌素和敏感品系耐低温能力的比较

通过杂交筛选得到小菜蛾对多杀菌素敏感和高抗的纯合子品系，对二个品系在适温和经低温处理后的生长发育特性进行了比较，以探明其抗性是否伴有适合度的变化以及适合度变化与温度的关系。结果发现:高抗品系的卵经6℃低温处理14 d，孵化出的幼虫仅有7.7％正常化蛹，显著低于敏感品系61.4％的正常化蛹率；经6℃低温处理28 d，高抗和敏感品系的卵孵化率分别为27％和75％，二者差异显著；高抗品系的蛹经 5℃低温处理7～14 d后，蛹的 发育历期显著延长，其子代卵的存活力也显著下降。在适温25℃下，抗性和敏感品系之间多项生物学特性均无显著差异或差异很小。这些结果表明，小菜蛾对多杀菌素的抗性伴随有耐低温能力的适合度代价。     

抗Bt杀虫蛋白棉铃虫种群的相对适合度

在室内条件下,比较了对苏云金杆菌（Bacillus thuringinesis,Bt)杀虫蛋白（ICP）有20倍抗性的棉铃虫（Helicoverpa armigera Huebner)种群（R种群）与同源对照种群（S种群）之间的相对适合度,结果表明,与S种群相比,R种群的产卵量,卵孵化率和化蛹率明显降低,幼虫历期和蛹历期明显延长,R种群相对于S种群的适合度为0．65。杂交F1代RS种群相对于S种群的适合度为1．6,显示出杂交优势,正反交F1代种群对Bt ICP敏感性的差异不显,表明棉铃虫对Bt ICP的抗性遗传不存在性连锁,为常染色体遗传。     

温度对不同品系丽蚜小蜂发育、存活和寿命的影响

比较了两个品系 (分别来自北京和美国 )丽蚜小蜂在不同温度下寄生番茄烟粉虱的发育历期 ,取食不同食物的寿命 ,发育起点温度和有效积温。结果表明 ,在 1 8～ 3 3℃ ,丽蚜小蜂的发育历期随温度升高而加快。两品系在 1 8℃下发育历期最长 ,美国品系为 3 4.7d ,北京品系为 3 6.1d ;在 3 3℃下发育历期最短 ,分别为 7.8和 8.4d ;且在 1 8和 2 3℃下 ,美国品系的发育历期显著短于北京品系。与饥饿处理相比 ,喂食 1 0 %蜜水和 /或 3～ 4龄粉虱若虫 ,可延长成虫寿命 ;且不同温度条件下成虫寿命差异显著 ,两品系均表现出 1 8℃下寿命最长 ,3 3℃时寿命最短。丽蚜小蜂由产卵至成虫羽化、成虫期和全世代的发育起点温度和有效积温 :美国品系分别为 1 3 .1、1 2 .3、1 2 .8℃和 1 77.2 3、1 79 1 1、3 53 .53日度 ;北京品系分别为 1 3 .2、1 1 .4、1 2 .4℃和 1 88.2 5、1 68.58、3 58.2 8日度。     

利用桃蚜和人工卵赤眼蜂蛹连代饲养东亚小花蝽的比较研究

比较了用桃蚜和人工卵赤眼蜂蛹连续饲养东亚小花蝽的效果。用赤眼蜂蛹连续饲养的6代东亚小花蝽 ,其若虫发育和成虫产卵能力均与用自然寄主桃蚜饲养的相同世代的小花蝽没有显著差异 ,各代间若虫发育和成虫产卵能力也基本相同。表明用赤眼蜂蛹做饲料可以满足东亚小花蝽生长发育和繁殖的需要。用赤眼蜂蛹做饲料 ,雌、雄成虫平均发育历期分别为1 1 5d和 1 0 9d ,单雌产卵量为 56 5粒 ,雌成虫产卵期和寿命分别为 9 8d和 1 2 7d。用桃蚜做饲料 ,雌、雄成虫平均发育历期分别为 1 1 2d和 1 1 0d ,单雌产卵量为 50 0粒 ,雌成虫产卵期和寿命分别为 9 2d和 1 2 9d。用赤眼蜂蛹饲养小花蝽的饲料成本不超过 0 2 4元 /头     

转Bt基因玉米(瑞丰125、DBN9936、DBN9978)对亚洲玉米螟的抗虫效果研究

评价转Bt基因玉米对靶标生物亚洲玉米螟的杀虫作用是转基因玉米研发的重要一环。本文采用室内生测法对3种转Bt基因抗虫玉米‘瑞丰125’(表达Cry1Ab/Cry2Aj杀虫蛋白),‘DBN9936’‘DBN9978’(表达Cry1Ab杀虫蛋白)对亚洲玉米螟敏感品系ACB-S及抗Cry1Ab品系ACB-AbR、抗Cry1Ac品系ACB-AcR、抗Cry1F品系ACB-FR、抗Cry1Ah品系ACB-AhR、抗Cry1Ie品系ACB-IeR的杀虫活性进行测定,同时采用心叶期和抽丝期人工接虫法进行田间抗虫效果鉴定。结果表明,取食3种Bt玉米的ACB-S幼虫, 3 d死亡率100%,而取食对照常规玉米3 d存活率100%。取食3种Bt玉米的5个抗性品系幼虫除ACB-AbR和ACB-AcR有2%~6%的个体存活4~5 d, 6 d死亡率也达到了100%,其余品系均在3 d全部死亡,而取食对照玉米5~6 d的死亡率仅为4%~14%,差异显著。田间心叶期食叶级别及穗期活虫数、雌穗被害和茎秆被蛀等为害等级说明3种Bt玉米高抗亚洲玉米螟。明确了‘瑞丰125’‘DBN9936’和‘DBN9978’对亚洲玉米螟有很高的杀虫活性和田间防治效果。5个Bt蛋白抗性亚洲玉米螟品系幼虫在常规玉米上显示一定的适合度劣势。     

蠋蝽猎物—黏虫的室内种群复壮

猎物的质量直接决定了天敌的质量和饲养规模。蠋蝽是一种重要的捕食性天敌,其若虫和成虫对鳞翅目害虫幼虫均有较强的捕食能力。目前蠋蝽主要依靠黏虫来饲养。但在长期室内饲养过程中黏虫种群出现衰退现象,进而制约了蠋蝽规模化繁育。本文旨在研究黏虫种群复壮措施,为蠋蝽的规模化繁育提供技术支撑。为此,采用回接自然寄主和室内与室外种群杂交的方式评价了黏虫的种群复壮效果。结果表明,回接自然寄主玉米叶后黏虫的幼虫发育历期(18.03 d)较人工饲料饲养组(21.26 d)显著缩短,蛹重(369.00 mg)和成虫产卵量(770.88粒/雌)显著高于人工饲料饲养组(323.56 mg, 532.73粒/雌),但二者的蛹历期和成虫寿命无显著差异。杂交试验结果表明,4种交配方式产生的F₁代产卵前期、雌雄成虫寿命及其子代幼虫和蛹的发育历期无显著差异,但产卵期、产卵量及蛹重存在差异。其中以田间雌性×田间雄性(YF×YM)组合的产卵期最长(8.07 d)和产卵量最高(938.77粒/雌),而以田间雌性×室内雄性(YF×EM)组合的蛹最重(354.59 mg)。这些结果显示,通过回接自然寄主和室内与室...     

棉铃虫对Cry1Ac抗性的稳定性及其对适合度的影响

为明确棉铃虫Helicoverpa armigera（Hübner）对苏云金芽胞杆菌Bacillus thuringiensis（Bt）Cry1Ac毒蛋白抗性的稳定性及其适合度变化,利用生物测定的方法研究了Cry1Ac抗性品系棉铃虫转到正常饲料饲养后的抗性衰退及再次筛选后抗性的恢复情况,并比较了敏感、抗性和抗性衰退后各品系间的适合度差异。在失去选择压的情况下,高抗品系棉铃虫对Cry1Ac的抗性迅速衰退,经过4代后抗性水平由最初的3626.67倍下降到1436.67倍;到第12代时抗性水平已低于10倍,随后品系保持较稳定的低抗水平;当重新进行抗性再筛选时,其抗性水平可快速恢复,抗性倍数快速回升,5代后恢复到1123.33倍。与敏感品系相比,高抗棉铃虫品系的适合度明显降低,相对适合度仅为0.33,但转到正常饲料连续饲养14代后,棉铃虫适合度明显上升,相对适合度为0.87,主要表现为卵孵化率和幼虫存活率等显著提高。     

敏感和抗阿维菌素小菜蛾的生物适合度

阿维菌素汰选的小菜蛾抗性种群(ABM-R)与相对敏感种群(ABM-S)相比不表现繁殖不利性。ABM-R种群的交配率、有效产卵指数和孵化率均显著大于ABM-S种群 ,ABM-R种群的内禀增长率为0.139,是ABM-S种群的1.19倍 ,相对适合度为ABM-S种群的1.49倍。建立了ABM-S和ABM-R种群的生命表 ,并对抗性治理进行了讨论。     

二斑叶螨对阿维菌素抗性和敏感品系相对适合度的研究

在室内25℃条件下通过构建实验种群生命表,比较二斑叶螨对阿维菌素抗性品系(R)和敏感品系(S)的一系列生长发育和繁殖特征参数。结果表明:二斑叶螨抗性品系(R)的发育历期、孵化率、幼螨存活率、有效产卵量等诸多指标与敏感品系(S)相比均存在一定的不利性。抗性品系的相对适合度仅为敏感品系的0.53倍,存在适合度缺陷。     

Reduced fitness associated with spinosad resistance in <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

The fitness cost of spinosad resistance was investigated in the cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). Laboratory experiments were conducted to compare relative fitness of H. armigera between the spinosad-susceptible and -resistant strains. During the experiments, the average development periods of the resistant strain were lengthened by 4–5 days, reflected in a prolongation of egg, larval and pupal periods. Furthermore, pupal survival, pupal weight, the mean life span of emerged adults, eggs laid and hatched decreased greatly in the resistant strain in comparison with the susceptible strain. Other life-cycle parameters such as larval survival, larval wet weights, prepupal periods, pupation ratio, and sex ratio did not change significantly. As a result, both net replacement rate (R ₀) and intrinsic rate of increase (r _m) were reduced for the resistant strain. Our results clearly indicated that relative fitness of resistant individuals was reduced in the absence of spinosad. Rational measures including pesticide rotations should be expected to delay development of resistance to spinosad in H. armigera field populations from China.     

Mechanisms of resistance to diflubenzuron in the house fly, Musca domestica (L.)

The mechanisms of resistance to the chitin synthesis inhibitor diflubenzuron were investigated in a diflubenzuron-selected strain of the house fly (Musca domestica L.) with > 1000 × resistance, and in an OMS-12-selected strain [O-ethyl O-(2,4-dichlorophenyl)phosphoramidothioate] with 380 × resistance to diflubenzuron. In agreement with the accepted mode of action of diflubenzuron, chitin synthesis was reduced less in larvae of the resistant (R) than of a susceptible (S) strain. Cuticular penetration of diflubenzuron into larvae of the R strains was about half that of the S. Both piperonyl butoxide and sesamex synergized diflubenzuron markedly in the R strains, indicating that mixed-function oxidase enzymes play a major role in resistance. Limited synergism by DEF (S,S,S-tributyl phosphorotrithioate) and diethylmaleate indicated that esterases and glutathione-dependent transferases play a relatively small role in resistance. Larvae of the S and R strains exhibited a similar pattern of in vivo cleavage of ³H- and ¹⁴C-labeled diflubenzuron at N₁C₂ and N₁C₁ bonds. However, there were marked differences in the amounts of major metabolites produced: R larvae metabolized diflubenzuron at considerably higher rates, resulting in 18-fold lower accumulation of unmetabolized diflubenzuron by comparison with S larvae. Polar metabolites were excreted at a 2-fold higher rate by R larvae. The high levels of resistance to diflubenzuron in R-Diflubenzuron and R-OMS-12 larvae are due to the combined effect of reduced cuticular penetration, increased metabolism, and rapid excretion of the chemical.     

The joint action of insect growth regulators and insecticides on strains of Spodoptera littoralis Boisd. That are susceptible or resistant to aminocarb

An investigation was made of the action of the juvenile hormone analogues (JHAs) methoprene (ZR-515) and 3-[5-(4-ethylphenoxy)-3-methylpent-3-enyl]-2, 2-dimethyloxirane (R-20458), and the insecticides chlorpyrifos and methomyl, when applied, separately or in combination, to the late insect stages of susceptible (S) and aminocarb-resistant (R_m) strains of Spodoptera littoralis Boisd. Sixth-instar larvae of the R_m strain showed detectable levels of cross-resistance to chlorpyrifos, methomyl and R-20458. However, cross-resistance to methoprene was less pronounced in the R_m strain. Treatment of the same instar with the ED₅₀ of methoprene produced an appreciable level of sterility in the S strain, but this level decreased in the R_m strain. Similar treatment with R-20458 caused a lower level of sterility in the S strain and the R_m strain was less affected. In the S strain, the ED₂₅ of either chlorpyrifos or methomyl when applied simultaneously with the ED₂₅ of R-20458, produced an antagonistic effect and the R_m strain was more capable of resisting the joint action of these compounds. The treatment, ED₂₅ chlorpyrifos + ED₂₅ methoprene produced an additive effect on the S strain, while the R_m strain tolerated their combined action. Nevertheless, the treatment, ED₂₅ methomyl + ED₂₅ methoprene produced additive effects on both the S and R_m strains. The prepupae of the R_m strain tolerated the action of the insecticides methomyl and chlorpyrifos. A similar pattern of cross-resistance was also detected against the action of the two hormones at the ED₂₅ level, while at the ED₂₅ level, both the S and R_m strains were almost equally sensitive to the action of the two juvenoids. Chlorpyrifos-JHA combinations produced additive effects on prepupae of the S strain while the R_m strain completely resisted their joint action. Methomyl-JHA combinations produced high potentiation in the S strain, but the R_m strain remained insensitive to their joint action. Detectable levels of tolerance to the action of chlorpyrifos and methomyl at the ED₂₅ and ED₅₀ levels were indicated in 2-day-old pupae of the R_m strain. This was less evident in the case of JHAs, particularly methoprene, which was to some extent equally effective on both strains; the reproductive ability of the S and R_m strains was highly affected by this compound. The pupae of the R_m strains were equally as affected as those of the S strain by the combination ED₂₅ chlorpyrifos+ ED₂₅ R-20458. Nevertheless, the two strains showed antagonism to the action of chlorpyrifos with methoprene. A high level of potentiation was produced in the S strain to the combination of methomyl and R-20458 but the R_m strain was able to withstand their combined action. Of interest in this respect was the action of the combination of methomyl and methoprene, for which high levels of potentiation were detected in pupae of the S and R_m strains. This combination also Produced a high percentage of sterility in mated females of the R_m strain.     

Absence of enhanced detoxication of permethrin in pyrethroid-resistant house flies

The mechanisms of resistance to pyrethroids were studied in a permethrin-selected (147-R) strain of the house fly, Musca domestica L. Approximately 12-fold synergism was obtained with a mixture of (1R)-trans-permethrin:piperonyl butoxide (1:5) so that the resistance decreased from 97-fold to 22-fold. Tests with the esterase inhibitor S,S,S-tributyl phosphorotrithioate produced very little synergism in either the resistant (R) strain (1.6-fold) or the susceptible (S) strain (1.9-fold). An investigation of the microsomal components revealed that compared to the S strain, the R strain demonstrated twice as much cytochrome P-450 and cytochrome b₅ and double the rate of NADPH-cytochrome c reductase activity. In addition, the rate of p-nitroanisole O-demethylation was found to be six times greater in the R strain. An in vivo accumulation study showed that the R strain displayed a decreased rate of penetration of trans-[¹⁴C]permethrin. When treated at equitoxic doses the R strain was found to tolerate 50-fold more internal permethrin than the S strain. An in vitro metabolism study indicated that there was no difference between strains in the overall rate of metabolism of trans-[¹⁴C]permethrin. The evidence obtained supports the conclusion that several resistance factors are involved but that decreased sensitivity of the nervous system to the action of pyrethroids is the principal mechanism of resistance in the 147-R strain.     

Effect of emamectin benzoate on life history traits and relative fitness of Spodoptera litura (Lepidoptera: Noctuidae)

Emamectin benzoate, a semisynthetic bioinsecticide, has been used frequently for the management of lepidopteran pests of cotton worldwide. To assess the resistance risk and design strategy for resistance management, life history traits were established for emamectin benzoate-resistant, unselected and susceptible S. litura strains based on the laboratory observations. Bioassay results showed that the emamectin benzoate-selected strain developed a resistance ratio of 911-fold compared with that of the susceptible strain. The emamectin-selected strain had a relative fitness of 0.37 and lower prepupal and pupal weights, prolonged larval duration and development time, lower fecundity and hatchability compared with the susceptible strain. Mean population growth rates, such as intrinsic rate of population increase and biotic potential, were lower for the emamectin-selected strain compared with the susceptible strain. Development of resistance can cost considerable fitness for the emamectin-selected strain. The present study provided useful information for determining potential management strategies to overcome development of resistance.