Cross-resistance and inheritance of resistance to Bacillus thuringiensis toxin Cry1Ac in diamondback moth (Plutella xylostella L) from lowland Malaysia

A field population of Plutella xylostella from Malaysia (SERD4) was divided into five sub-populations and four were selected (G2-G5) with the Bacillus thuringiensis insecticidal crystal (Cry) toxins Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da. Bioassay at G6 gave resistance ratios of 88, 5, 2 and 3 for Cry1Ac, Cry1Ab, Cry1Ca and Cry1Da respectively compared with the unselected sub-population (UNSEL-SERD4). The Cry1Ac-selected population showed little cross-resistance to Cry1Ab, Cry1Ca and Cry1Da, (3-, 2- and 3-fold compared with UNSEL-SERD4), whereas the Cry1Ab-SEL sub-population showed marked cross-resistance to Cry1Ac (40-fold), much greater than Cry1Ab itself. In contrast, the Cry1Ca- and Cry1Da-SEL sub-population showed little if any cross-resistance to Cry1Ac and Cry1Ab. The mode of inheritance of resistance to Cry1Ac was examined in Cry1Ac-selected SERD4 by standard reciprocal crosses and back-crosses using a laboratory insecticide-susceptible population (ROTH). Logit regression analysis of F1 reciprocal crosses indicated that resistance to Cry1Ac was inherited as an incompletely dominant trait. At the highest dose of Cry1Ac tested, resistance was recessive, while at the lowest dose it was almost completely dominant. The F2 progeny from a back-cross of F1 progeny with ROTH were tested with a concentration of Cry1Ac that would kill 100% of ROTH. The mortality ranged between 50 and 95% in seven families of back-cross progeny, which indicated that more than one allele on separate loci were responsible for resistance to Cry1Ac.     

Long-term selection for resistance to transgenic cotton expressing Bacillus thuringiensis toxin in Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)

Selection experiments for resistance to transgenic Bt cotton expressing Cry1Ac toxin in Helicoverpa armigera (Hübner) were conducted using a leaf-feeding method with 42 selection episodes over 45 generations. The cotton bollworm developed resistance to transgenic Bt cotton after 12 generations (F12) of selection. The survival rate of F12 neonates feeding on leaves of seedling stage for 4 days and boll-opening stage for 5 days of R19 line were ca 34 and 72%, respectively, compared with ca 0 and 40% for a non-selected sister strain (NYCS), but lower than or similar to that of F12 feeding on leaves of non-Bt cotton, Sumian 12 (ca 87 or 76%). Resistance to B thuringiensis HD-1 Dipel in neonates (F12) was ca 6-fold. After 42 generations of selection, the strain developed a very high level of resistance to Cry1Ac protoxin, 210 g kg(-1) MVPII wettable powder and 200 g litre(-1) MVPII liquid formulation, the resistance ratios being 1680-, 1780- and ca 1200-fold, respectively, compared with a laboratory susceptible strain (HZS). When compared with the non-selected NYCS, the resistance ratios to the above toxins were ca 540-, 580- and 510-fold, respectively, but to Dipel only ca 16-fold. The results indicated that it is very important to develop and implement effective resistance-management strategies and to detect early resistance to Bt cotton in field populations.     

苏云金芽孢杆菌cry基因在大肠杆菌中表达产物和生物活性

研究了几种Bt cry基因于大肠杆菌(Escherichia coli)中表达产物在pH 10.0的50mmol/L碳酸钠和20mmol/L乙醇胺溶解液中的溶解性 ,发现同样的Cry蛋白在碳酸钠中的溶解度大于乙醇胺。通过胰蛋白酶消化 ,明确Cry1Ca7、Cry1Ia8酶解产物为 38kD多肽 ;Cry1Ie1、Cry1Cb2、Cry2Ab4酶解产物为 41kD多肽 ;Cry1Ac酶解产物为60kD多肽。采用FPLC层析方法对 6种原毒素及其酶解后得到的毒素多肽进行了分离纯化 ,比较了原毒素和毒素的杀虫活性的差异。其结果表明 ,Cry1Ac的原毒素和毒素对棉铃虫初孵幼虫的校正死亡率均为 100% ,Cry2Ab4的原毒素的毒力高于其酶解毒素。     

Bt菌株FB的生物学特性及其cry、vip基因型鉴定

菌株FB是1株对小菜蛾Plutella xylostella幼虫具有高毒力的苏云金芽胞杆菌Bacillus thuringiensis （Bt）。本研究通过扫描电子显微镜、大质粒电泳、总蛋白SDS-PAGE及菌株生长特征观察的方式研究了菌株FB特征,克隆得到了基因cry1Ia、cry1Ea、cry1Ab、cry2Ab和vip3Aa全长,依据全基因组测序结果得到了1个cry8基因部分片段,首次在Bt菌株中同时发现基因cry1类和cry8类,这五种基因推导的氨基酸序列与已知基因序列相比,最高相似性分别为99%、98%、99%、100%、99%,而cry8半长基因与已知基因仅为63%。生测结果表明,蛋白Cry1Ia、Cry1Ea和Cry1Ab对小菜蛾幼虫具有较高杀虫活性。     

Effects of metabolic inhibitors on activity of Cry1Ab toxin to inhibit growth of Ephestia kuehniella larvae

BACKGROUND: Although the toxins of Bacillus thuringiensis Berliner (Bt) are frequently used to control lepidopteran pests, the tolerance or resistance of some lepidopteran moth strains may limit Bt applications. In this study, insecticidal cocktails consisting of sublethal doses of Cry1Ab toxin and additive compounds were tested for their suppressive effect on larval relative growth rate (RGR) in Ephestia kuehniella Zeller under laboratory conditions.RESULTS: In the first step, the suppressive effect of diflubenzuron, soybean trypsin inhibitor (STI) and chitinase on RGR was confirmed. In the second step, these compounds were incorporated into a mixture of crushed kernels of Bt maize hybrid MON 810-YieldGard((R)) and its isoline with concentrations of Cry1Ab toxin ranging from 0.011 to 0.091 microg g(-1) diet. An additive effect on the suppression of larval RGR in E. kuehniella was found in a combination of diflubenzuron, STI and STI + chitinase as secondary compounds in insecticidal cocktails. Chitinase showed no additive effect on RGR.CONCLUSION: The highest suppression level was found in cocktails with STI + chitinase as a secondary compound. It is hypothesized that the protease inhibitor (STI) protects both chitinase and Cry1Ab proteins from endogenous proteases in the larval midgut and prolongs their insecticidal activities. The possible application of insecticidal cocktails in the control of E. kuehniella is discussed. Copyright (c) 2008 Society of Chemical Industry.     

钙粘蛋白氨基酸点突变介导红铃虫对Cry1Ac的抗性

为明确室内筛选的红铃虫Pectinophora gossypiella抗性品系AQ-R对Cry1Ac的抗性机制,采用室内生物测定法明确该品系对Cry1Ac和Cry2Ab的敏感性,通过遗传杂交和基因克隆分析抗性基因的显隐性及突变位点,并进行细胞学试验分析突变蛋白的亚细胞定位。结果显示：红铃虫AQ-R抗性品系对Cry1Ac的抗性倍数为181.67倍,对Cry2Ab没有交互抗性;该品系携带了一种新型的隐性钙粘蛋白抗性等位基因PgCad1,其编码蛋白的钙粘蛋白重复区、前蛋白区和近膜区共发生了17个氨基酸替换。表达野生型PgCad1-s基因的Hi5细胞对Cry1Ac敏感,且钙粘蛋白定位于细胞膜;而表达抗性PgCad1-r基因的Hi5细胞则对Cry1Ac不敏感,且钙粘蛋白错误定位到内质网。表明钙粘蛋白氨基酸点突变能导致其定位错误,从而促成红铃虫AQ-R品系对Cry1Ac产生抗性。     

Susceptibility of field-collected populations of the southwestern corn borer,Diatraea grandiosella,to Bacillus thuringiensis

The susceptibilitity of newly hatched larvae of laboratory-adapted and field-collected populations of the Southwestern corn borer, Diatraea grandiosella (Dyar) (Lepidoptera: Crambidae), to a Bacillus thuringiensis protein (Cry1Ab) was examined using a larval feeding bioassay. D grandiosella populations were collected from five states: Missouri, Kansas, Texas, Tennessee and Kentucky. Using larval mortality as the end-point of the bioassay, the magnitude of differences in the susceptibility of the laboratory-adapted and the field-collected populations to Cry1Ab protein varied from one to 46 times depending on the time of observation and the standard of comparison (LC50 or LC95). However, significant differences in susceptibility to Cry1Ab protein among these populations were not detected when the comparisons were based on growth inhibition (EC50 or EC95); the magnitude of differences was less than fourfold. Either using larval mortality or larval growth inhibition, the results indicated that the field-collected populations of D grandiosella were susceptible to Cry1Ac, and differences in susceptibility may reflect natural variation among populations. The bioassay using larval growth inhibition offers advantages over that using larval mortality, including giving more accurate representation of the toxicological effects of the toxin.     

小菜蛾Btk抗性品系对四种Bt杀虫晶体蛋白抗性发展的研究

使用苏云金芽胞杆菌库斯塔克亚种（Btk）可湿性粉剂对小菜蛾进行继代汰选获得F₈₀代和F₁₀₀代抗性品系。通过分别测定Cry1Ab、Cry1Ac、Cry1Ah和Cry1Ca四种杀虫晶体蛋白对小菜蛾Btk抗性品系F₈₀代和F₁₀₀代的室内毒力,明确了小菜蛾Btk抗性品系对四种Bt杀虫晶体蛋白抗性发展规律。研究结果表明,汰选至F₈₀代时,Cry1Ca对小菜蛾的毒力最高,LC₅₀约12.1 mg/L,其次为Cry1Ac,LC₅₀约47.7 mg/L;而汰选至F₁₀₀代时,仍以Cry1Ca对小菜蛾的毒力最高,LC₅₀约21.4 mg/L,其次为Cry1Ab,LC₅₀约72.2 mg/L。与相对敏感品系相比,小菜蛾抗性品系对Cry1Ac的抗性发展较快（抗性倍数高达67.3～106.8倍）,对Cry1Ab的次之（抗性倍数高达60.0～66.1倍）,而对Cry1Ca和Cry1Ah的抗性发展较慢（抗性倍数分别为3.4～6.0倍和1.6～2.5倍）。以上结果说明,在主效杀虫基因为Cry1Ac的Btk药剂选择压力下,小菜蛾对四种Bt杀虫晶体蛋白的抗性发展速度差异较大,且Cry1Ac和Cry1Ab存在交互抗性风险。     

不同条件下转cry1Ab基因玉米植株残体中杀虫蛋白降解动态

为明确转cry1Ab基因玉米植株残体中Cry1Ab杀虫蛋白在不同条件下的降解动态,选取转cry1Ab基因玉米MON810和Bt11,采用ELISA方法测定4种条件下秸秆中Cry1Ab杀虫蛋白的残留量。结果表明,在不同条件、不同取样时间,2种玉米秸秆中Cry1Ab杀虫蛋白的残留量差异显著;整株秸秆中的Cry1Ab杀虫蛋白降解速度比粉碎后的慢;秸秆粉碎埋入土壤后播种冬小麦,玉米秸秆中Cry1Ab杀虫蛋白降解速度最快,且可完全降解;在不同条件下,MON810玉米秸秆中Cry1Ab杀虫蛋白的降解速度比Bt11玉米慢,MON810和Bt11玉米秸秆中Cry1Ab杀虫蛋白的DT50分别为10.2~207.8、13.6~124.0 d,DT90分别为185.1~368.3、45.2~224.0 d。研究表明,在不同条件下MON810和Bt11玉米秸秆中Cry1Ab杀虫蛋白的降解速度不同,依次为秸秆粉碎后埋在土壤后种植冬小麦秸秆粉碎埋在玉米田土壤中秸秆粉碎后放在地表整株秸秆放在地表。     

亚洲玉米螟对Cry9Ee与Cry1Ab蛋白的交互抗性分析

Cry9Ee是近年来发现的对亚洲玉米螟Ostrinia furnacalis(Guenée)等害虫具有高毒力的蛋白,具有良好的应用前景。为了明确亚洲玉米螟对Cry9Ee和Cry1Ab蛋白是否存在交互抗性,本文首先分别表达、活化、纯化了Cry9Ee和Cry1Ab蛋白,进而对敏感和Cry1Ab抗性亚洲玉米螟进行生物活性测定;随后对2种蛋白在敏感亚洲玉米螟中肠刷状缘膜囊泡(brush border membrane vesicles,简称BBMVs)上的结合进行分析比较。生物活性测定结果表明,Cry9Ee和Cry1Ab蛋白的活性片段对敏感亚洲玉米螟的LC₅₀分别为3.04和0.89 μg/g;而Cry9Ee活性片段在5.00 μg/g的浓度下,对Cry1Ab蛋白抗性亚洲玉米螟致死率高达96%,与对敏感种群活性相当。竞争结合试验表明,Cry9Ee和Cry1Ab两种蛋白间不存在竞争结合,推测它们在亚洲玉米螟中肠上存在不同的受体。综合生物活性测定及体外结合试验两方面结果得出结论：亚洲玉米螟对Cry9Ee与Cry1Ab蛋白不存在交互抗性。cry9Ee基因可以作为理想的候选基因,用于我国新一代转基因抗虫玉米的研制,为延缓和克服亚洲玉米螟对转基因抗虫玉米抗性的产生提供重要保证。     

对黏虫具有杀虫活性的Bt蛋白筛选及分析

为筛选对黏虫[Mythimna separata(Walker)]具有毒杀作用的苏云金芽胞杆菌杀虫蛋白,本研究提取Cry1类、Cry2类、Cry9类及Vip3A类等11种蛋白,通过人工饲料喂毒方法对黏虫进行生物活性测定。结果表明,Cry1Ac、Cry1Ab、Cry2Ab、Cry1Be及Cry1Bb蛋白对黏虫具有杀虫活性,其致死中浓度依次为5.09、17.71、26.75、27.42及43.93μg/g;Cry9Aa、Cry9Eb、Cry9Ee蛋白对黏虫生长具有抑制作用,其浓度为10μg/g时的体重抑制率分别为78.4%、79.0%、86.9%,浓度为100μg/g时的体重抑制率分别为92.8%、95.7%、96.7%;Cry1Ba、Cry1Ca和Vip3Aa蛋白对黏虫无显著活性。本研究为黏虫的生物防治奠定了基础,并为抗虫转基因作物的研究提供优良的候选基因。     

二化螟Cry1Ac汰选品系对不同Bt蛋白的敏感性

为明确靶标害虫对Bt蛋白的抗性及对不同类型Bt蛋白的交互抗性,采用生物测定法进行了二化螟Chilo suppressalis(Walker)敏感品系和Cry1Ac汰选品系在Cry1Ac毒饲料上的时间-死亡率反应、对不同Bt杀虫蛋白的敏感性及不同Bt蛋白复配组合对二化螟毒力效果的研究。结果表明,二化螟Cry1Ac汰选品系已对36.67μg/mL(LC_(50))的Cry1Ac杀虫蛋白产生了一定的适应性,但对308.69μg/mL(LC90)的Cry1Ac蛋白反应仍较敏感。Cry1Ac敏感品系和汰选品系对Cry1Ab蛋白的LC_(50)分别为1.40μg/mL和3.86μg/mL,二者差异显著,但对Cry1Ca(1.63μg/mL和1.73μg/mL)或Cry2Aa(127.48μg/mL和144.50μg/mL)的LC_(50)差异不显著,即Cry1Ac汰选品系与Cry1Ab存在明显的交互抗性,但与Cry1Ca和Cry2Aa不存在交互抗性。在不同Bt蛋白复配组合中(1∶1复配),Cry1Ab+Cry1Ca、Cry1Ab+Cry2Aa和Cry1Ca+Cry2Aa增效作用最为显著。表明抗虫基因cry1Ca和cry2Aa可作为双价转基因抗虫水稻研发的候选基因。     

转Bt cry1Ab基因水稻花粉对中华 草蛉成虫产卵和寿命的影响

用ELISA法测定了转Bt基因水稻克螟稻1号(KMD1)和克螟稻2号(KMD2)花粉中Cry1Ab含量.将转Bt基因水稻和其亲本对照秀水11(XS11)花粉加入到草蛉人工干粉饲料中,评价了对中华草蛉Chrysoperla sinica Tjeder成虫产卵和寿命等参数的影响.结果显示,转Bt基因水稻"克螟稻"花粉中表达cry1Ab杀虫蛋白,且表达量较高.分别用含5%KMD1、KMD2和XS11花粉的人工饲料饲喂中华草蛉初羽化成虫,发现两类Bt水稻花粉对该虫产卵前期、产卵量、产卵天数和成虫寿命等参数均无显著影响.人工饲料中水稻花粉的比例上升至20%和80%后,KMD1、KMD2和XS11花粉饲料处理中的草蛉均出现产卵前期延长、产卵量减少和产卵天数缩短的趋势,但在同一花粉比例下这些参数在3个花粉饲料处理间均无显著差异.结果表明,Bt水稻花粉中cry1Ab杀虫蛋白对该草蛉成虫产卵和寿命等参数无显著的负面影响.     

Cry1Ba3、Cry1Ia8蛋白对Cry1Ac抗性小菜蛾的杀虫活性研究

利用2种苏云金芽胞杆菌原毒素Cry1Ba3、Cry1Ia8及其组合,分别对Cry1Ac抗性种群小菜蛾幼虫进行生物活性测定。结果表明Cry1Ba3、Cry1Ia8对2种目标试虫均有高毒力,LC50分别为0.2175、0.6706μg/mL;Cry1Ba3毒力3倍于Cry1Ia8。2种蛋白混配的结果也表现出高毒力,LC50为0.4375μg/mL,没有显著的协同增效作用,也不存在拮抗。敏感与抗性小菜蛾种群生测结果统计分析比较,结果表明这2种蛋白及其组合与Cry1Ac并无交互抗性。     

苏云金芽孢杆菌Cry8Ca2蛋白的纯化与活性的研究

cry8 Ca2基因是本实验室自行分离克隆的一种新型苏云金芽孢杆菌(Bacillus thuringiensis,Bt)杀虫晶体蛋白基因,其表达130 kDa蛋白对铜绿异丽金龟(Anomala corpulenta)和黄褐异丽金龟(A.exoleta)幼虫具有较高的活性。本研究对Cry8Ca2蛋白原毒素及胰凝乳蛋白酶消化片断的纯化条件及活性进行研究,最适的消化条件为质量比1∶20,37℃,消化1 h。通过阴离子交换层析得到纯的活性毒素蛋白。用原毒素与纯化的毒素对铜绿丽金龟幼虫进行生测,Cry8Ca2原毒素蛋白的LC₅₀为0.47μg/g土,纯化的毒素的LC50为0.08μg/g土,毒素的杀虫活性可以达到原毒素的6倍。     

四种Bt毒素蛋白对二点委夜蛾幼虫毒力测定及中肠组织病理学变化

为更好地了解苏云金芽胞杆菌Bacillus thuringiensis毒素蛋白对二点委夜蛾Athetis lepigone的毒力以及作用机理,通过饲喂含有Cry1Ac、Cry1Ab、Cry2Ab和Vip3Aa四种不同Bt毒素蛋白饲料,测定Bt毒素蛋白对二点委夜蛾幼虫的毒力,并观察取食4种毒素蛋白后幼虫中肠组织的病理学变化。结果显示,二点委夜蛾幼虫取食毒素蛋白后72 h,Cry1Ab和Cry1Ac毒素蛋白对二点委夜蛾幼虫的杀虫活性较高,校正死亡率为84.7%和76.4%;Vip3Aa和Cry2Ab毒素蛋白的毒力较弱。二点委夜蛾幼虫取食4种Bt毒素蛋白后,中肠柱状细胞微绒毛脱落,杂乱地分散在肠腔内,杯状细胞变形和腔内微绒毛脱落,线粒体和内质网等变形破裂,细胞核的核膜消失、核质凝聚和形状发生变化,经Cry1Ab和Cry1Ac毒素蛋白处理后中肠细胞的病变症状和速度明显高于Cry2Ab和Vip3Aa毒素蛋白处理。表明Cry1Ab和Cry1Ac毒素蛋白对二点委夜蛾幼虫杀虫活性较高,显著高于Cry2Ab和Vip3Aa毒素蛋白,且对其中肠细胞的破坏作用也较强。     

Field-evolved resistance to Bt toxin Cry1Ac in the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae), from India

BACKGROUND: The pink bollworm is one of the most destructive pests of cotton. Transgenic cotton producing Bt toxin Cry1Ac or a combination of Cry1Ac and Cry2Ab2 has been used effectively against this pest. However, some other insects have evolved resistance to Bt toxins in the field. During the 2007–2008 and 2008–2009 seasons, pink bollworm populations in India were surveyed to evaluate their responses to Cry1Ac and seed powder containing Cry1Ac and Cry2Ab2. RESULTS: The results provide evidence that resistance to Cry1Ac had evolved by 2008 in a population sampled from non‐Bt cotton in the Amreli district of Gujarat in western India. The median lethal concentration of Cry1Ac for five‐day‐old larvae (LC₅₀) was significantly higher for insects derived in 2008 from Amreli than for any of the other field populations tested from four locations in India. For Cry1Ac, the mean LC₅₀ for the strain derived from Amreli in 2008 was 44 times higher than for the most susceptible population. However, for seed powder of Bollgard II containing primarily Cry2Ab2, the 2008 Amreli population was only slightly less susceptible than the most susceptible population. CONCLUSIONS: The data reported here constitute the first evidence of field‐evolved resistance of pink bollworm to Cry1Ac. This initial evidence spurred more extensive evaluations during the 2009–2010 growing season, which confirmed field‐evolved resistance to Cry1Ac in Amreli. The lack of cross‐resistance to Cry2Ab2 suggests that plants producing this toxin are likely to be more effective against resistant populations than plants producing only Cry1Ac. Copyright © 2011 Society of Chemical Industry     

Selection and heritability of resistance to Bacillus thuringiensis subsp kurstaki and transgenic cotton in Helicoverpa armigera (Lepidoptera: Noctuidae)

Compared with an unselected susceptible population, a cotton bollworm, Helicoverpa armigera (Hübner), population selected for 22 generations with transgenic cotton leaves (modified Cry1A) in the laboratory developed 11.0-fold resistance to Cry1Ac (one single-protein product MVPII). Resistance to Bacillus thuringiensis Berliner subsp kurstaki (Btk) was selected for 22 generations with a 5.2-fold increase in LC50. The estimated realized heritabilities (h2) of resistance for transgenic-cotton- and Btk-selected populations were 0.1008 and 0.2341, respectively. This reflects the higher phenotypic variation in response to Cry1Ac in the transgenic-cotton-selected population. This variation may have been caused by differences in protein toxin levels expressed in different growth stages of the transgenic cotton. Because of the different slopes of the probit regression lines between Cry1Ac and Btk, the estimated realized h2 cannot be used visually to compare resistance development to Cry1Ac and Btk in H armigera. Thus, the response quotient (Q) of resistance was also estimated. The Q values of resistance for transgenic-cotton- and Btk-selected populations were 0.0763 and 0.0836, respectively. This showed that the rate of resistance development would be similar in both selection populations. This result indicates that the selection of resistance using transgenic cotton is different from that selected using the single toxin. Resistance risk to transgenic cotton and Btk in field populations was assessed assuming different pressures of selection by using the estimated h2. Assuming the h2 of resistance in a field population was half of the estimated h2, and the population received prolonged and uniform exposure to transgenic cotton or Btk causing >70% mortality in each generation, we predicted that resistance would increase 10-fold after <23 generations for Cry1Ac in transgenic cotton-selected-populations and after <21 generations for Btk in Btk-selected populations. Cross-resistance would be expected after <48 generations for Btk in transgenic-cotton-selected populations and after <21 generations for Cry1Ac in Btk-selected population. The results show that the potential to evolve resistance is similar in both transgenic-cotton- and Btk-selected populations, but that cross-resistance development to Btk is slower in transgenic-cotton-selected populations than cross-resistance development to Cry1Ac in Btk-selected populations.     

转Bt 基因抗虫玉米对棉铃虫杀虫活性的初步评价

国内外在转 Bt基因抗虫作物的研究和应用上已取得重大进展 ,其中 Bt抗虫棉已在美国、澳大利亚、中国等进入商品化应用阶段 ,近年来种植面积增长很快 ,并取得了显著的经济、生态和社会效益。 1 997年下半年 ,我国农业部分别批准了孟山都公司申报的保铃棉○R在河北省商业化生产和 Bt玉米在我国多省份的田间种植。其中保铃棉 ○R已由河北省定名为新棉 33B,1 998年在全省实际种植了近 1 0万 hm2 ,1 999年的种植面积已达 1 5万 hm2 。我国自主研制的 Bt抗虫棉也于 1 998年开始商品化应用 ,当年种植面积即达 1 0万 hm2以上 ,1 999年推广总面积…     

Cry1Ab杀虫蛋白对淡足侧沟茧蜂生长发育的影响

以黏虫［〖WTBX〗Mythimna separata〖WTBZ〗 (Walker)］为寄主,研究了亚致死浓度的Bt杀虫蛋白Cry1Ab对淡足侧沟茧蜂［〖WTBX〗Microplitis pallidipes 〖WTBZ〗(Szepligeti)］生长发育的影响。结果表明,当寄主从淡足侧沟茧蜂寄生后开始取食含Cry1Ab杀虫蛋白浓度为1、2、4 μg/g和 8 μg/g的饲料时,淡足侧沟茧蜂卵 幼虫发育历期比以对照黏虫为寄主的显著延长,茧（蛹）重和成虫体重显著下降,但对茧历期及成虫寿命没有显著影响。淡足侧沟茧蜂的卵 幼虫发育历期随着寄主取食Cry1Ab杀虫蛋白浓度的增加而显著延长,茧重和成虫体重则随Bt蛋白浓度的上升而显著下降。因此,尽管Cry1Ab杀虫蛋白对淡足侧沟茧蜂的生长发育具有一定程度的负面影响,但其仍可以在取食Bt毒蛋白的黏虫上完成整个世代发育。