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1.
Abstract.  1. Changes in the frequency of Cry1Ac resistance genes and shifts in tolerance of cotton bollworm, Helicoverpa armigera , to the Cry1Ac toxin were assessed using bioassays of F1 and F2 offspring of isofemale lines from Anci County of Hebei Province (a multiple-crop system including corn, soybean, peanut, and Bt cotton) and Xiajin County of Shandong Province (an intensive Bt cotton planting area) in Northern China during 2002–2005.
2. A conservative analysis of the overall results indicated that there was a small increase in the frequency of major, non-recessive resistance genes over time.
3. The relative average development ratings [RADR – growth rate of a line on a Bt diet in proportion to the growth rate on a non-Bt (NBT) diet] of the bollworm larvae in F1 tests increased significantly from year to year, indicating a gradual trend towards higher tolerance to Cry1Ac in the field populations.
4. There were also significant positive correlations between RADR of the lines in the F1 generation and the RADR of their F2 offspring, indicating that the tolerance was genetically based.
5. Quantitative genetic simulation analysis showed that resistance of H . armigera to Bt cotton in Xiajin could evolve to a high level in 11–15 years if no effective resistance management measures are carried out.  相似文献   

2.
The BKBT strain of Helicoverpa armigera was derived from a susceptible BK77 strain (collected from Bouake, Cote D’Ivoire in 1977) through 30 generations of selection with activated Bacillus thuringiensis δ‐endotoxin Cry1Ac. Unlike recessive inheritance of Cry1Ac resistance in H. armigera from previous reports, resistance to activated Cry1Ac in the BKBT strain is dominant. A backcross approach was used to map dominant resistance to Cry1Ac in the BKBT strain. One hundred and forty‐seven informative amplified fragment length polymorphism (AFLP) DNA markers covered all 31 linkage groups of H. armigera. Five AFLP markers linked to Cry1Ac resistance in the BKBT strain were on the same autosomal linkage group, which is the only linkage group contributing dominant Cry1Ac resistance in the BKBT strain of H. armigera.  相似文献   

3.
The crystal proteins of Bacillus thuringiensis (Bt) are widely used for insect control. Helicoverpa armigera is the model insect for Bt studies. In this study, brush border membrane vesicle (BBMV) proteins from fifth instar larvae of Helicoverpa armigera were prepared, and proteomic approaches based on two-dimensional (2D) gel electrophoresis and mass spectrometry were used to elucidate changes in BBMV proteins with and without Cry1Ac toxin treatment. Sixty-one protein bands separated by 1D electrophoresis were cut out from the gel for tryptic digestion and were detected with molecular mass spectrometry (ESI-Q-TOF) and High Capacity Ion Trap Ultra (HCT Ultra). BBMV proteins of interest separated by 2D electrophoresis were excised and digested with trypsin, and the resulting peptides were analyzed by mass spectrometry. Mass fingerprints were compared with the non-redundant NCBI Metazoa (Animals) database. We found a noticeable increase in the level of aminopeptidase N (APN) that is important for detoxification reactions. Additionally, a significant decrease in the level of trypsin-like protease is important during early responses and adaptation of the insect to Bt and exposure to its toxins. Furthermore, the increase in V-ATPase subunits indicate elevated cellular energy profile which is necessary to combat toxin stress. The increased level of actin in larvae provides immediate protection by strengthening the midgut epithelium and enhancing cellular defenses in the tissue. This study presents the differences in the BBMV proteins of Helicoverpa armigera with and without Cry1Ac toxin treatment, and provides a theoretical basis for research on the mechanism of action of Bt toxin.  相似文献   

4.
苏云金芽孢杆菌 (Bacillusthuringiensis,Bt)WY 197菌株是从 4 0 0多株野生型Bt菌中筛选分离的1株对甜菜夜蛾和棉铃虫都具有高效杀虫活性的菌株。初步比较WY -197菌株和HD 1的形态特征、生理生化特性和伴孢晶体蛋白 ,结果表明 ,WY -197属于H3a3b3c血清型 (subsp .kurstaki) ;伴孢晶体形态主要为大小不一的菱形、小正方形。SDS -PAGE电泳图谱表明主要由 135ku和 6 5ku两种蛋白成分组成 ,在菌株生长形态、发酵培养特征、生理生化特性方面与生产菌株HD-1差别不大。采用生物测定的方法 ,进一步鉴定比较它们对甜菜夜蛾初孵、二龄、三龄幼虫和棉铃虫的毒效差异。结果表明 ,BtWY 197菌株发酵液对甜菜夜蛾初孵、二龄、三龄幼虫的LC50 分别为 0 .31、0 .6 1、2 .5 7μL/mL ,其中对甜菜夜蛾初孵幼虫的毒效是对照菌HD 1发酵液的 7倍 ,表明BtWY 197菌株对甜菜夜蛾三龄以下幼虫具有高毒力。对棉铃虫的毒力效价为 30 0 0IU/ μL ,略低于HD- 1菌株。  相似文献   

5.
文章以转Cry1Ac基因棉(中棉所41)和常规棉(中棉所49)为对照,研究了转Cry1Ac+Cry2Ab基因棉(639020)在棉花生长的关键时期——蕾期(二代棉铃虫发生期)、花期(三代棉铃虫发生期)和花铃期(四代棉铃虫发生期)对棉铃虫的控制作用,同时研究了639020棉田主要捕食性天敌(中华草蛉幼虫、龟纹瓢虫、小花蝽和草间小黑蛛)对烟粉虱的捕食功能,明确了639020棉花在生长的关键时期对棉铃虫的控制效果及对棉田主要捕食性天敌捕食功能反应的影响。结果表明,639020棉花对二代和三代棉铃虫具有良好的控制作用,抗虫性分别比中棉所41提高了52.85%和16.22%,其中前者差异达显著水平,后者差异不显著。在棉花蕾期、花期和花铃期,639020棉田棉铃虫落卵量都比中棉所41棉田和中棉所49棉田低(除二代棉铃虫发生期);棉铃虫幼虫数量都极显著低于常规棉,且都低于防治指标,但与中棉所41棉田无显著差异。639020棉田中华草蛉、龟纹瓢虫、小花蝽和草间小黑蛛对烟粉虱的捕食功能与中棉所41棉田和常规棉田相比无显著变化。研究结果以期为新型转基因棉花环境安全性研究及其外源基因的抗虫遗传效应和生产应用前景进行安全性评价。  相似文献   

6.
为了监测南疆主要Bt棉区棉铃虫田间种群对Bt棉的抗性频率,分别采集库尔勒、阿克苏、泽普三地的棉铃虫单雌系,以Bt毒蛋白作为人工饲料,采用单雌系F1代法进行棉铃虫田间种群抗性个体检测.本文从库尔勒、阿克苏、泽普三地分别筛选了57个、106个、92个棉铃虫单雌系.三地棉铃虫单雌系幼虫在正常饲料和Cry1Ac饲料上的平均发育...  相似文献   

7.
Transgenic crops expressing toxin proteins from Bacillus thuringiensis (Bt) have been deployed on a large scale for management of Helicoverpa armigera. Resistance to Bt toxins has been documented in several papers, and therefore, we examined the role of midgut microflora of H. armigera in its susceptibility to Bt toxins. The susceptibility of H. armigera to Bt toxin Cry1Ac was assessed using Log‐dose‐Probit analysis, and the microbial communities were identified by 16S rRNA sequencing. The H. armigera populations from nine locations harbored diverse microbial communities, and had some unique bacteria, suggesting a wide geographical variation in microbial community in the midgut of the pod borer larvae. Phylotypes belonging to 32 genera were identified in the H. armigera midgut in field populations from nine locations. Bacteria belonging to Enterobacteriaceae (Order Bacillales) were present in all the populations, and these may be the common members of the H. armigera larval midgut microflora. Presence and/or absence of certain species were linked to H. armigera susceptibility to Bt toxins, but there were no clear trends across locations. Variation in susceptibility of F1 neonates of H. armigera from different locations to the Bt toxin Cry1Ac was found to be 3.4‐fold. These findings support the idea that insect migut microflora may influence the biological activity of Bt toxins.  相似文献   

8.
转基因抗虫棉种植面积变化对花生田棉铃虫种群影响   总被引:1,自引:0,他引:1  
【目的】棉铃虫Helicoverpa armigera(Hübner)是花生田主要害虫之一。转基因抗虫棉全面推广后,棉铃虫种群(包括棉田、花生田、玉米田)得到有效控制。近年,随着转基因抗虫棉种植面积逐年下降,花生田棉铃虫种群呈现逐年上升趋势。【方法】本文通过调查山东省花生主产区(非棉区)龙口、招远、莱阳、文登四个县级市花生田棉铃虫成虫、卵量、幼虫量等的发生情况,分析了棉铃虫发生面积及种群数量15年(2000—2014年)的变化规律,并重点分析了主要影响因素。【结果】结果表明:花生棉铃虫发生面积受棉花种植面积影响较大,二者呈显著负相关性;花生田棉铃虫累计诱蛾量总体呈下降趋势,但与棉花种植面积相关性不显著;棉铃虫卵量、虫量与抗虫棉种植面积呈显著负相关性。【结论】所以,转基因抗虫棉种植面积减少是导致花生田棉铃虫种群数量上升的主要因素。另外,近年玉米田棉铃虫发生面积也呈逐年上升趋势,与抗虫棉种植面积呈显著负相关。所以,随转基因抗虫棉种植面积的下降,若不采取有效措施,棉铃虫种群可能会出现大发生趋势。  相似文献   

9.
Transgenic cotton that produces insecticidal proteins from Bacillus thuringiensis (Bt), often referred to as Bt cotton, is widely grown in many countries. Bt cotton with a single cry1A gene and stacked also with cry2A gene has provided satisfactory protection against the damage by the lepidopteran bollworms, especially the cotton bollworm, Helicoverpa armigera (Hübner) which is considered as a key pest. The baseline susceptibility of the larvae of H. armigera to Cry1Ac and other toxins carried out in many countries has provided a basis for monitoring resistance. There is no evidence of development of field-level resistance in H. armigera leading to the failure of Bt cotton crop anywhere in the world, despite the fact that Bt cotton was grown on the largest ever area of 12.1 million hectares in 2006 and its cumulative cultivation over the last 11 years has surpassed the annual cotton area in the world. Nevertheless, the Bt resistance management has become a necessity to sustain Bt cotton and other transgenic crops in view of potential of the target insects to evolve Cry toxin resistance.  相似文献   

10.
为了明确新疆棉区棉铃虫Helicoverpa armigera(Hübner)种群对Bt Cry1Ac毒蛋白的敏感性变化,本次研究采用单雌系F1/F2代诊断剂量法于2013-2019年连续监测了新疆库尔勒市棉铃虫种群对Cry1Ac毒蛋白的抗性频率以及种群敏感度的变化.结果表明,2013-2019年新疆库尔勒市棉铃虫种群...  相似文献   

11.
Cotton bollworm, Helicoverpa armigera (Hübner) is a cosmopolite insect pest of a wide spectrum of crops such as cotton, maize, tomato, soybean, etc. Egg parasitoids mainly Trichogramma brassicae Bezdenko and Bacillus thuringiensis Berliner (Bt) are biological control agents, that are used as components of sustainable and environmentally compatible IPM systems. Although Bt does not come in direct contact with egg parasitoids, it may persist within the host’s body and affect the quality of the host’s eggs via biochemical changes in their mother and possibly behaviour and potency of the parasitoids. In this study, the functional response of T. brassicae to different densities of H. armigera eggs was investigated in two sets of experiments at 26?±?1?°C, 65?±?5% RH, and 16: 8?h photoperiod. The first group was a control and the second one were eggs laid by hosts treated as 3rd instar larvae with LC20 of Bt (determined as 9.8?×?105?IU/l of artificial diet based on a preliminary bioassay). A type III functional response was observed in both treatments with a direct density dependent mortality up to eight host eggs and an inverse one upward. Both handling time and searching efficiency were affected by Bt treatment as the handling time was increased by a factor of 1.5 and the searching efficiency was decreased by a factor of 0.6. The searching efficiencies were 0.0310?±?0.003 and 0.0182?±?0.005?h?1, and handling times were 1.134?±?0.042 and 1.672?±?0.082?h in control and Bt treatment respectively.  相似文献   

12.
Studies on the susceptibility of F1 neonates of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) collected from chickpea in Delhi and cotton in Punjab, Haryana and Rajasthan in northern India, to Bacillus thuringiensis ssp. kurstaki HD‐73, and the impact of host crop diets on insect susceptibility, were carried out by diet incorporation bioassays. The susceptibility of F1 neonates of H. armigera to Bacillus thuringiensis ssp. kurstaki HD‐73 ranged from twofold (LC50 96 h, 84.5–164.2 µg (ai) l?1) for chickpea to about fivefold (LC50 96 h, 51.1–247.7 µg (ai) l?1) for cotton. The F1 neonates of insects collected from pearl millet were twice as tolerant as those collected from cotton and sunflower at Sirsa to B. thuringiensis ssp. kurstaki HD‐73, suggesting that there was an influence of host crops on insect susceptibility. Insects originally collected from cotton fields at Bhatinda and reared for four generations on a chickpea‐based meridic diet were used to initiate host‐specific colonies of H. armigera. These host‐specific colonies were allowed to complete one generation on meridic diets prepared with different hosts, viz., cabbage, cauliflower, chickpea, green pea, pearl millet, and pigeon pea. Larvae of H. armigera were heaviest on the 15th day, and had a higher growth rate on a pigeon pea‐based diet than all other host diets. The larval period was shorter on chickpea and pigeon pea, with higher percentage pupation than all other host‐diets. The pupal weight of H. armigera was greater on chickpea and pigeon pea diets than on other host diets. The growth and development of larvae was significantly poorer on pearl millet diet than on other host diets. The F1 neonates of H. armigera belonging to cabbage, cauliflower, and pearl millet host‐specific colonies were more susceptible than those belonging to chickpea, green pea, and pigeon pea host‐specific colonies to B. thuringiensis ssp. kurstaki HD‐73, suggesting the importance of proteinaceous nutrients in tolerance. The F1 neonates of the pearl millet colony of H. armigera grown on a chickpea‐diet for 4 days were significantly more tolerant to B. thuringiensis ssp. kurstaki HD‐73 than those reared on the pearl millet‐based diet. These studies show the impact of the host diet of H. armigera on tolerance to B. thuringiensis.  相似文献   

13.
肠道菌对苏云金芽胞杆菌杀虫活性的研究   总被引:4,自引:0,他引:4  
苏云金芽胞杆菌(Bacillus thuringiensis,Bt)在生长发育过程中伴随芽胞的形成高效表达对昆虫具有特异毒性的杀虫晶体蛋白,从而被广泛应用于害虫防治上。有关Bt的杀虫机制,近年来有学者提出了肠道菌模型,认为肠道菌在Bt发挥杀虫活性中是必须的,也有人提出相反的观点。以棉铃虫作为供试昆虫,利用Cry1Ac10晶体蛋白研究了棉铃虫肠道菌在Bt杀虫过程中所发挥的功能。结果发现,在棉铃虫中肠道菌并非Bt杀虫所必需,并且在肠道菌存在的情况下,Bt杀虫活性反而明显降低,通过肠道菌回接试验发现5号肠道菌对棉铃虫的保护作用最为明显。  相似文献   

14.
Abstract:  Laboratory studies were performed to characterize the lepidopteran toxicity of cotton plants expressing two different toxin proteins from Bacillus thuringiensis (Bt), in order to assess insect resistance management implications of a commercial, two-toxin transgenic cotton. An independent and additive interactive effect of two Bt δ -endotoxins expressed by the transgenic cotton variety 15985 was demonstrated by examining the responses of Heliothis virescens (F.), Helicoverpa zea (Boddie), and Spodoptera frugiperda (J.E. Smith) larvae to field- or greenhouse-grown tissue from genetic near-isolines, which expressed Cry1A only, Cry2Ab only, or both toxins. In all cases, the Cry2Ab component was the larger contributor to total toxicity in the two-toxin isoline. Toxin-specific, quantitative enzyme-linked immunosorbent assay (ELISA) tests confirmed that the levels of each toxin in tissues of the two-toxin isoline were not statistically different (P > 0.05) from the levels found in the corresponding tissues of the respective single-toxin isoline. Resistance management considerations were discussed. Considering the additive interaction of toxins, a relatively simple insect resistance-monitoring procedure was proposed for the monitoring of commercial cotton varieties expressing both toxins.  相似文献   

15.
汪飞  徐静  封红兵  张青文 《昆虫知识》2003,40(2):131-135
棉铃虫Helicoverpaarmigera高龄幼虫取食转Bt基因棉花组织后 ,化蛹率、羽化率、蛹重、体长均有显著下降 ,在转Bt基因棉花上棉铃虫的取食行为也受到较大的影响 ,表现为取食次数明显减少、吐丝下垂次数明显增加 ;无论是转Bt基因棉花还是常规棉花 ,棉铃虫 3龄幼虫主要分布于繁殖器官上 ,在转Bt基因棉花各繁殖器官上的分布概率为 :花 >棉铃 >棉蕾 ,常规棉花上分布概率为 :棉蕾 >棉铃 >花 ;棉铃虫高龄幼虫取食转Bt基因棉花各组织 ,成虫羽化后产卵量、卵孵化率均有明显下降 ;在较低的棉铃虫虫口密度下 ,转Bt基因棉花对棉铃虫有一定的产卵排趋性。  相似文献   

16.
The insecticidal toxin gene of Bacillus thuringiensis (Bt) is the most commonly used to develop insect‐resistant living modified organisms (LMOs). Insecticidal proteins produced in transgenic plants are released into the soil from the roots. In this study, possible effects of crystal 1Ac (Cry1Ac) protein on the soil microbial community in Korea were studied. To purify the insoluble Cry1Ac protein expressing Escherichia coli cells, we performed repeated sonication and PBS washing of the insoluble part and Cry1Ac protein was isolated in soluble form from the insoluble form using 100 mM Na2CO3 buffer (pH 9.6) without affinity bead. Also, size‐exclusion chromatography (SEC) was performed to increase the purity of the isolated Cry1Ac protein. The final protein product was identified as Cry1Ac protein through MALDI‐TOF. Insecticidal activity of Cry1Ac protein was demonstrated through the death of Plutella xylostella treated with Cry1Ac protein. Purely isolated Cry1Ac protein showed the same insecticidal activity as Cry1Ac expressed in LM crops. To investigate the change of soil microbial distribution using maize field soils treated with Cry1Ac protein, we isolated high quality metagenomic DNAs from buffer‐ and Cry1Ac protein‐treated soil groups, and analyzed the distribution of soil microorganisms through next‐generation sequencing (NGS) analysis. NGS results showed a similar microbial distribution in both buffer‐ and Cry1Ac protein‐treated samples. These results suggest a useful risk assessment method for domestic targeted insect and soil microorganisms using the Cry1Ac protein.  相似文献   

17.
为了扩大苏云金芽胞杆菌的杀虫谱及生防范围,通过抑真菌和杀虫生物活性测定,筛选到一株抑真菌并对甜菜夜蛾高效的菌株Bt519-1.此菌株对所测试的小麦赤霉、黄瓜灰霉等8种真菌都有不同程度的抑制作用,且完全抑制这些真菌孢子的萌发.通过室内生物测定发现该菌株对甜菜夜蛾具有很高的杀虫活性,半致死浓度(LC50>)仅为5.5 μg/mL.经特异引物检测,证明该菌株含有6种杀虫蛋白基因:crylAa、crylAb、crylAc、cry1I、cry2和vip3A.经SDS-PAGE分析,Bt519-1菌株分别产生分子量大约为135 kD~130 kD、95 kD、80 kD、70 kD和65 kD~60 kD的几种杀虫晶体蛋白.在有无几丁质的培养基中都能产生较高活性的几丁质酶.试验证明苏云金芽胞杆菌Bt519-1是一株既杀虫又拮抗真菌的多功能生防菌株.  相似文献   

18.
简述了苏云金杆菌Bacillus thuringiensisBt)毒素的作用方式及杀虫机理,分析了Bt棉种植过程中面临的生态风险。综述了昆虫对Bt毒素的抗性机理、监测方法及治理策略方面的研究进展。棉铃虫对Bt棉的抗性可能主要与中肠上皮细胞膜上的特异性结合受体中结合位点的改变有关。在多种抗性治理策略中,庇护所策略被公认为是目前最有效的并已广泛采用的抗性治理措施。应针对Bt棉在我国的种植情况,在棉铃虫还未在田间表现出抗性以前,制定合理的抗性预防、治理措施。  相似文献   

19.
Abstract: Feeding behaviour of Helicoverpa armigera Hübner (Lep.; Noctuidae) larvae on non‐transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum L.), Zhong 30, and transgenic cowpea trypsin inhibitor (CpTI)‐Bt cotton, SGK 321, and non‐transgenic cotton, Shiyuan 321, was investigated in both choice tests and no‐choice tests. The results of choice tests suggested that neonates have the ability to detect and avoid transgenic cotton. In the choice tests of neonates with both transgenic and non‐transgenic cotton leaves, a significantly greater proportion of larvae and higher consumption were observed on non‐transgenic cotton than on the transgenic Bt or CpTI‐Bt cotton. In the choice tests with leaves of two transgenic cotton lines, the proportion of neonates on leaf discs of the two lines was not significantly different, but there was significantly higher consumption on CpTI‐Bt transgenic cotton than that on Bt transgenic cotton. In addition, significantly more neonates were found away from the leaf discs, lower consumption and higher mortality were achieved in the choice test with two transgenic cotton leaves than in the choice tests containing non‐transgenic cotton leaves. Leaves and buds were examined in choice tests of fourth instars. It appeared that fourth instars were found in equal numbers on transgenic and non‐transgenic cotton, except when larvae were exposed to leaves for 3 h. However, the total consumption on transgenic cotton was lower than that of the non‐transgenic cotton, so fourth instars may still have the capacity to detect transgenic cotton and reduce feeding on it, although they showed no preference on either transgenic or non‐transgenic cotton. More larvae were found off diet in the treatments with leaves than that of buds, and the number of injured leaf discs by per fourth instar was significantly higher than that of buds in choice tests, suggesting that leaf is a less preferred organ for H. armigera larvae, elicited more larval movements. Similarly, in no‐choice tests of fifth instars, significantly fewer feeding time and more moving time occurred on leaf than that of bud, boll and petal. When cotton line was considered, compared with non‐transgenic cotton, significantly lower feeding time and higher resting time occurred on the two transgenic cottons. Overall, H. armigera larvae have the ability to detect the transgenic Bt and CpTI‐Bt cottons or the less preferred organs and selectively feed more on the non‐transgenic cotton or the preferred organs, especially the neonates, which have a high capacity for avoiding transgenic cotton.  相似文献   

20.
Brush border membrane vesicles (BBMV) isolated from insect midguts have been widely used to study CrylA binding proteins. Sample preparation is important in two- dimensional electrophoresis (2-DE), so to determine a suitable BBMV preparation method in Helicoverpa armigera for 2-DE, we compared three published BBMV preparation methods mostly used in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS- PAGE). All methods yielded similar types and numbers of binding proteins, but in different quantities. The Abdul-Rauf and Ellar protocol was the best of the three, but had limitations. Sufficient protein quantity is important for research involving limited numbers of insects, such as studies of insect resistance to Bacillus thuringiensis in the field. Consequently, we integrated the three BBMV isolation methods into a single protocol that yielded high quantities of BBMV proteins from H. armigera larval midguts, which proved suitable for 2- DE analysis.  相似文献   

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