转Bt基因稻谷对印度谷螟生长发育的影响

为建立仓储阶段转Bt水稻安全性评价中靶标害虫抗性汰选研究体系,配制了含不同比例(70%,50%,30%,10%)转Bt基因(Cry1Ab/Cry1Abc)明辉63水稻谷粉(简称Bt谷粉)的人工饲料饲喂印度谷螟Plodia interpunctella(Hübner),测定其对1～3龄幼虫在72h内的急性毒力,及对印度谷螟种群生长发育的影响,并采用ELISA法检测转基因稻谷和末龄幼虫体内Bt蛋白含量。结果发现:4种比例人工饲料对幼虫的毒力作用均发生在取食48h后,72h后剂量效应明显。含Bt水稻较高比例的饲料对印度谷螟发育的负面效应明显:幼虫死亡率高,发育历期延长。Bt蛋白在幼虫体内含量与对应饲料中的含量基本成正比。综合考虑,将Bt杀虫蛋白含量2.35μg/g作为转Bt基因稻谷对印度谷螟的亚致死剂量最为合适。     

Transfer of Cry1Ac and Cry2Ab proteins from genetically engineered Bt cotton to herbivores and predators

With the cultivation of Bt cotton, the produced insecticidal Cry proteins are ingested by herbivores and potentially transferred along the food chain to natural enemies, such as predators. In laboratory experiments with Bollgard II cotton, concentrations of Cry1Ac and Cry2Ab were measured in Lepidoptera larvae (Spodoptera littoralis, Heliothis virescens), plant bugs (Euschistus heros), aphids (Aphis gossypii), whiteflies (Bemisia tabaci), thrips (Thrips tabaci, Frankliniella occidentalis), and spider mites (Tetranychus urticae). Tritrophic experiments were conducted with caterpillars of S. littoralis as prey and larvae of ladybird beetles (Harmonia axyridis, Adalia bipunctata) and lacewings (Chrysoperla carnea) as predators. Immunological measurements (ELISA) indicated that herbivores feeding on Bt cotton contained 5%–50% of the Bt protein concentrations in leaves except whiteflies and aphids, which contained no or only traces of Bt protein, and spider mites, which contained 7 times more Cry1Ac than leaves. Similarly, predators contained 1%–30% of the Cry protein concentration in prey. For the nontarget risk assessment, this indicates that Bt protein concentrations decrease considerably from one trophic level to the next in the food web, except for spider mites that contain Bt protein concentrations higher than those measured in the leaves. Exposure of phloem sucking hemipterans is negligible.     

Bt Crops Producing Cry1Ac,Cry2Ab and Cry1F Do Not Harm the Green Lacewing,Chrysoperla rufilabris

The biological control function provided by natural enemies is regarded as a protection goal that should not be harmed by the application of any new pest management tool. Plants producing Cry proteins from the bacterium, Bacillus thuringiensis (Bt), have become a major tactic for controlling pest Lepidoptera on cotton and maize and risk assessment studies are needed to ensure they do not harm important natural enemies. However, using Cry protein susceptible hosts as prey often compromises such studies. To avoid this problem we utilized pest Lepidoptera, cabbage looper (Trichoplusia ni) and fall armyworm (Spodoptera frugiperda), that were resistant to Cry1Ac produced in Bt broccoli (T. ni), Cry1Ac/Cry2Ab produced in Bt cotton (T. ni), and Cry1F produced in Bt maize (S. frugiperda). Larvae of these species were fed Bt plants or non-Bt plants and then exposed to predaceous larvae of the green lacewing Chrysoperla rufilabris. Fitness parameters (larval survival, development time, fecundity and egg hatch) of C. rufilabris were assessed over two generations. There were no differences in any of the fitness parameters regardless if C. rufilabris consumed prey (T. ni or S. frugiperda) that had consumed Bt or non-Bt plants. Additional studies confirmed that the prey contained bioactive Cry proteins when they were consumed by the predator. These studies confirm that Cry1Ac, Cry2Ab and Cry1F do not pose a hazard to the important predator C. rufilabris. This study also demonstrates the power of using resistant hosts when assessing the risk of genetically modified plants on non-target organisms.     

Effects of Bt maize expressing Cry1Ab and Bt spray on Spodoptera littoralis

Various studies have been conducted to assess the damage caused by secondary lepidopteran pests to transgenic Bt maize expressing Cry1Ab. However, to date little is known on the effects of transgenic maize on Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae), a polyphagous herbivore which is considered a pest in Mediterranean maize growing areas. Here we present results on the effects of Bt maize (Bt‐11) and Bt spray (Dipel) on the various life stage parameters of this herbivore. We further assess the expression of Cry1Ab in different leaves and leaf parts in maize at a given plant growth stage, and determine whether the feeding damage of 3rd instar S. littoralis is influenced by Bt toxin expression. Contrary to previous literature reporting that S. littoralis is not sensitive to Bt Cry1Ab toxin, our results show that insects fed on either transgenic or Bt sprayed plants were negatively affected. Young S. littoralis larvae (1st and 2nd instars) were found to be the most sensitive to the Bt toxin. This was represented by a higher mortality and a slower developmental time of larvae maintained on transgenic or sprayed plants when compared to insects maintained on control plants. Moreover, Bt maize had a stronger and prolonged detrimental effect on insects when compared to Bt spray in maize. This was revealed by the fact that insects maintained on transgenic plants from 3rd instar to pupation took longer to reach adult emergence compared to insects that were maintained on sprayed plants. This was likely due to the continuous exposure of insects to the toxin when kept on transgenic maize. ELISA results showed a variation in the amount of Bt toxin among different leaf sections in transgenic maize at a given plant growth stage. These differences in Bt toxin were primarily found in the youngest leaf of growing plants. Although the lowest amounts of Bt toxin were detected in the growing leaf section of young leaves, this difference did not appear to influence the feeding behavior of 3rd instar S. littoralis.     

转基因(Cry1Ac)抗虫棉对土壤微生物的影响

对不同种植年限的转基因(Cry1Ac)抗虫棉田土壤中主要微生物数量变化进行了测定,结果表明：（1）种植转基因抗虫棉后对土壤微生物细菌、放线菌和真菌数量的影响趋势基本相似;（2）种植抗虫棉1年后,土壤中细菌、放线菌、真菌数量将有所增加,连续4年达到高峰,然后数量开始下降,连续种植7年后,棉田微生物数量接近于种植1年的棉田;（3）种植1年后又种植非转基因棉花的棉田,土壤微生物数量低于种植1年抗虫棉的棉田,与种植非转基因棉的数量无明显差异。由此可见,种植转基因抗虫棉对土壤微生物数量有一定的影响。     

A Comprehensive Assessment of the Effects of Transgenic Cry1Ac/Cry1Ab Rice Huahui 1 on Adult Micraspis discolor (Fabricius) (Coleoptera: Coccinellidae)

Micraspis discolor (Fabricius) (Coleoptera: Coccinellidae) is a widely distributed coleoptera predator in southern Asia in rice ecosystem, and adult M. discolor feed on both rice pollen and soft-bodied arthropods. Bitrophic bioassay and tritrophic bioassay were conducted to evaluate the potential impact of Cry1Ac/Cry1Ab-expressing rice Huahui 1 and its non-transgenic counterpart Minghui 63 on fitness parameters of adult M. discolor. The results showed that the survival, and fecundity of this beetle’ adults were not different when they fed on Bt rice or non-Bt rice pollen or Nilaparvata lugens (Stål) reared on Bt rice or non-Bt rice. Toxicity assessment to ensure M. discolor adults were not sensitive to Cry1Ab or Cry1Ac protein independent from the pollen background, M. discolor adults were fed with an artificial diet containing Cry1Ac, Cry1Ab or both protein approximately 10 times higher concentration than in Huahui 1 rice pollen. No difference was detected for any of the life-table parameters tested between Cry protein-containing and pure diet. Artificial diet containing E-64 (N-(trans-Epoxysuccinyl)-L-leucine 4-guanidinobutylamide) was included as a positive control. In contrast, the pre-oviposition and fecundity of M. discolor were significantly adversely affected by feeding on E-64-containing diet. In both bioassays, the uptakes of Cry protein by adult M. discolor were tested by ELISA measurements. These results indicated that adults of M. discolor are not affected by Cry1Ab- or Cry1Ac-expressing rice pollen and are not sensitive to Cry protein at concentrations exceeding the levels in rice pollen in Huahui1. This suggests that M. discolor adults would not be harmed by Cry1Ac/Cry1Ab rice if Bt rice Huahui 1 were commercialized.     

Efficacy of Genetically Modified Bt Toxins Alone and in Combinations Against Pink Bollworm Resistant to Cry1Ac and Cry2Ab

Evolution of resistance in pests threatens the long-term efficacy of insecticidal proteins from Bacillus thuringiensis (Bt) used in sprays and transgenic crops. Previous work showed that genetically modified Bt toxins Cry1AbMod and Cry1AcMod effectively countered resistance to native Bt toxins Cry1Ab and Cry1Ac in some pests, including pink bollworm (Pectinophora gossypiella). Here we report that Cry1AbMod and Cry1AcMod were also effective against a laboratory-selected strain of pink bollworm resistant to Cry2Ab as well as to Cry1Ab and Cry1Ac. Resistance ratios based on the concentration of toxin killing 50% of larvae for the resistant strain relative to a susceptible strain were 210 for Cry2Ab, 270 for Cry1Ab, and 310 for Cry1Ac, but only 1.6 for Cry1AbMod and 2.1 for Cry1AcMod. To evaluate the interactions among toxins, we tested combinations of Cry1AbMod, Cry1Ac, and Cry2Ab. For both the resistant and susceptible strains, the net results across all concentrations tested showed slight but significant synergism between Cry1AbMod and Cry2Ab, whereas the other combinations of toxins did not show consistent synergism or antagonism. The results suggest that the modified toxins might be useful for controlling populations of pink bollworm resistant to Cry1Ac, Cry2Ab, or both.     

Capturing the interaction types of two Bt toxins Cry1Ac and Cry2Ab on suppressing the cotton bollworm by using multi‐exponential equations

Transgenic crops are increasingly promoted for their practical effects on suppressing certain insect pests, but all transgenic crops are not equally successful. The insect pests can easily develop resistance against single Bacillus thuringiensis (Bt) toxin transgenic crops. Therefore, transgenic crops including two or more mixed Bt‐toxins can solve this problem by delaying the resistance development and killing the majority of targeted pests before the evolution of resistance. It is important to test the controlling effects of transgenic crops including multiple mixed toxins on a particular insect pest. Previous research has checked the cross‐resistance and interactions between Bt toxins Cry1Ac and Cry2Ab against one susceptible and four resistant strains of cotton bollworm. The results showed that independence was the main interaction type between two toxins for the susceptible strain, whereas synergism was the main interaction type for any one resistant strain. However, the optimal combinations of two toxins were not obtained. In the present study, we developed two multi‐exponential equations (namely bi‐ and tri‐exponential equations) to describe the combination effects of two Bt toxins. Importantly, the equations can provide predictions of combination effects of different continuous concentrations of two toxins. We compared these two multi‐exponential equations with the generalized linear model (GLM) in describing the combination effects, and found that the bi‐ and tri‐exponential equations are better than GLM. Moreover, the bi‐exponential equation can also provide the optimal dose combinations for two toxins.     

Effects of transgenic Cry1Ac and Cry2Ab cotton on life table parameters and population dynamics of the cotton aphid

为研究新型转Cry1Ac+Cry2Ab基因棉对棉蚜Aphis gossypii Glover生命表参数及种群动态的影响.2010-2011年以常规棉中棉所49为对照,对新型转Cry1Ac+Cry2Ab基因棉在室内进行了生物测定和田间进行了系统的调查.结果表明,和常规棉相比,转Cry1Ac+Cry2Ab基因棉花上棉蚜的净增值率降低81.69％,差异达显著水平;内禀增长率和周限增长率分别降低65.00％和13.01％,但差异不显著;平均世代周期和种群加倍时间分别增加5.54％和154.19％,后者差异达显著水平.和常规棉相比,2010年转Cry1Ac+Cry2Ab基因棉花百株苗蚜、伏蚜和秋蚜的数量分别降低10.79％、37.18％和17.49％,差异均未达显著水平;2011年转Cry1Ac+Cry2Ab基因棉花百株苗蚜的数量增加2.03％,伏蚜和秋蚜的数量分别降低37.41％和64.03％,差异均未达显著水平.     

转Cry1Ac+Cry2Ab基因棉对棉蚜生命表参数及种群动态的影响

为研究新型转Cry1Ac+Cry2Ab基因棉对棉蚜Aphis gossypii Glover生命表参数及种群动态的影响。2010—2011年以常规棉中棉所49为对照,对新型转Cry1Ac+Cry2Ab基因棉在室内进行了生物测定和田间进行了系统的调查。结果表明,和常规棉相比,转Cry1Ac+Cry2Ab基因棉花上棉蚜的净增值率降低81.69%,差异达显著水平;内禀增长率和周限增长率分别降低65.00%和13.01%,但差异不显著;平均世代周期和种群加倍时间分别增加5.54%和154.19%,后者差异达显著水平。和常规棉相比,2010年转Cry1Ac+Cry2Ab基因棉花百株苗蚜、伏蚜和秋蚜的数量分别降低10.79%、37.18%和17.49%,差异均未达显著水平;2011年转Cry1Ac+Cry2Ab基因棉花百株苗蚜的数量增加2.03%,伏蚜和秋蚜的数量分别降低37.41%和64.03%,差异均未达显著水平。     

Resistance of Trichoplusia ni Populations Selected by Bacillus thuringiensis Sprays to Cotton Plants Expressing Pyramided Bacillus thuringiensis Toxins Cry1Ac and Cry2Ab

Two populations of Trichoplusia ni that had developed resistance to Bacillus thuringiensis sprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. The T. ni colonies resistant to Bacillus thuringiensis serovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistant T. ni strains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in the T. ni populations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptible T. ni strain. The resistance to Cry2Ab in resistant T. ni was an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops.     

转Cry1Ac+Cry2Ab棉花生长势及其对棉田节肢动物物种丰富度的影响

【背景】转基因棉花在商业化种植之前,必须评价其环境安全性。其中新型棉花材料的生存竞争能力和对物种丰富度的影响是评价的重要内容。【方法】以转Cry1Ac＋Cry2Ab基因棉为试验材料,转Cry1Ac棉花中棉所41和非转基因棉花中棉所49为对照品种,分别于2014年5~9月对棉花株高、主茎叶片数、叶绿素含量、比叶面积、果枝数、蕾铃数等生长参数进行比较,同时对二代、三代和四代棉铃虫发生期棉田物种丰富度进行系统调查。【结果】转Cry1Ac＋Cry2Ab棉花的生长势与转Cry1Ac棉花和非转基因棉花基本相当,没有表现出明显的竞争优势;产量构成参数在成铃和脱落等方面比非转基因棉表现出良好的优势。对棉田节肢动物物种丰富度的影响表明,转Cry1Ac＋Cry2Ab棉花对靶标害虫棉铃虫具有良好的控制效果,对主要刺吸性害虫棉蚜、棉蓟马、烟粉虱、绿盲蝽与天敌龟纹瓢虫、草间小黑蛛、草蛉和小花蝽等的种群丰富度在个别时期有所影响,但总体上与转Cry1Ac棉田和非转基因棉田没有显著性差异。【结论与意义】转Cry1Ac＋Cry2Ab棉花无竞争优势,但目标性状优势较好;对棉田节肢动物物种丰富度无明显影响。研究结果为新型转Cry1Ac＋Cry2Ab棉花对棉田环境安全方面的研究进一步补充了内容,为转基因棉花的环境安全评价提供科学数据。     

Frequency of alleles conferring resistance to the Bt toxins Cry1Ac and Cry2Ab in Australian populations of Helicoverpa armigera (Lepidoptera: Noctuidae)

Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an important lepidopteran pest of cotton (Gossypium spp.) in Australia and the Old World. From 2002, F2 screens were used to examine the frequency of resistance alleles in Australian populations of H. armigera to Bacillus thuringiensis (Bt) CrylAc and Cry2Ab, the two insecticidal proteins present in the transgenic cotton Bollgard II. At that time, Ingard (expressing Cry1Ac) cotton had been grown in Australia for seven seasons, and Bollgard II was about to be commercially released. The principal objective of our study was to determine whether sustained exposure caused an elevated frequency of alleles conferring resistance to Cry1Ac in a species with a track record of evolving resistance to conventional insecticides. No major alleles conferring resistance to Cry1Ac were found. The frequency of resistance alleles for Cry1Ac was <0.0003, with a 95% credibility interval between 0 and 0.0009. In contrast, alleles conferring resistance to Cry2Ab were found at a frequency of 0.0033 (0.0017, 0.0055). The first isolation of this allele was found before the widespread deployment of Bollgard II. For both toxins the experiment-wise detection probability was 94.4%. Our results suggest that alleles conferring resistance to Cry1Ac are rare and that a relatively high baseline frequency of alleles conferring resistance to Cry2Ab existed before the introduction of Bt cotton containing this toxin.     

Acquisition of Cry1Ac Protein by Non-Target Arthropods in Bt Soybean Fields

Soybean tissue and arthropods were collected in Bt soybean fields in China at different times during the growing season to investigate the exposure of arthropods to the plant-produced Cry1Ac toxin and the transmission of the toxin within the food web. Samples from 52 arthropod species/taxa belonging to 42 families in 10 orders were analysed for their Cry1Ac content using enzyme-linked immunosorbent assay (ELISA). Among the 22 species/taxa for which three samples were analysed, toxin concentration was highest in the grasshopper Atractomorpha sinensis and represented about 50% of the concentration in soybean leaves. Other species/taxa did not contain detectable toxin or contained a concentration that was between 1 and 10% of that detected in leaves. These Cry1Ac-positive arthropods included a number of mesophyll-feeding Hemiptera, a cicadellid, a curculionid beetle and, among the predators, a thomisid spider and an unidentified predatory bug belonging to the Anthocoridae. Within an arthropod species/taxon, the Cry1Ac content sometimes varied between life stages (nymphs/larvae vs. adults) and sampling dates (before, during, and after flowering). Our study is the first to provide information on Cry1Ac-expression levels in soybean plants and Cry1Ac concentrations in non-target arthropods in Chinese soybean fields. The data will be useful for assessing the risk of non-target arthropod exposure to Cry1Ac in soybean.     

Cytotoxicity and binding profiles of activated Cry1Ac and Cry2Ab to three insect cell lines

While Cry1Ac has been known to bind with larval midgut proteins cadherin, APN (amino peptidase N), ALP (alkaline phosphatase) and ABCC2 (adenosine triphosphate‐binding cassette transporter subfamily C2), little is known about the receptors of Cry2Ab. To provide a clue to the receptors of Cry2Ab, we tested the baseline cytotoxicity of activated Cry1Ac and Cry2Ab against the midgut and fat body cell lines of Helicoverpa zea and the ovary cell line of Spodoptera frugiperda (SF9). As expected, the descending order of cytotoxicity of Cry1Ac against the three cell lines in terms of 50% lethal concetration (LC₅₀) was midgut (31.0 μg/mL) > fat body (59.0 μg/mL) and SF9 cell (99.6 μg/mL). By contrast, the fat body cell line (LC₅₀ = 7.55 μg/mL) was about twice more susceptible to Cry2Ab than the midgut cell line (16.0 μg/mL), the susceptibility of which was not significantly greater than that of SF9 cells (27.0 μg/mL). Further, ligand blot showed the binding differences between Cry1Ac and Cry2Ab in the three cell lines. These results indicated that the receptors of Cry2Ab were enriched in fat body cells and thus largely different from the receptors of Cry1Ac, which were enriched in midgut cells.     

The effects of Cry2Ab and Cry1Ac insecticidal proteins on protease activity in the midgut of Helicoverpa armigera

为明确Cry2Ab和Cry1Ac 2种Bt杀虫蛋白单用与混用对棉铃虫Helicoverpa armigera(Hübner)中肠主要蛋白酶活性的影响,本文测定了取食含不同Bt蛋白人工饲料后棉铃虫中肠总蛋白酶、类胰蛋白酶和类胰凝乳蛋白酶活性的差异.结果发现:Cry2Ab处理12h后对棉铃虫中肠总蛋白酶影响不大;对类胰蛋白酶的影响最大,除最高浓度处理外,其他浓度处理后棉铃虫类胰蛋白酶的活性明显高于对照;但对类胰凝乳蛋白酶活性的影响呈倒“V”字型,只有6.67μg／g Cry2Ab处理后的棉铃虫酶活力显著高于对照,其他浓度处理与对照差异不显著或略低于对照;随着取食含Cry2Ab饲料时间的增加,棉铃虫中肠类胰蛋白酶和类胰凝乳蛋白酶的活性比对照显著增加;与对照相比,处理36h后类胰蛋白酶活性最高可增加到6.43倍.Cry1Ac处理棉铃虫12h后总蛋白酶、类胰蛋白酶和类胰凝乳蛋白酶活性都明显增加,而且与处理浓度呈正相关;但是24h后,处理后棉铃虫的总蛋白酶和类胰凝乳蛋白酶活性明显降低,只有类胰蛋白酶活性仍高于对照,但活性增长倍数低于12h时的处理.Cry2Ab和Cry1Ac 2种蛋白混用处理棉铃虫后,2种酶的酶活力基本低于Cry1Ac和Cry2Ab单用的酶活力之和;只有2种蛋白浓度均为2.22μg/g混用时,处理12b后类胰蛋白酶和类胰凝乳蛋白酶的活性高于2种蛋白单用时酶活力之和,且都显著的高于对照.     

转（Bt Cry1Ac+CP4EPSPS）基因抗虫抗草甘膦棉花对草甘膦的耐受性研究

本研究比较了转Bt Cry1Ac+CP_4EPSPS基因抗棉铃虫抗草甘膦棉花与常规棉花在新疆棉区对草甘膦的耐受性差异。两年的研究结果表明,转Bt Cry1Ac+CP_4EPSPS基因抗棉铃虫抗草甘膦棉花对草甘膦有较好的耐受性,而对照棉花中棉所49对草甘膦耐受性较差。苗期喷施草甘膦后转基因抗棉铃虫抗草甘膦棉花生长发育没有受到影响,而对照棉花中棉所49喷施草甘膦后生长发育受到了明显的影响,个别植株甚至死亡。转Bt Cry1Ac+CP_4EPSPS基因抗棉铃虫抗草甘膦棉花株高、真叶数、蕾数、产量等指标与对照相比差异显著。转Bt Cry1Ac+CP_4EPSPS基因棉花对草甘膦的耐受程度显著高于非转基因棉花。草甘膦对转基因抗草甘膦棉花无负面影响。     

Bio‐safety evaluation of Cry1Ac,Cry2Ab,Cry1Ca,Cry1F and Vip3Aa on Harmonia axyridis larvae

Dietary exposure studies are initial steps in environmental risk assessments of genetically engineered plants on non‐target organisms. These studies are conducted in the laboratory where surrogate species are exposed to purified and biologically active insecticidal compounds at higher concentrations than those expected to occur in transgenic crops foliage. Thus, dietary exposure (early tier) tests provide robust data needed to make general conclusions about the susceptibility of the surrogate species to the test substance. For this, we developed suitable artificial diet and used it to establish a dietary exposure test for assessing the toxicity of midgut‐active insecticidal compounds to the larvae of the Asian ladybird beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Using boric acid as a model compound, we validated the bioassay established for H. axyridis larvae. An artificial diet containing boric acid which negatively affected survival, development and adult weights was offered to larvae and indicated that the bioassay was able to detect toxic effects of insecticidal substances incorporated in diets. Using this dietary exposure test, environmental risk assessment of Cry1Ac, Cry2Ab, Cry1Ca, Cry1F and the non‐Cry protein Vip3Aa was evaluated by analysing pupation rates, adult emergence rates, 7‐day larval weights, and freshly emerged male and female weights among the toxin treatments and a pure artificial diet. These life‐table parameters did not vary among artificial diets containing 200 μg/g Bt proteins or pure artificial diet. In contrast, boric acid adversely affected all life‐table parameters. Thus on these bases, we concluded H. axyridis larvae are not sensitive to these Bt proteins expressed in genetically engineered crops.     

Bt毒蛋白Cry1Ac在人造土壤中对赤子爱胜蚓毒理及生化影响

Bt毒素能通过转基因作物的花粉、根和残株进入土壤.为评估转基因作物对土壤动物的影响,本文模拟转基因棉的Bt毒素进入土壤的发生程度,用含不同浓度Bt毒蛋白Cry1Ac的人造土壤处理蚯蚓,测定蚯蚓存活率、重量变化及体内总蛋白含量和过氧化氢酶(CAT)、乙酰胆碱酯酶(AchE)、谷胱甘肽-S-转移酶(GST)和纤维素酶活性.结果表明,Bt毒蛋白对蚯蚓的生物量和生理水平影响均不明显,不存在急毒性和亚致死毒性影响,对蚯蚓比较安全.     

Cry1Ac和Cry2Ab杀虫蛋白对粘虫幼虫生长发育的影响

【目的】为探究Bt杀虫蛋白对次要靶标害虫粘虫Mythimna separata (Walker)(鳞翅目:夜蛾科)的杀虫活性及对其生长发育的影响。【方法】本文通过浸叶法饲喂初孵及2龄末粘虫不同剂量的Cry1Ac及Cry2Ab杀虫蛋白后,观察其死亡率,称量幼虫重,并统计了幼虫历期、化蛹率、蛹重、蛹期、蛹的羽化率、畸形率等指标。【结果】初孵幼虫取食浸泡含16、64、128μg/mLCry1Ac及Cry2Ab的玉米叶片后,随着时间的延长及浓度的增加,死亡率逐渐增加,且Cry1Ac杀虫蛋白对粘虫的生物活性高于Cry2Ab蛋白,在128μg/mL浓度下,取食Cry1Ac和Cry2Ab蛋白13d时的死亡率分别达到了65%及60%。取食两种蛋白后,初孵幼虫和2龄末幼虫重量均受到显著抑制,短期取食两种蛋白对幼虫历期、化蛹率、蛹重、蛹期、蛹的羽化率、畸形率没有影响。【结论】取食Cry1Ac和Cry2Ab杀虫蛋白后,对初孵幼虫有很好的杀虫活性,且Cry1Ac杀虫活性高于Cry2Ab杀虫蛋白;短期饲喂两种杀虫蛋白时,对2龄粘虫后期生长影响不大。本文结果为转Bt基因作物更好的应用于粘虫的防治提供了理论基础。