添加剂对苏云金杆菌制剂杀虫效果的影响

供试13种化学物质中,12种物质对Bt制剂的杀虫效果有增效作用,各物质的不同质量浓度对杀虫效果影响差异显,在1g/L的剂量以下,多数添加剂的增效作用,随剂量的增加而增强,添加0．5g/L巯基乙醇增效作用最佳,增效倍数达3．61倍,0．5g/L的甲酸和尿素,及0．1g/L碳酸钾具有较好的增效作用,增效倍数分别为2．52,2．32和2．56和2．56倍,0．5g/L的马来酸,氯化钙,乙二胺四乙酸,氯化镁,硼酸,碳酸钠和1g/L的柠檬酸,磷酸氢二钾8种添加剂的增效倍数为0．53－1．88倍。     

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)。     

Synergism between Bacillus thuringiensis and Xenorhabdus nematophila against resistant and susceptible Plutella xylostella (Lepidoptera: Plutellidae)

The diamondback moth (DBM) Plutella xylostella (L.) is one of the most destructive pests of crucifer crops in many parts of the world. Inappropriate applications have caused DBM to become resistant to most insecticides. We tested the combined effects of the bacteria Bacillus thuringiensis (Bt) and Xenorhabdus nematophila (Xn) against DBM. Populations of Bt-resistant moths (DBM-R), selected repeatedly with B. thuringiensis subsp. kurstaki HD-73 (Bt HD-73), showed resistance rates of 105.43 and 0.92 for Bt HD-73 and X. nematophila HB310 (Xn HB310), respectively. These results not only indicated that DBM-R is highly resistant to Bt HD-73 and only slightly resistant to Xn HB310, but also showed that there is no interactive resistance between the two bacteria. For the third-instar larvae of DBM-R and DBM-S, no significant differences were found in the oral insecticidal activities of Bt HD-73?+?Xn HB310 combination treatments or Bt HD-73 alone. However, mortality rates were significantly increased in response to Xn HB310?+?Bt HD-73 when compared with the Xn HB310-alone treatment. These results demonstrate a synergism of Bt on Xn, but no such effect of Xn on Bt. Therefore, our findings highlight the potential for both bacteria to be used in a mixture for field applications.     

Fitness costs and stability of resistance to Bacillus thuringiensis in a field population of the diamondback moth Plutella xylostella L.

1. The stability of resistance to Bacillus thuringiensis Crystal (Cry) toxins in highly and moderately resistant sub‐populations of a Plutella xylostella field population (SERD4) was compared under laboratory conditions. The relative rate of decrease in resistance was greater in a highly resistant Cry1Ac‐selected population than in moderately resistant Cry1Ab‐ and Cry1Ca‐selected populations. 2. The intrinsic rate of population increase (r_m) was similar in all populations tested. 3. These results suggest that there are no obvious overall fitness benefits as the frequency of the resistance alleles is reduced.     

小菜蛾对杀虫剂的敏感性与其抗药性的相关性

在开展云南省通海县小菜蛾Plutella xylostella(L.)种群对11种杀虫剂的敏感性的同时,对小菜蛾抗药性进行了测定,并分析二者之间的相关性,结果表明:小菜蛾对杀虫剂的敏感性与其抗药性总体上呈现负相关,即随着抗药性的增加,小菜蛾对杀虫剂的敏感性呈下降趋势,但相关性并不显著。如在无抗性至高抗性的杀虫剂之间,其敏感性并无明显的变化,处理间无差异,只有对其极高抗性的阿维菌素、虫酰肼和高效氯氰菊酯才表现出明显的下降趋势。因此,在实际生产过程中,一种药剂是否因抗药性增加而不能使用,还应该参照田间防治效果。     

Screening of oilseed rape cultivars relation to diamondback moth,Plutella xylostella (Lep.: Plutellidae) in fields of Tehran

The diamondback moth (DBM), Plutella xylostella (L.) (Lep., Plutellidae), is one of the most important pests of oilseed rape, Brassica napus L., in the world. In this study, resistance of oilseed rape cultivars to DBM was evaluated in fields of Tehran based on injury rate of the cultivars. To evaluate cultivar resistance, 19 cultivars of oilseed rape were planted in randomised complete-block design with three replications. Total experiments were conducted in experimental field of Shahed University. Results showed that DBM had activity on the plants during season and peak of the injury occurred on 27 May. Results indicated that the total of oilseed rape cultivar was spotty. Statistical analysis showed that there was significant difference among determined characteristics in all cultivars. The highest and lowest numbers of holes in the leaf were observed in Midas, Karaj3, Zarfam and Hyola420, Hyola308 cultivars, respectively, in sampling of the end growth. Opera and Midas cultivars have the highest percentage of leaf infestation and the lowest percentage of leaf infestation was observed in Hyola420 and Hyola308. Also, Karaj3 and Zarfam cultivars have the highest percentage of meristem infestation and the lowest percentage of meristem infestation was observed in Licard and Hyola420 cultivars. Based on peak of the injury rate and importance of meristem injury, Hyola420 and Hyola308 cultivars were relatively resistant to DBM, and Karaj3 and Zarfam were relatively sensitive to DBM.     

Diamondback moth resistance to Bacillus thuringiensis transgenic canola: evaluation of refugia size with non-recessive resistant insects

Abstract:  Current recommendations to delay the evolution of resistance to Bacillus thuringiensis crops are that a minimum of 5–50% of a crop-growing region should include non- B. thuringiensis varieties as refuges. These recommendations are based in part on the assumption that resistance will be inherited as a recessive trait. Laboratory microcosm experiments are described with transgenic canola expressing Cry1Ac and a non-recessive Cry1Ac resistant population of the diamondback moth Plutella xylostella , in which the effect of different sizes of refugia (0%, 20% and 50%) on resistance was compared over five generations. The LC₅₀ values for Cry1Ac increased markedly in the P. xylostella sub-populations with 0% (>100-fold) and 20% refugia (>35-fold) but showed little change (less than fivefold increase) with 50% refugia. The results support the idea that relatively high levels of refugia (non- B. thuringiensis varieties) may be required where resistance is not functionally recessive at the level of toxin expressed in the B. thuringiensis crop.     

Antimicrobial peptides are not involved in Plutella xylostella resistance to Cry1Ac

Previous studies on Bacillus thuringiensis (Bt) resistance in the diamondback moth (DBM) Plutella xylostella have often focused on receptor proteins in the gut. In recent years, many studies have indicated that insect resistance to Bt is related to the immune system. Moreover, our group demonstrated that the expression of peptidoglycan recognition protein (PGRP) genes, which are located upstream of the insect humoral immune system signalling pathway, is significantly different between Cry1Ac-resistant and Cry1Ac-susceptible strains of DBM. Thus, whether antimicrobial peptides (AMPs), which are the major downstream effectors of the insect humoral immune system signalling pathway, are also related to the resistance of DBMs to Bt is a question worthy of in-depth study. In the present study, we sought to (a) clone the CDS of AMP genes expressed in DBMs and (b) explore the effect of the cloned AMPs on the biological characteristics and Bt resistance of DBMs. Here, we revealed three kinds of AMPs (PxDef, PxMor and PxCec), and each of their full-length CDSs was cloned. The recombinant PxDef, PxMor or PxCec proteins, which were expressed in a prokaryotic expression system, have a significant protective effect on DBMs in response to the complex microbial environment of the outside world but have no significant effect on the resistance of DBMs to Cry1Ac toxin. We believe that AMPs are not suitable as the primary entry point for studying the relationship between the immune system of DBMs and their resistance to Bt. This result will enable investigation of breakthrough ideas for further elucidating the mechanism of Bt impact on the insect immune system.     

Insecticidal effects of selected biological control agents on the larvae of Plutella xylostella (Lepidoptera: Plutellidae)

To identify a more effective and safe biological control agent against a common cabbage pest, Plutella xylostella (L.) (Lepidoptera: Plutellidae), the insecticidal effects of selected biological agents were evaluated. The highest insecticidal effects determined were 100, 73.5, 45.5, 47 and 55.3% using toxin HD‐1 (isolated from the Harry Dumagae strain of Bacillus thuringiensis), toxin BTS‐1 (isolated from the tenebrionis strain of B. thuringiensis), B. thuringiensis Berliner, B. thuringiensis israelensis and B. thuringiensis kurstaki, respectively.     

一株对小菜蛾高毒力的苏云金杆菌的选育及研究

利用醋酸钠 抗生素法从土壤中分离出 1株对小菜蛾 (Plutellaxylostella)高毒力的苏云金杆菌Bt 990 5。该菌对小菜蛾 4 8h的平均死亡率为 98.5 %。高于标准菌株HD 1(81.2 % )。同时 ,对该菌的形态、培养特征 ,生化特性和杀虫晶体蛋白的分子量的测定以及cry基因类型的鉴定进行了研究。     

小白菜种质资源对小菜蛾的抗性评价

本文就小白菜种质资源对小菜蛾的抗性进行室内鉴定,结果表明268份材料的虫害指数分布在18.10～100.00之间,种质资源间抗虫性差异达到显著水平.聚类分析将268份种质资源分为6大类,与高抗、抗、中抗、中感、感、高感相对应,其中筛选出高抗和抗性材料分别为6和11份.对268份材料的主要形态性状与虫害指数和抗性级别的相关分析表明,小白菜种质资源叶面的皱缩度与抗虫性存在一定的相关性,认为从叶面平滑型的种质资源中筛选抗虫性材料的可能性更大.     

Control of Lepidopteran insect pests in transgenic Chinese cabbage (Brassica rapa ssp. pekinensis) transformed with a synthetic Bacillus thuringiensis cry1C gene

 A synthetic Bacillus thuringiensis cry1C gene was transferred to three Korean cultivars of Chinese cabbage via Agrobacterium tumefaciens-mediated transformation of hypocotyl explants. Hygromycin resistance served as an efficient selective marker. The transformation efficiency ranged from 5% to 9%. Transformation was confirmed by Southern blot analysis, PCR, Northern analysis, and progeny tests. Many transgenic plants of the closed-head types (lines Olympic and Samjin) flowered in vitro. Over 50 hygromycin-resistant plants were successfully transferred to soil. The transgenic plants and their progeny were resistant to diamondback moths (DBM, Plutella xylostella), the major insect pest of crucifers world-wide, as well as to cabbage loopers (Trichoplusia ni) and imported cabbage worms (Pieris rapae). Both susceptible Geneva DBM and a DBM population resistant to Cry1A protein were controlled by the Cry1C-transgenic plants. The efficient and reproducible transformation system described may be useful for the transfer of other agriculturally important genes into Chinese cabbage. Received: 12 June 2000 / Revision received: 21 August 2000 / Accepted: 22 August 2000     

小菜蛾对九种杀虫剂的抗药性

采用叶片药膜法测定了9种杀虫剂对海南、山东、广东、湖北武汉和襄樊等5个地区小菜蛾Plutella xylostella(L.)田间种群的毒力,和室内相对敏感品系比较。结果显示,5个地区的小菜蛾种群都对氯氰菊酯产生了10倍以上的抗性,广东和山东种群达到30倍以上的抗性。对阿维菌素的抗性山东小菜蛾种群达到135倍,广东种群达到30倍,其他地区均在10倍以下。但是,作用机制与阿维菌素类似的药剂,氟虫腈的抗性5个地区均在5倍或5倍以下。对昆虫生长调节剂定虫隆和氟虫脲的抗性除广东种群分别在10倍和20倍以上外,其他地区均在5倍以下。广东种群对多杀菌素的抗性为7.8倍,其他地区的种群没有产生抗性,多杀菌素和杀虫双均为作用于乙酰胆碱受体的药剂,但是作用的位点不同。杀虫双对5个种群的LC50值均是比较大的(>800 mg/L),尽管没有明显的抗性,不适宜用于小菜蛾田间防治。对呼吸链电子转移抑制剂溴虫腈的抗性均在10倍以下。对辛硫磷的抗性在2~5倍。     

小菜蛾取食后上海青的保护酶活力变化

上海青遭受小菜蛾取食为害后,0.5小时内叶片的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、多酚氧化酶(PPO)和总酚含量发生变化。就一天内的变化趋势而言,受害叶片的SOD、CAT、POD、PPO活力和总酚含量总体上比正常叶片低,但在15：00时,正常叶片的SOD、CAT和POD活力最低时,受害叶片的三种酶活力却明显上升,在11：00时,正常叶片PPO活力为最低值时,受害叶片的PPO活力达最高,这可能是过度胁迫造成的,正常叶片的PPO活力与总酚量负相关,但受害叶片不呈现这种关系,此外,受害植株的未受害叶的保护酶活力也不同程度地发生变化,可见上海青对小菜蛾的取食胁迫后保护酶的反应是系统性的。     

小菜蛾咬食后青菜释放的挥发性物质成分和含量的变化

在虫害条件下,青菜释放出的挥发性化学物质成分较多．其中饱和烷烃类物质占多数,其次是芳烃类物质,其它为少量的不饱和烷烃、醛、醇、酮、酸和杂环化合物等．经小菜蛾取食危害的青菜释放的挥发性物质的量比未受损伤的青菜高3倍,且挥发性物质种类也多些．前者的挥发性物质多为分子量较小的物质,后者的挥发性物质多为分子量较大的物质．     

小菜蛾幼虫对不同寄主的取食嗜好性及其适宜性

对不同寄主种类、不同寄主形态和不同寄主饲喂的小菜蛾(Plutella xylostella)幼虫之间的取食嗜好性比较试验表明,小菜蛾幼虫优先取食大白菜、萝卜或菜心幼苗,其次为油菜和甘蓝幼苗,在大白菜与油菜幼苗之间的取食选择比例是93.33%和6.67％;在甘蓝与菜心幼苗之间的取食选择比例是16.67%和83.33%.小菜蛾幼虫的取食嗜好性受饲喂寄主种类的影响,偏食大白菜或菜心幼苗.小菜蛾幼虫选择寄主取食的次序与寄主体内可溶性糖或淀粉含量没有明显关系,但与两者的相对量呈一定的负相关.取食大白菜或菜心幼苗的小菜蛾生长良好,单头取食达0.583～0.637 cm², 单头体重达2.07～2.18 mg, 与取食甘蓝或油菜幼苗的幼虫在取食量、个体发育方面有明显差异.小菜蛾幼虫也喜好取食已经被虫危害过的幼苗.     

乙基多杀菌素抗性小菜蛾代谢解毒酶酶活性研究

【目的】阐明小菜蛾Plutella xylostella(L.)对乙基多杀菌素的代谢抗性机理,为延缓小菜蛾对乙基多杀菌素抗药性发展及抗性治理技术提供支持。【方法】通过酶动力学方法测定了小菜蛾对乙基多杀菌素高抗、中抗和敏感种群的谷胱甘肽-S-转移酶、羧酸酯酶、乙酰胆碱酯酶和多功能氧化酶4种代谢解毒酶的比活力。【结果】乙基多杀菌素高抗小菜蛾种群的谷胱甘肽-S-转移酶、羧酸酯酶、乙酰胆碱酯酶的比活力分别为15.38、3.15和7.30 OD·min~(-1)·mg~(-1)pro,显著高于敏感种群;但乙酰胆碱酯酶在中抗种群和敏感种群中比活力差异不显著;多功能氧化酶在高抗、中抗和敏感种群中的比活力分别为4.97、4.08和4.23 OD·min~(-1)·mg~(-1)pro,差异不显著。【结论】谷胱甘肽-S-转移酶、羧酸酯酶和乙酰胆碱酯酶的酶活随着小菜蛾对乙基多杀菌素抗性的增强而增强,而多功能氧化酶的酶活在抗性种群与敏感种群间差异不显著,因此小菜蛾对乙基多杀菌素的代谢抗性机理研究应重点关注这3种酶。     

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。     

Monitoring of resistance for the diamondback moth to Bacillus thuringiensis Cry1Ac and Cry1Ba toxins and a Bt commercial formulation

Abstract:  To monitor the resistance of field populations of the diamondback moth Plutella xylostella in China to the insecticidal protein Cry1Ac, Cry1Ba and commercial formulation Bacillus thuringiensis var. kurstaki (Btk), six representative populations of the diamondback moth were collected from Shanghai, Shandong, Hubei, Hunan, Zhejiang and Guangdong provinces of China where crucifer crop plants are intensively planted. Bioassay results showed that the populations of the diamondback moth from different locations exhibited different levels of resistance, compared with a susceptible laboratory population. The Guangdong field population was 56.15- and 21.90-fold resistant to Cry1Ac and Btk, respectively. Shanghai, Hunan, Shandong and Zhejiang populations were 37.85-, 17.24-, 10.24- and 9.41-fold resistant to Cry1Ac, respectively, but were not resistant to Btk. The Hubei population did not show resistance to Cry1Ac and Btk. Almost all tested populations were susceptible to Cry1Ba, but the Guangdong population showed some tolerance to Cry1Ba with a LC₅₀ of 0.69  μ g/ml which was 6.17-fold higher than that of the susceptible population. The results suggested that the complex resistance patterns of field populations of P. xylostella need to be considered for expression of Bt toxin genes in genetically-engineered crop plants and commercial formulations.     

Seasonal population fluctuations of the diamondback moth,Plutella xylostella (L.) (Lep.: Plutellidae) on different cauliflower cultivars

The diamondback moth, Plutella xylostella (L.) (Lep.: Plutellidae) is one of the most important pests of cruciferous plants throughout the world. In recent years, it has been identified as a serious pest of the cauliflower fields in Tehran province. Resistance of P. xylostella to all main groups of insecticides has been recorded and it is ranked in the 20 most resistant pest species reported until now. According to many researchers, to solve the problem of pest resistance to chemical pesticides, an integrated pest management programme should be used. Despite this condition, it seems that the use of resistant cauliflower cultivars is an appropriate policy for integrated control of the pest in the field. In order to identify the most resistant cultivar in the field, eight cauliflower cultivars in a completely randomised design with five replicates were planted at the Shahed University research field (south of Tehran). Density of eggs, larvae and pupae of P. xylostella were measured every 10 days in these cultivars. The results showed that there is no significant difference between numbers of eggs per plant on different cultivars. But number of larvae and pupae per plant were significantly different among different cultivars. Smilla and Snow mystique cultivars had the highest number of larvae and pupae. On the other hand, Buris and Snow crown cultivars had the lowest number of pupae and Snow crown and SG cultivars had the lowest number of larvae per plant. According to the results, the Buris and Snow crown cultivars had the lowest infestation and had a kind of resistance to pest.