Sr18菌代谢产物对线虫应激能力的影响

基于Sr18菌代谢产物在24 h内具有显著的杀线虫活性,为进一步探究其杀线虫机理和作用规律,测定其在16 h内对线虫应激能力的影响。结果表明,在4 h时处理组对外界条件刺激的敏感性明显提高,运动频率均高于对照组,表明4 h为Sr18菌代谢产物对线虫产生作用的转折点;8 h后处理组活跃程度明显减弱,对刺激的反应较对照组缓慢,随着刺激时间增加,处理组的活跃性有所增加但不显著,表明Sr18菌代谢产物已产生明显的药效作用,致使线虫对刺激反应迟钝。Sr18菌代谢产物对线虫应激能力的影响呈现"平稳-上升-下降"的规律,进一步探究Sr18菌代谢产物的作用机理为实践中的合理用药提供理论依据。     

树干注射和根施农药控制松材线虫病试验

采用树干注射16%虫线清乳油500 mL/L溶液兼根施3%呋喃丹颗粒剂的施药技术,对重点风景名胜区、佛教胜地、重要生态区域松材线虫病发生区50年以上的马尾松实施保护性防治,取得了良好的防治效果,与对照区比较,防治后的第1~3年,病死树分别减少51.6%-52.9%、39.8%-80.9%和100%,有效地保护了具重要价值的马尾松树林和生态环境安全。     

Detection and analysis of inter- and intraspecific diversity of Pratylenchus spp. using isozyme markers

The root-lesion nematodes of the genus Pratylenchus are an economically important group of plant parasitic nematodes that show high similarity among sibling species. Isozyme patterns obtained by isoelectrofocusing (IEF) were used to differentiate and establish genetic relatedness among Pratylenchus species. A total of 40 populations comprising 9 Pratylenchus species and Radopholus similis from broad host and geographic origins was examined to compare isozyme patterns of esterase (EST), hexoquinase (HK), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH), phosphoglucose isomerase (PGI), phosphoglucomutase (PGM) and superoxide dismutase (SOD). Of these systems, only EST, MDH, PGI and PGM were useful for differentiation of P. vulnus , P. goodeyi , P. penetrans , P. scribneri , P. thornei and R. similis populations. The greatest intraspecific diversity was found within P. coffeae based on the isozyme patterns for MDH, PGI and PGM. Intraspecific variability was also detected among R. similis populations, which showed two isozyme patterns in EST and PGI systems. Less intraspecific variation was found within the P. penetrans group. The P. goodeyi population from Cameroon differed from the other populations in this specific group in its MDH, PGI and PGM phenotypes. Highly similar banding patterns of EST, MDH and PGI activity were found among the P. scribneri populations and the one population of P. agilis . A cluster analysis of the 40 populations, generated from the four enzyme banding patterns, produced groupings that broadly matched the previous classification into specific groups, reflecting intraspecific variability in some cases. The results confirm the potential use of isozyme patterns as markers for these nematode species and their value for diagnostic application.     

鄂尔多斯细毛羊7种常见消化道线虫卵原始图像库的初步建立

为实现粪便虫卵检查法的数字化和自动化,本文在调查鄂尔多斯细毛羊消化道主要线虫病流行病学基础上,广泛收集感染率普遍较高的细颈线虫(Nematodirus)、夏伯特线虫(Chabertia)、捻转血矛线虫(Haem onchus contor-tus)、毛圆线虫(Trichostrongylus)、仰口线虫(O esophagostomum)、食道口线虫(Bunostomum)和奥斯特线虫(O stertagia)卵原始图像,并经photoshop9.0应用软件进行人工分割和背景清理,初步建立了以上7种线虫卵的原始图像库。虫卵图像库共包含1 320幅原始图像,每种虫卵图像至少100幅以上,基本涵盖了每种虫卵图像的多种表现形式,为后期的虫卵图像数字化描述和自动识别奠定了基础。     

根瘤内生细菌对大豆胞囊线虫及根腐病菌的影响

为了明确大豆根瘤内生芽孢杆菌Snb2对大豆胞囊线虫的毒性和大豆根腐病菌的抑制作用,用菌悬液处理和对峙培养法分别测定了Snb2对两种病原微生物的作用效果.结果表明:Snb2的菌悬液能够明显抑制大豆胞囊线虫胞囊的孵化,相对抑制率达到94.9%;菌悬液处理J2 96 h时死亡率达到66.7%;Snb2菌株对4种大豆根系病原真菌表现不同程度的拮抗作用,对尖孢镰刀菌和茄腐镰刀菌的拮抗作用最明显,抑菌圈达到10 mm左右,抑制作用可持续10 d;经细菌悬浮液浸种测定,处理后的大豆子叶节到根尖的距离为9.1±4.54 cm,较对照增加了15.19%%,对幼苗生长有明显的促进作用;通过温室盆栽防效试验,进一步表明Snb2菌悬液进行种子浸种对大豆胞囊线虫病有明显的抑制作用,防治效果达到62.5%.     

昆虫病原线虫和共生细菌培养系统中噬菌体的检测

本文利用紫外照射、温度、pH、盐度诱导五株溶源性共生菌株Xenorhabdus和Photorhabdus同时测定斯氏和异小杆属线虫Steinernema carpocapsae A24,S.carpacapsae ALL,S.feltiae English,S.feltiae SN,Heterorhabditis bacterophora H06在体外培养过程中是否存在感染共生细菌的噬菌体。结果未发现噬菌斑，说明实验菌株在实验诱导条件下以及昆虫病原线虫固体培养系统中不可能诱发噬菌体的危害。     

甘肃省高寒草原牧草孢囊线虫的鉴定

2013年8月下旬,对甘肃天祝高寒草甸草原孢囊线虫发生情况进行调查,从嵩草和矮嵩草根部和根际土样中分离得到孢囊线虫。通过对孢囊和孢囊阴门锥的形态观察,初步鉴定为禾谷孢囊线虫(Heterodera avenae)。其特征为孢囊浅褐色,阔柠檬形,阴门锥双膜孔,未见阴门下桥,泡状突明显。利用通用引物AB28和TW81对其群体rDNA-ITS区进行PCR扩增和序列测定,得到ITS区序列长度为1045 bp。将所测得序列在Genbank和Blast上比对,结果显示,此禾谷孢囊线虫群体与H. avenae群体相似度达99%~100%。进一步证实寄生于甘肃天祝高寒草甸草原嵩草和矮嵩草的孢囊线虫均为H. avenae,这是首次报道莎草科嵩草和矮嵩草也是禾谷孢囊线虫的寄主。     

Resistance to a triple-combination anthelmintic in Trichostrongylus spp. on a commercial sheep farm in New Zealand

Abstract

AIM: To evaluate resistance to anthelmintics containing abamectin, levamisole, and oxfendazole (AB-LEV-OX), derquantal and abamectin (DEQ-AB), moxidectin, and monepantel in naturally acquired gastrointestinal nematodes present on a sheep farm.

METHODS: Faecal nematode egg count reduction tests (FECRT) were carried out on lambs that were approximately 7 months-old and infected with naturally acquired nematodes. Lambs were randomly allocated to one of five groups (n=15 per group): treatment with 2?mg/kg derquantel and 0.2?mg/kg abamectin; 0.2?mg/kg abamectin, 8?mg/kg levamisole HCl and 4.5?mg/kg oxfendazole; 2.5?mg/kg monepantel; 0.2?mg/kg moxidectin, or no treatment. Post-treatment samples were collected 12 days later. Abomasa and small intestines were collected from two slaughtered lambs from each of the DEQ-AB, AB-LEV-OX, moxidectin and control groups 15 days after treatment, for nematode counting.

RESULTS: The FECRT demonstrated that efficacy was 90.3 (95% CI=84.2–94.1)% for AB-LEV-OX, 54.5 (95% CI=28.4–71.1)% for moxidectin, 99.2 (95% CI=97.4–99.8)% for DEQ-AB and 100% for monepantel, across all genera. For Trichostrongylus spp. efficacy was 85.5% for AB-LEV-OX and 46.7% for moxidectin. Haemonchus spp. were fully susceptible to all treatments. Post-treatment nematode counts indicated that the resistant Trichostrongylus spp. were from the small intestine.

CONCLUSIONS: Anthelmintic resistance to both AB-LEV-OX and moxidectin was present in the Trichostrongylus genus on a commercial sheep farm. Monepantel and DEQ-AB were both effective against Trichostrongylus spp. based on FECRT results.

CLINICAL RELEVANCE: This finding of resistance to an AB-LEV-OX triple-combination anthelmintic in the Trichostrongylus genus in sheep in New Zealand further limits anthelmintic treatment options available, and calls into question whether this combination is suitable for use as a quarantine treatment.     

二甲基二硫的生物活性评价及对土壤养分的影响

采用室内生物活性测定方法,评价二甲基二硫(dimethyl disulfide,DMDS)对土壤病原线虫和土传病原菌的毒力,比较不同浓度药剂处理对土壤理化性质和土壤呼吸的影响,为探究DMDS作为新型土壤熏蒸剂提供切实可行性的依据。结果表明:DMDS熏蒸对土传病原线虫和镰刀菌属的LD_(50)分别为4.743 mg/kg和1.513 mg/kg,可见DMDS对病原线虫和镰刀菌有良好的生物活性。对土壤理化性质进行数据分析发现:DMDS能显著增加土壤铵态氮含量,抑制硝化作用过程,减少NO~-_3-N的产生,提高植物可吸收态氮素水平。DMDS处理的土壤有机质含量和电导率均显著高于对照土壤,而土壤pH和速效钾含量较对照均有降低。此外,熏蒸土壤中有效磷含量较对照减少,但两者无显著差异。对DMDS熏蒸后土壤进行底物诱导呼吸试验,表明DMDS能够在试验初期抑制土壤微生物生物量。本试验结果可为指导DMDS的科学使用提供理论依据及对土壤微生物活性的影响作出科学评价。     

Effect of a multispecies nematode population on the root, corm, and shoot growth of East African Musa genotypes

A study to determine the impact of a multispecies nematode population on the root, corm, and shoot growth of East African Musa genotypes was carried out. Eight genotypes comprising the plantain “Gonja” (Musa AAB group), the dessert banana “Sukali Ndizi” (AAB), the beer banana “Kayinja” (ABB), and five East African Highland bananas (AAA-EA) were assessed at flower emergence of the plant crop. Root damage and plant growth characteristics were assessed on both infected and noninfected plants. This study showed that Radopholus similis and Helicotylenchus multicinctus were recovered in highest numbers from infected mother plants. Significantly (P<0.05) higher shoot and root damage was observed in the infested plot compared to the noninfested plot. The differences in nematode damage observed among the different Musa genotypes confirm the variability in susceptibility to nematodes. Most of the East African Highland bananas and “Gonja” had a significant reduction in root system size. In addition, toppling and lengthening of the period to flower emergence of the plant crop was much more pronounced in these genotypes. In contrast to previous reports, this study indicated that a multispecies nematode infection significantly (P<0.05) reduced shoot and root growth of “Kayinja”. “Sukali Ndizi”, however, was observed to be tolerant to nematode infection as a small reduction in the root system size was associated with a negligible effect on the corm and shoot growth characteristics. Therefore, the percentage reduction in root and shoot growth due to nematode infection is not constant but depends on the plant genotype.