木醋液的杀线活性及对根结线虫病的防治效果研究

 【目的】初步探究木醋液对根结线虫2龄幼虫的抑制作用,以及木醋液及其配剂对根结线虫病的田间防治效果。【方法】采用浸渍法测定不同稀释浓度的木醋液对根结线虫2龄幼虫抑制作用,根据实验室测定结果设计小区试验,进行木醋液及其配剂对石榴根结线虫病、番茄根结线虫病的大田防治。【结果】不同稀释浓度的木醋液对4种常见根结线虫的2龄幼虫均有抑制作用,随着稀释倍数的增加,抑制作用减小。木醋液稀释浓度为150倍处理72 h时,北方根结线虫、花生根结线虫、南方根结线虫、爪哇根结线虫的校正死亡率分别达到了76.3%、78.４%、77.9%和72.2%。木醋液和木醋液配剂对石榴根结线虫病有较好的防治效果,防治效果分别达到了63.9%和50.5%。木醋液和木醋液配剂对番茄根结线虫病的防治效果,寻甸分别为54.1%和28.6%,个旧的为27.8%和19.6%。【结论】初步证明木醋液对根结线虫2龄幼虫有抑制作用,对石榴根结线虫病和番茄根结线虫病有防治效果,对防治根结线虫病有研究价值、应用价值和开发前景。     

蓖麻叶水提取液对花生根结线虫的防治作用研究

通过应用不同浓度的蓖麻叶水提取液对花生根结线虫防治作用的研究,结果表明,蓖麻叶水提取液对花生根结线虫二龄幼虫和卵的孵化均有明显防治作用。蓖麻叶水提取液浓度为100g/L处理48h,花生根结线虫校正死亡率为81．25％,致死中浓度（LD50）为25．96g/L。蓖麻叶水提取液25g/L时处理10d对卵孵化抑制率达59．86％。     

南方根结线虫对不同寄主植物侵染能力的比较

[目的]筛选南方根结线虫的易感寄主。[方法]通过接种试验比较了南方根结线虫对5种寄主植物（黄瓜、番茄、茄子、菠菜及辣椒）的侵染能力。[结果]南方根结线虫对不同寄主植物的侵染能力存在显著差异。黄瓜和番茄的根结百分率显著高于菠菜、茄子和辣椒,黄瓜和番茄根际土壤中2龄幼虫数、雌成虫数及卵块数都显著高于菠菜、茄子和辣椒。[结论]南方根结线虫对黄瓜和番茄的侵染能力显著强于菠菜、茄子和辣椒,为南方根结线虫的易感寄主植物。     

The potential of combining <Emphasis Type="Italic">Pasteuria penetrans</Emphasis> and neem (<Emphasis Type="Italic">Azadirachta indica</Emphasis>) formulations as a management system for root-knot nematodes on tomato

Initial applications of 10⁴ spores g⁻¹ of Pasteuria penetrans, and dried neem cake and leaves at 3 and 2% w:w, respectively, were applied to soil in pots. Juveniles of Meloidogyne javanica were added immediately to the pots (500, 5,000 or 10,000) before planting 6-week-old tomato seedlings. The tomatoes were sampled after 64 days; subsequently a second crop was grown for 59 days and a third crop for 67 days without further applications of P. penetrans and neem. There was significantly less root-galling in the P. penetrans combined with neem cake treatment at the end of the third crop and this treatment also had the greatest effect on the growth of the tomato plants. At the end of the third crop, 30% of the females were infected with P. penetrans in those treatments where spores had been applied at the start of the experiment. The effects of neem leaves and neem cake on the nematode population did not persist through the crop sequences but the potential for combining the amendments with a biological control agent such as P. penetrans is worthy of further evaluation.     

Suitability of weed species prevailing in Spanish vineyards as hosts for root-knot nematodes

Commercial vineyards in southern Spain were surveyed and sampled during October to December 2004 to determine the extent to which common weeds present were suitable hosts of root-knot nematodes infesting soils of those vineyards. Seven weed species commonly growing in grapevine soils in southern Spain were found infected by either Meloidogyne incognita or M. javanica: Amaranthus retroflexus (redroot pigweed), Anchusa azurea (ox-tongue), Chenopodium album (goosefoot), Erodium moschatum (musk stork’s bill), Malva rotundifolia (low mallow), Sinapis alba (white mustard), and Solanum nigrum (black nightshade). The host suitability of the weeds to root-knot nematodes was evaluated on the basis of root galling severity and nematode population densities in soil and roots. Also, the host–parasite relationship in these naturally Meloidogyne-infected weeds was examined. All the weed species in the study were considered suitable hosts for M. incognita and M. javanica because: (a) high Meloidogyne spp. populations occurred in roots and surrounding soil of the weed species; (b) the severity of root galling was high, and (c) well-established permanent feeding sites were observed in the histopathological studies of infected root tissues. In addition, this study presents the first reports of S. alba and A. azurea as hosts for M. incognita, and of E. moschatum as a new host for M. javanica, thus increasing the list of reported weed hosts for Meloidogyne spp. These results indicate that noticeable population densities of M. incognita and M. javanica can be maintained or increased in these weeds, at population levels higher than those previously reported for the same nematodes infecting grapevine roots. The weeds infesting vineyards thus represent an important source of inoculum of Meloidogyne spp., and furthermore may act as reservoirs of these nematodes which can be disseminated within or among vineyards by agricultural operations.     

Rapid detection of Meloidogyne spp. by LAMP assay in soil and roots

Loop-mediated isothermal amplification (LAMP), a novel DNA amplification technique, has been used to detect a variety of pathogens including viruses, fungi, bacteria and parasites. However, diagnosis of sedentary plant-parasitic nematode (PPN) species has not yet been attempted. In this study, we developed a universal LAMP set (RKN-LAMP) for the diagnosis of four common Meloidogyne species (Meloidogyne incognita, M. arenaria, M. javanica and M. hapla), and M. incognita-specific LAMP set (Mi-LAMP). In both assays, a typical ladder-like pattern on gel electrophoresis was observed in all positive samples but not in the negative controls. Amplification products were further confirmed using restriction analysis of the Hpa II enzyme, detection by visual inspection using SYBR Green I and the lateral flow dipstick (LFD) assay. The two LAMP sets were specifically able to detect four common Meloidogyne species and M. incognita populations having several different geographical origins and pathotypes. No cross reaction with DNA of other PPNs was observed. Sensitivity of the RKN- and Mi-LAMP was 10 and 100 fg of pure genome DNA respectively. Both LAMP sets could also amplified crude DNA isolated from the galled root tissue and from soil containing juveniles of M. incognita. The RKN- and Mi-LAMP sets offer the advantages of simplicity, rapidity and cost effectiveness. Both LAMP sets will be instrumental for the diagnosis of Meloidogyne spp. by local extension and regulatory personnel.     

巴拉那根结线虫的鉴定及生物学特性

巴拉那根结线虫(Meloidogyne paranaensis)是咖啡上最具有毁灭性的根结线虫之一,可造成咖啡减产高达50%,目前主要发生在巴西、危地马拉和墨西哥,我国没有分布。本文介绍了巴拉那根结线虫的形态鉴定特征和生物学特性等内容。     

苏云金杆菌00-50-5发酵上清液对南方根结线虫杀虫活性研究

室内条件下,分别测定了苏云金杆菌Bt 00-50-5菌株液体和固体发酵物对南方根结线虫的毒力效果。结果显示,牛肉膏蛋白胨液体发酵法在72h所得上清液的毒性最高,南方根结线虫死亡率达到99.0%,而固体麸皮发酵物对线虫的最高毒性为发酵8h,南方根结线虫死亡率为89.0%。液体发酵上清液经葡聚糖凝胶G-75柱层析分离,柱下物在280nm处的吸收值呈现出4个峰I、II、III和IV,其值0.601,1.475,1.641和0.392,其中峰II、III、IV处收集的蛋白对南方根结线虫有毒杀作用,分子量最小的IV蛋白杀线虫活性最高。上清液天然聚丙烯酰胺凝胶电泳分离杀虫蛋白结果显示6条清晰蛋白带,其中37kDa蛋白含量最多。     

拮抗南方根结线虫PKS基因的筛选及活性评价

土壤环境中蕴藏着巨大的微生物资源,而99%的土壤微生物不能用传统的纯培养。本研究基于西藏米拉山高寒草甸土壤微生物宏基因组Fosmid文库,采用PCR方法从文库中筛选PKS基因,以南方根结线虫(Meloido-gyne incognita)为靶标测定其杀线活性,并验证温室盆栽防效。从Fosmid文库中筛选得到2个含PKS基因的克隆K99和K82。K99属于Ⅰ型PKS,K82属于杂合PKS/NRPS;K99发酵液、热处理发酵液浸泡南方根结线虫J2 12 h后,杀线活性为100%。温室盆栽防效结果表明,K99的发酵菌液对南方根结线虫的防效为89%。K99能产生一种外分泌有杀线活性的物质,其热稳定性好,具有重要的开发利用价值。     

根际细菌9个菌株对南方根结线虫的盆栽防效

通过盆栽试验,观察了土壤细菌9个菌株对番茄上南方根结线虫的生物防治效果。结果表明:供试菌株能够降低番茄线虫的根结指数,且对番茄生长有一定的促进作用。119号菌株处理30 d后,防治效果最好,平均防效达57.75%;处理60 d后,平均防效达55.88%。333号菌株处理30 d后,番茄植株生长最好,株高达43.00 cm,株鲜质量达11.17 g,分别比对照提高了37.25%和76.46%。对单个菌株防效比较好的菌株进行初步混用试验,结果表明:部分菌株混用的防治效果不太理想,但对番茄的株高和鲜质量有促进作用,且与对照差异显著。通过16S rDNA序列分析,并结合形态学和生理生化特征试验,初步鉴定119号菌株为巨大芽孢杆菌Bacillus megaterium。