Differential effect of nematicide treatments on tuber yields in early- and late-maturing potato cultivars

A 3-year field study examined the effects of 1,3-dichloropropene or oxamyl on tuber yields in four early- and five late-maturing potato cultivars. The nematicide treatments increased total tuber yield by ≈ 12% for early-maturing cultivars, but by less than 2% for the late-maturing cultivars. The treatments reduced the numbers of root lesion nematodes (primarily Pratylenchus penetrans ), which were the dominant plant parasitic nematodes at the site. Covariance analysis indicated that treatment effects on total tuber yield were no longer significant after adjusting for root lesion nematodes in soil at harvest, confirming that these nematodes had a direct effect on the host. As expected, there were significant inverse relationships ( P  = 0·05) between total tuber yields and numbers of root lesion nematodes in soil and in roots. However, the application of nematicides in late-maturing cultivars was found to be of no practical value. Crop production systems designed to reduce or optimize pesticide applications can form one criterion in the development of more environmentally sensitive management strategies. The merit of utilizing chemicals for root lesion nematode control are considered with regard to cultivar maturity.     

Influence of irrigation on the distribution and control of the nematode Meloidogyne javanica by the biocontrol bacterium Pasteuria penetrans in the field

Pasteuria penetrans, a bacterial parasite of plant-parasitic nematodes, is used to control root-knot nematode Meloidogyne spp. populations in vegetable crops. But its efficiency is variable, mostly because of the patchy distribution of the bacteria in arable fields. As the infective P. penetrans are non-motile bacteria in soil, abiotic soil factors can affect the bacteria–nematode relationships. An epidemiological study, conducted in a vegetable field, showed that abiotic factors such as irrigation, soil water holding capacity and texture, affected the efficiency of P. penetrans. A correspondence analysis between these abiotic factors and the density of P. penetrans spores in the soil, and the proportion of Meloidogyne javanica juveniles infected by the bacteria, revealed that irrigation affected directly the distribution of the spores in soil pores related to their passive transport by water flow. Laboratory experiments conducted on the passive transport of spores confirmed that intensive irrigation leached the spores down the soil profile and decreased the percentage of infected Meloidogyne juveniles.     

中国真径茧蜂属Euagathis Szepligeti一新种及一新记录（膜翅目：茧蜂科：窄径茧蜂亚科）

窄径茧蜂亚科是鳞翅目幼虫的重要内寄生蜂．该亚科在中国大陆的区系尚无研究报道．本文记述真径茧样属ＥｕａｇａｔｈｉｓＳｚｅｐｌｉｇｅｔｉ的中国一新种—多刺真径茧蜂ＥｕａｇａｔｈｉｓｓｅｎｔｏｓｕｓＣｈｅｎ＆Ｙａｎｇ．及一中国分布新记录—透翅真径茧蜂Ｅｕａｇａｔｈｉｓｐｅｎｅｔｒａｎｓ（Ｓｍｉｔｈ），并提供了该属中国已知７种的分种检索表．新种的模式标本保存于福建农业大学植物保护系益虫研究室．     

云南水稻根际土壤中的线虫种类鉴定

描述了云南水稻根际土壤中发现的3种植物寄生线虫燕麦真滑刃线虫A phelenchus avenae Bastian, 1865,多带螺旋线虫Helicotylechus multicinctus (Cobb, 1893) Golden, 1956和穿刺短体线虫Pratylenchus penetrans (Cobb, 1917) Chitwood & Otifa, 1952.这3种寄生线虫均为云南省新记录.     

南方根结线虫被穿刺巴斯德芽菌侵染后寿命和生殖相关基因的表达变化

为了探讨南方根结线虫在植物体外被穿刺巴斯德芽菌感染后存活率的变化及感染初期线虫寿命和生殖相关基因的表达情况。首先利用单卵块孵化法对从野外采集的根结线虫进行纯化和分子鉴定。以穿刺巴斯德芽菌孢子体外吸附的南方根结线虫为材料,在显微镜下观察供试线虫的存活情况,每24 h计数一次死亡线虫的条数,总共观察12 d。在被穿刺巴斯德芽菌吸附的第3天收集根结线虫,提取线虫总RNA,采用实时荧光定量PCR检测线虫寿命相关基因cyp-33和生殖相关基因lin-45/mek-2的表达情况。结果表明：通过分子鉴定确认纯化的根结线虫为南方根结线虫;感染了穿刺巴斯德芽菌的南方根结线虫死亡率显著升高;同时在穿刺巴斯德芽菌吸附南方根结线虫的初期,线虫寿命相关基因cyp-33和生殖相关基因lin-45/mek-2的表达水平与对照组相比均下调（p<0.05）。这说明穿刺巴斯德芽菌在吸附南方根结线虫的初期能够促使线虫的存活率降低,并抑制其生殖能力,这可能与基因cyp-33、lin-45和mek-2的调控有关。     

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.     

百合种球包衣防治鳞茎病害的试验研究

田间试验结果表明,用18%绿野种衣剂以药剂、种子重量1∶50的比例对百合种球进行包衣,其综合效果最好,成苗率达100%,产量较对照增加150.00%,对茎腐病和根腐病的防效分别达89.41%和87.85%,且对百合生长安全。其他10种药剂处理中,只有50%施保功处理的效果较好。     

线虫寄生菌巴斯德杆菌的生物多样性研究进展

巴斯德杆菌(Pasteuriaspp. )是一类结构特殊且能产芽孢的革兰氏阳性菌,能寄生于多种重要的植物病原线虫,在控制线虫群体方面效果明显.作为一类线虫寄生菌,该菌属内种间、分离物间、种与分离物之间在表型特征、寄主范围、遗传本质等多方面存在差异,并呈现出较为明显的多样性.本文就该菌的生物多样性研究状况作一总结,并阐明其在线虫生防中的意义.