牦牛重要传染病和寄生虫的防治与展望

本文概述了牦牛常见重要传染病和寄生虫病的防治研究进展,指出了目前牦牛重要疾病防治工作上的不足,并探讨了牦牛疾病防治的发展方向。     

非人灵长类肠道寄生虫研究进展

随着经济社会活动正日益增加,几乎没有非人灵长类的栖息环境能逃脱干扰,这不可避免增加了非人灵长类与人类的接触机会,也极大地增加人兽共患寄生虫交叉感染的风险。我国非人灵长类不仅面临着生境减少的威胁,更为严重的是很多保护区或者旅游景区将野生猴科灵长类作为招揽游客的手段,没有任何防护措施的人猴近距离接触更增加了寄生虫传播的危险。总结了国内外非人灵长类肠道寄生虫的相关研究成果,包括肠道寄生虫的种类、传播途径、危害及预防措施,为濒危非人灵长类的综合保护提供科学依据,对其保护方法和方针提供指导,具有一定的借鉴意义。     

Absence of three known benzimidazole resistance mutations in Trichostrongylus tenuis, a nematode parasite of avian hosts

Benzimidazole (BZ) resistance is widespread in nematode parasites of livestock, but very little is known about the levels of BZ resistance in parasites with avian hosts. We investigated BZ resistance in Trichostrongylus tenuis, a nematode parasite of red grouse, Lagopus lagopus scotica. BZ anthelmintics had been in use in this system for up to 15 years, yet existing phenotypic evidence for resistance was inconclusive. We screened 1530 individuals from 14 populations at the principal β-tubulin locus for BZ resistance (isotype 1, residue 200) and 940 of these at two further resistance sites (isotype 1, residue 167; isotype 2, residue 200). No BZ resistant genotypes were found. Alternative mechanisms may be responsible for BZ resistance in this system, or the method and timing of treatments may reduce selection pressure for BZ resistance by creating substantial refugia for susceptible genotypes.     

Epizootics of metazoan gill parasites did not threaten feasibility of farming southern bluefin tuna (Thunnus maccoyii) in a trial extending over summer months

Tuna farming off Port Lincoln, Australia, involves catching wild 2–4-year-old southern bluefin tuna in summer and then fattening for periods of 2–8 months. As fresh product is not available year-round, the feasibility of maintaining tuna for longer periods was trialled, including over a summer season, when temperatures may exceed 24 °C. As the rates of growth and reproduction in ectoparasites of fishes are usually most rapid during warm temperatures, parasite epizootics at this time may adversely affect the health of tuna. We collected epidemiological data on burdens of metazoans on the gills of tuna from the time of stocking in April 2005 through to final harvest in August 2006 (N = 220). We document an epizootic of the copepod Pseudocycnus appendiculatus, characterised by a significant increase in both prevalence and mean intensity in the first winter, followed by a decline in these parameters over the next 12 months. This epizootic pattern appears to be independent of seasonal changes in temperature. For two other species, a second copepod (Euryphorus brachypterus) and a polyopisthocotylean flatworm (Hexostoma thynni), there were no clearly discernible trends in infections. As the high water temperatures over the summer period did not lead to increased infections of any species of gill parasites, we conclude that they do not threaten the feasibility of farming of Thunnus maccoyii.     

植物病原菌寄生适合度测定方法的研究（以小麦条锈菌为例）

 在多品种-多小种系统的群体动态研究中,各小种在各品种上的相对寄生适合度的测定是一个关键问题。根据推理论证和模拟试验,作者认为:采用相对r值作为寄生适合度的量化指标是合理可行的。相对r值可以采用分小种方块圃法或根据田间病情进行直接测定,也可采用分小种短行圃法进行间接测定,即根据流行组分观察数据或反应型、普遍率、严重度和潜育期的记载,通过模型模拟推算出相对寄生适合度。间接测定较易操作,但它要求有一个相当可靠的流行模拟模型,并在模拟中选用适当的环境条件。根据反应型、普遍率、严重度和潜育期推算和模拟寄生适合度,是较最简便的间接测定方法,此法可利用品种抗病性分小种鉴定的数据来推算寄生适合度。     

南方根结线虫寄生真菌的分离和鉴定

 1992年和1993年,在广东和广西采集南方根结线虫样品44个,分离129个菌株,它们分属9属18种.     

利用微生物防除根寄生杂草列当

根寄生杂草列当(Orobanche spp.)已经严重制约全球许多地区的农业发展,寻找有效防除措施迫在眉睫。由于列当具有特殊生活史且与寄主关系密切,常规防除杂草措施难以达到理想防效。目前,尚无既能有效防除列当又不对寄主造成危害且便于大规模推广应用的列当防除措施。在众多列当防除措施中,微生物防除越来越引起关注和重视。本文对微生物防除列当的国内外研究进展及防除机理进行了综述。目前,列当生防微生物的研究主要集中在镰刀菌(Fusarium spp.)等列当病原菌和根瘤菌(Rhizobium spp.)等列当寄主植物共生菌上。微生物防除列当的机制主要包括两方面:一是通过产生代谢产物直接影响列当的萌发和生长,或通过降解列当种子萌发诱导物质间接影响列当的萌发;二是通过提高寄主植物自身对列当的抗性间接影响列当的寄生和生长。此外,本文还重点介绍了植物土传病害的土壤拮抗微生物防除列当杂草的可行性及研究进展。植物土传病害病原菌和列当均首先通过在地下侵染作物的根系进而危害作物正常生长,而作物抗土传病害的机理也与抗列当的机理类似。因此,存在于土壤中具有防治植物土传病害能力的微生物可能也具有防除根寄生杂草列当的功能。本团队前期试验从植物土传病害的土壤拮抗微生物中筛选到在盆栽试验中能够有效防除向日葵列当(O.cumana Wallr.)和瓜列当(O.aegyptiaca Pers.)的放线菌各1株,分别为淡紫褐链霉菌(Streptomyces enissocaesilis Sveshnikova)和密旋链霉菌(Streptomyces pactum Bhuyan B.K)。其中,密旋链霉菌的菌剂在田间试验中既降低了瓜列当的出土数量又增加了番茄的产量。总之,微生物是防除根寄生杂草列当的一条有效途径。     

不同生境下泽兰实蝇的寄生状况及其影响因素分析

[目的]研究不同生境下泽兰实蝇的寄生状况及其影响因素。[方法]通过对云南大中山地区紫茎泽兰入侵生境中泽兰实蝇的寄生状况抽样调查,分别从环境因素和紫茎泽兰生长状况两方面,分析了影响泽兰实蝇寄生的因素。[结果]不同生境泽兰实蝇的寄生状况有显著差异,其中林区公路和林区空旷地寄生率、虫瘿数和虫瘿内幼虫数最高,显著大于华山松林和落叶阔叶林。乔木层盖度与泽兰实蝇的寄生率、虫瘿数、虫瘿重呈显著负相关,而灌木层盖度与泽兰实蝇的寄生率呈显著正相关。泽兰实蝇寄生率与紫茎泽兰均高和开花率均呈极显著的正相关。[结论]开阔的生境有助于泽兰实蝇的寄生和扩散,林下的光照条件对泽兰实蝇的寄生亦有影响。泽兰实蝇偏好寄生林区公路边和林区空旷地植株较大、分枝较多的植株,泽兰实蝇对花期的植株可能更具有趋性。     

重庆地区栗瘿蜂寄生蜂种类及其控制作用的研究

通过野外调查和室内饲养,研究重庆市栗瘿蜂寄生蜂的种类及其对寄主种群消长的调控作用,结果表明,在重庆地区栗瘿蜂的主要寄生蜂有9种,分别隶属于膜翅目长尾小蜂科[中华长尾小蜂Torymus sinensis Kamijo、葛氏长尾小蜂Torymus geranial（Walker）、日本大痣长尾小蜂Megastigmus nipponicus Kamijo、斑翅大痣长尾小蜂Megastigmus maculipennis Kamijo、姬黄色长尾小蜂Megastigmus koebelei Ashmead]、旋小蜂科（栗瘿旋小蜂Eupelmus urozonus Dalman）、跳小蜂科（跳小蜂Encyrtidae sp.）、刻腹小蜂科（栗瘿刻腹小蜂Ormyrus sp.）、广肩小蜂科（广肩小蜂Eurytoma sp.）,全部为幼虫期体外寄生性小蜂,中华长尾小蜂Torymus sinensis Kamijo为优势种。个体数量较多的中华长尾小蜂Torymus sinensis Kamijo、栗瘿旋小蜂Eupelmus urozonus Dalman和栗瘿刻腹小蜂Ormyrus sp.分别占寄生蜂总个体数量的30.77%,20.98%,18.88%。在重庆地区寄生蜂是控制栗瘿蜂种群数量变动的主要因子。     

Organic matter and seed survival of Striga hermonthica – Mechanisms for seed depletion in the soil

Seed survival of Striga hermonthica is influenced by amendments of organic matter; however, the role of organic matter quality (C:N ratio) and mechanisms for enhanced seed decay are inadequately understood. In a field experiment, plots received a single dose of 6 t organic matter per hectare but with large differences in quality in terms of C:N ratio. Soil moisture, soil temperature and soil ethylene concentrations were measured, while buried nylon seed bags were periodically withdrawn from the soil and assayed for seed viability and germination. Organic matter amendments incorporated in the soil significantly depressed S. hermonthica seed survival. The effect was strongest with organic matter of high quality. Organic matter of low-quality enhanced soil water content during the first five days after a rainfall event and resulted in a 0.5 °C lower soil temperature. The highest observed ethylene concentrations in the soil were between 2 and 3 ppm, high enough to stimulate S. hermonthica seed germination. Maximal seed germination in vitro was obtained after 48 h of exposure to 1 ppm ethylene. However, observed changes in seed germination and viability of retrieved seed batches (seed survival) did not correlate with soil ethylene concentrations. The latter in turn did not differ between qualities of the applied organic matter. Seed survival decreased with increasing time of burial, especially after 4–8 weeks. As S. hermonthica attachment mainly occurs during the first four weeks of the cropping season the observed effect of seed decay may hardly be beneficial for the on-going cropping season. Nutrient release through decomposition of organic matter, enhancing decay of S. hermonthica seeds, is proposed as the probable cause of seed depletion in the soil.