Top 20 environmental weeds for classical biological control in Europe: a review of opportunities, regulations and other barriers to adoption

Classical biological control remains the only tool available for permanent ecological and economic management of invasive alien species that flourish through absence of their co‐evolved natural enemies. As such, this approach is recognized as a key tool for alien species management by the Convention on Biological Diversity (CBD), the European and Mediterranean Plant Protection Organization (EPPO) and the European Strategy on Invasive Alien Species (ESIAS). Successful classical biological control programmes abound around the world, despite disproportionate attention being given to occasional and predictable non‐target impacts. Despite more than 130 case histories in Europe against insect pests, no exotic classical biological control agent has been released in the EU against an alien invasive weed. This dearth has occurred in the face of increasing numbers of exotic invasive plants being imported and taking over National Parks, forests and amenity areas in this region, as well as a global increase in the use of classical biological control around the world. This paper reviews potential European weed targets for classical biological control from ecological and socioeconomic perspectives using the criteria of historical biological control success, taxonomic isolation from European native flora, likely availability of biological control agents, invasiveness outside Europe and value to primary industry and horticulture (potential for conflicts of interest). We also review why classical biological control of European exotic plants remains untested, considering problems of funding and public perception. Finally, we consider the regulatory framework that surrounds such biological control activities within constituent countries of the EU to suggest how this approach may be adopted in the future for managing invasive exotic weeds in Europe.     

Cohort-dependent seedling recruitment, survival and reproductive capacity of Tribulus terrestris

Knowledge of the population biology of the summer annual Tribulus terrestris can provide valuable information for managing the risk of its colonising crop fields. Because of spring‐summer crop management practices, fields can exhibit bare ground in late April and early May. In this situation, four cohorts in 2000 and three cohorts in 2001 were censused and monitored throughout the vegetative and reproductive season, in order to evaluate the relationship between time of emergence, survival, vegetative growth and plant reproductive capacities. To a great extent, seedling survivorship depended on emergence timing; the earlier the emergence of the seedlings, the higher was the proportion of survivorship (64% and 4%, for early and late emergences). The time of emergence also influenced plant development; in both years, surviving individuals of the first cohorts presented significantly greater plant biomass and larger numbers of reproductive structures (60.5 fruits per plant) than those of later cohorts (0.8 fruits per plant). Reproductive meristem allocation was also highest in the earliest cohorts. Results showed that T. terrestris can increase its population size in fields if gaps of bare soil surface are available from mid spring to early summer.     

Plant yield response to artificial infestation of the false chinch bug,Nysius raphanus, confined on spring canola

A 2-year study was conducted to evaluate the relationship of plant yield responses to artificial infestations of the false chinch bug (FCB)Nysius raphanus (Howard) on spring canola in Colorado, USA. Yield losses were greater when infestation occurred at the early flowering stage (EFS) than at the early pod stage (EPS), in both 2001 and 2002. In the first trial in 2001, with infestations of 10, 20 and 40 FCB/head, the respective average yield losses over all cultivars were 43%, 68% and 69%, respectively, compared with the non-infested control at the EFS, but 11%, 26% and 23% at the EPS. In the second trial in 2001, with infestations of 10, 20 and 40 FCB/head, the respective average yield losses over all cultivars were 26%, 58% and 55% at the early EFS, but 35%, 20% and 35% at the EPS. Yield reductions from FCB infestation were lower in 2002 than in 2001. In the first trial in 2002, with infestations of 10, 20 and 40 FCB/head, the respective average yield losses of all cultivars combined were 31%, 51% and 68% at the EFS, and 13%, 32% and 18% at the EPS. However, in the second trial in 2002, with the same numbers of FCB per head, no yield reductions were observed at either EFS or EPS. The number of FCB causing 10% yield loss in the four trials ranged from 6.1 to 39.4 FCB/head (avg. 14.8) following infestation at the EFS and 15.4–109.8 (avg. 41.8) following infestation at the EPS. Cultivar responses to FCB may also influence FCB yield reductions. However, in these studies all eight tested cultivars sustained yield loss in at least one trial at some FCB infestation level. Variation between trials was substantial but a significant level of resistance to FCB injury did not occur among the tested cultivars. http://www.phytoparasitica.org posting Sept. 18, 2006.     

早熟禾品种耐寒变异植株无性系的建立

对草地早熟禾的小矮人品种耐寒变异植株无性系的建立进行了研究,并成功地诱导出小矮人嫩叶的愈伤组织,分化出丛生不定芽.诱导愈伤组织的理想培养基是MS BA 0.1mg/L 2,4-D 1 mg/L;由愈伤组织分化出苗的理想培养基是1/2 MS BA 0.1 mg/L 2,4-D 0.1 mg/L;试管苗极易移栽成活,耐寒变异性状保持不变.     

紫花苜蓿对九种杂草的化感作用

试验运用生物测定法研究了紫花苜蓿叶化感物质对九种受体植物的作用.结果表明,紫花苜蓿叶提取物对多变小冠花的发芽势和发芽率具有抑制作用,与对照差异显著(P＜0.05);提取物对高羊茅种子的发芽势有促进作用,与对照差异显著(P＜0.05),其最终发芽率也增加(P＜0.05);除狗尾草外,其余八种受体植物的胚根长度都受到紫花苜蓿叶提取物的抑制,与对照的差异均显著(P＜0.05);提取物对稗草、狗尾草、高羊茅、毛马唐和多变小冠花的苗长具有促进作用,与对照差异均显著(P＜0.05);反枝苋的苗长则受到抑制(P＜0.05);提取物对受体植物的幼苗鲜重均有不同程度的影响,虎尾草、匍匐翦股颖、巴哈雀稗、反枝苋和多变小冠花幼苗鲜重明显降低,与对照差异达显著水平(P＜0.05).     

苍耳等药用植物提取物对小菜蛾的拒食作用和产卵忌避效果

室内采用叶碟法,研究苍耳(Xanthium sibiricumPetril)等8种药用植物乙醇提取物对小菜蛾(Plutel-la xylostella)的拒食和产卵忌避活性。结果表明,苍耳(果实)、雷公藤(根)和商陆(根)乙醇提取物对小菜蛾4龄幼虫的取食均有较强的抑制作用,选择性拒食率分别为86.16%、49.06%和43.82%;非选择性拒食效果仍以苍耳(果实)提取物最好,达45.23%。选择性产卵忌避率以雷公藤(根)提取物为最高(69.52%),其次是苍耳(果实)和山苍树(枝叶)提取物,分别为62.50%和57.72%,雷公藤(根)、商陆(根)、窃衣(茎叶)和苍耳(果实)的非选择性产卵忌避作用均在77%以上。苍耳和雷公藤提取物在对小菜蛾的拒食和产卵忌避的各测试中,均表现较强活性。     

茶树新品系福选9号的观察研究

为观察鉴定茶树新品系福选9号在重庆市巴南区的适应性及表现,以福鼎大白茶为对照品种,于2002-2004年进行了品比试验。结果表明,福选9号表现出如下特性:(1)春芽萌动特早,较对照提早11～13d,春茶产量较高。(2)育芽能力强,生长势旺盛,秋梢休止期较对照晚5～7d,全年生育期较对照长16～20d,平均单产高20.5%。(3)抗逆性强,耐寒性和抗旱性与对照相当,抗病虫性稍强。(4)发芽整齐度高,适宜机械化作业。(5)制绿茶品质优良,适制性强。     

Influence of growing season and donor plant age on anther culture response of some pepper cultivars (Capsicum annuum L.)

The effects of growing season and donor plant age on anther culture in Capsicum were investigated. Pepper cultivars Kekova and Sera Demre 8 were grown under unheated greenhouse conditions in winter season and field conditions in summer season. Flower buds were collected and cultured in weekly intervals from November to May in winter and from April to December in summer. The results of this study indicated that anthers from these two pepper genotypes gave different embryogenic response to seasonal effects. Kekova cultivar gave the highest embryogenic yield in summer season while this was occurred in winter season for Sera Demre 8 cultivar. The results of the study revealed that the effect of donor plant age was also an important factor in anther culture of pepper. Since 4-month-old plants gave the highest embryo yield in both cultivars in each seasons, it is possible to say that anthers collected from old plants have sufficient embryogenic response when the optimum developmental stage is selected.     

杀虫植物非洲山毛豆的研究

非洲山毛豆原产于热带非洲,是一种优异的杀虫植物。本文对其生物活性、杀虫有效成分、作用机理、加工使用等方面进行了概述。     

药用植物半夏细胞悬浮培养和植株再生体系建立研究

为了建立甘肃产药用植物半夏的细胞悬浮培养和植株再生体系,通过对其不同外质体筛选、愈伤组织诱导和悬浮培养的愈伤组织类型、激素水平、起始密度、震荡速率等影响因素以及细胞生长状态、生长曲线和pH值变化等指标的研究.结果表明:以叶柄为外质体,选择"松散型"愈伤组织和2×105个/mL的起始培养密度,在附加2,4-D 2.0 mg/L BA 0.5 mg/L NAA0.5 mg/L的1/2 MS培养基上培养,温度(23±2)℃,转速90 rpm,pH值6.0,黑暗培养为最适悬浮培养体系;经检测细胞生长曲线呈"S"型,培养液pH随着细胞的生长先上升后下降,18 d时细胞基数达到最大值;悬浮继代培养后,通过降低或停止震荡转速,在添加BA 0.5 mg/L NAA0.5 mg/L的MS液体和固体培养基上可诱导分化出芽和根,进一步形成完整的植株.