Options for Managing Invasive Marine Species

Marine biological invasions are increasingly recognised as a threat to biodiversity and coastal industry, including fisheries. Globally, efforts are underway to contain, if not eradicate, several high-impact marine invasive species. However, working in a marine environment places unique social, political and technical constraints on options for pest control, which we explored in a series of stakeholder workshops. Results suggest that current efforts are low risk and publicly acceptable, but have a low probability of success against established invaders. However, techniques deemed likely to be successful and ultimately needed in a marine context are currently more contentious for social and political reasons. To control introduced marine pests, scientists and managers will need to overcome perceptual biases among marine stakeholders, develop a decision-making framework for what is perceived to be an open system, and focus on technologies likely to be both effective and publicly and politically acceptable.     

Mate Discrimination in Invasive Whitefly Species

Mate discrimination could be critical for invasive species that need to locate rare suitable mates and avoid costs associated with misdirected courtships to establish in new environments. Here, we tested whether individuals of two invasive whitefly species in the Bemisia tabaci species complex, commonly known as the B and Q biotypes, could discriminate between potential mates based on their species and sex. Behavioral observations showed that B females were more discriminating than Q females. Males of both species were able to discriminate between mates based on their species and sex, but in general B males discriminated more effectively than Q males. By incorporating these behavioral data into a conceptual model, we show that variation in mating behavior between females of different species was a more significant factor affecting mating than variation between males. These results indicate that mate discrimination could affect interactions between whitefly species and influence a species’ ability to colonize novel environments.     

Compensation and Plasticity in an Invasive Plant Species

Plant plasticity under varying resources is one character that contributes to competitiveness and invasibility. The plasticity of plant modules of the invasive Japanese stilt grass (Microstegium vimineum) was examined under different light and nutrient levels using a balanced field and greenhouse study. Ample light and nutrients resulted in the greatest biomass accumulation in all plant modules. However, M. vimineum showed extreme plasticity, producing stolons and flowers (reproductive structures) under a wide range of environmental conditions except infertile, low light. The addition of nutrients under various shading regimes compensated for lower light levels, rendering little change in the allocation of carbon to reproductive structures. Data from the field study corroborate the greenhouse results, but also suggest plasticity in response to competition.     

火与外来植物相互关系的研究进展

入侵种对本地的生态系统和生物多样性均有不良的影响,严重的会造成物种的灭绝和生态系统的崩溃,这已在全球范围引起广泛关注.在植物外来种与火生态因子的作用研究中发现,火与外来种的关系随物种生物学特性、火作用的时间、频度、强度不同而不同,火有时会有效地抑制外来种的生长和入侵,有时会促进一些外来种的生长和入侵.反之,一些外来种会对火的产生起到积极的作用,一些外来种又会抑制火的发生.火作为控制入侵种的一种方法,经科学地运用,可对某些入侵种起到有效的控制作用.     

Composting One Invasive Species to Control Another

The need for research and development of effective approaches to weed control continues to increase globally. Adaptive protocols using diverse control methods are often required in ecological restoration as recruitment of native species is highly site‐specific, species‐specific, and experimental. The use of composted weed refuse to control other weeds may be a practical option; yet, the option is not well studied due to the accompanied risk of introducing weed propagules to areas where weed control is desired. Here, we tested the effectiveness of different physical control techniques including the use of mulch made by composting weed refuse on‐site. English ivy (Hedera helix), a non‐native, invasive species in the Pacific northwestern United States, was removed from a heavily invaded site, shredded, and composted. The mulch was compared with other methods of suppressing herb Robert (Geranium robertianum), another invasive species on‐site. Five treatments were tested: flame‐weeding, hand‐pulling, mulching, hand‐pulling followed by mulching, and flame‐weeding followed by mulching. The mulch and pull/mulch treatments were the most effective, reducing G. robertianum cover by 92 and 86% of pre‐treatment levels, respectively, and suppressing G. robertianum 2.9 and 1.6 times more than the control, respectively. The mechanism behind the effectiveness of the mulch is uncertain, but may be related to weed seed burial or the allelopathic potential of the mulch. Composting one invasive species to use as mulch to control another can be effective and merits trial elsewhere.     

入侵种的DNA条形码鉴定

生物安全研究的范畴涉及任何由生物威胁所造成的风险。随着害虫优先考虑级别的不断变化,以及国家和部门间相互协作的不断加强,对DNA分子鉴定技术的标准化提出了更迫切的要求,而DNA条形码的出现为此类问题的解决提供了很好的机遇。我们以前人对毒蛾和果蝇的研究为例,比较了DNA条形码技术与PCR-RFLP等传统方法的鉴定效果,在此基础上提出了建立一个可对不同入侵种进行快速和准确鉴定的条形码技术平台的构想。     

外来入侵生物相似穿孔线虫的风险分析

相似穿孔线虫(Radopholus similis)是一种危险性外来入侵生物,使发生的国家造成极大的损失。相似穿孔线虫具有很强的适应性,地理分布达到59个国家和地区,寄主达到360多种,且具有一定的检验难度,其入侵会造成农业生产上巨大的经济损失;结合国内寄主植物分布和种植情况,确定了其在中国具有传入、定殖和扩散的可能性。依据国际植物检疫措施标准(ISPM)规定的有害生物风险分析程序(PRAS),采用多指标综合评估方法,对各指标进行赋值运算,获得总指标值R为2.6,符合高风险的检疫性有害生物标准。因此将相似穿孔线虫列入香蕉、花卉等经济植物的一类检疫性有害生物名单,实施外来入侵物种的风险管理。     

An Essay on Some Topics Concerning Invasive Species

Abstract There is a tendency for both scientists and lay people to regard invading alien species as inherently ‘bad’ and native species as inherently ‘good.’ Past invasions occurred commonly without human assistance. They rarely caused large, lasting decreases in species richness or ecological damage. Current invasions provide opportunities for scientific study. They are unintentional, uncontrolled experiments, which can provide insights into attributes of successful colonists, relationships with native species, and impacts on the structure and function of ecological systems.     

景区入侵生物之防控

生物入侵可导致严重的直接危害和衍生危害。鉴于景区的特殊性,提出景区对外来入侵物种的防控策略与措施。     

云南种子植物中的新入侵和新分布种

报道了两个云南的新入侵植物及两个新分布种,分别是光冠水菊和细叶旱芹及俯垂粉报春和针叶韭,并对新入侵植物的危害性及防治措施等进行了初步讨论。     

Rapid Shift in Pollinator Communities Following Invasive Species Removal

Ecological restoration is increasingly used to reverse degradation of rare ecosystems and maintain biological diversity. Pollinator communities are critical to maintenance of plant diversity and, in light of recent pollinator loss, we tested whether removal of invasive glossy buckthorn (Frangula alnus L.) from portions of a prairie fen wetland altered plant and pollinator communities. We compared herbaceous plant, bee, and butterfly abundance, diversity, and species composition in buckthorn invaded, buckthorn removal, and uninvaded reference plots. Following restoration, we found striking differences in plant and pollinator abundance and species composition between restored, unrestored, and reference plots. Within 2 years of F. alnus removal, plant species diversity and composition in restored plots were significantly different than invaded plots, but also remained significantly lower than reference plots. In contrast, in the first growing season following restoration, bee and butterfly abundance, diversity, and composition were similar in restored and reference plots and distinct from invaded plots. Our findings indicate that a diverse community of mobile generalist pollinators rapidly re‐colonizes restored areas of prairie fen, while the plant community may take longer to fully recover. This work implies that, in areas with intact pollinator metapopulations, restoration efforts will likely prevent further loss of mobile generalist pollinators and maintain pollination services. On the other hand, targeted restoration efforts will likely be required to restore populations of rare plants and specialist pollinators for which local and regional species pools may be lacking.     

Rapid Species Diagnosis for Invasive Candidiasis Using Mass Spectrometry

Background

Matrix-assisted laser desorption ionisation time of flight mass spectrometry (MALDI TOF-MS) allows the identification of most bacteria and an increasing number of fungi. The potential for the highest clinical benefit of such methods would be in severe acute infections that require prompt treatment adapted to the infecting species. Our objective was to determine whether yeasts could be identified directly from a positive blood culture, avoiding the 1–3 days subculture step currently required before any therapeutic adjustments can be made.

Methodology/Principal Findings

Using human blood spiked with Candida albicans to simulate blood cultures, we optimized protocols to obtain MALDI TOF-MS fingerprints where signals from blood proteins are reduced. Simulated cultures elaborated using a set of 12 strains belonging to 6 different species were then tested. Quantifiable spectral differences in the 5000–7400 Da mass range allowed to discriminate between these species and to build a reference database. The validation of the method and the statistical approach to spectral analysis were conducted using individual simulated blood cultures of 36 additional strains (six for each species). Correct identification of the species of these strains was obtained.

Conclusions/Significance

Direct MALDI TOF-MS analysis of aliquots from positive blood cultures allowed rapid and accurate identification of the main Candida species, thus obviating the need for sub-culturing on specific media. Subsequent to this proof-of-principle demonstration, the method can be extended to other clinically relevant yeast species, and applied to an adequate number of clinical samples in order to establish its potential to improve antimicrobial management of patients with fungemia.     

Establishment and Control of Hay-scented Fern: A Native Invasive Species

Hay-scented fern (Dennstaedtia punctilobula (Michx.) Moore) is a native forest understory species that behaves as an invasive plant under certain conditions. Previous work has shown that both increased understory light intensity following overstory thinning and removal of competing plants by herbivores can lead to accelerated growth of hay-scented fern, allowing it to develop dense, nearly monospecific understories that inhibit tree seedling regeneration. To study the relationship between these two factors, we sampled 28 forest stands thinned at different times and subjected to different levels of browsing by white-tailed deer (Odocoileus virginianus), and concluded that more than 15 years of intensive browsing following thinning was necessary for ferns to form closed understory canopies with densities of >90 fronds/m² and canopy heights of 60–80 cm; thinning alone or intensive browsing alone was not sufficient to cause this level of fern invasion. We applied three treatments to dense fern understories to determine the relative importance of the fern canopy and the dense mat of roots, rhizomes, and dead fronds in the inhibition of tree seedling establishment. Results after two years were: (1) complete removal of the organic mat produced a large germination response of woody and herbaceous species; (2) mixing the organic mat into the mineral soil produced an initial germination response but poor seedling survivorship, as the fern canopy regrew to near pretreatment density; (3) repeatedly clipping the ferns for two years without disturbing the organic mat resulted in a lower germination response than the removal treatment, but rapid growth of seedlings.