杂草生防作用物对本土生物群落的影响

传统生物防治是治理外来入侵杂草危害切实可行的有效策略和途径,近来对传统生物防治的批评主要集注于,引进的生防作用物攻击威胁本土非靶标生物。引进的生防作用物可能对本土非靶标生物产生直接和间接影响,这类影响通过不同营养级生物之间的取食关系,以及通过同一营养级内生物间的竞争关系,而影响本土非靶标生物群落。列举若干杂草生物防治案例对以上影响方式及其发生途径进行了评述。就防范杂草生防作用物对非靶标生物的负面影响,提出了以下对策:(i)把引进天敌防治外来入侵生物作为最后的有效手段;(ii)适当增加对非靶标生物潜在影响的生态学评估;(iii)选择寄主专一性强而且能有效控制靶标杂草的天敌;(iv)加强对杂草传统生物防治的生态学研究。     

Methods Used to Assess Non-target Effects of Invertebrate Biological Control Agents of Arthropod Pests

The number of concerns regarding potential non-target effects of invertebrate biological control agents of arthropods has risen over the last decade and an increasing number of studies have since dealt with this topic. Despite some recent international initiatives aimed at providing guidance for risk assessment of biological control agents, detailed methods on how tests should be designed and conducted to assess for potential non-target effects still need to be provided. It is believed that this review comes at an ideal time, giving an overview of methods currently applied in the study of non-target effects in biological control of arthropod pests. It provides the first step towards the ultimate goal of devising guidelines for the appropriate methods that should be universally applied for the assessment and minimisation of potential non-target effects. The main topics that are reviewed here include host specificity (including field surveys, selection of non-target test species and testing protocols), post-release studies, competition, overwintering and dispersal. Finally, a number of conclusions that have emerged from this comprehensive compilation of studies are drawn, addressing potential non-target effects in arthropod biological control.     

Risk analysis and management decisions for weed biological control agents: Ecological theory and modeling results

Biologically based control methods offer many advantages for the control of invasive plant species; however, these methods are not without risks to native species. Thus, there is a need for more effective and efficient methods of risk analysis for biological control agents. We show how the process of ecological risk assessment established by the United States’ Environmental Protection Agency may be adapted to improve assessment of the risks of proposed biological control agents. We discuss the risks posed by weed biological control agents, and present a simple individual-based model of herbivorous insect movement and oviposition on two species of host plant, a target invasive plant species and a non-target native species, in simulated landscapes. The model shows that risks of non-target impacts may be influenced by the details of the movement behavior of biological control agents in heterogeneous landscapes. The specific details of insect movement that appear to be relevant are readily measured in field trials and the general modeling approach is readily adapted to real landscapes. Current biological control risk assessments typically emphasize effects analysis at the expense of exposure analysis; the modeling approach presented here provides a simple and feasible way to incorporate exposure analyses. We conclude that models such as ours should be given serious consideration as part of a comprehensive strategy of risk assessment for proposed weed biological control agents.     

Risk analysis and management decisions for weed biological control agents: Ecological theory and modeling results

Biologically based control methods offer many advantages for the control of invasive plant species; however, these methods are not without risks to native species. Thus, there is a need for more effective and efficient methods of risk analysis for biological control agents. We show how the process of ecological risk assessment established by the United States’ Environmental Protection Agency may be adapted to improve assessment of the risks of proposed biological control agents. We discuss the risks posed by weed biological control agents, and present a simple individual-based model of herbivorous insect movement and oviposition on two species of host plant, a target invasive plant species and a non-target native species, in simulated landscapes. The model shows that risks of non-target impacts may be influenced by the details of the movement behavior of biological control agents in heterogeneous landscapes. The specific details of insect movement that appear to be relevant are readily measured in field trials and the general modeling approach is readily adapted to real landscapes. Current biological control risk assessments typically emphasize effects analysis at the expense of exposure analysis; the modeling approach presented here provides a simple and feasible way to incorporate exposure analyses. We conclude that models such as ours should be given serious consideration as part of a comprehensive strategy of risk assessment for proposed weed biological control agents.     

Risks of biological control for conservation purposes

Striking successes in classical biological control in agriculture and rangelands engender great interest in using this technology for wildlands conservation and environmental purposes. However, well known unintended consequences of several biological control projects have led to concern that possible environmental benefits do not warrant inherent risks. Four risks demand attention: (1) direct attack on non-targets; (2) indirect effects on non-targets; (3) dispersal of a biocontrol agent to a new area, either autonomously or with deliberate or inadvertent human assistance; (4) changed relationships between a control agent and a native species, particularly as generated by global climate change. Procedures for assessing risk of direct attack on non-targets by phytophagous biological control agents have steadily improved and an expanded centrifugal phylogenetic approach appears to provide adequate insight. Direct non-target impacts by entomophages are more difficult to predict. Myriad possible indirect effects, some subtle but nonetheless important, present a far greater challenge, and techniques of assessing such risks are in their earliest infancy and not as closely regulated. Despite prominent examples in both the general invasion literature and that for biological control, the risk that a species, once introduced, will spread beyond its intended range, and the consequences of such spread, are not routinely treated by risk assessors. This phenomenon deserves far more attention. Global changes—especially climate change—can lead to modified ranges and efficacies of introduced biological control agents and their targets. Although many examples show that climatic niches are often not conserved, an important first routine step would be to combine climatic envelopes with general circulation models for predicted future climates. Finally, actions based on a risk assessment are always implemented in a framework of predicted costs and benefits, which are inevitably asymmetric, so it is critically important that all stakeholders, including conservationists, participate in the decision-making process.     

Biological control agents elevate hantavirus by subsidizing deer mouse populations

Biological control of exotic invasive plants using exotic insects is practiced under the assumption that biological control agents are safe if they do not directly attack non-target species. We tested this assumption by evaluating the potential for two host-specific biological control agents ( Urophora spp.), widely established in North America for spotted knapweed ( Centaurea maculosa ) control, to indirectly elevate Sin Nombre hantavirus by providing food subsidies to populations of deer mice ( Peromyscus maniculatus ), the primary reservoir for the virus. We show that seropositive deer mice (mice testing positive for hantavirus) were over three times more abundant in the presence of the biocontrol food subsidy. Elevating densities of seropositive mice may increase risk of hantavirus infection in humans and significantly alter hantavirus ecology. Host specificity alone does not ensure safe biological control. To minimize indirect risks to non-target species, biological control agents must suppress pest populations enough to reduce their own numbers.     

外来入侵杂草传统生物防治的生态风险及其防范对策

长期大量实践说明,引进天敌防治外来入侵杂草的传统生物防治方法是治理外来入侵杂草的一条切实可行的有效途径,但对其潜在的生态风险——对本土生物的直接或间接不良影响不容忽视。利用传统评价方法预测候选天敌的生态风险存在缺陷,主要表现在：（1）寄主专一性测定过分依赖室内进行的生理寄主范围测定结果,对生态寄主范围（实际寄主范围）问题重视不够,后者指在新环境中的一系列物理和生物条件下的寄主利用预测;（2）在生理寄主范围测定中,过分依赖完成生长发育的可能性,对行为、遗传性状以及系统发育关系重视不够;（3）在风险评估中,过多强调对经济作物的风险,而对自然生态系统的风险重视不够。对此,建议：（1）鼓励对已释放的天敌进行回顾性跟踪研究,从而为杂草生物防治实践提供生态学理论支撑;（2）在运用生物防治手段对付外来入侵杂草实践中,建议采用“有害推论”的预防性原则,以避免在面临入侵生物重大威胁时草率做出释放天敌的决策;（3）在评估候选天敌风险中重视生态效应的风险评估。     

Predictability of pathogen host range in classical biological control of weeds: an update

Before an exotic pathogen can be released as a classical biological control agent the likely positive and negative outcomes of that introduction must be predicted. Host range testing is used to assess potential damage to non-target plants. To-date 28 species of fungi have been released as classical biological control agents against weeds world-wide. These pathogens have been reported infecting only six non-target plant species outdoors and all of these incidents were predicted. Many more non-target plant species developed disease symptoms in glasshouse tests than in the field. Consequently, data from other sources are needed to ensure potential agents are not prematurely rejected. Predictions of pathogen host range to date have been sufficiently accurate to prevent unpleasant surprises. Exotic pathogens are a safe and useful tool for weed control, especially in natural areas rich in valued non-target species.     

Exotic biological control agents: A solution or contribution to arthropod invasions?

Biological control is a valuable and effective strategy for controlling arthropod pests and has been used extensively against invasive arthropods. As one approach for control of invasives, exotic natural enemies  from the native range of a pest are introduced to areas where control is needed. Classical biological control began to be used in the late 1800s and its use increased until, beginning in 1983, scientists began raising significant concerns and questions about nontarget and indirect effects that can be caused by these introductions. In recent years, similar issues have been raised about augmentative use of exotic natural enemies. Subsequently, international guidelines, national regulations and scientific methods being used for exotic natural enemies in biological control have changed to require appropriate specificity testing, risk assessment and regulatory oversight before exotic natural enemies can be released. National and international standards aimed at minimizing risk have increased awareness and promoted more careful consideration of the costs and benefits associated with biological control. The barriers to the implementation of classical and augmentative biological control with exotic natural enemies now are sometimes difficult and, as a consequence, the numbers of classical biological control programs and releases have decreased significantly. Based in part on this new, more careful approach, classical biological control programs more recently undertaken are increasingly aimed at controlling especially damaging invasive arthropod pests that otherwise cannot be controlled. We examine evidence for these revised procedures and regulations aimed at increasing success and minimizing risk. We also discuss limitations linked to the apparent paucity of post-introduction monitoring and inherent unpredictability of indirect effects.     

Assessing Risks of Plant-Based Pharmaceuticals: II. Non-Target Organism Exposure

Plant-based pharmaceuticals potentially offer a cleaner method of producing a protein for drug manufacturing than traditional methods because plants are free of mammalian infectious agents. However, in the open environment they have the potential for intra-and inter-species gene flow, protein exposure to the public and non-target organisms, and they also have the potential to contaminate livestock feed. This study used probabilistic approaches to quantify the non-target organism risks associated with three pharmaceutical proteins produced in field-grown maize. The risk assessment for plant-based pharmaceuticals was conducted for four receptor species used as surrogates for a wider range of species. Body weights and maize consumption rates for each species were modeled from currently available information and used to calculate the exposure based on expression levels of three proteins. The acute dietary exposure for the receptor species was a single-day event in which the total maize consumption came from the recombinant maize. The non-target organism risk assessment demonstrated that risks will vary between species and between proteins, based primarily on differences in toxic endpoint and consumption rates. It also shows the utility of probabilistic, quantitative risk assessment methodologies and the importance of assessing risks from plant-based pharmaceuticals on a case-by-case basis.     

Harmonia axyridis: an environmental risk assessment for Northwest Europe

In this paper, we summarize the international situation with respect to environmental risk assessment for biological control agents. Next, we apply a recently designed, comprehensive risk evaluation method consisting of a stepwise procedure to evaluate the environmental risks of Harmonia axyridis in Northwest Europe. This resulted in the very clear conclusion that H. axyridis is a potentially risky species for Northwest Europe, because it is able to establish, it has a very wide host range including species from other insect orders and even beyond the class of Insecta, it may feed on plant materials, it can cover large distances (>50 km per year), it does move into non-target areas, it may attack many non-target species including beneficial insects and insects of conservation concern, its activities have resulted in the reduction of populations of native predators in North America, it is known as a nuisance in North America and recently also in Northwest Europe, and it may develop as a pest of fruit in North America. Considering the H. axyridis case, current knowledge would lead to the conclusion that, although the predator is capable to effectively control several pest species, its risks are manifold and it should, thus, not have been released in Northwest Europe. At the time of the first releases in Nortwest Europe in 1995, the available scientific literature made clear that H. axyridis is a large sized polyphagous predator and has a great reproductive capacity in comparison with other ladybird beetles, and that there was a need to study non-target effects because of its polyphagous behaviour. In retrospect, this information should have been sufficient to reject import and release of this species, but it was apparently ignored by those who considered release of this predator in Northwest Europe. The case of Harmonia releases in Northwest Europe underlines that there is an urgent need for harmonized, world-wide regulation of biological control agents, including an information system on risky natural enemy species.     

Environmental risk assessment of exotic natural enemies used in inundative biological control

In the past 100 years many exotic naturalenemies have been imported, mass reared andreleased as biological control agents. Negativeenvironmental effects of these releases haverarely been reported. The current popularity ofinundative biological control may, however,result in problems, as an increasing number ofactivities will be executed by persons nottrained in identification, evaluation andrelease of biological control agents.Therefore, a methodology for risk assessmenthas been developed within the EU-financedproject `Evaluating Environmental Risks ofBiological Control Introductions into Europe[ERBIC]' as a basis for regulation of importand release of exotic natural enemies used ininundative forms of biological control (i.e.not in `classical biological control' thoughsome of the same principles and approachesapply). This paper proposes a general frameworkof a risk assessment methodology for biologicalcontrol agents, integrating information on thepotential of an agent to establish, itsabilities to disperse, its host range, and itsdirect and indirect effects on non-targets. Ofthese parameters, estimating indirect effectson non-targets will be most difficult, asmyriads of indirect effects may occur whengeneralist natural enemies are introduced. Theparameter `host range' forms a central elementin the whole risk evaluation process, becauselack of host specificity might lead tounacceptable risk if the agent establishes anddisperses widely, whereas, in contrast, amonophagous biological control agent is notexpected to create serious risk even when itestablishes and disperses well. Drawing onpublished information and expert opinion, theproposed risk assessment methodology is appliedto a number of biological control agentscurrently in use. These illustrative casehistories indicate that the risk assessmentmethodology can discriminate between agents,with some species attaining low `risk indices'and others scoring moderate or high. Riskindices should, however, not be seen asabsolute values, but as indicators to which ajudgement can be connected by biologicalcontrol experts for granting permission torelease or not.     

Biological Control not on Target

Non-target effects of exotic biological control agents, parasitoids and predators, released worldwide to control insect pests, are becoming more apparent. This paper summarizes previously recorded information on the diet breadth of natural enemies released to control insect pests worldwide. It also summarizes the diet breadth of native parasitic hymenoptera in North America to determine whether the diet breadths of native and exotic parasitoids differ. Of released biocontrol agents, 48% were recorded as generalists (attacking more than one genus of host) and another 29.2% attacked more than one species in a genus. Only 22.5% were recorded as specialists on the target pests. This suggests that many natural enemies released in biocontrol programs against insect pests have broad diets and that non-target effects are likely. Data from native hymenoptera in North America also show that many species attack multiple host genera and species, with an average of 5.8 genera and 7.3 species attacked, indicating broad agreement with data from biological control releases.     

Utilization of the Exotic Weed Pluchea odorata (Asteraceae) and Related Plants by the Introduced Biological Control Agent Acinia picturata (Diptera: Tephritidae) in Hawaii

The flower-head feeding fly Acinia picturata (Diptera: Tephritidae) was deliberately introduced from Mexico into Hawaii in 1959 for biological control of the exotic weed Pluchea odorata (Snow) (Asteraceae). Neither field efficacy nor possible non-target effects of the fly have been evaluated in the 40 years since the introduction. We assessed the impact of the fly on both its target host and on seven non-target plant species. The impact on the target weed was limited, with only 5-13% of the developing seeds in P. odorata flowerheads being destroyed by larval feeding. We did not detect any host range expansion of A. picturata onto flowerheads of two exotic or 5 endemic non-target plant species in the family Asteraceae.     

Bt水稻田重要非靶标节肢动物暴露于Cry2Aa蛋白的程度分析

根据风险=危险×暴露的原理,在实验室条件下评价转基因作物对非靶标节肢动物影响时,所选择的代表性非靶标生物通常是在农田系统中较高地暴露于转基因外源杀虫蛋白的节肢动物种.为了弄清Bt稻田主要节肢动物暴露于Cry蛋白的程度,选择合适的非靶标节肢动物,用于转基因抗虫水稻的风险评价,本文采用酶联免疫技术检测了水稻不同生长期从转cry2Aa基因水稻田采集的不同节肢动物体内Cry2Aa蛋白的含量.结果表明: 不同节肢动物种体内的Cry蛋白含量差异显著.一些节肢动物体内不含Cry蛋白,而一些节肢动物体内含有较高的Cry蛋白;相对于花期后采集的节肢动物,在Bt水稻花期采集的节肢动物,特别是捕食性节肢动物体内的Cry蛋白含量较高;寄生性节肢动物体内未检测到Cry蛋白.这为在实验室条件下评价转基因水稻对农田非靶标节肢动物的影响奠定了基础.     

Species Risk Assessment of Microscopic Exotic Organisms Associated with Forest-Related Commodities and Goods

Recent increases in international trade have increased the cost to control and eradicate exotic species. Although many species are under quarantine control for agriculture, forestry, and public health, most species invisible to the naked eye are ignored because of the lack of both specialized assessors and risk assessments. We developed a species risk assessment particularly adapted to fungi, nematodes, and mites, that might be unintentionally introduced with exotic forest products and become threats to terrestrial ecosystems. We developed our assessment with reference to existing risk assessments for exotic organisms, including their ecological features such as phoresy and parasitism. We then tested our assessment with well-known organisms and assessed the risks of organisms unintentionally introduced into Japan. The assessment demonstrated scientifically acceptable scores for each organism. We suggest quarantine control of risk pathways as a practical approach for controlling unintentionally introduced organisms that are invisible to the naked eye.     

Selecting non-target species for risk assessment of entomophagous biological control agents: Evaluation of the PRONTI decision-support tool

The release of entomophagous biological control agents can pose risks to non-target invertebrate species in the release area and beyond. Pre-release risk assessment of these agents often involves tests with non-target species; however, selecting appropriate test species can be difficult when there is a large number to choose from. The PRONTI (priority ranking of non-target invertebrates) tool has been developed to aid this selection process. This automated tool prioritises species for testing using five criteria: (1) direct and indirect hazards posed by the agent, (2) likelihood of exposure to the hazards, (3) ecological impacts that may result from that exposure, (4) species’ anthropocentric value and (5) testability. Criteria (1) and (2) produce a risk estimate that drives the ranking process. In a test of PRONTI’s ability to identify non-target species at most risk from a proposed biological control agent, we used a generalist predator already present in New Zealand, the Asian paper wasp Polistes chinensis, as if it were the agent in a hypothetical biocontrol programme aimed at lepidopteran pests in New Zealand kiwifruit orchards. A ranked list of 340 invertebrate taxa known to occur in kiwifruit orchards was produced. To validate the risk estimates for a direct attack by P. chinensis on each taxon, wasps were introduced to kiwifruit orchards and prey taxa identified. Risk estimates were accurate except where identified prey taxa had not previously been recorded from kiwifruit orchards.     

What Magnitude Are Observed Non-Target Impacts from Weed Biocontrol?

A systematic review focused by plant on non-target impacts from agents deliberately introduced for the biological control of weeds found significant non-target impacts to be rare. The magnitude of direct impact of 43 biocontrol agents on 140 non-target plants was retrospectively categorized using a risk management framework for ecological impacts of invasive species (minimal, minor, moderate, major, massive). The vast majority of agents introduced for classical biological control of weeds (>99% of 512 agents released) have had no known significant adverse effects on non-target plants thus far; major effects suppressing non-target plant populations could be expected to be detectable. Most direct non-target impacts on plants (91.6%) were categorized as minimal or minor in magnitude with no known adverse long-term impact on non-target plant populations, but a few cacti and thistles are affected at moderate (n = 3), major (n = 7) to massive (n = 1) scale. The largest direct impacts are from two agents (Cactoblastis cactorum on native cacti and Rhinocyllus conicus on native thistles), but these introductions would not be permitted today as more balanced attitudes exist to plant biodiversity, driven by both society and the scientific community. Our analysis shows (as far as is known), weed biological control agents have a biosafety track record of >99% of cases avoiding significant non-target impacts on plant populations. Some impacts could have been overlooked, but this seems unlikely to change the basic distribution of very limited adverse effects. Fewer non-target impacts can be expected in future because of improved science and incorporation of wider values. Failure to use biological control represents a significant opportunity cost from the certainty of ongoing adverse impacts from invasive weeds. It is recommended that a simple five-step scale be used to better communicate the risk of consequences from both action (classical biological control) and no action (ongoing impacts from invasive weeds).     

Exotic ladybirds for biological control of herbivorous insects – a review

Since the late 19th century, exotic ladybirds (Coleoptera: Coccinellidae) have been used extensively for suppressing herbivorous insects of economic importance. In recent decades, the introduction of non‐native biological control (BC) agents has been greatly limited due to the awareness of the potential non‐target effects of introductions. Nonetheless, recent episodes of biological invasions of economically important pests have raised the need to carefully consider whether the expected benefits of pest control go beyond the possible environmental risks of introduction. To better understand the factors that contributed to successful BC programs, here we review the literature behind classical and augmentative BC using exotic ladybirds. Additionally, by means of case studies, we discuss the BC efficacy of selected exotic species, e.g., Coccinella septempunctata L., Harmonia axyridis (Pallas), and Hippodamia variegata (Goeze), and their position within the communities of predators in the introduced areas of USA, Canada, and Chile. In Europe, much of the research on exotic ladybirds has been conducted on the undesired impact of H. axyridis. Therefore, we summarize the risk assessment data for this species and review the field research investigating the ecological impact on European aphidophagous predators. According to the BIOCAT database of classical BC programs, 212 ladybird species belonging to 68 genera have been released in about 130 years of BC activity, with 14.6% of introductions having resulted in partial, substantial, or complete control of the target pest. However, because post‐release evaluation of establishment and BC success has not always been conducted, this rate could underestimate the successful cases. Among other factors, ladybird establishment and pest suppression mostly depend on (1) intrinsic factors, i.e., high voracity, synchronized predator‐prey life cycle, and high dispersal ability, and (2) extrinsic factors, i.e., adaptability to the new environment and landscape composition. This review contributes to improved understanding of ladybirds as exotic BC agents.     

Bad side of a good beetle: the North American experience with Harmonia axyridis

The multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is a generalist predator of aphids and other soft-bodied insects and has been utilized in biological control programs around the world. Over the last two decades, this species has spread throughout much of the continental USA and southern Canada. Despite the benefits it offers as a biological control agent, H. axyridis is perhaps most well known for its adverse impacts. In this paper we provide a review of the North American experience with H. axyridis, focusing on these adverse impacts, which can be classified into three general categories: impacts on non-target arthropods, impacts on fruit production and impacts as a household invader. The impacts of H. axyridis on non-target arthropods and, to lesser extent, the impacts as a household invader possibly could have been anticipated, due to its generalist feeding preferences and overwintering behavior in Asia. However, it is unlikely that the impacts on fruit production could have been anticipated. Therefore, even in retrospect, it is difficult to predict the potential impacts that an introduced natural enemy might have in its adventive range.