Weed biological control: applying science to solve seemingly intractable problems

Abstract   Exotic weeds pose a problem of considerable economic and environmental importance to Australia. As a consequence, Australia has developed into a leading centre of research on weed biological control, with over 60 weeds the targets of past and current projects. Using primarily entomological examples, this review highlights the contributions made by Australian scientists to the development of theory and the improvement of practice in weed biological control. It also shows how biological control practitioners have made use of, and contributed to, broader theory and knowledge of plant-herbivore relationships. Finally, it concludes with some reflections on the future direction of biological control in Australia.     

福寿螺的生物防治现状、问题与对策

福寿螺(Pomacea canaliculata)作为一种世界性入侵生物,引入中国已有30余年,现已在中国南方十多个省市大面积分布,造成不可估量的经济损失和生态灾害。本文系统总结了福寿螺生物防治中的天敌资源种类,涵盖了腹足纲、环带纲、昆虫纲、软甲纲、辐鳍鱼纲、爬行纲、鸟纲、哺乳纲等8个类别。并从天敌的引入、研发、利用等方面以及福寿螺应对天敌的防御策略上指出了目前福寿螺生物防治中面临的主要问题。最后对其未来的研究提出了展望,即重点从原产地天敌、寄生性天敌、微生物、生物防治植物和本地经济动物等方面进行筛选,以期为利用中国丰富的生物资源进行福寿螺的生物防治提供参考。     

Approaches to nonconventional control of plant virus diseases

Plant viruses cause significant losses to crops worldwide and the three basic approaches to controlling them have not been overly successful. The new concept of nonconventional resistance, which involves transforming plants with nucleic acid sequences that interfere with the viral infection cycle, is a promising new approach. The current nonconventional strategies, those of coat protein‐mediated protection, antisense nucleic acids, satellite sequences, defective interfering molecules, and nonstructural genes, are reviewed with their advantages and disadvantages being discussed. The question of what exactly is nonconventional resistance is raised and suggestions are made for defining resistance. A range of strategies that are likely to be developed in the future are outlined together with some guiding principles for selection and deployment of these forms of resistance.     

Theoretical contributions to biological control success

Ecologists have long tried, with little success, to develop ecological theory for biological control. Biological control illustrates how science often follows, rather than precedes, technological advances. A scientific theory of biological control remains a worthy and achievable goal. We need to (1) combine deductions from mathematical models with rigorous empiricism measuring and modeling the effects of abiotic and biotic environmental drivers on demography and population dynamics of real biological control systems in the field, (2) use a wider range of model systems to explore how population structure, movement, spatial heterogeneity, and external environmental conditions influence population and community dynamics, and (3) combine deductive and inductive approaches to address the day-to-day concerns of biocontrol scientists including how to rear and release a control organism, suppress the target organism, and minimize harm to non-target organisms. Further progress will require more fundamental research in population and community ecology directly relevant to biological control.     

Approaches to genetic control for the use of pesticides

Analysis of data available in literature has shown that 65% of 400 pesticides studied for their mutagenicity exert a mutagenic effect on any test-object. The number of revealed mutagens approaches 100% when four or more test-objects are used. Recommendations for quantitative estimation of genetic risk worked out under conditions of model experiments with standard mutagens are not available for pesticides since they are slight mutagens. The necessity for genetic stage-by-stage monitoring of pesticide use is substantiated. This monitoring should be carried out at the stage of experimental studies by means of classifications by the degree of potential mutagenic danger (the method is described) and at the stage of ecological and genetic investigations--by means of the regulation for application with due regard for the summary mutagenic background.     

Approaches to the control of acellular pertussis vaccines.

The quality control of acellular pertussis vaccines presents particular problems related to the differences in composition and method of detoxification used in the various type of preparation. These vaccines are not amenable to potency assay by the active mouse protection test used for whole-cell pertussis vaccines and assurance of protective activity is problematic.In contrast, monitoring of these vaccines for safety is relatively straightforward and is centred on assays for the lipooligosaccharide endotoxin, active pertussis toxin and absence of reversion to toxicity of detoxified product. The absence of heat-labile toxin, tracheal cytotoxin and adenyl cyclase toxin is assumed provided that adequate validation of the process has been performed.Confirmation of the antigenic content of the detoxified bulk components is difficult to achieve by conventional binding assays based on monoclonal antibodies because of changes in accessibility of reactive sites post-toxoiding. However, single radial diffusion assay using polyclonal antisera permits estimation of pertussis toxoid (PT), filamentous haemagglutinin (FHA) and pertactin (P69). Dot blot immunoassay can be used for the fimbrial agglutinogens 2 and 3 (Fim 2 and 3) and potentially could also be used to check the composition of final filling lots for PT, FHA, P69 and Fim 2 and 3.Gel electrophoresis and immunoblotting can be applied to monitor purity of purified bulk components and the characteristics of these change after chemical detoxification. Electron microscopy provides a useful semi-quantitative supporting method for checking purity of bulk components. Physico-chemical examination, particularly CD and fluorescence spectroscopy, offer a means of monitoring the consistency of detoxified bulk components.No completely satisfactory method is available for monitoring potency. Immunogenicity assays may be useful for checking consistency but do not necessarily correlate with protection. At present, active protection against aerosol challenge offers the best prospect of a functional assay.     

Quasi-elastic light scattering. Application to biological problems]

The origin of the light scattered from macromolecular solutions is considered and a discussion is made around the use of laser and light beating spectroscopy to analyze the scattered field spectrum. Several experiments are reviewed where quasi elastic light scattering has been applied.     

Regional nitrogen budgets: Approaches and problems

Regional nitrogen budgets are useful for assessing what is known about nitrogen cycling in important ecosystems of a region, for placing the various regional fluxes and pools into perspective, and for providing insight into the processes that regulate both regional and global nitrogen cycling. Existing regional budgest have been used both to study groundwater nitrate pollution and to help identify local ecosystems that are important on a land-use basis but that are poorly described biogeochemically. Avoidable problems common to many budgets include inappropriate compartment components, inadequate documentation, and unjustified certainty. Though imprecise, large-scale nutrient budgets at our present stage of understanding offer to researchers and system managers important advantages that would otherwise not be available.     

Improving biological control

Nature Wars: People vs. Pests by Mark L. Winston Harvard University Press, 1997. ￡16.50/$24.95 hbk (x +210 pages) ISBN 0 674 60541 1.     

Political deafness may impede transition to biological control

Biological control has developed into a realistic alternative to replace chemical pesticides. A long-awaited paradigm shift is now adopted by the European Commission through a proposed new Regulation on sustainable use of plant protection products. Unfortunately, the scientific framework underpinning biocontrol is seriously neglected, impeding transition to sustainable plant production.     

Entomopathogenic fungi as biological insecticides to control malaria

Malaria is arguably the most serious vector-borne disease worldwide. The already-alarming number of deaths caused by malaria is increasing, caused in part by the increase in mosquito resistance to chemical insecticides. In two recent articles, the use of an approach was reported that could open a new front in the fight against malaria. Laboratory and field studies demonstrate that entomopathogenic fungi can efficiently kill adult anopheline mosquitoes, the females of which are the obligatory vectors for malaria parasites.     

Yeasts as biological agents to control Botrytis cinerea

Yeasts, isolated from different sources, were identified and tested for inhibition using YMA-MB plates seeded with Botrytis cinerea strains. A total of 42 yeast strains of 20 different species were tested in vitro for antagonism against 18 pathogenic B. cinerea strains. Pichia membranifaciens, P. anomala and Debaryomyces hansenii displayed the most important inhibitory effect against Botrytis strains. In small-scale trials, post-harvest application of P. membranifaciens CYC 1106 to apple wounds inhibited B. cinerea CYC 20010. Purified killer toxin from P. membranifaciens CYC 1106 inhibited B. cinerea CYC 20010. Results indicated that certain yeasts, or their toxins such us P. membranifaciens CYC 1106 killer toxin, might have potential as novel agents to control B. cinerea.     

Mycotoxins in house dust problems and analytical Approaches

People in developed countries spend up to 90% of their time indoors. This led to an increased awareness for problems regarding indoor environment in the recent years. It is known that mycotoxins formed by moulds can be harmful to human health.The body burden of mycotoxins is caused primarily by the uptake of cereals and related products but sometimes also by animal products. However the health effects caused by indoor moulds are currently under investigation. Therefore the aim of an investigation program is to study mould-dependent health effects in a burdened population of the city of Leipzig, Germany. To estimate exposure situation house dust samples are collected from loaded apartments. To realise the measurements of selected mycotoxins in house dust the development of a suitable analytical method was necessary. Capillary electrophoresis in combination with a special clean up of the samples was found to be an useful tool for these investigations.     

21世纪我国害虫生物防治研究的进展、问题与展望

害虫生物防治是昆虫学的重要分支学科,进入21世纪以来,随着生命科学和生物技术的发展以及新原理、新方法的不断渗透、交叉与融合,使该分支学科在我国得到了快速发展。本文就近年来我国在天敌昆虫及其利用、昆虫病原微生物及其利用、昆虫信息素及其应用、生物农药及其推广应用、新兴生物技术在害虫生物防治中的应用等方面所取得的主要进展作了简要的回顾与总结;并在分析我国本领域学科发展水平与国际差距的基础上,指出了我国生物防治领域存在的主要问题及几个亟待加强的优先发展领域。