Potential for biological control of field bindweed in California's coastal vineyards

The possibility of using biological control against field bindweed, Convolvulus arvensis L., was studied in four vineyards along the California coast. Field bindweed is a dominant member of the weed community and the principal plant pest in these vineyards. There is considerable insect and mite damage to its foliage during late summer and autumn, but the stress this places on the weed is unknown. The most significant natural enemies of field bindweed are defoliating caterpillars, Bedellia somnulentella Zeller, Chaetocnema confinis Crotch, and spider mites. Non of the natural enemies present appeared to be suitable as biological control agents. However, some arthropods, such as Noctuelia floralis (Huebner), associated with field bindweed in Mediterranean Europe and Pakistan, could be useful in the California grape agroecosystem, once cleared for importation and release in North America. Others, unsuitable to release in California because of feeding on closely related native plants, may be of value in other parts of the world where no such conflicts of interest exist. It would be feasible to use biological control against field bindweed in California's coastal vineyards and, perhaps, also in orchards under present systems of cultivation. Its effectiveness could be enhanced by certain changes in growing practices, particularly the acceptance of some weed growth, and by changes in existing pest controls. Biological control of field bindweed should be considered in the development of pest management programs for such crops in California and wherever this plant is a serious pest.     

Occurrence of phytophagous insects on wild Vigna sp. and cultivated cowpea: comparing the relative importance of host-plant resistance and millet intercropping

The effects of host-plant resistance on cowpea phytophagous insects and their natural enemies under pure and mixed crop conditions was evaluated at Minjibir, Kano State, Nigeria, in 1992–1994 crop seasons. Cowpea Vigna unguiculata cv ‘IT86D-715' (susceptible to insect pests) and a wild Vigna line Vigna vexillata ‘TVnu 72' (resistant to most insect species) were planted alone and in mixtures with millet (Pennisetum glaucum) in plots of 25×25 m.Mixed cropping had limited effect on major insects and natural enemies. Colonies of Aphis craccivora were significantly smaller and there were more adults of Maruca vitrata in crop mixtures than in monocultures. However, flower and raceme infestation by larval M. vitrata, Megalurothrips sjostedti, and Sericothrips sp. were similar in crop mixtures and monocultures. Empoasca sp. populations and seedling infestation by beanfly Ophiomyia phaseoli were also similar in mixtures and monocultures as well as pod damage by M. vitrata and populations of Clavigralla tomentosicollis. Parasitization rates of M. vitrata, C. tomentosicollis and O. phaseoli and predator–prey ratios of spiders and Orius sp. were similar across cropping systems. Host-plant resistance in TVnu 72 drastically reduced insect populations and damage. Grain yield per hill was high in cowpea IT86D-715 and was not affected by intercropping with millet. Grain yield of TVnu 72 was poor and reflected the low yield potential of this accession.Host-plant resistance is an effective means of controlling insect pest damage in cowpea and there is no evidence that high levels of resistance reduced natural biological control.     

Survey of current crop management practices in a mixed-ricefield landscape,Mekong Delta,Vietnam — potential of habitat manipulation for improved control of citrus leafminer and citrus red mite

In the Mekong Delta, Vietnam, the citrus leafminer Phyllocnistis citrella (CLM) and the citrus red mite Panonychus citri are major pests in both sweet orange (Citrus sinensis) and Tieu mandarin (C. reticulata). Survey data indicate that these pest problems might be aggravated after farmers have completely destroyed the weed flora in their orchard. As citrus farmers only perceive the larger predators such as the weaver ant Oecophylla smaragdina and spiders, and have no idea about the existence of predatory mites or parasitoids, they do not know about potential positive attributes of weeds in pest management which sustain populations of natural enemies and their alternative food. IPM training programmes could use the weaver ant as an introduction to educating farmers about predatory mites and parasitoids, and should likewise emphasise the importance of beneficial asteraceous weeds such as Ageratum conyzoides. Non-crop trees such as Spondias dulcis, Mangifera indica, Eucalyptus tereticornis and Ceiba pentandra are commonly known to offer good refuge for the weaver ant. These trees should be further studied for their temporal contribution as food resource for other natural enemies of CLM and mites. Small adjustments of current weed management techniques are suggested to improve availability of pollen and nectar for beneficials at crucial moments in the cropping season, with due respect to implications at the landscape level.     

Interactions of host-plant resistance in cotton with predators and parasites

Results from no-choice field and greenhouse studies established an inverse relationship between plant trichome density in cotton and the level of successful attacks on Heliothis zea (Boddie) eggs by the parasite, Trichogramma pretiosum (Riley) and the predator, Chrysopa rufilabris (Burmeister). Thus, plant damage from H. zea can be reduced on glabrous cotton phenotypes due to antixenosis and increased entomophage effectiveness compared to hirsute and pilose phenotypes. Studies by other scientists which demonstrate interactions of natural enemies with host-plant resistance in cotton are also discussed. Symbiotic relationships between the host-plant and its associated predator/parasitoid complex may significantly influence the expression of host-plant resistance in cotton. Scientists involved in programs for development of host-plant resistant cultivars are encouraged to utilize sources of resistance which increase effectiveness of key natural enemies of the major pest species.     

The ecological basis of boll weevil (Anthonomus grandis Boheman) management

The boll weevil (Anthonomus grandis Boheman), generally considered to be native to Mexico or Central America, spread into the southern United States of America in the late 1800s and seriously threatened the cotton industry. As there were no effective alternatives, pest control specialists studied the insect's ecology and advocated cultural practices that would disrupt its environment and maximize the benefits of natural biological and environmental controls. An ecologically orientated pest management scheme founded on cultural practices emerged well before suitable chemical control technology became available and allowed farmers to live with the weevil problem.Despite the ingenuity of the early management scheme, it frequently did not provide satisfactory boll weevil control gauged by present standards. Control of the pest thus shifted largely from an ecological to a chemical approach as effective synthetic organic insecticides became available after World War II. The chemical approach was successful for a number of years, but problems of insecticide-resistant strains of pests, secondary pest outbreaks, environmental quality, and increased costs of the insecticides have forced pest control specialists to re-emphasize the nonchemical techniques used widely against the boll weevil before World War II and to revive the ecological approach to weevil management.This article examines boll weevil ecology as related to management of the insect and reviews the status and prospects of ecologically-based weevil management techniques in the United States.     

Public acceptance of tree health management: Results of a national survey in the UK

Assumptions about public stakeholder attitudes to pest and disease management can influence the decisions of forest managers and NGOs involved in responding to pests and diseases; however, they are rarely assessed directly. Evidence on the social acceptability of tree health management methods is required to inform government led policy and management. A nationally representative survey of 2000 members of the UK public was used to address two research questions: (1) How acceptable are tree health management methods to the public? (2) How do opinions about woodland functions, concern and awareness of tree pests and diseases, and demographics influence acceptance of management methods? We found that public stakeholders are highly supportive of tree health management; however, knowledge about tree pests, diseases, and management options is low. Methods seen as more targeted and ‘natural’ were preferred, e.g. felling and burning only affected trees and using biological control rather than chemical control. There were demographic differences in attitudes: men and older people are more likely to support management interventions and stronger management methods than females and younger people. Acceptance of management can also differ according to location and local context (e.g. management is less supported when it may impact on wildlife) and values (e.g. those with economic values are more supportive of management). These findings provide evidence to support current government initiatives on tree health and should improve confidence amongst managers tasked with carrying out tree pest and disease management. However, there is a need for in-depth qualitative studies to explain the beliefs which influence demographic variations in acceptance and the influence of concepts such as ‘nativeness’ and ‘naturalness’.     

Impact of variable nitrogen fertilisation on arthropods in cotton in Georgia, USA

Reducing fertiliser applications can reduce production costs for cotton (Gossypium hirsutum L.) growers, as well as nitrogen (N) leaching into the soil and contamination of surface and ground water. But altered N fertilisation may also affect pests and their natural enemies. In this study, plots with four different levels of fertiliser input (0, 45, 90 and 135 kg ha⁻¹ N) were used to investigate the influence of N on cotton pest and beneficial arthropod populations, and on cotton yield in Tifton, GA, USA. We predicted that (1) N fertilisation will correlate positively with cotton plant growth; (2) increased N fertilisation will increase pest populations because plants with more N will be more nutritious for and attractive to herbivores; (3) populations of beneficial arthropods and predation of pests will decline with increased N fertilisation because of reduced plant signaling; (4) increased N fertilisation will increase pest mortality due to parasitoids because of increased host quality. Cotton plant growth was enhanced by N fertilisation but yield was unaffected. N fertilisation significantly affected some pest arthropods but inconsistently. Mirids were most abundant in the high N treatment in 1 year of the study and cotton aphids were most abundant in the highest N treatment in the other year of the study. Arthropod predators were generally more abundant in the high N treatment but only spiders and Geocoris spp. were significantly affected by N treatment, with highest numbers present in the highest N treatment but the significant differences were each only in a single year. The greatest mortality of sentinel pest eggs (Spodoptera exigua) due to predation occurred under low N conditions. N fertilisation had no significant effects on parasitism of feral or sentinel caterpillars.     

防治外来入侵物种水葫芦对环境保护的研究

对水葫芦所产生的损害进行评估,为鉴定生态恢复的范围以及对破坏做出补救所需采取的措施奠定基础.从预防、根除与控制水葫芦的角度,确定从利用生物控制剂管理水葫芦的技术考量因素.由于水葫芦在中国发生的危害特点与其他国家不尽相同,通过提高本地独特的天敌的防治效果更为重要.根据《国际植物检疫措施》第2、3和11号标准,将其性质定位外来入侵物种,并例入《中华人民共和国进境植物检疫性有害生物名录》加以规制,来防治水葫芦入侵,保证中国环境的安全.     

农业技术推广过程中制度因素的影响——湖北省天门市棉花害虫综合防治项目案例分析报告

针对中国主产棉区在病虫害防治中大量施用化学农药加重农业污染，以及害虫产生抗药性导致防治失灵等问题，由亚洲开发银行（ＡＤＢ）资助，英联邦国际生物防治研究所（ＣＡＢＩ）负责实施，于１９９３～１９９６年在中国湖北省天门市建立害虫综合防治（ＩＰＭ）项目试点，旨在研究和开发控制病虫危害和改善生态环境的适用于中国主产棉区的ＩＰＭ技术体系。ＩＰＭ项目有两个特点：①与以往因土地、人口压力而引致的技术变革不同，ＩＰＭ项目是一项因环境压力而引致的技术变革；②以往的技术变革的阻力大多来自于乡村社会结构尤其是农民对新技术的不接受，而ＩＰＭ项目在运作层面首先遇到了高度集中的防治体系的阻碍，即受到制度因素的影响。本文着重分析高度集中的防治体系形成的过程和原因，以及制度因素影响ＩＰＭ项目实施的作用机制，并提出解决问题的政策建议。     

Crop losses: The need to quantify the effects of pests,diseases and weeds on agricultural production

Crop losses caused by pests, including rodents and birds, and by diseases and weeds, are defined, and previous studies reviewed. Information about losses is needed to monitor the effects of pests and diseases on crop production, in individual countries and worldwide, important for food policy and economic reasons; to make decisions and allocate resources on the study, management and control of pests and diseases; to stimulate action against them; to provide guidelines for research on crop improvement to prevent pest and disease attack; and as a basis for judgement on the importance of pests, diseases and weeds in relation to agriculture and the environment.The causes of such losses, why information must be up to date, and methods of assessing pests, diseases, weeds and losses are examined. The part played by losses in the development and use of economic pest and disease control action thresholds is discussed, including pest, disease, crop, climatic, economic and farmer attitude factors. The types of relation between yield and pest and disease attack are reviewed, how to measure the relation in practice, how to obtain different amounts of attack, surveys of losses, and the difficulties met in the study of losses: interaction; compensation; interplot interference; variation; and distribution. Sources of information on world losses, training and the work of the FAO are reviewed. General guidelines on crop loss assessment are given.     

A review of the use of models of weed control in Integrated Crop Protection

An examination is made of the role that mathematical modelling can have in developing integrated strategies, involving reduced dependence on chemicals, for controlling weeds, pests and diseases in crops. From a detailed survey of the application of models to weed control, it is concluded that modelling has fundamentally been concerned with answering issues that contribute comparatively little to our understanding of ‘sustainable’ systems of crop protection. There has been a strong concentration of effort on simulating the impacts of herbicides and on identifying ‘threshold’ levels for spraying. Issues such as herbicide resistance, weed-crop interference and integrated weed management systems have received scant attention. None-the-less, given the complexity of the management systems involved in Integrated Crop Protection, mathematical modelling would seem to be a potentially valuable tool. In the case of some forms of control, such as biological and genetic, it is also arguable that modelling the consequences is imperative, given the potential risks involved.     

鲁西南粮棉产区生态控制农田害虫技术研究

根据生态类型区的农业生态现状，以种植结构调整为基础，发挥生态因素控制害虫作用为重点，充分利用害虫天敌，生物制剂的控害作用，必要时辅以化学防治调节，达到生态控制农作物害虫的目的。     

Defensive responses by a social caterpillar are tailored to different predators and change with larval instar and group size

Gregariousness in animals is widely accepted as a behavioral adaptation for protection from predation. However, predation risk and the effectiveness of a prey's defense can be a function of several other factors, including predator species and prey size or age. The objective of this study was to determine if the gregarious habit of Malacosoma disstria caterpillars is advantageous against invertebrate natural enemies, and whether it is through dilution or cooperative defenses. We also examined the effects of larval growth and group size on the rate and success of attacks. Caterpillars of M. disstria responded with predator-specific behaviors, which led to increased survival. Evasive behaviors were used against stinkbugs, while thrashing by fourth instar caterpillars and holding on to the silk mat by second instar caterpillars was most efficient against spider attacks. Collective head flicking and biting by groups of both second and fourth instar caterpillars were observed when attacked by parasitoids. Increased larval size decreased the average number of attacks by spiders but increased the number of attacks by both stinkbugs and parasitoids. However, increased body size decreased the success rate of attacks by all three natural enemies and increased handling time for both predators. Larger group sizes did not influence the number of attacks from predators but increased the number of attacks and the number of successful attacks from parasitoids. In all cases, individual risk was lower in larger groups. Caterpillars showed collective defenses against parasitoids but not against the walking predators. These results show that caterpillars use different tactics against different natural enemies. Overall, these tactics are both more diverse and more effective in fourth instar than in second instar caterpillars, confirming that growth reduces predation risk. We also show that grouping benefits caterpillars through dilution of risk, and, in the case of parasitoids, through group defenses. The decreased tendency to aggregate in the last larval instar may therefore be linked to decreasing predation risk.     

Alkaloid concentration of the invasive plant species Ulex europaeus in relation to geographic origin and herbivory

In the study of plant defense evolution, invasive plant species can be very insightful because they are often introduced without their enemies, and traits linked to defense can be released from selective pressures and evolve. Further, studying plant defense evolution in invasive species is important for biological control and use of these species. In this study, we investigated the evolution of the defensive chemicals quinolizidine alkaloids (QAs) in the invasive species gorse, Ulex europaeus. Using a common garden experiment, our goals were to characterize the role of QAs relative to specialist enemies of gorse and to investigate if QA concentration evolved in invaded regions, where gorse was introduced without these enemies. Our results showed that pod infestation rate by the seed predator Exapion ulicis and infestation by the rust pathogen Uromyces genistae-tinctoriae were negatively correlated to concentration of the QA lupanine. Quinolizidine alkaloid concentration was very variable between individuals, both within and among populations, but it was not different between native and invaded regions, suggesting that no evolution of decreased resistance occurred after gorse lost its enemies. Our study also suggests that QA concentrations are traits integrated into seed predation avoidance strategies of gorse, with plants that mass-fruit in spring but do not escape pod infestation in time being richer in QAs.     

Integrated mite control in apples in Queensland, Australia

An interdisciplinary team introduced Integrated Mite Control (IMC) to the Queensland apple industry in Australia from 1989 to 1992. Project funding supported the employment of a consultant to monitor mite levels and provide management advice to growers who paid for the service. Interviews at the beginning and end of the project showed widespread adoption of IMC over this period. Overall use of chemicals was not reduced, but the use pattern changed towards wider use of chemicals that are less toxic to predatory mites. The future of IMC in the Queensland apple industry is in doubt because the seasonal nature of apple production does not allow the paid consultancy service to be self-sustaining. Indications are that the integrated approach to pest management may not be generally accepted as a strategic management process while the availability of effective chemicals allows the continuation of a spray routine for mite control. The lack of availability of effective and proven methods of pest control was seen by growers as the major constraint to adoption of IMC.     

A review of electrokinetically enhanced bioremediation technologies for PHs

Since the early 1980’s there have been several different strategies designed and applied to the remediation of subsurface environment including physical, chemical and biological approaches. They have had varying degrees of success in remediating contaminants from subsurface soils and groundwater. The objective of this review is to examine the range of technologies for the remediation of contaminants, particularly petroleum hydrocarbons, in subsurfaces with a specific focus on bioremediation and electrokinetic remediation. Further, this review examines the efficiency of remediation carried out by combining bioremediation and electrokinetic remediation. Surfactants, which are slowly becoming the selected chemicals for mobilizing contaminants, are also considered in this review. The current knowledge gaps of these technologies and techniques identified which could lead to development of more efficient ways of utilizing these technologies or development of a completely new technology.     

有毒化学品的污染评价与控制技术

对有毒化学品进行简介 ;建议从生理毒性、属性毒性及生命周期等方面建立有毒化学品的污染评价系统 ,为有毒化学品的应用、管理和处理处置提供理论依据 ;针对不同的有毒化学品及其排放情况与浓度组分拟选用物化处理法、化学处理法及生物处理法作为污染控制技术。     

Development of a generalist predator,Podisus maculiventris,on glucosinolate sequestering and nonsequestering prey

Insect herbivores exhibit various strategies to counter the toxic effects of plant chemical defenses. These strategies include the detoxification, excretion, and sequestration of plant secondary metabolites. The latter strategy is often considered to provide an additional benefit in that it provides herbivores with protection against natural enemies such as predators. Profiles of sequestered chemicals are influenced by the food plants from which these chemicals are derived. We compared the effects of sequestration and nonsequestration of plant secondary metabolites in two specialist herbivores on the development of a generalist predator, Podisus maculiventris. Profiles of glucosinolates, secondary metabolites characteristic for the Brassicaceae, are known to differ considerably both inter- and intraspecifically. Throughout their immature (=nymphal) development, the predator was fed on larval stages of either sequestering (turnip sawfly, Athalia rosae) or nonsequestering (small cabbage white butterfly, Pieris rapae) prey that in turn had been feeding on plants originating from three wild cabbage (Brassica oleracea) populations that have previously been shown to differ in their glucosinolate profiles. We compared survival, development time, and adult body mass as parameters for bug performance. Our results show that sequestration of glucosinolates by A. rosae only marginally affected the development of P. maculiventris. The effects of plant population on predator performance were variable. We suggest that sequestration of glucosinolates by A. rosae functions not only as a defensive mechanism against some predators, but may also be an alternative way of harmlessly dealing with plant allelochemicals.     

Indirect interactions between a phytopathogenic and an entomopathogenic fungus

Slow growth in herbivores may lead to higher mortality, due to prolonged exposure to natural enemies. A number of studies has tested the 'slow-growth, high-mortality' hypothesis using predators or parasitoids as natural enemies of the herbivore, but the possible role of pathogens is poorly documented. We provide evidence that phytopathogenic infection of a plant enhances the susceptibility of herbivore larvae to a generalist entomopathogen. Larvae of the mustard leaf beetle Phaedon cochleariae grow more slowly when feeding on Chinese cabbage leaves infected by the phytopathogenic fungus Alternaria brassicae than larvae feeding on healthy leaves. Treatment of such larvae feeding on diseased plants with an LD₅₀ of the entomopathogenic fungus Metarhizium anisopliae resulted in 100% mortality, compared with a mortality rate of 54% in the control larvae feeding on uninfected leaves. This is the first demonstration of an interaction between a phyto- and an entomopathogenic fungus.