GROUND WATER, Issue 6 2009
Michael N. Fienen
Ground water model calibration has made great advances in recent years with practical tools such as PEST being instrumental for making the latest techniques available to practitioners. As models and calibration tools get more sophisticated, however, the power of these tools can be misapplied, resulting in poor parameter estimates and/or nonoptimally calibrated models that do not suit their intended purpose. Here, we focus on an increasingly common technique for calibrating highly parameterized numerical models,pilot point parameterization with Tikhonov regularization. Pilot points are a popular method for spatially parameterizing complex hydrogeologic systems; however, additional flexibility offered by pilot points can become problematic if not constrained by Tikhonov regularization. The objective of this work is to explain and illustrate the specific roles played by control variables in the PEST software for Tikhonov regularization applied to pilot points. A recent study encountered difficulties implementing this approach, but through examination of that analysis, insight into underlying sources of potential misapplication can be gained and some guidelines for overcoming them developed. [source]

Transient Leakance and Infiltration Characteristics during Lake Bank Filtration

GROUND WATER, Issue 1 2009
B. Wiese
Infiltration capacity of bank filtration systems depends on water extraction and hydraulic resistance of the bed sediments. Lakebed hydraulics may be especially affected by clogging, which is dependent on settlement of fine particles, redox potential, and other factors. In the field, most of these processes are difficult to quantify, and thus, when calculating response to pumping the water flux across the sediment surface is assumed to be linearly dependent on the hydraulic gradient. However, this assumption was not adequate to describe conditions at a bank filtration site located at Lake Tegel, Berlin, Germany. Hence, we first assumed the leakage coefficient (or leakance) is spatially distributed and also temporally variant. Furthermore, observations show that the leakance is considerably higher in shallow than in deeper areas; hence, leakance was assumed to be dependent on the existence and thickness of an unsaturated zone below the lake. The proposed explanation of spatial and temporal variability in leakance involves a hypothesis for redox dependent and reversible biogeochemical clogging, supported by geochemical observations in surface water and ground water. Four leakance approaches are implemented in the ground water flow code MODFLOW2000 and calibrated by inverse modeling using the parameter estimation software PEST. These concepts are evaluated by examining the fit to the hydraulic heads, to infiltration measurements, transport modeling results, and considering the degrees of freedom due to the number of calibration parameters. The leakage concept based on the assumption of the influence of an unsaturated zone on clogging processes best explains the field data. [source]

Strategic management of the Tokyo taxi cab industry: an exploratory study

KNOWLEDGE AND PROCESS MANAGEMENT: THE JOURNAL OF CORPORATE TRANSFORMATION, Issue 1 2007
Walter Skok
Taxicabs are an indispensable means of transportation in Tokyo, as they provide a 24/7 door-to-door service for a daily average of 1.3 million people. In 2002, legislation was introduced to abolish restrictions on the number of taxicabs on the road. This relaxation of regulation, together with the corresponding recession, raised new issues such as increasing cab numbers and reducing drivers' wages. The wide variety of stakeholders involved within the taxicab industry have conflicting positions, resulting in little agreement on the possible way forward. An exploratory study was therefore undertaken in order to investigate the management of Tokyo's taxicab operations in order to formulate strategies for improving the service. Two related papers report on the study. This paper starts by providing an understanding of the current situation, examining the roles of the major stakeholders and outlining day-to-day operations. Academic frameworks, for example PEST, Critical Success Factors and the Cultural Web, from the strategic management literature, are used to identify the structure of the industry and analyse the environment in which it operates. The results found that Tokyo's taxicab industry is highly efficient operationally, due to the high standard of customer service, effective driver's learning scheme and active use of IT. However, a paradoxical situation has been identified where the demand for cabs has decreased even though the available vehicles have increased. Finally, a uniform method to measure the level of taxicab service is recommended. Copyright © 2007 John Wiley & Sons, Ltd. [source]

FORECASTING AND MANAGEMENT OF MIGRATORY PESTS IN AUSTRALIA

INSECT SCIENCE, Issue 4 2002
David Hunter
Abstract, The Decision Support System (DSS) used by the Australian Plague Locust Commission for management of several important migratory insect pests in Australia is described. The DSS is based on a Geographic Information System that integrates data on weather and habitat condition with the migration, development and distribution of the pest to prepare forecasts and aid decisions for control. The GIS is module based with the number and nature of the modules easily modified depending on the detail of data required to manage the pest concerned. [source]

Organisation of proficiency testing for plant health diagnostic tests: the experience of FAPAS®

EPPO BULLETIN, Issue 1 2010
A. Reynolds
Proficiency testing (PT) is an established quality assurance measure and is based on the comparison of laboratories' results in an inter-laboratory trial. It highlights problems in laboratory analysis and is an educational tool to help improve data quality. This article describes how PT is organised by FAPAS®. FAPAS® is an international PT provider (external quality assessments) for food chemistry, food microbiology, genetically modified material and water/environmental samples. Since 2007, FAPAS® have organized plant health proficiency tests in conjunction with the Plant Pest and Disease Identification Programme at the Food and Environment Research Agency (Fera). Up until 2009, FAPAS® has organised seven plant health proficiency tests that covered the identification of lyophilised bacteria, viruses in leaves and fungi in agar plugs. In 2009, FAPAS® organized over 10 plant health proficiency tests under the banner of ,PhytoPAS', including Potato spindle tuber viroid, Phytophthora ramorum, Thrips palmi, Erwinia amylovora, Clavibacter michiganensis subsp. sepedonicus, etc. DNA extracts, cyst nematodes (Globodera pallida) and slides/immunofluorescence (IF) slides have been added to the programme. The organization of the plant health proficiency tests follows a similar pattern. Suitable test materials are prepared and tested for quality before distribution to requesting participants. Laboratories usually have 1,2 months to analyze their samples and return their results. A report is then compiled for issue to laboratories and these contain all results in an anonymous form, so that laboratories can compare their results with those of other participants. If a laboratory's performance is unsatisfactory then it is up to them to investigate the situation. Thus, the primary purpose of PT is the detection of inaccuracy in a laboratory's results, so that they can investigate the problems and initiate corrective procedures. [source]

Titanium Silicon Carbide Pest Induced by Nitridation

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 2 2008
Haibin Zhang
The thermal stability of bulk Ti3SiC2 in high-purity nitrogen was investigated. It was surprising to observe that Ti3SiC2 underwent rapid and catastrophic disintegration above 1300°C, although this material was thermally stable below this temperature. This degradation was unexpected and extremely serious, and has been termed "Ti3SiC2 pest." This phenomenon was related to the volume change associated with the formation of mixtures of TiCx, Ti(C, N)x, and TiN, which caused internal tensile stresses and cracked the resulting layers. "Ti3SiC2 pest" could be prevented by increasing oxygen partial pressure in nitrogen. [source]

Pest and vector control.

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 1 2005
HF van Emden, MW Service.
No abstract is available for this article. [source]

Pest or Guest: The Zoology of Overabundance

AUSTRAL ECOLOGY, Issue 7 2008
ELIZABETH A. DALEY
No abstract is available for this article. [source]

Spray Oils Beyond 2000 , Sustainable Pest and Disease Management

AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2004
Roger Broadley
No abstract is available for this article. [source]

Pests of Stored Food-stuff and their Control

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2005
Article first published online: 16 FEB 200
No abstract is available for this article. [source]

Advantages of Different Tillage Systems and Their Effects on the Economically Important Pests, Thrips tabaci Lind. and Aphis gossypii Glov. in Cotton Fields

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 6 2004
I. Gencsoylu
Abstract An experiment to assess advantages of different tillage and their effects on Aphis gossypii Glov. and Thrips tabaci Lind was conducted during the 2000 and 2001 cotton growing seasons in cotton fields at Adnan Menderes University, Agricultural Faculty Research Center, located in Ayd,n Province, Turkey. The tillage systems examined were conventional, strip, precision and ridge tillage. Two insect population densities were not affected by the type of tillage systems during either year. However, significant differences in populations were observed in thrips populations on 31 May 2000 and 18 May 2001 and aphid populations on 24 May 2000 and 11 May 2001. The results show that the highest yield was observed in all conservation tillage systems in 2000 and ridge tillage system in 2001. Early maturity was higher in both precision and ridge tillage systems. In addition, tillage systems did not affect fibre properties. As a result, the application of conservation tillage is more advantageous in cotton in respect of early maturity and total yield. [source]

Pests, pesticide use and alternative options in European maize production: current status and future prospects

JOURNAL OF APPLIED ENTOMOLOGY, Issue 5 2010
M. Meissle
Abstract Political efforts are made in the European Union (EU) to reduce pesticide use and to increase the implementation of integrated pest management (IPM). Within the EU project ENDURE, research priorities on pesticide reduction are defined. Using maize, one of the most important crops in Europe, as a case study, we identified the most serious weeds, arthropod pests, and fungal diseases as well as classes and amounts of pesticides applied. Data for 11 European maize growing regions were collected from databases, publications and expert estimates. Silage maize dominates in northern Europe and grain production in central and southern Europe. Crop rotations range from continuous growing of maize over several years to well-planned rotation systems. Weeds, arthropod pests and fungal diseases cause economic losses in most regions, even though differences exist between northern countries and central and southern Europe. Several weed and arthropod species cause increasing problems, illustrating that the goal of reducing chemical pesticide applications is challenging. Pesticides could potentially be reduced by the choice of varieties including genetically modified hybrids, cultural control including crop rotation, biological control, optimized application techniques for chemicals, and the development of more specific treatments. However, restrictions in the availability of alternative pest control measures, farm organization, and the training and knowledge of farmers need to be overcome before the adoption of environmentally friendly pest control strategies can reduce chemical pesticides in an economically competitive way. The complex of several problems that need to be tackled simultaneously and the link between different control measures demonstrates the need for IPM approaches, where pest control is seen in the context of the cropping system and on a regional scale. Multicriteria assessments and decision support systems combined with pest monitoring programs may help to develop region-specific and sustainable strategies that are harmonized within a EU framework. [source]

Enhancing Biological Control: Habitat Management to Promote Natural Enemies of Agricultural Pests

JOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2002
Article first published online: 9 OCT 200
First page of article [source]

Oak Pests and Their Natural Enemies

JOURNAL OF APPLIED ENTOMOLOGY, Issue 7 2001
A.; KULFAN, J.; KRI, J.; ZACH, P. (eds.): Oak Pests, Their Natural Enemies. (Die Eichenschädlinge und ihre Feinde).
[source]

Compendium of Hop Diseases and Pests

JOURNAL OF PHYTOPATHOLOGY, Issue 5 2010
Rudolf Heitefuss
No abstract is available for this article. [source]

Compendium of Beet Diseases and Pests

JOURNAL OF PHYTOPATHOLOGY, Issue 5 2010
Rudolf Heitefuss
No abstract is available for this article. [source]

Pests and Diseases of Prehistoric Crops: A Yield ,Honeymoon' for Early Grain Crops in Europe?

OXFORD JOURNAL OF ARCHAEOLOGY, Issue 1 2001
Petra Dark
Before the agricultural improvements of recent centuries, grain yields in medieval Europe appear to have been extremely low: well below the full potential of the crops. If yields were similarly low in prehistory, the adoption of cereal cultivation could have conveyed few benefits in terms of productivity. Consideration of the key constraints on cereal yield highlights the previous neglect of the role of pests and diseases. It is suggested that these may have been particularly damaging in the medieval period, but much less so during the early stages of the adoption of agriculture. Textual and archaeological evidence for the past occurrence of pests and diseases is discussed and, combined with consideration of the development of pest and pathogen problems of recent crop introductions, used to provide a possible outline of the early development of the pest/disease burden. It is suggested that when grain crops were first introduced into temperate Europe there may have been a ,honeymoon period' with high yields: pests and diseases which had been endemic on cereals in semi-arid, continental, or Mediterranean climates did not thrive in the temperature climate, while species native to north-west Europe may not have been adapted to attack cereals. Subsequently, however, some pests and diseases evolved to attack cereals in this environment. These may have prompted changes in grain production methods to reduce the risk of damage. Pests and diseases must have been a driving force in agrarian change for several millennia, and cannot be ignored in attempts to understand the history of agriculture. [source]

Insect Pests in Tropical Forestry

AUSTRALIAN JOURNAL OF ENTOMOLOGY, Issue 1 2002
Article first published online: 26 FEB 200
No abstract is available for this article. [source]

Cacao boom and bust: sustainability of agroforests and opportunities for biodiversity conservation

CONSERVATION LETTERS, Issue 5 2009
Yann Clough
Abstract Cacao cultivation holds a sweet promise, not only for chocolate consumers and cacao farmers but also for conservationists who argue that diverse cacao agroforests may be used to sustain both livelihoods of smallholders and ecological benefits such as the conservation of biodiversity within human-dominated tropical landscapes. However, regional boom-and-bust cycles are the rule in global cacao production: after initial forest conversion to cacao agroforests, sustaining production is difficult due to dwindling yields as trees age and pest and disease pressure increases. The failure to revitalize plantations often leads to a shift of cacao production to other regions. Shade removal dynamics within these cycles substantially reduce most of the biodiversity benefits. We investigate the conservation implications of these processes. Using examples from the current cacao crisis in Indonesia, we show that until now commitments to sustainability by the cacao-chocolate sector have not been successful, which endangers remaining forests. Conservation can be combined with smallholder cacao production, but if this is to be achieved, greater quantitative and qualitative efforts to halt cacao cycles are needed on the part of the industry by making use of existing opportunities to combine sustainability, carbon storage, and biodiversity conservation. [source]

The fundamental and realized niche of the Monterey Pine aphid, Essigella californica (Essig) (Hemiptera: Aphididae): implications for managing softwood plantations in Australia

DIVERSITY AND DISTRIBUTIONS, Issue 4 2004
Trudi N. Wharton
ABSTRACT Essigella californica is a pine aphid native to western North America. In Australia, E. californica is considered an invasive pest that has the potential to cause severe economic loss to the Australian forestry industry. Two CLIMEX models were developed to predict the Australian and global distribution of E. californica under current climate conditions based upon the aphid's known North American distribution. The first model (model I) was fitted using the reasonably contiguous set of location records in North America that constituted the known range of E. californica, and excluded consideration of a single (reliable) location record of the aphid in southern Florida. The second model (model II) was fitted using all known records in North America. Model I indicated that the aphid would be climatically restricted to the temperate, Mediterranean and subtropical climatic regions of Australia. In northern Australia it would be limited by hot, wet conditions, while in more central areas of Australia it is limited by hot, dry conditions. Model II is more consistent with the current Australian distribution of E. californica. The contrast in geographical range and climatic conditions encompassed between the two models appears to represent the difference between the realized niche (model I) and fundamental niche (model II) of E. californica. The difference may represent the strength of biotic factors such as host limitation, competition and parasitism in limiting geographical spread in the native range. This paper provides a risk map for E. californica colonization in Australia and globally. E. californica is likely to remain a feature of the Australian pine plantations, and any feasibility studies into establishing coniferous plantations in lower rainfall areas should consider the likely impact of E. californica. [source]

Risk assessment for nonindigenous pests: 1.

DIVERSITY AND DISTRIBUTIONS, Issue 5 2001
Mapping the outputs of phenology models to assess the likelihood of establishment
Abstract This paper demonstrates the use of phenology models mapped over the landscape as a tool in support of risk assessments for nonindigenous plant pests. Drawing on the relationship between pest development and temperature, the approach uses gridded sequential interpolated temperatures at a resolution of 1 km, linked with phenology models, to predict the potential for a pest to develop throughout the landscape. The potential for establishment of Colorado beetle (Leptinotarsa decemlineata) in England and Wales was used as an illustration. The likelihood of the pest completing a single generation during a 30-year period (1961,90) was computed. Summaries of phenology, based firstly upon point temperature series from weather stations and secondly upon temperatures interpolated across the landscape, were compared. The results revealed that the use of point data led to a 70% likelihood of over-estimating the area at risk from year to year. In the case of average long-term risk however, the point-based and landscape-wide distributions of establishment potential were similar. We demonstrate how the use of phenology models running on a daily time scale provides date based results, so allowing outputs to be tied in with periods in the cropping cycle. The application of daily data in computing the phenological results, unlike the main body of published work on pest risk assessment which uses averaged monthly data, reflects more fully the underlying variability and degrees of sensitivity of the pest to changes in weather. [source]

Risk assessment for nonindigenous pests: 2.

DIVERSITY AND DISTRIBUTIONS, Issue 5 2001
Accounting for interyear climate variability
Abstract The paper firstly discusses the importance of accounting for interyear variability when assessing the likelihood of establishment of an alien pest. The potential establishment of Colorado beetle (Leptinotarsa decemlineata) is used as an illustration within the geographical context of England and Wales. An aggregate risk index is introduced as a probabilistic representation of the likelihood that a pest might complete a single generation over a 30-year period (1961,90). Data for individual years were used to compute, objectively, the interyear distribution of risk across the landscape. The standard deviation in area at risk (26 800 km2) was high relative to the average proportion of the landscape potentially at risk (95 700 km2). In 40% of years, the area at risk was estimated to be higher than ,average'. Secondly, the paper demonstrates multiple indices of risk that reflect different aspects of pest risk assessment. Viewing risk from a variety of perspectives provides a means of gauging the consistency and therefore reliability of the results. This contrasts with current practice, where a single mapped output is commonly presented to decision makers. Modelling using a daily time step allowed the use of indices to investigate the long-term probabilities of biotic and abiotic events of short duration. These indices include estimates of pest activity and flight potential. [source]

Seasonal polydomy in a polygynous supercolony of the odorous house ant, Tapinoma sessile

ECOLOGICAL ENTOMOLOGY, Issue 6 2008
GRZEGORZ BUCZKOWSKI
Abstract 1.,The odorous house ant, Tapinoma sessile, is a native ant species common throughout North America. In its natural habitat, T. sessile is a low-key species that consists of small colonies. In invaded urban areas, T. sessile exhibits extreme polygyny and polydomy and becomes a dominant invasive pest. 2.,The current study examined: (i) the density, persistence, and the spatial distribution of nests in a large supercolony of T. sessile, (ii) trail abundance and overall colony connectivity as facilitated by the network of trails, (iii) the abundance and the spatial distribution of competing ant species, and (iv) the effect of environmental factors on the number and distribution of T. sessile nests. 3.,A distinct pattern of seasonal polydomy was observed, whereby the colony undergoes an annual fission-fusion cycle. The colony occupies one or a few nests during the winter, experiences rapid exponential growth in the spring to colonize available nesting sites, reaches maximum nest density in the summer, and again coalesces in the winter, returning to the same winter location year after year. The trails show spatio-temporal variation as well, depending on the location of nesting and foraging sites. Furthermore, nest movements may be driven by soil microclimate and proximity to man-made structures. 4.,In total, 119 ant nests were discovered in a 3.15 ha plot, 90 (76%) of which belonged to T. sessile. Tapinoma sessile exhibited strong colony connectivity as 78/90 (87%) of nests were connected to at least one other nest by a trail. Mean persistence time for T. sessile nests was 133 ± 5 days. 5.,Results indicate that T. sessile is a highly adaptable native ant species that exhibits a high degree of flexibility in its colony social structure. A high degree of polygyny and polydomy may contribute to its ecological dominance and pest status in urban environments. [source]

Phorid fly parasitoids of invasive fire ants indirectly improve the competitive ability of a native ant

ECOLOGICAL ENTOMOLOGY, Issue 5 2004
Natasha J. Mehdiabadi
Abstract., 1.,The red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), is an invasive species of south-eastern U.S.A. Since its introduction from South America approximately 70 years ago, this pest has devastated natural biodiversity. 2.,Due to such ecological costs, Pseudacteon phorid fly parasitoids (Diptera: Phoridae) from South America are being introduced into the U.S.A. as a potential biological control agent. Here, the indirect effects of these specialised parasitoids on an interspecific native ant competitor, Forelius mccooki (Hymenoptera: Formicidae), are evaluated. 3.,Over the course of a 50-day laboratory experiment, the results show that the native ant improved aspects of exploitative, but not interference, competition when S. invicta -attacking flies were present compared with when they were absent. 4.,Forelius mccooki colonies from the phorid treatment had approximately twice as many foragers at food baits relative to controls; however, there was no significant difference in interference aspects of competition or native ant colony growth between the two treatments. 5.,These results suggest that the S. invicta -specialised parasitoids help shift the competitive balance more in favour of F. mccooki than if these flies were not present; however, this competitive advantage does not translate into increased colony growth after 50 days. These laboratory findings are interpreted with regard to the more complex interactions in the field. [source]

Running to stand still: adaptation and the response of plants to rapid climate change

ECOLOGY LETTERS, Issue 9 2005
Alistair S. Jump
Abstract Climate is a potent selective force in natural populations, yet the importance of adaptation in the response of plant species to past climate change has been questioned. As many species are unlikely to migrate fast enough to track the rapidly changing climate of the future, adaptation must play an increasingly important role in their response. In this paper we review recent work that has documented climate-related genetic diversity within populations or on the microgeographical scale. We then describe studies that have looked at the potential evolutionary responses of plant populations to future climate change. We argue that in fragmented landscapes, rapid climate change has the potential to overwhelm the capacity for adaptation in many plant populations and dramatically alter their genetic composition. The consequences are likely to include unpredictable changes in the presence and abundance of species within communities and a reduction in their ability to resist and recover from further environmental perturbations, such as pest and disease outbreaks and extreme climatic events. Overall, a range-wide increase in extinction risk is likely to result. We call for further research into understanding the causes and consequences of the maintenance and loss of climate-related genetic diversity within populations. [source]

Synergistic sex pheromone components of the grey-spotted tussock moth, Orgyia ericae

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2010
Guo-Fa Chen
Abstract The grey-spotted tussock moth, Orgyia ericae Germar (Lepidoptera: Lymantriidae), is an important pest of deciduous trees and woody scrublands in northern China. In a field trapping experiment conducted during the flight of the first generation of 2009, synthetic (Z)-6-heneicosen-11-one, a common Orgyia spp. sex pheromone component, attracted O. ericae males. Gas chromatography-mass spectrometry analyses (full scan or selected ion-monitoring mode) of pheromone gland extracts from females revealed the presence of a major, a minor, and a trace component, i.e., (6Z,9Z)-heneicosa-6,9-diene, (6Z,9Z)-tricosa-6,9-diene, and (Z)-6-heneicosen-11-one, respectively. Field experiments during the flight of the second generation showed that (6Z,9Z)-tricosa-6,9-diene, the minor component, was inactive alone or in any combination with the other two components, whereas (6Z,9Z)-heneicosa-6,9-diene and (Z)-6-heneicosen-11-one were weakly attractive when tested individually. However, traps baited with a binary blend of (6Z,9Z)-heneicosa-6,9-diene and (Z)-6-heneicosen-11-one caught seven-fold more moths than any other treatment (except the ternary blend), indicating a strong synergistic interaction between the two components. The analytical and field trapping data suggested that (6Z,9Z)-heneicosa-6,9-diene and (Z)-6-heneicosen-11-one are likely the key sex pheromone components of female O. ericae. This synergistic blend will be useful as an efficient monitoring tool, and possible control tool, to combat this economically and ecologically important forest defoliator. [source]

Choosing natural enemies for conservation biological control: use of the prey detectability half-life to rank key predators of Colorado potato beetle

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2010
Matthew H. Greenstone
Abstract Determining relative strengths of trophic links is critical for ranking predators for conservation biological control. Molecular gut-content analysis enables ranking by incidence of prey remains in the gut, but differential digestive rates bias such rankings toward predators with slower rates. This bias can be reduced by indexing each predator's half-life to that of the middle-most half-life in a predator complex. We demonstrate this with data from key species in the predator complex of Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), comprising adults and immatures of four taxonomically diverse species. These animals display order-of-magnitude variation in detectability half-life for the cytochrome oxidase I DNA sequence of a single CPB egg: from 7.0 h in larval Coleomegilla maculata (DeGeer) (Coleoptera: Coccinellidae) to 84.4 h in nymphal Perillus bioculatus (Fabricius) (Hemiptera: Pentatomidae). The raw species-specific incidence of L. decemlineata DNA in the guts of 351 field-collected predators ranged from 11 to 95%, ranking them as follows: C. maculata adults < Lebia grandis Hentz (Coleoptera: Carabidae) adults < Podisus maculiventris (Say) (Hemiptera: Pentatomidae) adults < P. maculiventris nymphs < P. bioculatus adults < P. bioculatus nymphs. Half-life adjustment reorders the rankings: C. maculata adults < P. bioculatus adults < P. bioculatus nymphs < P. maculiventris nymphs < L. grandis adults < P. maculiventris adults. These changes in status demonstrate the value of half-life-adjusted molecular gut-content data for ranking predators. This is the first study to measure prey detectability half-lives for the key arthropod predators of a major insect pest, and to use them to evaluate the relative impact of all adults and immatures in this predator complex. [source]

Development of a biological control-based Integrated Pest Management method for Bemisia tabaci for protected sweet pepper crops

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2009
F. J. Calvo
Abstract The tobacco whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a key pest in commercial sweet pepper crops in southeast Spain. Its biological control is currently based on augmentative introductions of the parasitic wasp Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), which need to be occasionally supplemented with pesticide applications. These pesticides can be harmful for the biological control agents. Therefore, it is important to improve the current strategy by reducing dependency on pesticides. Two potential solutions are conceivable: addition of another effective biocontrol agent or application of pesticide prior to the release of biocontrol agents. The mirid bug Nesidiocoris tenuis Reuter (Heteroptera: Miridae) and the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) are promising candidates as additional biocontrol agents. The aim of the present study was to test these possible solutions in two subsequent trials, i.e., a ,selection' and an ,improvement' experiment. In the selection experiment, four treatments were compared: E. mundus, N. tenuis + E. mundus, A. swirskii + E. mundus, and A. swirskii + N. tenuis + E. mundus. Amblyseius swirskii appeared able to significantly increase effectiveness against the pest, in contrast to N. tenuis, which did not contribute to whitefly control. The best strategy was the combination of E. mundus and A. swirskii. In the improvement experiment, three treatments were compared: E. mundus, A. swirskii + E. mundus, and A. swirskii + E. mundus + pesticides. Amblyseius swirskii again proved capable of significantly reducing whitefly populations, and the implementation of pesticides before the release of the biocontrol agents was shown to increase the effectiveness against the pest even more. [source]

Behavioral evidence for a female-produced sex attractant in Diaphorina citri

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2008
Erik J. Wenninger
Abstract Diaphorina citri Kuwayama (Hemiptera: Psyllidae) is an important worldwide pest of citrus. It vectors three phloem-restricted bacteria in the genus Candidatus Liberibacter that cause huanglongbing (citrus greening disease). Studies were conducted to examine the behavioral responses of male and female D. citri to conspecifics of the same and opposite sex, with and without associated citrus host plants, in both open-air arena choice assays and Y-tube olfactometer assays. Virgin and mated male D. citri colonized citrus plants that were currently or had been previously colonized by virgin or mated female D. citri in greater numbers than control plants without females. However, males or females did not accumulate more on plants colonized by conspecifics of the same sex compared to uninfested plants, and females showed no preference for plants pre-infested with males compared with uninfested controls. In complementary Y-tube olfactometer assays, virgin and mated males chose arms with odor sources from mated females compared with blank controls in the absence of associated citrus host plant volatiles. In both behavioral assays, mated female D. citri appeared more attractive than virgin females. The vibrational calling behavior of male D. citri was reduced when males were challenged by the odors of conspecific mated females relative to when males were challenged by the odor of other males. Collectively, our results provide behavioral evidence for a female-produced volatile sex attractant pheromone in D. citri. Future identification and synthesis of a sex attractant pheromone will be an important contribution to current monitoring and management practices for D. citri. [source]

Impact of chemical elicitor applications on greenhouse tomato plants and population growth of the green peach aphid, Myzus persicae

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 3 2006
Anthony J. Boughton
Abstract Recent advances in the understanding of plant signaling pathways have opened the way for using elicitor-induced plant resistance as a tactic for protecting plants against arthropod pests. Four common elicitors of induced responses in tomato, Lycopersicon esculentum Mill. (Solanaceae), were evaluated with regard to phytotoxicity, induction of plant defensive proteins, and effects on population growth and fecundity of a common pest, the green peach aphid, Myzus persicae (Sulzer) (Homoptera: Aphididae). Ethephon and methyl jasmonate (MJ) treatments caused varying degrees of phytotoxicity. Ethephon caused pronounced changes in plant growth form and severe, dose-dependent negative impacts on plant growth and flowering. Effects with MJ were milder, but still caused temporary inhibition of development, leading to smaller plants and delayed flowering. The commercial elicitors benzothiadiazole (BTH) and harpin did not cause detectable phytotoxicity. The highest doses of ethephon and MJ significantly increased leaf peroxidase (POD) levels but only MJ treatments significantly increased polyphenol oxidase (PPO) levels. BTH and harpin had no detectable effects on POD and PPO. Populations of green peach aphids grew significantly more slowly on plants treated with BTH or MJ than on control plants or plants treated with harpin or ethephon. Slowed aphid population growth on BTH-treated plants was due to significant reductions in aphid fecundity, although this was independent of changes in time to onset of reproduction or time to death. Aphid fecundity was also reduced on MJ-treated plants relative to controls, but this difference was not statistically significant, suggesting that other mechanisms are involved in slowing aphid population growth on MJ-treated plants. Growth of aphid populations on plants treated with a MJ,BTH mixture was reduced almost as much as with treatments of MJ alone, suggesting that antagonism between JA-dependant and SA-dependent plant signaling pathways is only mild with regard to induced defenses against aphids. [source]