556 resultados para redbay ambrosia beetle
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Issued Nov. 1974.
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"The preliminary American second edition of A.L.A. catalog rules, on Part I of which the present volume is based, was prepared by: American Library Association, Catalog Code Revision Committee." The 1st ed., published in 1908, has title: Catalog rules, author and title entries.
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Cover title.
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Elevated jasmonic acid (JA) concentrations in response to herbivory can induce wounded plants to produce defences against herbivores. In laboratory and field experiments we compared the effects of exogenous JA treatment to two closely related cabbage species on the host-searching and oviposition preference of the diamondback moth (DBM), Plutella xylostella. JA-treated Chinese cabbage (Brassica campestris) was less attractive than untreated Chinese cabbage to ovipositing DBM, while JA-treatment of common cabbage (B. oleracea) made plants more attractive than untreated controls for oviposition by this insect. Similar effects were observed when plants of the two species were damaged by DBM larvae. In the absence of insect-feeding, or JA application, Chinese cabbage is much more attractive to DBM than common cabbage. Inducible resistance therefore appears to occur in a more susceptible plant and induced susceptibility appears to occur in a more resistant plant, suggesting a possible balance mechanism between constitutive and inducible defences to a specialist herbivore.
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Offspring size can have pervasive effects throughout an organism's life history. Mothers can make either a few large or many small offspring, and the balance between these extremes is determined by the relationship between offspring size and performance. This relationship in turn is thought to be determined by the offspring's environment. Recently, it has become clear that events in one life-history stage can strongly affect performance in another. Given these strong carryover effects, we asked whether events in the larval phase can change the relationship between offspring size and performance in the adult phase. We manipulated the length of the larval period in the bryozoan Bugula neritina and then examined the relationship between offspring size and various parameters of adult performance under field conditions. We found that despite the adult stage being outplanted into identical conditions, different offspring sizes were predicted to be optimal, depending on the experience of those adults as larvae. This work highlights the fact that the strong phenotypic links between life-history stages may result in optimal offspring size being highly unpredictable for organisms with complex life cycles.
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Over the past 30 years, numerous attempts to understand the relationship between offspring size and fitness have been made, and it has become clear that this critical relationship is strongly affected by environmental heterogeneity. For marine invertebrates, there has been a long-standing interest in the evolution of offspring size, but there have been very few empirical and theoretical examinations of post-metamorphic offspring size effects, and almost none have considered the effect of environmental heterogeneity on the offspring size/fitness relationship. We investigated the post-metamorphic effects of offspring size in the field for the colonial marine invertebrate Botrylloides violaceus. We also examined how the relationship between offspring size and performance was affected by three different types of intraspecific competition. We found strong and persistent effects of offspring size on survival and growth, but these effects depended on the level and type of intraspecific competition.. Generally, competition strengthened the advantages of increasing maternal investment. Interestingly, we found that offspring size determined the outcome of competitive interaction: juveniles that had more maternal investment were more likely to encroach on another juvenile's territory. This suggests that mothers have the previously unrecognized potential to influence the outcome of competitive interactions in benthic marine invertebrates. We created a simple optimality model, which utilized the data generated from our field experiments, and found that increasing intraspecific competition resulted in an increase,in predicted optimal size. Our results suggest that the relationship between offspring size and fitness is highly variable in the marine environment and strongly dependent on the density of conspecifics.
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Expansion of planted forests and intensification of their management has raised concerns among forest managers and the public over the implications of these trends for sustainable production and conservation of forest biological diversity. We review the current state of knowledge on the impacts of plantation forestry on genetic and species diversity at different spatial scales and discuss the economic and ecological implications of biodiversity management within plantation stands and landscapes. Managing plantations to produce goods such as timber while also enhancing ecological services such as biodiversity involves tradeoffs, which can be made only with a clear understanding of the ecological context of plantations in the broader landscape and agreement among stakeholders on the desired balance of goods and ecological services from plantations.
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Melaleuca quinquenervia (Cav.) Blake (Myrtaceae) was imported into Florida from Australia over a century ago as a landscape plant. A favorable climate and periodic wildfires helped M. quinquenervia thrive; it now occupies about 200,000 hectares in southern Florida. A biological control (i.e., biocontrol) program against M. quinquenervia has been initiated, but not all biocontrol releases are successful. Some scientists have argued that poor biocontrol agent success may relate to genetic differences among populations of invasive weeds. I tested this premise by determining (1) the number and origins of M. quinquenervia introductions into Florida, (2) whether multiple introduction events resulted in the partitioning of Florida's M. quinquenervia populations into discrete biotypes, and (3) whether Oxyops vitiosa, an Australia snout beetle imported to control this weed, might discriminate among putative M. quinquenervia biotypes. Careful scrutiny of early horticultural catalogs and USDA plant introduction records suggested at least six distinct introduction events. Allozyme analyses indicated that the pattern of these introductions, and the subsequent redistribution of progeny, has resulted in geographic structuring of the populations in southern Florida. For example, trees on Florida's Gulf Coast had a greater effective number of alleles and exhibited greater heterozygosity than trees on the Atlantic Coast. Essential oil yields from M. quinquenervia leaves followed a similar trend; Gulf Coast trees yielded nearly twice as much oil as Atlantic Coast trees when both were grown in a common garden. These differences were partially explained by the predominance of a chemical phenotype (chemotype) very rich in the sesquiterpene (E)-nerolidol in M. quinquenervia trees from the Gulf Coast, but rich in a mixture of the monoterpene 1,8-cineole and the sesquiterpene viridiflorol in trees from the Atlantic Coast. Performance of O. vitiosa differed dramatically in laboratory studies depending on the chemotype of the foliage they were fed. Larval survivorship was four-fold greater on the (E)-nerolidol chemotype. Growth was also greater, with adult O. vitiosa gaining nearly 50% more biomass on the (E)-nerolidol plants than on the second chemotype. The results of this study thus confirmed the premise that plant genotype can affect the population dynamics of insects released as weed biocontrols. ^
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Forest disturbances are major sources of carbon dioxide to the atmosphere, and therefore impact global climate. Biogeophysical attributes, such as surface albedo (reflectivity), further control the climate-regulating properties of forests. Using both tower-based and remotely sensed data sets, we show that natural disturbances from wildfire, beetle outbreaks, and hurricane wind throw can significantly alter surface albedo, and the associated radiative forcing either offsets or enhances the CO2 forcing caused by reducing ecosystem carbon sequestration over multiple years. In the examined cases, the radiative forcing from albedo change is on the same order of magnitude as the CO2 forcing. The net radiative forcing resulting from these two factors leads to a local heating effect in a hurricane-damaged mangrove forest in the subtropics, and a cooling effect following wildfire and mountain pine beetle attack in boreal forests with winter snow. Although natural forest disturbances currently represent less than half of gross forest cover loss, that area will probably increase in the future under climate change, making it imperative to represent these processes accurately in global climate models.
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Acknowledgements This project was undertaken as part of my doctoral studies funded by the Commonwealth Scholarship Commission (CACR-2009-39) in the United Kingdom. I would like to thank my supervisors Karen Milek and Andrew Dugmore for their help and support. I also wish to thank Jónas Helgason, his son Alexius Jónasson and Baldur Vilhelmsson for kindly having allowed access to the eiderdown stores and workshops at Æðey and Vatnsfjörður and for having provided assistance when needed. I would like to thank Fornleifastofnun Íslands for supporting my fieldwork at Vatnsfjörður, as well as Paul Ledger and Garðar Guðmundsson for their help during fieldwork. I am especially grateful to Richard Marriott for his invaluable help with flea identifications and for lending me reference material. Erling Ólafsson and Jan Klimaszewski also helped with the beetle identifications. Consultation of the BugsCEP database (Buckland and Buckland, 2006) aided the redaction of this paper.
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Acknowledgements This project was undertaken as part of my doctoral studies funded by the Commonwealth Scholarship Commission (CACR-2009-39) in the United Kingdom. I would like to thank my supervisors Karen Milek and Andrew Dugmore for their help and support. I also wish to thank Jónas Helgason, his son Alexius Jónasson and Baldur Vilhelmsson for kindly having allowed access to the eiderdown stores and workshops at Æðey and Vatnsfjörður and for having provided assistance when needed. I would like to thank Fornleifastofnun Íslands for supporting my fieldwork at Vatnsfjörður, as well as Paul Ledger and Garðar Guðmundsson for their help during fieldwork. I am especially grateful to Richard Marriott for his invaluable help with flea identifications and for lending me reference material. Erling Ólafsson and Jan Klimaszewski also helped with the beetle identifications. Consultation of the BugsCEP database (Buckland and Buckland, 2006) aided the redaction of this paper.
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Acknowledgements This project was undertaken as part of my doctoral studies funded by the Commonwealth Scholarship Commission (CACR-2009-39) in the United Kingdom. I would like to thank my supervisors Karen Milek and Andrew Dugmore for their help and support. I also wish to thank Jónas Helgason, his son Alexius Jónasson and Baldur Vilhelmsson for kindly having allowed access to the eiderdown stores and workshops at Æðey and Vatnsfjörður and for having provided assistance when needed. I would like to thank Fornleifastofnun Íslands for supporting my fieldwork at Vatnsfjörður, as well as Paul Ledger and Garðar Guðmundsson for their help during fieldwork. I am especially grateful to Richard Marriott for his invaluable help with flea identifications and for lending me reference material. Erling Ólafsson and Jan Klimaszewski also helped with the beetle identifications. Consultation of the BugsCEP database (Buckland and Buckland, 2006) aided the redaction of this paper.