Host Preferences of Biocontrol Weevils for a Threatened Thistle and an Invasive Weed PDF Download

Author: Christopher Russell Warnecke
Publisher:
ISBN:
Category : Biological control systems
Languages : en
Pages : 148

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Author: Erin E. Fegley
Publisher:
ISBN:
Category : Beetles
Languages : en
Pages : 99

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Book Description
Better understanding of the ecological and evolutionary consequences of plant-insect interactions has important applications in ecology, agriculture, and pest management. Larinus planus Fabricius (Coleoptera: Curculionidae), a Eurasian seed predator, was distributed in the U.S. and Canada as a biocontrol for weedy thistles. It now has non-target impacts on natives, including the federally listed shoreline endemic, Cirsium pitcheri [Torr. ex Eaton] Torr. and A. Gray (Pitcher's thistle). Females weevils lay eggs (oviposit) in floral heads; larvae then consume ovules and seeds as they develop. I asked: 1) What factors put some C. pitcheri plants at risk from L. planus? and 2) How might non-target impacts affect population dynamics? Damage from Larinus planus on flowering C. pitcheri occurred mostly in the northern and shoreward dunes. Impact of L. planus on C. pitcheri can be influenced by: 1) abundance of C. pitcheri as host plant and 2) other plant associates in the community. I measured these factors in 77 randomly distributed 100 m2 plots in two state parks in northern lower Michigan, including a long-term study site at Sturgeon Bay, Wilderness State Park. Larinus planus damage was not significantly associated with abundance of flowering C. pitcheri or percent cover of other plant associates. I also used discriminant function analysis (DFA) to ask which C. pitcheri plants were at risk of damage by L. planus including the factors of northing and easting coordinates, host abundance, and percent vegetation cover. The DFA forecasted 73.1% of plants that would have received damage from L. planus. We rely on the use of models to predict population size and viability for the conservation of rare species. I compared L. planus impacts on a C. pitcheri population using two population models: stage-based matrix (SBM) and integral projection (IPM) models. SBM has some biases; IPM is offered as an alternative model. The models showed similar trends in yearly population growth rates and predicted similar time to extinction for C. pitcheri populations. Seed predation by weevils decreased population time to extinction in both models, but SBM showed a greater decrease than IPM. My elasticity analysis also confirms earlier suggestions that survival of the smallest individuals most affects population growth and should be the focus of conservation. Effective pest management, including unintended damage from biocontrol agents, requires extensive biological knowledge of plant-insect interactions. For L. planus, host plant abundance and other plant associates do not appear to directly influence host choice; however, sample sizes and use of non-parametric analyses may limit the strength of my inferences. Further study is needed on behavior, population dynamics, and overwintering of this weevil. For C. pitcheri, less intensive stage-based modelling offers outcomes similar to integral projection approaches and remains a viable tool for conservation. Further development of appropriate assessment of Pitcher's thistle fecundity, relative to plant size and seedling recruitment, is a needed next step. Population-level impacts from seed predators are significant, no matter what the model, and are greater for rare plants. Assessment of new threats from regular monitoring and adaptive management are critical for effective conservation, particularly in a time of global change.

Author: Monica Paniagua Montoya
Publisher:
ISBN:
Category : Compositae
Languages : en
Pages : 98

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Book Description
Plant associations occur when host selection of a focal plant is reduced or increased by the presence of another plant species. Larinus planus is an invasive weevil whose larvae feed in the flower heads of native and federally threatened Pitcher's thistle (Cirsium pitcheri). Studies have linked the presence of neighboring plants to increased host selection of Pitcher's thistle by the weevil, but the factors contributing to host selection remain unknown. In our study, we determined if there were differences among abiotic factors, host selection and weevil behavior at Pitcher's thistles surrounded by beach grass, sand and at high elevation.

Author: John Thomas Curtis
Publisher: Univ of Wisconsin Press
ISBN: 9780299019402
Category : Nature
Languages : en
Pages : 718

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One of the most important contributions in the field of plant ecology during the twentieth century, this definitive survey established the geographical limits, species compositions, and as much as possible of the environmental relations of the communities composing the vegetation of Wisconsin.

Author: Gregory James Wiggins
Publisher:
ISBN:
Category :
Languages : en
Pages : 173

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Rhinocyllus conicus Fröelich and Trichosirocalus horridus (Panzer) were introduced from Europe into North America as biological control agents of the exotic weed species Carduus nutans L. Concern exists over the feeding of these weevils on at least 25 species of native Cirsium thistles. Research was conducted to 1) estimate phenological synchrony of the eight thistle species in Tennessee with R. conicus and T. horridus, 2) investigate naturally-occurring populations of the five native Cirsium thistle species for non-target activity by R. conicus and T. horridus, 3) quantify the impacts to plants of each thistle species to feeding of R. conicus and T. horridus, and 4) identify potential areas of non-target feeding by the weevils using spatial analysis. Phenologies of two native species, C. carolinianum and C. horridulum, are synchronous with R. conicus reproduction, and all eight thistle species are phenologically synchronous with the reproduction of T. horridus. No non-target activity by R. conicus was observed in naturally-occurring populations of Cirsium thistles, but adults of T. horridus were documented for the first time on the native species C. carolinianum, C. horridulum, and C. muticum. In caged plant studies, larvae of R. conicus completed development in heads of C. carolinianum and C. horridulum and reduced seed numbers of both native species. Basal meristems of all eight thistle species exposed to T. horridus were damaged at varying levels in caged plant studies, but no other impacts to plants were observed. Spatial analyses showed associations between Mahalanobis distance values and plant counts of Carduus nutans and Cirsium carolinianum in predicted habitats, and the occurrence of Carduus nutans was associated with the occurrence of both weevil species in these habitats. About 12% of the total study area consisted of habitats where C. nutans and Cirsium carolinianum overlap. The potential exists for these weevils to utilize native Cirsium species found in Tennessee as plant hosts. The spatial model developed during this study not only allows potential monitoring of populations of C. carolinianum to be more targeted, but also may be modified to apply to other systems involving interactions among introduced and native species.

Author: Ann E. Hajek
Publisher: Cambridge University Press
ISBN: 9780521653855
Category : Gardening
Languages : en
Pages : 396

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Author: Rachel Winston
Publisher: Government Printing Office
ISBN: 9780160942891
Category : Gardening
Languages : en
Pages : 338

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Book Description
This guide focuses on the most problematic weeds in eastern North America for which there are at least some biocontrol agents established and/or available. Multiple photos and descriptions of each weed included in this guide emphasize key identification traits and plant ecology. For each weed included in this guide, all biocontrol agents released or currently found in North America are described individually. Photos highlighting key identification features and damage are included. The release history, current status, and recommended use of each biocontrol agent are described in detail. Recommendations and current impact often vary between the US and Canada, therefore, the information is presented separately. Includes international code of best practices for classical biological control of weeds.

Author: G. Gurr
Publisher: Springer Science & Business Media
ISBN: 9401140146
Category : Science
Languages : en
Pages : 433

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Book Description
As well as examining successful biological control programmes this book analyses why the majority of attempts fail. Off-target and other negative effects of biological control are also dealt with. Chapters contributed by leading international researchers and practitioners in all areas of biological control afford the book a breadth of coverage and depth of analysis not possible with a single author volume. Combined with the use of other experts to review chapters and editorial oversight to ensure thematic integrity of the volume, this book provides the most authoritative analysis of biological control published. Key aspects addressed include how success may be measured, how successful biological control has been to date and how may it be made more successful in the future. With extensive use of contemporary examples, photographs, figures and tables this book will be invaluable to advanced undergraduate and postgraduate students as well as being a `must' for all involved in making biological control successful.

Author: Roy van Driesche
Publisher: John Wiley & Sons
ISBN: 1118392590
Category : Science
Languages : en
Pages : 369

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Book Description
Invasive species have a critical and growing effect upon natural areas. They can modify, degrade, or destroy wildland ecosystem structure and function, and reduce native biodiversity. Landscape-level solutions are needed to address these problems. Conservation biologists seek to limit such damage and restore ecosystems using a variety of approaches. One such approach is biological control: the deliberate importation and establishment of specialized natural enemies, which can address invasive species problems and which should be considered as a possible component of restoration. Biological control can be an effective tool against many invasive insects and plants but it has rarely been successfully employed against other groups. Safety is of paramount concern and requires that the natural enemies used be specialized and that targeted pests be drivers of ecological degradation. While modern approaches allow species to be selected with a high level of security, some risks do remain. However, as in all species introductions, these should be viewed in the context of the risk of failing to reduce the impact of the invasive species. This unique book identifies the balance among these factors to show how biological control can be integrated into ecosystem restoration as practiced by conservation biologists. Jointly developed by conservation biologists and biological control scientists, it contains chapters on matching tools to management goals; tools in action; measuring and evaluating ecological outcomes of biological control introductions; managing conflict over biological control; and includes case studies as well as an ethical framework for integrating biological control and conservation practice. Integrating Biological Control into Conservation Practice is suitable for graduate courses in invasive species management and biological control, as well as for research scientists in government and non-profit conservation organizations.

Author: M. H. Julien
Publisher: Oxford University Press, USA
ISBN:
Category : Gardening
Languages : en
Pages : 244

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Book Description
Each entry details the target weed, control agent, year of first release, country of origin of agent, status and degree of control, research organisation involved, and key references. The catalogue format has been modified slightly from earlier editions to improve ease of use. The book provides an invaluable means of keeping track of the world situation, and is a handy reference for professionals, research workers and students interested in the biological control of weeds.