Predicting Non-target Impacts from a Biocontrol Weevil on a Federally Threatened Thistle of the Upper Great Lakes PDF Download

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: 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: Jaclyn N Inkster
Publisher:
ISBN:
Category :
Languages : en
Pages : 77

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Book Description
Biological control is one of the tools used for integrated pest management of invasive plant species but it is not without risks to native plants. I researched the non-target impacts of the biological control agent, the seed head weevil Larinus planus (Coleoptera: Curculionidae) on the Great Lakes dune and cobble shore endemic threatened thistle, Cirsium pitcheri (Asteraceae). Pitcher's thistle is an herbaceous perennial monocarpic plant with no means of vegetative reproduction, relying solely on seed set for population persistence. The seed head weevil is univoltine and lays eggs in thistle heads. The developing larva chews the ovules or seeds before emerging as an adult to overwinter in leaf litter. I repeatedly surveyed Pitcher's thistle plants from three populations in northern lower Michigan for impacts. The insect oviposits on thistle heads from mid-June to early July, before C. pitcheri flowering. Heads that received oviposition were on average 12-14 mm in diameter. Approximately 32% of the 1,695 heads surveyed had oviposition. A subset of dissected heads had 56% weevil egg mortality. With weevil survival, the number of filled seeds was reduced by 62%. A generalized linear mixed binary logistic model reported date of oviposition and size of heads as significant predictors of oviposition on heads. I tested the effectiveness of an organic insect deterrent, Surround[registered] WP, in reducing impacts on C. pitcheri. The kaolin clay is mixed in water and then applied to the plant create a protective film after drying. I first needed to confirm that kaolin clay did not negatively impact pollinator visits, which are important for seed set. To test this, I performed simultaneous 10 min observations on kaolin clay treated plants and untreated plants. Kaolin clay did not deter insect visits, affect species richness of visiting insects or change the length of the visit. To test the effectiveness in deterring the weevil I applied either kaolin clay or a water control to pairs of heads at Petoskey State Park. The clay-treated heads had significantly fewer oviposition holes, and were less likely to have oviposition holes at all. There was no significant difference in the mean number of chewed seeds between treatments; however, there were significantly more filled seeds in heads treated with kaolin clay than in water-treated heads. I recommend the application of kaolin clay to reproductive Pitcher's thistle plants mid-June to early July every 3-7 days on heads not yet flowering. Reduction of impact from Larinus planus is critical for conservation of this species and may also be important for the entire network of insect flower visitors in the dune ecosystem. Pitcher's thistle flowers from late-June to early August. Many species of insect from several taxonomic orders visit Pitcher's thistle flower heads indicating a generalist pollination syndrome. Generalist plants are often important floral resources that maintain plant-pollinator network structure, potentially as keystone species. I hypothesized that Pitcher's thistle is an important floral resource for the flower-visiting insects during its flowering period. To test this hypothesis I performed insect visitor observations on all the insect pollinated plants in randomly selected plots in the dunes of Sturgeon Bay, Wilderness State Park, MI. C. pitcheri received more visits and had more visitor species than any other plant in the network by a large margin. I used R Bipartite package to calculate species-level network metrics such as species strength and weighted connectedness and betweenness. I consistently found Pitcher's thistle to have the highest scores. The index d' rated Pitcher's thistle as the most generalized, i.e., received the most insect visitors. C. pitcheri also had a disproportionate effect on the flower-visiting insect fauna, relative to the abundance of its floral resources (number of open flowers, number of plants observed). Other plants in plant-pollinator networks have been shown to be important, perhaps keystone species, using this technique of species-level network metrics. Pitcher's thistle is an important species for the plant-insect network of the dune ecosystem. Insects and the flowering plants they visit and should be prioritized for conservation.

Author: Tina Marie Czaplinska
Publisher:
ISBN:
Category : Compositae
Languages : en
Pages : 90

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Book Description
Lake Michigan dwelling dune thistle, Circium pitcheri, is a federally threatened plant, whose reproduction is affected by a non-native weevil, Larinus planus. Originally introduced as a biological control agent to combat the spread of Canada thistle, Circium arvense, this weevil is instead using C. pitcheri as a host for its larvae. The goal of this study was to observe L. planus behavior to determine why there is a correlation between increased density of beach grass and high levels of C. pitcheri damage. We hypothesize that C. pitcheri's neighboring grass community is used as a dispersal aid for the non-native weevil, making neighboring thistle hosts more susceptible to weevil damage in grassy environments.

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

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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: Therese M. Poland
Publisher: Springer Nature
ISBN: 3030453677
Category : Science
Languages : en
Pages : 455

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Book Description
This open access book describes the serious threat of invasive species to native ecosystems. Invasive species have caused and will continue to cause enormous ecological and economic damage with ever increasing world trade. This multi-disciplinary book, written by over 100 national experts, presents the latest research on a wide range of natural science and social science fields that explore the ecology, impacts, and practical tools for management of invasive species. It covers species of all taxonomic groups from insects and pathogens, to plants, vertebrates, and aquatic organisms that impact a diversity of habitats in forests, rangelands and grasslands of the United States. It is well-illustrated, provides summaries of the most important invasive species and issues impacting all regions of the country, and includes a comprehensive primary reference list for each topic. This scientific synthesis provides the cultural, economic, scientific and social context for addressing environmental challenges posed by invasive species and will be a valuable resource for scholars, policy makers, natural resource managers and practitioners.

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: David Pimentel
Publisher:
ISBN:
Category : Pesticides
Languages : en
Pages : 228

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Author: Navjot S. Sodhi
Publisher: OUP Oxford
ISBN: 0191574252
Category : Science
Languages : en
Pages : 368

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Book Description
Conservation Biology for All provides cutting-edge but basic conservation science to a global readership. A series of authoritative chapters have been written by the top names in conservation biology with the principal aim of disseminating cutting-edge conservation knowledge as widely as possible. Important topics such as balancing conversion and human needs, climate change, conservation planning, designing and analyzing conservation research, ecosystem services, endangered species management, extinctions, fire, habitat loss, and invasive species are covered. Numerous textboxes describing additional relevant material or case studies are also included. The global biodiversity crisis is now unstoppable; what can be saved in the developing world will require an educated constituency in both the developing and developed world. Habitat loss is particularly acute in developing countries, which is of special concern because it tends to be these locations where the greatest species diversity and richest centres of endemism are to be found. Sadly, developing world conservation scientists have found it difficult to access an authoritative textbook, which is particularly ironic since it is these countries where the potential benefits of knowledge application are greatest. There is now an urgent need to educate the next generation of scientists in developing countries, so that they are in a better position to protect their natural resources.