Invasive alien species (IAS) pose a serious threat to ecosystems and societies worldwide. Local ecological knowledge (LEK) is increasingly valued as a means of understanding environmental issues; however, its application in the context of IAS research has been limited. The overall objective of this study was to document the LEK of farmers and Weed Supervisors to gain insight into a recent IAS, Odontites serotina. I conducted semi-structured interviews with farmers and Weed Supervisors with O. serotina management experience. Results indicated that the socio-economic impacts for farmers were severe in affected rural communities. However, participants had developed promising control techniques, including the application of compost mulch. I used this LEK as well as data on species occurrence, environmental variables, and measures of propagule pressure to forecast the potential distribution of O. serotina across Manitoba. The risk map generated will be useful for guiding future monitoring and public outreach efforts.

Lake Winnipeg has been subject to intense eutrophication and invasive species such as Rainbow Smelt and Eubosmina coregoni for the last 40 years. This study demonstrated significant increases in total phosphorus, total nitrogen, chlorophyll-a, overall zooplankton abundance, and specifically Cladocera, between 1969 and the first decade of the 21st century. There were specific basin differences in the long-term changes of the Cladocera community, with the species Chydorus sphaericus and Ceriodaphnia quadrangula negatively affected by high levels of phosphorus, nitrogen and chlorophyll-a. Moreover, long-term change in the Cladocera community composition and abundance throughout the years (1969-2011) during summer was correlated with intensifying eutrophication. Additionally, weak diel vertical migration in the zooplankton community was observed for the first time in Lake Winnipeg.

The invasion of natural environments by alien species is a significant threat to the ecological integrity of these systems. Senna obtusifolia is an aggressive invasive weed recently introduced to Australia that is having significant impacts on grassland ecosystems on the Cape York Peninsula. Currently the species is inadequately managed and so range expansion continues. The invasion potential of S. obtusifolia in Australia remains unknown, as does much about its behaviour and management in natural systems. This project undertakes extensive mapping and modelling of the current and future distributions and the invasion dynamics of S. obtusifolia in Australia to facilitate early detection of outbreak populations and the development of appropriate management strategies. The mapping and modelling of S. obtusifolia was conducted at three different scales: continental, landscape and local (population). To address these spatial scales, eco-climatic modelling, remote sensing analysis, field experimentation and creation of a model of seed fate was undertaken. Using the climatic preferences of S. obtusifolia displayed internationally, an eco-climatic model (using CLIMEX software) ascertained that S. obtusifolia has a very large invasive potential in Australia. The predicted geographic distribution comprised the entire eastern and northern Australian coastlines, with spread further inland being largely restricted by a lack of moisture. The regional distribution of S. obtusifolia was not successfully delineated using remote sensing technology. Despite possessing favourable traits for detection by remote sensors, poor data quality and inappropriate image scales prevented the weed from being distinguished from other vegetation by multi-spectral satellite imagery and aerial photography. However, the results indicated that refining the data and the techniques used, single S. obtusifolia populations may be detectable in the future. Investigation of the invasion dynamics of S. obtusifolia at the local scale involved multiple field surveys and manipulative experiments during 2002-2005. Field work indicated that little variation in population characteristics (e.g. stem density, soil seed reserve, seed production) existed within populations, but there was variability across populations and between years: the variation between years was very significant. The vegetation type adjacent to the weed population did not affect population attributes; however less competitive, more open and disturbed environments may better facilitate the invasion. The compartment model of seed fate reflecting S. obtusifolia population dynamics demonstrated that change in annual rainfall was unlikely to explain the variation evident between populations and years. Instead, the rate at which dormancy is broken in seeds and the intensity and regularity of fire provided a better explanation of the weed's population dynamics. Early detection of invaders and the prediction of likely sites of invasion provide the most effective means of preventing future invasions. How best to achieve these goals still remains largely unknown. The process undertaken in this study was a relatively quick and reliable method for assessing the seriousness of S. obtusifolia, predicting future outbreaks and for providing clues to long term management. The appropriate use of fire, maintaining high interspecific competition and shade, as well reducing the rate at which dormancy is broken in seeds are all possible methods of managing S. obtusifolia.

Invasive plant species in natural ecosystems have been shown to have a wide range of potential impacts on community composition and ecosystem function. Alligator weed (Alternanthera philoxeroides) is invasive in New Zealand and elsewhere. An aggressive competitor and difficult to control, its impacts in productive ecosystems are widely documented. However, little information exists about alligator weed’s effects in natural ecosystems. This thesis therefore investigated potential effects of alligator weed on decomposition and nutrient cycling, as well as on invertebrate and plant communities in a “native” ecosystem, thus integrating effects on ecosystem processes and community composition. These aspects were compared between vegetation dominated by alligator weed or by one of two native sedges, Isolepis prolifer and Schoenoplectus tabernaemontani, in a northern New Zealand lake. In addition, the potential of shading to control alligator weed was assessed. Herbivory by the biocontrol agent Agasicles hygrophila resulted in substantial alligator weed defoliation, differing in timing and magnitude from biomass dynamics of the native sedges. Alligator weed also decomposed faster than either native sedge. Changes in decomposition dynamics led to a shift towards fungivore dominated beetle communities. This illustrates the potentially complex ecosystem effects of biocontrol agents as well as invasive weeds. Alligator weed decomposition rates and invertebrate communities were more similar to those of I. prolifer than S. tabernaemontani. This pattern was attributed to the greater chemical and architectural similarity of alligator weed to I. prolifer compared with S. tabernaemontani. Invasive plants’ impacts may thus be partially influenced by the degree of similarity between the invasive species and the dominant vegetation they invade. Alligator weed was associated with decreased cover of native plants, potentially placing them at greater risk of local extinction. Greenhouse and field experiments showed that shading significantly reduced alligator weed growth. However, clonal support from unshaded areas, and competitive release from less shade tolerant plants, may potentially impede the success of shade based control. This research demonstrates that alligator weed can have a range of complex and multi-trophic effects in a natural ecosystem. Further, characteristics of both invasive and competing vegetation can influence the success of cultural control methods such as shading.

Invasive plant species in natural ecosystems have been shown to have a wide range of potential impacts on community composition and ecosystem function. Alligator weed (Alternanthera philoxeroides) is invasive in New Zealand and elsewhere. An aggressive competitor and difficult to control, its impacts in productive ecosystems are widely documented. However, little information exists about alligator weed’s effects in natural ecosystems. This thesis therefore investigated potential effects of alligator weed on decomposition and nutrient cycling, as well as on invertebrate and plant communities in a “native” ecosystem, thus integrating effects on ecosystem processes and community composition. These aspects were compared between vegetation dominated by alligator weed or by one of two native sedges, Isolepis prolifer and Schoenoplectus tabernaemontani, in a northern New Zealand lake. In addition, the potential of shading to control alligator weed was assessed. Herbivory by the biocontrol agent Agasicles hygrophila resulted in substantial alligator weed defoliation, differing in timing and magnitude from biomass dynamics of the native sedges. Alligator weed also decomposed faster than either native sedge. Changes in decomposition dynamics led to a shift towards fungivore dominated beetle communities. This illustrates the potentially complex ecosystem effects of biocontrol agents as well as invasive weeds. Alligator weed decomposition rates and invertebrate communities were more similar to those of I. prolifer than S. tabernaemontani. This pattern was attributed to the greater chemical and architectural similarity of alligator weed to I. prolifer compared with S. tabernaemontani. Invasive plants’ impacts may thus be partially influenced by the degree of similarity between the invasive species and the dominant vegetation they invade. Alligator weed was associated with decreased cover of native plants, potentially placing them at greater risk of local extinction. Greenhouse and field experiments showed that shading significantly reduced alligator weed growth. However, clonal support from unshaded areas, and competitive release from less shade tolerant plants, may potentially impede the success of shade based control. This research demonstrates that alligator weed can have a range of complex and multi-trophic effects in a natural ecosystem. Further, characteristics of both invasive and competing vegetation can influence the success of cultural control methods such as shading.

Invasive plant species in natural ecosystems have been shown to have a wide range of potential impacts on community composition and ecosystem function. Alligator weed (Alternanthera philoxeroides) is invasive in New Zealand and elsewhere. An aggressive competitor and difficult to control, its impacts in productive ecosystems are widely documented. However, little information exists about alligator weed’s effects in natural ecosystems. This thesis therefore investigated potential effects of alligator weed on decomposition and nutrient cycling, as well as on invertebrate and plant communities in a “native” ecosystem, thus integrating effects on ecosystem processes and community composition. These aspects were compared between vegetation dominated by alligator weed or by one of two native sedges, Isolepis prolifer and Schoenoplectus tabernaemontani, in a northern New Zealand lake. In addition, the potential of shading to control alligator weed was assessed. Herbivory by the biocontrol agent Agasicles hygrophila resulted in substantial alligator weed defoliation, differing in timing and magnitude from biomass dynamics of the native sedges. Alligator weed also decomposed faster than either native sedge. Changes in decomposition dynamics led to a shift towards fungivore dominated beetle communities. This illustrates the potentially complex ecosystem effects of biocontrol agents as well as invasive weeds. Alligator weed decomposition rates and invertebrate communities were more similar to those of I. prolifer than S. tabernaemontani. This pattern was attributed to the greater chemical and architectural similarity of alligator weed to I. prolifer compared with S. tabernaemontani. Invasive plants’ impacts may thus be partially influenced by the degree of similarity between the invasive species and the dominant vegetation they invade. Alligator weed was associated with decreased cover of native plants, potentially placing them at greater risk of local extinction. Greenhouse and field experiments showed that shading significantly reduced alligator weed growth. However, clonal support from unshaded areas, and competitive release from less shade tolerant plants, may potentially impede the success of shade based control. This research demonstrates that alligator weed can have a range of complex and multi-trophic effects in a natural ecosystem. Further, characteristics of both invasive and competing vegetation can influence the success of cultural control methods such as shading.

Thesis (M.S.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Roger L. Sheley. Includes bibliographical references (leaves 26-30).

Petróleo Brasileiro S.A. / As espécies de corais invasores, Tubastraea tagusensis e T. coccinea foram acidentalmente introduzidos no Brasil através de plataformas de petróleo. O rápido crescimento e estágio reprodutivo, competição contra espécies nativas, defesas químicas contra predadores e competidores naturais e uso amplo em diferentes substratos utilizados contribuem para o sucesso e expansão de Tubastraea spp. na costa brasileira. O presente estudo teve dois objetivos principais: 1) investigar uma metodologia que resulte em uma maior eficiência e custo-benefício nos processsos de monitoramento dos corais invasores Tubastraea spp. no litoral brasileiro; 2) mapear a distribuição geográfica, caracterizar as populações e estudar o efeito da inserção dos corais na comunidade bêntica de costões rochosos do litoral norte do estado de São Paulo (LNSP). O primeiro avaliou quatro metodologias, comparando o método do censo visual, e outras três metodologias que utilizam fotografia e filmagem. O método do censo visual mostrou ser mais eficiente na obtenção dos resultados quando comparado com os outros métodos, principalmente para identificar pequenos organismos. Contudo, seu tempo em campo e seus custos foram maiores. O segundo utilizou o método visual para estudar o efeito da inserção dos corais invasores na comunidade local do LNSP. Ainda, foi realizado um monitoramento espacial semi-quantitativo em larga escala para caracterizar a distribuição espacial dos corais invasores; transectos com quadrados amostrais foram usados para estimar a densidade de Tubastraea ao longo da profundidade, e transectos e arcos graduados empregados para estimar a ocorrência de colônias em diferentes inclinações do substrato, no LNSP. Os corais invasores estão aumentado sua distribuição, causando diversos impactos nas comunidades e nos organismos nativos. T. tagusensis é comumente encontrado dominando diversos costões rochosos, com uma densidade maior em ambientes mais profundos e com maior ocorência em substratos de inclinções verticais e negativas no LNSP. A erradicação e/ou controle do coral invasor é recomendado no litoral brasileiro, principalmente onde as populações estão isoladas ou ainda são pequenas. / The invasive coral species, Tubastraea tagusensis and T. coccinea were accidentally introduced into Brazil by oil platforms. The rapid growth and reproductive stage, competition against native species, chemical defenses against natural predators and competitors and ample use of different substrates contribute to the success and expansion of Tubastraea spp. on the Brazilian coast. This study had two aims: 1) investigate a methodology that results in more efficient and cost-effective monitoring of the Tubastraea spp. invaders on the Brazilian coast, 2) map the geographical distribution, characterize the populations and study the effect of corals insertion in the community on the northern coast of São Paulo (LNSP). The first aim evaluated four methods by comparing the visual census method and three other methods that use photography and filming. The visual census method proved to be more efficient in achieving the results compared with other methods, primarily to identification of smaller organisms; however, time in the field and costs were higher. The second aim used the visual method to study the effect of insertion of coral invaders into the community. Also, a semi-quantitative monitoring of spatial scale to characterize the spatial distribution of coral invaders was carried out; transects with squares were used to estimate the density of Tubastraea spp. along the depth gradient, and transects and graduated arcs employed to estimate the occurrence of colonies at different inclinations of the substrate, in LNSP. The invader corals are increasing their distribution, causing several impacts on native communities and species. T. tagusensis is actually found dominating several rocky shores, with a higher density deeper and in a vertical and negative substrates slopes in LNSP. Eradication and/or control of the invasive corals are recommended on the Brazilian coast, especially where populations are isolated or are still small.

Insect pests represent major threats to food production, biodiversity conservation, and human and animal health. Currently, the most widespread strategy to control their populations is through the spraying of synthetic chemical insecticides. However, the overuse of these compounds has had significant negative environmental consequences. Additionally, our reliance on insecticides has resulted in major reductions in their efficacy through pest-evolved resistance. To successfully manage insect pests, while avoiding environmental degradation, thus requires the development of novel, more sustainable, pest management strategies. Recent advances in our understanding of recombinant DNA methods and molecular biology have allowed the application of transgenic tools to pest management. Here, synthetic genes can be engineered, transformed into the genomes of pest species, and transported into wild target populations through the natural mating behaviour of the insect. A strategy in which these transgenes are lethal to those insects inheriting them in the field is known as RIDL – Release of Insects carrying a Dominant Lethal. A variant of RIDL limits this lethality to females – female specific RIDL (fsRIDL) – which explicitly targets the reproductive capacity of a target population. The aim of this thesis is to investigate the application of such an fsRIDL strategy to the diamondback moth (Plutella xylostella L.). This economically important pest of brassica crops is highly adept at developing resistance to insecticides and is considered extremely difficult to manage effectively. I present findings which demonstrate the power of diamondback moth lines transformed with fsRIDL transgenes to eliminate target pest populations, and combine synergistically with other transgenic control strategies such as Bt crops in counteracting the evolution of pesticide resistance. Additionally, an exploration into an alternative gene expression system to that used in current RIDL strategies – the Q system – suggests that not all expression systems will be suitable for transgene control within this highly specific framework. It is hoped that this work will contribute towards the effective control of the diamondback moth, and form a model for the sustainable control of other lepidopteran species through genetic pest management.

Petróleo Brasileiro S.A. / As espécies de corais invasores, Tubastraea tagusensis e T. coccinea foram acidentalmente introduzidos no Brasil através de plataformas de petróleo. O rápido crescimento e estágio reprodutivo, competição contra espécies nativas, defesas químicas contra predadores e competidores naturais e uso amplo em diferentes substratos utilizados contribuem para o sucesso e expansão de Tubastraea spp. na costa brasileira. O presente estudo teve dois objetivos principais: 1) investigar uma metodologia que resulte em uma maior eficiência e custo-benefício nos processsos de monitoramento dos corais invasores Tubastraea spp. no litoral brasileiro; 2) mapear a distribuição geográfica, caracterizar as populações e estudar o efeito da inserção dos corais na comunidade bêntica de costões rochosos do litoral norte do estado de São Paulo (LNSP). O primeiro avaliou quatro metodologias, comparando o método do censo visual, e outras três metodologias que utilizam fotografia e filmagem. O método do censo visual mostrou ser mais eficiente na obtenção dos resultados quando comparado com os outros métodos, principalmente para identificar pequenos organismos. Contudo, seu tempo em campo e seus custos foram maiores. O segundo utilizou o método visual para estudar o efeito da inserção dos corais invasores na comunidade local do LNSP. Ainda, foi realizado um monitoramento espacial semi-quantitativo em larga escala para caracterizar a distribuição espacial dos corais invasores; transectos com quadrados amostrais foram usados para estimar a densidade de Tubastraea ao longo da profundidade, e transectos e arcos graduados empregados para estimar a ocorrência de colônias em diferentes inclinações do substrato, no LNSP. Os corais invasores estão aumentado sua distribuição, causando diversos impactos nas comunidades e nos organismos nativos. T. tagusensis é comumente encontrado dominando diversos costões rochosos, com uma densidade maior em ambientes mais profundos e com maior ocorência em substratos de inclinções verticais e negativas no LNSP. A erradicação e/ou controle do coral invasor é recomendado no litoral brasileiro, principalmente onde as populações estão isoladas ou ainda são pequenas. / The invasive coral species, Tubastraea tagusensis and T. coccinea were accidentally introduced into Brazil by oil platforms. The rapid growth and reproductive stage, competition against native species, chemical defenses against natural predators and competitors and ample use of different substrates contribute to the success and expansion of Tubastraea spp. on the Brazilian coast. This study had two aims: 1) investigate a methodology that results in more efficient and cost-effective monitoring of the Tubastraea spp. invaders on the Brazilian coast, 2) map the geographical distribution, characterize the populations and study the effect of corals insertion in the community on the northern coast of São Paulo (LNSP). The first aim evaluated four methods by comparing the visual census method and three other methods that use photography and filming. The visual census method proved to be more efficient in achieving the results compared with other methods, primarily to identification of smaller organisms; however, time in the field and costs were higher. The second aim used the visual method to study the effect of insertion of coral invaders into the community. Also, a semi-quantitative monitoring of spatial scale to characterize the spatial distribution of coral invaders was carried out; transects with squares were used to estimate the density of Tubastraea spp. along the depth gradient, and transects and graduated arcs employed to estimate the occurrence of colonies at different inclinations of the substrate, in LNSP. The invader corals are increasing their distribution, causing several impacts on native communities and species. T. tagusensis is actually found dominating several rocky shores, with a higher density deeper and in a vertical and negative substrates slopes in LNSP. Eradication and/or control of the invasive corals are recommended on the Brazilian coast, especially where populations are isolated or are still small.