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Minakawa, Noburu. "The dynamics of aquatic insect communities associated with salmon spawning /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/5496.
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Srivastava, Diane Sheila. "Ecological evolutionary limits of local species richness." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244120.
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Rott, Anja Sibylle. "Indirect interactions in host-parasitoid communities." Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243731.
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Wu, Dayong. "Bioassessing lotic systems using benthic insect communities in southeast Wyoming." Laramie, Wyo. : University of Wyoming, 2006. http://proquest.umi.com/pqdweb?did=1296087911&sid=2&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Fultz, Jessica Erin. "Effects of shelterwood management on flower-visiting insects and their floral resources." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/fultz/FultzJ0805.pdf.
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da, Silva Milton Barbosa. "Indirect interactions structuring ecological communities." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:4a093748-6192-4bbc-bf0f-854e909b47c0.
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Ecological communities are collections of species bound together by their influences on one another. Community structure, therefore, refers to the way in which these influences are organised. As a result, ecologists are mainly interested in the factors driving the structure, functioning, and persistence of communities. The traditional focus, however, has been on the feeding relationships among species (direct trophic interactions), whereas relationships mediated by a third species or the environment (indirect interactions) have been largely overlooked. I investigated the role of indirect interactions in structuring communities through a series of field experiments in a diverse assemblage of arthropods living on a Brazilian shrub species. I experimentally reduced the abundance of the commonest galler on the shrub and found that the perturbation resonated across the food web, affecting its structure and robustness. Since there was no potential for these effects to be propagated directly or indirectly via the documented trophic links, the effects must have spread non-trophically and/or through trophic links not included in the web. Thus, I investigated non-trophic propagation of effects in the system. I demonstrate that hatched galls of the commonest galler, which serve as habitat for other species, can mediate non-trophic interactions that feedback to the galler modifying its interactions with parasitoids and inquiline aphids. I performed further manipulative experiments, excluding ants, live galls and hatched galls, to reveal mechanisms for the non-trophic interaction modifications observed in this system. Finally, I explored how non-trophic interaction modification could affect the structure and stability of a discrete ecological community in the field. I investigated how the densities of certain pairs of groups relate to each other, and how their relationship changes in relation to a third group. Then, I assembled an "effect network" revealing, for the first time in an empirical community, a hidden web of non-trophic indirect interactions modifying the direct interactions and modifying each other. Overall, the thesis presents evidence that communities are strongly interconnected through non-trophic indirect interactions. This is one of the first empirical demonstrations of the context-dependent modification of interactions via non-trophic interactions. However, determining the mechanisms behind such interaction modifications may be unfeasible. Understanding how the observed effects relate to community structuring requires shifting our focus from bipartite interaction networks to a more holistic approach.
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Manrique, Mamani Fernando Miguel. "Diversity and abundance of insects from the Reduviidae and Pentatomidae families in three ecological niches of six communities in the Coroico and Coripata municipalities, Department of la Paz." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/5396.
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The Hemiptera order has 23,000 species that are distributed among many families. Two of these are the Pentatomidae and Reduviidae families. The aim of this study was to identify the different species of insects from the Reduviidae and Pentatomidae families as well as each species’ abundance in three ecological niches (forest, forest edge, and farm land). The study was conducted in six communities of Los Yungas, La Paz (Carmen Pampa, San Pablo, San Juan de la Miel, Altuspata, Choro Alto, and Choro). In each community, three Malaise traps were installed in the three ecological niches (forest, forest edge, and farm land). The six communities were evaluated for a period of one year. The work was divided among four groups due to the fact that two families were being studied in two different municipalities. In the Coroico municipality (Carmen Pampa, San Pablo, and San Juan de la Miel), the study took place from May 2006 to May 2007. In the Coripata municipality (Altuspata, Choro Alto, and Choro), the study took place from May 2007 to May 2008. The first group identified 34 morphospecies of the Pentatomidae family with 137 individuals in the Carmen Pampa, San Pablo, and San Juan de la Miel communities. The second group identified 19 species of the Pentatomidae family with 54 individuals in the Altuspata, Choro Alto, and Choro communities. The third group found 31 species of the Reduviidae family along with 77 individuals. The fourth group identified 14 species of the Reduviidae family along with 60 individuals. Carmen Pampa and San Juan de la Miel are similar in terms of plant life and climate. San Pablo, however, is different due to its much drier climate. Morphospecies number three from the Pentatomidae family was the most abundant in the farm land niche in San Juan de la Miel. In all six communities, we found that morphospecies 16 was the most abundant in the forest niche. In addition, we found that there is little similarity between the species that inhabit both the forest and farm land areas. A recurrent pattern in the six communities was the presence of similar species in the forest and forest edge niches. This is due to the transitional character of the forest edge niche. Morphospecies 16 of the Reduviidae family was found most often in the forest and forest edge niches of the Altuspata and Choro Alto communities. It was absent in the Choro community. The area of study has insect species of the Pentatomidae and Reduviidae families that play important ecological roles - in some cases they can be pests and in others they can be predators of pests. There is a notable difference in the presence of insects from the Reduviidae and Pentatomidae families between municipalities. This difference is explained by the increased application of agrochemicals in the municipality of Coripata.
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Chibaya, Colin. "An investigation into XSets of primitive behaviours for emergent behaviour in stigmergic and message passing antlike agents." Thesis, Rhodes University, 2014. http://hdl.handle.net/10962/d1012965.
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Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
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Hill, JoVonn Grady. "Environmental variables affecting ant (Formicidae) community composition in Mississippi's Black Belt and Flatwoods regions." Master's thesis, Mississippi State : Mississippi State University, 2006. http://library.msstate.edu/etd/show.asp?etd=etd-04192006-141353.
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Loreaux, Hosanna B. "Nutrient Flux from Aquatic to Terrestrial Invertebrate Communities Across a Lakeside Ecotone." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1557912595532676.
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Masheter, Alexander C. "Short-Term Effects of Lowhead Dam Removal on Emergent Aquatic Insect Communities in the Olentangy River, Ohio." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1532074575913958.
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Floss, Elzira Cecilia Serafini. "COMPOSIÇÃO E DISTRIBUIÇÃO ESPACIAL E TEMPORAL DE LARVAS DE CHIRONOMIDAE (INSECTA, DIPTERA), EM UM RIO EM REGIÃO MONTANHOSA, NO EXTREMO SUL DO BRASIL." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/5289.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>The composition and spatio-temporal distribution of the taxocenoses of the larvae of Chironomidae of a mountainous river, in southernmost Brazil were analyzed for this study. The diversity found was also compared to the taxocenoses of larvae inventoried in other Brazilian regions by means of tests of hypotheses, based on some environmental factors on a regional scale. About 100 taxa, classified at genus or species level, were found in the middle course of the Rio Jacuí basin (in the State of Rio Grande do Sul). The specimen collection took place in twelve different places between April 2000 and May 2002. The dominant taxa belong to species of the genera Rheotanytarsus, Cricotopus, Polypedilum and Pseudochironomus. Around 22% of the taxa were rare and 15 genera (Aedokritus, Axarus, Endotribelos, Kiefferulus, Manoa, Oukuriella, Phaenopsectra, Stenochironomus, Xenochironomus, Xestochironomus, Onconeura, Cardiocladius, Metriocnemus, Paracladius and Rheocricotopus) are new occurrences to Rio Grande do Sul. The clustering analysis applied to the genera, using larvae‟s taxocenoses inventoried in 32 regions of Brazil, formed three groups that showed similarity higher than 50%. The groups, when discarded the effects of spatial autocorrelation, displayed weak and positive correlation between the taxocenosis composition and the type of aquatic system and drainage basin and weak and negative in relation to the biome. The spatial and temporal structure of the taxocenoses, analyzed after four seasonal samplings (winter, spring, summer and autumn) in four different sampling locations showed that dominance, just like abundance and richness, varied amongst the different spots and seasons studied. Variations in spatial distribution were influenced by the existence of marginal vegetation, substratum heterogeneity, gradient of preservation and altitude. Variations in temporal distribution were influenced by factors such as mean temperature and precipitation levels, which were also related to the distribution of certain taxa and to the structure of the taxocenoses. The significant richness of the surveyed region corroborates some tendencies already noticed in other parts of the world, such as: i) lotic systems may constitute an exception to the rule that states that diversity is greater in tropical regions; ii) terrain transition regions may contain the greatest richness of Chironomidae; and iii) the spatial distribution of Chironomidae may be influenced in the greater extent due to local environmental characteristics than regional ones. On the other hand, human activity such as deforestation and construction of dams constitutes a serious threat to the conservation of the taxocenoses of Chironomidae since they directly affect the conservation of the riparian vegetation and the heterogeneity of the habitat.<br>A composição e a distribuição espaço-temporal das taxocenoses de larvas de Chironomidae, de um rio de região montanhosa no extremo sul do Brasil foram estudadas. A diversidade encontrada foi, também, comparada com taxocenoses de larvas inventariadas em outras regiões brasileiras, através de testes de hipóteses, baseados em alguns fatores ambientais em escala regional. Cerca de 100 táxons, classificados em nível de gênero ou espécie, foram encontrados no curso médio da bacia do Rio Jacuí (estado do Rio Grande do Sul), através de coletas realizadas em doze locais, entre abril de 2000 e maio de 2002. Os táxons dominantes pertencem a espécies dos gêneros Rheotanytarsus, Cricotopus, Polypedilum, e Pseudochironomus. Cerca de 22% dos táxons foram raros, e 15 gêneros (Aedokritus, Axarus, Endotribelos, Kiefferulus, Manoa, Oukuriella, Phaenopsectra, Stenochironomus, Xenochironomus, Xestochironomus, Onconeura, Cardiocladius, Metriocnemus, Paracladius e Rheocricotopus) são ocorrências novas para o Rio Grande do Sul. A análise de agrupamento, realizada com gêneros de larvas de Chironomidae inventariados em 32 localidades brasileiras, formou três grandes grupos com similaridade superior a 50%. Os agrupamentos, retirando o efeito da autocorrelação espacial, evidenciaram uma correlação fraca e positiva da composição das taxocenoses com tipo de sistema aquático e bacias hidrográficas, e fraca e negativa com tipo de bioma. A estrutura espacial e temporal das taxocenoses, analisada através de quatro amostragens sazonais (inverno, primavera, verão e outono), em quatro pontos de estudo, mostrou que dominância, assim como abundância e riqueza, variou entre os diferentes pontos e estações de estudo. Variações na distribuição espacial foram influenciadas por existência de vegetação marginal, heterogeneidade do substrato, preservação ambiental e altitude. Variações na distribuição temporal foram influenciadas por fatores como temperatura média e precipitação, os quais também estiveram relacionados à distribuição espacial de certos táxons e à estrutura das taxocenoses. A elevada riqueza detectada na região estudada corrobora algumas tendências registradas em outras regiões do mundo, tais como: i) sistemas lóticos podem constituir uma exceção à regra de que a diversidade é maior em regiões tropicais; ii) regiões de transição de relevo podem conter maior riqueza de Chironomidae; e iii) a distribuição espacial de Chironomidae pode ser mais influenciada por fatores ambientais de caráter local, do que regional. Por outro lado, na região de estudo, atividades humanas, como desmatamento e construção de barragens, constituem uma séria ameaça à conservação das taxocenoses de Chironomidae, uma vez que afetam diretamente a conservação da vegetação ripária e a heterogeneidade do habitat.
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Chisté, Melanie Nicole [Verfasser], Nico [Akademischer Betreuer] Blüthgen, and Andreas [Akademischer Betreuer] Jürgens. "Land-use mediated effects on communities and single species of herbivorous insects / Melanie Nicole Chisté ; Nico Blüthgen, Andreas Jürgens." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1149252642/34.
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Chisté, Melanie [Verfasser], Nico [Akademischer Betreuer] Blüthgen, and Andreas [Akademischer Betreuer] Jürgens. "Land-use mediated effects on communities and single species of herbivorous insects / Melanie Nicole Chisté ; Nico Blüthgen, Andreas Jürgens." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2017. http://d-nb.info/1149252642/34.
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Strasevicius, Darius. "Indirect effects of river regulation : consequences for landbirds of reduced numbers of aquatic insects." Doctoral thesis, Umeå University, Ecology and Environmental Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1107.
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<p>Abstrakt: Jag har undersökt hur älvreglering påverkar mängden knott (Tvåvingar: <i>Simuliidae</i>) längs flera norrlandsälvar och vilka konsekvenser denna påverkan får för den landlevande fågelfaunan. Studien visar att utbyggnad av älvar har en negativ effekt på mängden knott. Det fanns sju gånger högre tätheter av knott längs "orörda älvar" jämfört med utbyggda älvar.</p><p>Skillnaden i antal knott mellan älvtyperna var mycket större för knotthanar än för knotthonor, vilket förklaras av att honorna är rörligare eftersom de flyger och letar efter blod. Knott lever av blod från ett flertal däggdjur och fåglar och visar en stor variation i värd-specificitet mellan olika arter. Jag fann en högre frekvens av haemosporida blod parasiter (<i>Leucocytozoon</i>) i fåglar längs "orörda" Vindelälven jämfört med den reglerade Umeälven. Detta mönster stämmer väl överens med tätheten fågelparasiterande knott som är lägre längs Umeälven. Knott attackerade främst värdar som var stora och vanliga. Fågelsamhällets sammansättning skiljde sig mellan orörda och utbyggda älvdalar. Tätheten av icke insektsätande fåglar tenderade att minska, efter häcksäsongen, längs orörda älvar medan den ökade längs utbyggda älvar. Den insektsätande fågeln svartvit flugsnappare (<i>Ficedula hypoleuca Pallas</i>) uppvisade större häckningsframgång längs orörda älvar jämfört med utbyggda älvar. Detta är förmodligen en effekt av den större mängden insekter som finns längs orörda älvar.</p><br><p>The effects of river regulation on blackfly (Diptera: <i>Simuliidae</i>) abundances and consequences for the avifauna in terrestrial environments were studied along multiple rivers in northern Sweden. I found that impoundment of rivers has detrimental effect to blackfly abundances. The densities of large-river breeding blackfly species were several-fold higher along free-flowing than along regulated rivers. The difference in abundances was much larger in males than blood-seeking females. Blackflies attacked a variety of mammalian and avian hosts and showed different levels of host-specificity between species. I found higher prevalence of haemosporidian blood parasites (<i>Leucocytozoon</i>) in birds along the free-flowing Vindel River in comparison to the regulated Ume River, where the lower densities of ornithophilic blackflies were reduced. Blood-seeking blackflies predominantly attacked large and/abundant hosts.</p><p>Assemblages of birds differed between valleys of regulated and free-flowing rivers. Densities of noninsectivorous birds tended to decrease along free-flowing rivers in the post-breeding season, but increased along regulated rivers at the same time. Insectivorous European pied flycatcher (<i>Ficedula hypoleuca Pallas</i>) showed greater fledging success along free-flowing than regulated rivers, which probably reflects the higher insect abundances found along freeflowing rivers.</p>
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Alarcón, Eddy. "Biodiversity of Insects from the Syrphidae and Carabidae Families in Three Ecological Niches (Forest, Forest Boarder, and Farming Area) in Three Communities of the Coroico Municipality, Nor Yungas, La Paz." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/5327.
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Today, biodiversity is one of the most studied disciplines because it encompasses all species of plants, animals, and microorganisms that exist and act within an ecosystem. In recent decades, biodiversity has been degrading rapidly due to the simplification of agricultural systems, and the irrational use of pesticides that alter the normal function of ecosystems. Within nature, each insect population is attacked by one or more natural enemies. In this investigation, during a six month period from June to December 2006, the biodiversity of predatory insects from the syrphidae and carabidae families was determined in three ecological niches of three communities with two posed risks (Malaise and Pitfall) for the Carabidae family and one (Malaise) for the Syrphidae family. This investigation presents the differences in composition of morphospecies from three ecological niches in three communities of the yungas of La Paz. In total, we recorded 67 morphospecies from the Carabidae family in a population of 1107 individuals and 38 morphospecies from the Syrphidae family in a population of 1333 individuals. From the data above, it was found that the most diverse community was San Juan de la Miel with 33 morphospecies from the Syrphidae family and 42 morphospecies from the Carabidae family. However, in the case of the Syrphidae family, a smaller quantity of individuals found were related to the other communities whereas in the case of the Carabidae family, a larger quantity of individuals found were related. The similarity indices show only around 8-15% between the different ecological niches and communities which is relatively low and indicates that dominant species exist in these ecological niches, whether in the forest or in cultivated areas. The Carabids are insects similar to beetles, coming in varied sizes and colors, with dark and bright metallic colors being the most prominent. The family contains between 20,000 and 30,000 known species. The Syrphids are similar to dipterous insects, coming in different sizes and colors. Generally, black and yellow, or a combination of both similar to bees, are the most predominant colors. The family contains around 5,400 known species. The Carabids and Syrphids are very important in the biodiversity of ecosystems as well as in ecology because they regulate the pest populations through predation. In addition, when they are adults, they pollinate crops thus reducing the use of petrochemical insecticides. The area studied has a good diversity of species due to the geomorphology of the site. It has small patches of crops and fallow land surrounded by forests that allow the maintenance of its diversity, which is very important for the balance of ecosystems.
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Claros, Sossa Óscar Jaime. "Quantification of pollinating insects of the superfamily Apoidea in three ecological niches of three communities in the municipality of Coroico-Nor Yungas, department of La Paz." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/5349.
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The superfamily Apoidea (commonly referred to as bees), are insects whose diet consists of the nectar and pollen from flowering plants. Therefore, they are essential pollinators of many species, both wild and cultivated. Bees are similar to other Hymenoptera in appearance, size, and color variety. The superfamily Apoidea contains 17,000 known species and could possibly contain up to 30,000. Bees perform many tasks that benefit humanity such as pollinating the flowers of both wild and cultivated plants. Without this work, fruits and seeds necessary for the survival of different species, for our own food supply, and for industry would not be able to be produced. The study was done in three communities in the Yungas (Carmen Pampa, San Pablo, and San Juan de la Miel). In each community, three Malaise traps were introduced in three ecological ni ches (Forest, Forest Edge, and Crop Area). Each collection was done every 14 days throughout the six months of winter and spring. The quantification and identification of the Apoidea was conducted in a laboratory through identification keys for families, genera, and species. In total, 83 different morphospecies were identified. In the three communities, a total of 1117 individuals were recorded during the six months of field work. With regard to the niche factor, Partamona sp. (sp2) and Apis mellifera (sp1) were those species that contributed most to the abundance of individuals. In addition, both species contributed to the similarity and dissimilarity seen in the three ecological niches of the three communities. This indicates that they are the most abundant groups within the Yungas forests. They nest primarily in wood, are highly general, are highly social, and are present throughout the year. It is also worth mentioning that the community and station factors do not contribute to the differences in species diversity. Based on the results of this research, a new phase was initiated to identify the species contained within the 83 morphospecies found in the Yungas of La Paz.
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Burdon, Francis John. "The effects of stream productivity on aquatic-terrestrial linkages." Thesis, University of Canterbury. Biological Sciences, 2004. http://hdl.handle.net/10092/1415.
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The potential relationship between riparian arachnids and aquatic insect productivity was assessed in forest streams throughout the central South Island of New Zealand. Initially, a survey was conducted of thirty seven, first-third order forest streams. Streams were selected to represent a range of benthic invertebrate standing crops (as a surrogate measure of "productivity") from Banks Peninsula streams with relatively high benthic invertebrate densities to acid mine drainage streams near Reefton that were almost devoid of aquatic life. At each site benthic invertebrate densities and biomass were measured in riffle habitats and adjacent gravel bars were sampled for terrestrial invertebrates. At a sub-set of 16 sites, a 20 metre longitudinal web-building spider survey was conducted along each bank of the stream. As an additional component, a 20 metre transect starting at the stream margin and running perpendicularly into the forest was used to survey the density of web-building spiders with increasing distance from the stream. Results from the survey of in-situ stream insect biomass and gravel bar invertebrates showed a strong relationship between aquatic insect biomass and the biomass of riparian arachnids (R2 = 0.42, P < 0.001) having accounted for potentially confounding factors such as stream size, elevation, substrate and disturbance. The 20 metre longitudinal survey showed that streams with the highest in-situ insect biomass had significantly higher densities of web-building spiders along their banks (R2 = 0.28, P < 0.05), having accounted for potential confounding variables of elevation, habitat architecture and stream and channel width. The stream to forest survey showed a strong exponential decay in web-building spider densities with increasing distance from the stream (R2 = 0.96, P < 0.0001). Regardless of stream productivity web-building spiders were most abundant at the stream margins and rapidly declined to very low densities 20 metres from the stream. In order to further test the relationship between riparian web-building spider densities and stream insect productivity, a stream fertilization experiment was conducted on six first-second order streams in the Maimai experimental catchment, Reefton. Three streams were enriched by the addition of a fertiliser solution mainly consisting of sodium nitrate for seven months, and the other three streams were used as controls. Water chemistry, benthic invertebrate communities, emerging aquatic adults, and the densities of web-building spiders along the stream corridor and in the forest were monitored in three seasons (spring, summer and autumn) over the course of the nutrient-addition. By the end of the experiment, conductivity was significantly higher in nutrient-addition streams than in the control streams (F = 80.5, P < 0.001), but chlorophyll concentrations showed no significant differences between treatments. Both benthic mayfly densities (F = 6.15, P < 0.05) and the biomass of adult aquatic dipterans (Chironomidae, Simuliidae) (F = 9.25, P < 0.01) were significantly higher in nutrient-addition streams in the last sampling round. Spiders recorded from intercept traps indicated that by the end of the experiment spider activity was significantly higher within 2.5 metres of the nutrient-addition streams (F = 5.70, P < 0.01). However, seasonal densities of web-building spiders along the stream margin and in the forest decreased with no significant differences observed between nutrient-addition and control streams. The results from these studies indicate that adult insects emerging from streams represent an important source of prey that could influence the biomass and abundance of riparian arachnids. Additionally, the results imply that stream productivity and size could mediate the strength of the interaction between riparian and stream habitats. Moreover, feedback mechanisms present in both systems could have implications for such interactions. The elevated densities of web-building spiders observed at the stream margin led to the proposal of the "Highway Robber" hypothesis. This hypothesis suggests that such higher densities of spiders are the result of increased insect activity along the stream corridor: the emergence of adult aquatic insects was predicted to vary less over temporal and spatial scales than that of terrestrial insects due to the poorly synchronized life histories in many New Zealand stream insects. I conclude by suggesting that there are numerous anthropocentric perturbations such as loss of heterogeneity, introduced species, pollution and habitat degradation that could undermine and decouple the intimate linkages between aquatic and terrestrial ecosystems.
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Roth, Nicolas Mériadec Max André [Verfasser], Jörg [Gutachter] Müller, and Jan Christian [Gutachter] Habel. "Temporal development of communities with a focus on insects, in time series of one to four decades / Nicolas Mériadec Max André Roth ; Gutachter: Jörg Müller, Jan Christian Habel." Würzburg : Universität Würzburg, 2021. http://d-nb.info/1232647667/34.
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Pulliam, Lauren. "Biodiversity and Genetic Structure of Benthic Macroinvertebrates Along an Altitudinal Gradient: A Comparison of the Windhond and Róbalo River Communities on Navarino Island, Chile." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc849782/.
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Altitudinal gradients in Sub-Antarctic freshwater systems present unique opportunities to study the effect of distinct environmental gradients on benthic macroinvertebrate community composition and dispersal. This study investigates patterns in biodiversity, dispersal and population genetic structure of benthic macroinvertebrate fauna across an altitudinal gradient between two watersheds on Navarino Island in southern Chile. Patterns in diversity, density, evenness and functional feeding groups were not significantly different across the altitudinal gradient in both the Windhond and Róbalo Rivers. Taxa richness in both rivers generally increased from the headwaters of the river to the mouth, and functional feeding group patterns were consistent with the predictions of the River Continuum Concept.
Population genetic structure and gene flow was investigated by sampling the mitochondrial cytochrome oxidase I gene in two invertebrate species with different dispersal strategies. Hyalella simplex (Amphipoda) is an obligate aquatic species, and Meridialaris chiloeense (Ephemeroptera) is an aquatic larvae and a terrestrial winged adult. Contrasting patterns of population genetic structure were observed. Results for Hyalella simplex indicate significant differentiation in genetic structure in the Amphipod populations between watersheds and lower genetic diversity in the Róbalo River samples, which may be a result of instream dispersal barriers. Meridialaris chiloeense exhibited weak population structure but higher genetic diversity, which suggests this species is able to disperse widely as a winged adult.
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Zapata, Mayta Edwin. "Diversity of insects from the Vespidae family in three ecological niches (forest, forest border, and agricultural area) in six communities in the Coroico and Coripata municipalities, department of La Paz." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/5455.
Full textAbstract:
The Vespidae family (order Hymenoptera) is comprised of 4500 species of wasps in 268 genera and 7 subfamilies. These wasps prey upon a wide range of insects, including Lepidopteran caterpillars. Because of their low prey specificity, the use of Vespid wasps in biological control programs is limited. However, in their natural habitat, they play a role in controlling populations of some pest species. This study was conducted in six different communities in the department of La Paz within the municipalities of Coroico and Coripata. Three ecological niches were selected in each community: 1) the forest, 2) the edge of the forest and 3) a crop producing area. In each study unit, three Malaise traps were set up on a 14 day collection cycle from June to December 2007. Over the six month study period, we collected a total of 772 individuals and identified 36 different morphospecies from the six communities. The most abundant genera collected were Protopolybia sp., Mischocyttarus sp., and an unidentified genus (morphospecies #2) which had the greatest abundance of individuals in all of the different ecological niches. The niche factor did not have a significant influence on species diversity in the three ecological niches studied. Generally, this group of wasps is found in all three ecological niches.
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Morris, Rebecca Jane. "Indirect interactions in insect communities." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392402.
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Spon, Sandra T. (Sandra Teresa). "The Response of Aquatic Insect Communities and Caged In situ Asiatic Clams (Corbicula fluminea) to Dechlorinated Municipal Effluent in the Trinity River in North Texas." Thesis, University of North Texas, 1994. https://digital.library.unt.edu/ark:/67531/metadc278622/.
Full textAbstract:
Dischargers to the Trinity River in North Texas were required to dechlorinate their effluents in 1990-91. Field surveys were conducted above and below an outfall to
determine the response of resident immature insects and caged in situ juvenile Asiatic clams to chlorinated and dechlorinated effluent. Within six months after
dechlorination began, insect community composition and C. fluminea survival significantly improved at stations below the outfall. Significantly lower clam growth within one mile below the dechlorinated effluent indicated the presence of non-chlorine toxicants. Effects from chlorinated and dechlorinated effluent exposure were comparable between Ceriodaphnia dubia lab tests and in situ C. fluminea.
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Marsh, Charles John. "Spatial turnover of insect communities at rainforest edges." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/11100.
Full textAbstract:
Rainforest fragmentation is leading to huge increases in the quantity of forest in close proximity to edges. Edge effects may cause multiple alterations to ecological processes, however we do not know their impacts on the spatial turnover of communities, β-diversity. Using a dung beetle community in the north-east Brazilian Amazon, I addressed the problem in four, systematic steps. First, as β-diversity is spatially dependent it is essential to sample at small through to broad scales, presenting us with a limitation of sampling over large areas at fine scales. I present a scalable sampling design based upon a fractal series of equilateral triangles that proved in simulations to be more efficient at recovering accurate estimates of β-diversity than classical sampling designs. Second, I investigated optimal bait choice for accurately sampling the dung beetle community. A human-pig dung mix was found to be as effective as pure human dung baits, whilst removing possible dung source limitations. Third, I investigated the drivers of β-diversity based upon traits that govern foraging strategies. Wing and body morphology was found to be a significant predictor of the spatial scales at which species populations were structured. I then partitioned the variation attributed to environment and space for each morphological subset at three spatial scales. The drivers, and the scales at which they were most important, were dependent upon morphological traits, which further interacted with habitat modification. Finally, I investigated if β-diversity was greater in dung beetles at the forest edge. Linearising the fractal design, I estimated turnover within communities at set distances from the edge. Results were mixed: there was no elevation at a primary-Eucalyptus forest edge, but significantly higher turnover within communities at a primary-secondary forest edge than interior communities. This work increases our knowledge of how fragmentation and edge effects impact the underlying processes governing diversity.
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Reidinger, Stefan. "Multitrophic interactions between insect herbivores and soil microbial communities." Thesis, Royal Holloway, University of London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487317.
Full textAbstract:
Over the last two decades strong evidence has emerged that. interactions between .soil microbes, plants and higher trophic levels can translate into functional changes which affect ecosystem functioning and productivity. One of the most intensively studied soil microbial groups are the arbuscular mycorrhizal fungi that have been demonstrated not only to affect the performance of plants, but also to interact with insect herbivores via the common host. Howeyer, the ecological significance of such interactions on above- and belowground processes often remain~ obscure, since most previous studies were conducted under the . exclusion ofnon-mycorrhizal soil organisms. In order to study mycorrhiza-insect herbivore interactions under ecologically more realistic conditions, the large majority of experiments presented in this thesis were carried out with naturally co-occurring soil microbial communities. Chapter three of this thesis describes experiments in which I examined the effects of insect shoot herbivory on mycorrhizal colonisation and on the community structure of mycorrhizal fungi. Chapter four describes experiments in which I studied the combined effects of insect root herbivory and mycorrhizal fungi on aboveground insect attack. In chapter five I investigated, whether plant-soil feedbacks affect mycorrhizal colonisation, plant chemistry and aboveground insect attack. Furthermore, I tested whether insect herbivore-induced changes. in soil microbial communities affect the performance of a new generation of plants and insect herbivores. The results from these experiments suggest (1) that insect shoot herbivores have less impact on arbuscular mycorrhizal fungi than insect root herbivores, (2) that the outcome of mycorrhiza-insect interactions largely depends on the plant species identity involved, (3) that insect-indu~d changes in non-mycorrhizal soil microbial communities might be an important mechanism eA'Plaining the productivity and composition of plant communities as well as the abundance of insect herbivores and (4) that interactions between mycorrhizal fungi and insect herbivores might sometimes be of low ecological relevance.
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Laxton, Emma. "Relationship between leaf traits, insect communities and resource availability." Thesis, Electronic version, 2005. http://hdl.handle.net/1959.14/483.
Full textAbstract:
Thesis (PhD)--Macquarie University, Division of Environmental and Life Sciences, Dept. of Biological Sciences, 2005.<br>Bibliography: p. 178-203.<br>Introduction -- Study sites -- Leaf characteristics and resource availability -- Insect herbivory and resource availability -- Insect communities and resource availability -- Influence of resource availability on recovery from herbivory -- Conclusions.<br>This project used the resource availability hypothesis (Coley et al., 1985) as a framework for investigating the relationship between resource availability (as defined by soil nutrients), leaf traits, insect herbivore damage and insect community structure. According to the hypothesis, plants from low resource environments should be better-defended, have longer leaf lifespans and slower growth rates than plants from higher resource environments. Higher resource plant species are expected to suffer higher levels of herbivory and recover faster from herbivory than low resource plant species (Coley et al. 1985). A corollary to this hypothesis is that plants from higher resource sites should support greater densities of insect herbivores than low resource species. Comparisons between high and low resource sites were made in terms of: (i) leaf traits of mature and immature leaves; (ii) phenology of leaf maturation; (iii) herbivore damage in the field and laboratory; (iv) diversity and abundance of herbivorous insect fauna; and (v) ability to recover from herbivory.<br>Mode of access: World Wide Web.<br>243 p. ill., maps
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Spring, MaLisa R. "Impacts of Urban Greenspace Management on Beneficial Insect Communities." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492682461719594.
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Sircom, Julie. "DETERMINANTS OF THE BIODIVERSITY AND COMPOSITION OF STREAM INSECT COMMUNITIES." Springer, 2009. http://hdl.handle.net/10222/11486.
Full textAbstract:
The North Mountain of the Annapolis Valley, NS, in eastern Canada, is a ~200
km basalt ridge drained by many small first or second order streams in independent
catchments. The area is fairly uniform geologically, presenting an opportunity to compare
streams of similar chemistry, slope and aspect, that vary in other respects, such as
invertebrate community structure. In this thesis, I examine two macroinvertebrate
functional groups to determine key factors influencing their abundance, composition and
diversity across catchments.
Chapters 2 and 3 are concerned with the predatory invertebrate guild in eight of
the streams, in two groups separated by ~65 km. In Chapter 2, I assessed factors
influencing composition of the predator guild using similarity matrices. Similarity in
predator composition declined with distance, and streams that were more similar in
disturbance (spates) were more similar in predator composition. Similarity within one
family, Rhyacophilidae, was related to similarity in fish population. Chapter 3 reports the
results of laboratory experiments involving two widespread species. Field data suggested
an asymmetric interaction between Sweltsa onkos (Plecoptera: Chloroperlidae) and
Rhyacophila vibox (Trichoptera: Rhyacophilidae); behavioural observations in artificial
streams supported this. In the presence of R. vibox, S. onkos had higher mortality and
injury rates, and grew less. The results of these chapters suggest that, although
disturbance is important in shaping community structure, the results of interspecific
interactions can be detected at large scales. S. onkos can only attain high numbers in
streams where fish predation reduces the abundance of R. vibox.
Chapter 4 examines biodiversity patterns in the macroinvertebrate detritivore
guild in 25 streams encompassing ~80 km of the ridge. Using density and richness of the
detritivore community, detrital resource quantity, and top predator abundance, I looked
for evidence in support of several mechanisms that can lead to positive species-energy
relationships. Patterns conformed to expectations of the More Individuals Hypothesis. It
appears that taxonomic richness of the detritivore guild increases with detrital resource
availability because more taxa can attain their minimum viable population size where
more resources are available.
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Dunn, Joanna Mary. "Insect communities of farm woodlands in the Vale of York." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369305.
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Stenbacka, Fredrik. "Response of saproxylic insect communities to forestry implications for conservation /." Umeå : Dept. of Wildlife, Fish, and Environmental Studies, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200969.pdf.
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Coetzee, J. H. (Jacobus Hendrik). "Arthropod communities of Proteaceae with special emphasis on plant-insect interactions." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/66615.
Full textAbstract:
Thesis (PhD) -- Stellenbosch University, 1989.<br>ENGLISH ABSTRACT: Arthropod communities of five proteaceous species viz. Protea repens. P. neriifolia. P.cynaroides,
Leucospermum cordifolium and Leucadendron /aureolum were studied. A faunal list of the insects was
compiled according to the feeding guilds of insects. Six phytophagous guilds were recognized: flower
visitors, thrips, endophages, ectophages, sap-suckers, and ants. The guild composition, species packing and
seasonal distribution for the free-IMng insects, spiders and other arthropods were investigated on the
different plant species. The ants, flower visitors and sap-sucking species found on the plant species, were
very similar, but the number of leaf chewing species common to all the plant species was low, suggesting
that some species were monophagous. Insect abundance increased during the wet winter months when the
plants were in flower. Of the total number of herbivores collected, flower visitors represented 69,5%, leaf
feeders 14,5% and sap-suckers 16,1 %. The chewers constituted 60,1% of the total herbivore. biomass. Leaf
damage increased with age ; young leaves were practically free of herbivore damage, while older leaves
were stm acceptable as food. The degree of insect damage differed amongst the plant species varying from
2% to 15%. The following leaf characteristics were investigated to determine the factors involved in defence
against insect herbivory : total phenolic content, protein precipitating ability, cyanogenesis, nitrogen content,
leaf toughness, woodiness and fibre content lt appears that the plant species use different mechanisms to
protect their leaves. The infructescences of Protea repens were exploited by the larvae of four Coleoptera
and four Lepidoptera species. The community structure of these phytophagous insects was determined
largely by negative interactions. Various strategies are followed (e.g. niche segregation in time and space)
to lessen interspecific competition.<br>AFRIKAANSE OPSOMMING: 'n Studie van die arthropoocl gemeenskap op vyf proteasoorte, naamlik Protea repens. P. neriffolia. P.
cynaroides. Leucospennum cordffolium en Leucadendron laureolum is gedoen. 'n Faunalys van insekte
volgens hul voedingsgDdes is saamgestel. Die insekte is in ses fitofage gDdes verdeel naamlik
blombesoekers, blaaspootjies, endovoeders, ektovoeders, sapsuiers en miere. Die samestelling van die
gDdes, spesie-rangskikking en seisoenale verspreiding is bepaal vir die vrylewende insekte, spinnekoppe en
ander arthropode. Die miere, blombesoekers en sapsuierspesies wat op die plantsoorte gevind is, is byna
dieselfde, maar verslalle in die blaarvoederspesies is gevind wat 'n aanduiding is dat sommige spesies
monofaag mag wees. Gedurende die nat wintermaande toon die insekgetalle 'n toename. Blombesoekers
verteenwoordig 69,5%, blaarvoeders 14,5% en sapsuiers 16,1% van die aantal insekherbivore wat versamel
is. Die kouers vorm 60,1% van die totale herbivoor biomassa Soos die blare verouder, neem die skade
op die blare toe; jong blare toon byna geen skade nie, terwyl ouer blare steeds geskik is vir insekvoedsel.
Die insekskade op die blare wissel by die verslallende plante tussen 2% en 15%. Om te bepaal watter
blaareienskappe moontlik 'n rol kan speel in blaarverdediging teen insekte is die volgende ondersoek: totale
fenoliese inhoud, die vermoe om proteiene te presipiteer, sianogenese. stikstofinhoud, blaartaaiheid,
houtagtigheid en veselinhoud. Dit wil voorkom asof die plante verskillende meganismes gebruik om die blare
te beskerm. Saadkoppe van Protea repens word deur vier Coleoptera en vier Lepidoptera spesies benut
Die gemeenskapstruktuur van die boarders word tot 'n groat mate bepaal deur negatiewe interaksies.
Verskeie strategiee word gevolg (bv. nissegregasie in ~ en ruimte) om kompetisie tussen spesies te
verminder.
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Dicks, Lynn V. "The structure and functioning of flower-visiting insect communities on hay meadows." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249064.
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Håkansson, Michaela. "Farming system and landscape complexity affects pollinators and predatory insect communities differently." Thesis, Linköpings universitet, Biologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-110051.
Full textAbstract:
It has been argued that organic farming sustains a higher biodiversity than conventional farming. This might promote the ecosystem services that exist in agricultural landscapes such as pollination and pest control. Here, I examined the effect of farming system (organic vs. conventional) with respect to the time since farming system transition, landscape heterogeneity and plant richness on pollinating and predatory insects. In total, data from 30 farms were used, of which 20 were organic and 10 were conventional. The data were analyzed using general linear models and model averaging. The results show that insect groups responded differently to various factors. Pollinators were more sensitive to landscape complexity, showing an increase of abundance and species richness with an increased heterogeneity. Predators on the other hand reacted to farming system, where there was an increase in abundance and species richness on organic farms.
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Gely, Claire. "How will increased drought affect herbivory-based insect communities in Australian tropical rainforests?" Thesis, Griffith University, 2021. http://hdl.handle.net/10072/403645.
Full textAbstract:
Climate change is predicted to increase the frequency, duration and severity of drought in many regions. Predicting how forest ecosystems will respond to increased drought is a key issue in forest planning and forest management. Invertebrates play a central role in forest health and diversity, yet our understanding of the impact of drought on invertebrate communities in forests is very poor. This PhD addresses the impacts of increased drought on herbivory-based insect communities in tropical rainforests. Most of our current knowledge on that topic consists of observations from around the world that outbreaks of leaf feeders and bark beetles are typically preceded with unusually warm, dry weather. While there have been many experimental drought studies on plants and insects living on them, most of them were small scale experiments limited to one or a few individual plants rather than a whole forest ecosystem, and often reported contradictory results. A framework linking drought severity, plant defence production, plant nutritional quality, and insect response among different insect feeding guilds could help understand why different insects seem to respond differently to drought.
After reviewing the literature, I developed a framework that might predict how insects, and particularly herbivorous insects, may respond to prolonged drought. The framework incorporates the severity and longevity of drought and captures the plant physiological adjustments that follow moderate and severe drought and predicts the response of (i) different feeding guilds; (ii) flush feeders and senescence feeders; (iii) specialist and generalist insect herbivores; and (iv) temperate versus tropical forest communities. Intermittent and moderate drought may result in increases of carbon-based and nitrogenbased chemical defences, whereas long and severe drought events can result in decreases in plant secondary defence compounds. I predict that different herbivore feeding guilds will show different but predictable responses to drought events, with most feeding guilds being negatively affected by water stress, with the exception of wood borers and bark beetles during severe drought and sap-sucking insects and leaf miners during moderate and intermittent drought. Time of feeding and host specificity are important considerations. Some insects, regardless of feeding guild, prefer to feed on younger tissues from leaf flush, whereas others are adapted to feed on senescing tissues of severely stressed trees. I argue that moderate water stress could benefit specialist insect herbivores, while generalists might prefer severe drought conditions. In this thesis, I test some of these hypotheses using an experimentally droughted Australian rainforest site. In particular, I examined the effects of increased drought on i) intensity of wood-boring attack, ii) insect abundance and diversity and insect community composition, iii) insect seasonality, and iv) ant diets Rainforests in far North Queensland, Australia, experience a dry period with on average 5-6 months of less than 100mm rain per month. An experiment was established in the Daintree rainforest to simulate the effects of an increased and extended drought. Plastic panels were set up above the ground in half a hectare of rainforest to prevent rainfall from reaching the ground throughout the year. The experiment was implemented underneath the arc of a 47-m tall construction crane so that access could be made to the rainforest canopy for both the drought experiment and the juxtaposed area used as a control plot. Measurements of soil humidity from soil pits at the plots indicate that there was an overall reduction of soil humidity of at least 30% in the drought plot throughout the experiment.
I carried out two full years of insect collection on the drought experiment site two years after experimental droughting had commenced as well as on the nearby control plot. Insects were collected bi-monthly by beating leaves at the top of the canopy and from foliage at ground level, with the aim of exploring the effect of drought on insect abundance, diversity and community composition. I used stable isotope techniques to determine if drought could cause any variation in ant diets. Finally, I established 36 line transects across the study site to test whether wood boring activity would be more prevalent in increased drought conditions. Data on weekly soil-water availability from eight soil pits (four at the drought plot and four at the control plot) were used to measure impact of drought.
I found evidence that insect communities were deeply impacted by increased drought. First, I have found that saplings were significantly more affected by wood-borers under increased conditions. Second, I found that every feeding guild was less abundant on large trees under water stress than on control trees. On saplings, however, I found that some feeding guilds (sap-suckers and fungivores) were significantly more abundant with increased drought conditions. Insect diversity and community composition was also impacted by the drought experiment, as beetle species richness was significantly lower on drought-stressed large trees, and there was a great dissimilarity in ant and beetle assemblages on shrubs and saplings from the drought and control plot. In addition, I found that leaf-chewers did not show any strong seasonal patterns or peak in abundance during leaf flush when living in increased drought conditions. Overall, most hypotheses built in the framework proved to be correct, with the exception of sapsuckers and fungivores which were positively affected by drought on saplings, possibly because they might benefit from decreased levels of plant defences more than other feeding guilds. In addition, isotope analyses revealed that with increased drought, ants δ15N isotopic composition increased, which could indicate a shift from a diet relying on plant sources (extra-floral nectar, uptake of honeydew) towards a more predatory diet. However, the shift observed could also be due to the increase in δ15N in leaves in drought-stressed trees.
The framework I developed and the results of the drought experiment suggest a number of important avenues for further research on the impact of drought on insect communities. These include i) further assessment of how drought-induced changes in various plant traits, such as secondary compound concentrations and leaf water potential, affect herbivores, (ii) food web implications of changes in insect feeding guild structure and composition and how this might affect those that feed on them, and (iii) interactions between the effects on insects of increasing drought and other forms of environmental change including rising temperatures and CO2 levels. Since this is the first examination of how large-scale droughting affects insect communities, there is clearly a need for further large, temperate and tropical forest-scale drought experiments to look at herbivorous insect responses and their role in tree death.<br>Thesis (PhD Doctorate)<br>Doctor of Philosophy (PhD)<br>School of Environment and Sc<br>Science, Environment, Engineering and Technology<br>Full Text
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Spencer, Emma. "The Web of Death: Scavenger Communities and Interactions on Carrion in Australian Landscapes." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29410.
Full textAbstract:
Carrion is a nutrient-rich resource that attracts a diverse community of organisms, from insects and vertebrates to microbes. These organisms engage in a series of complex interactions, as they compete for a shared resource that is generally ephemeral and patchy in distribution. Carrion consumers may also interact with surrounding ecosystems, as they contribute to nutrient cycling and dispersal, and to carrion removal, which can limit potential disease spread. Further, as most animals that interact with carrion also take on predatory roles, carrion may impact local environments by enhancing or redirecting predation or fear effects. These interactions are largely shaped by the ecosystem context in which the carcass is situated. Yet there remains a paucity of data on the different environmental drivers affecting carrion ecology generally, especially in Australian environments. This thesis addressed this gap by exploring key aspects of the carrion community in Australia. It applies a large-scale standardised survey of the vertebrates and insects associated with over 120 experimentally positioned kangaroo (Osphranter and Macropus spp.) carcasses in three distinct biogeographic regions across Australia. Overall, this work comprises the largest replicated carrion ecology experiment on mainland Australia to date. The findings reveal novel insights into the structure and function of carrion communities across a range of bioregions. They also highlight the context dependency of carrion communities and their various interactions. I suggest that future work focuses on enhancing the spatial, temporal, and taxonomic scales upon which carrion research is focused, and support the development of global, standardised carcass monitoring surveys to build a more in-depth understanding of the factors that influence carrion community dynamics and ecosystem processes linked to decomposition.
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Rodstrom, Robert Andrew. "Epigeal insect communities & novel pest management strategies in Pacific Northwest hybrid poplar plantations." Thesis, Washington State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3587164.
Full textAbstract:
<p> Hybrid poplars are a short rotation woody crop grown for a variety of target markets including paper pulp, saw timber, and biofuels in the Pacific Northwest. Development of pest control strategies within hybrid poplar plantations over the last several decades has focused on controlling foliar feeding herbivores and wood boring pests, and has overlooked the epigeal arthropod community. Understanding this unstudied suite of organisms would allow pest managers to better evaluate the impact their management strategies have on the poplar agroecosystem. Qualitative surveys of the arthropod communities in hybrid poplar plantations and nearby native habitats demonstrated that a greater arthropod diversity persists in the surrounding native areas. Additionally, the poplar plantation's epigeal arthropod community was composed of species found within sampled native areas. </p><p> Historically poplar research focused on protecting trees in the years following establishment through harvest from emerging pests while discounting cutting mortality by replanting areas of failure. Describing unrooted cutting transplant morality and distribution within newly established planting block could provide a risk assessment tool that growers could utilize to evaluate their potential crop loss. It was determined through the examination of damaged cuttings that several pests were responsible for diminishing establishment success. Identification of these risks led to the development of a management strategy to reduce mortality in newly planted areas. Soaking cuttings in imidacloprid for 48 hrs provided superior herbivore protection for unrooted cuttings until root formation allowed for uptake from chemigation treatments. </p><p> An additional study was motivated by the increased concern in growing `clear wood' as poplar has migrated from pulp to saw timber. The accompanying renewed interest in reducing insect galleries in mature trees led to the exploration of deploying a mass trapping, or trap out, effort to reduce populations of <i> Prionoxystus robiniae</i> (Lepidoptera Cossidae) in specific areas of a hybrid poplar plantation. We show that a trap out effort of roughly 5 pheromone-baited traps/ha decimated <i>P. robiniae</i> populations in treated areas throughout the trap out effort and three years post application.</p>
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Abdlrahman, Abdlrahman Y. A. "Insect herbivores and neighbourhood effects in plant communities of Al Jabal Al Akhdar, Libya." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12122/.
Full textAbstract:
Neighbouring plants in the locale of an individual plant may help or hinder it in the task of defence against herbivores, depending on their levels of defence (chemical or physical), and their interactions with potential herbivores. Such ‘neighborhood effects’ are part of the complex network of species interactions that structure ecological communities. This thesis sets out to test whether there are neighbourhood effects on insect herbivory among the plants of the Al Jabal Al Akhdar region of Libya. Having chosen to concentrate on the two main species of three study sites, Juniperus phoenicea and Pistacia atlantica, nine plots were mapped in detail and the insect herbivores sampled from focal plants, and then from all plants. Leaves were sampled for chemical analysis of their phenol (tannin) content. The set of insect herbivores collected from plants in the plots were identified to species using the expertise of the staff of the Natural History Museum in London. Some insects recorded are new to Libya, and there are several species not previously recorded as feeding on either of the two plant species studied. Tannin levels were much higher in Pistacia than in Juniperus, and there were effects of elevation as well: plants from middle elevation plots had the highest levels, while those from the lowest elevation at the coast had the lowest levels of tannins. There were clear effects of neighbouring plants on the insects of individual plants, in both Pistacia and Juniperus. These were much more complex effects in Pistacia, but both sets of predictors of insect herbivore density or species richness contained clear signs of neighbourhood effects, where the existence of close neighbours reduced the herbivore load on individual plants. There were no signs of any protective neighbourhood effects of tannin levels. Thus in the plant communities of Al Jabal Al Akhdar, associational avoidance appears to be the major mechanism of neighbourhood effects, rather than associational resistance.
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Martin, Grant Douglas. "Drivers of macrophyte assemblages in South African freshwater systems." Thesis, Rhodes University, 2013. http://hdl.handle.net/10962/d1004127.
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Potentially damaging submerged invasive freshwater macrophytes have been identified in South African freshwater systems, but have received less attention than their floating counterparts. To ascertain the changes and effects that these species may have on macrophyte ecology, an understanding of the drivers of macrophyte assemblages is essential. The aims of this thesis were to investigate select abiotic and biotic factors driving introduction, establishment and spread of submerged macrophytes in South Africa. Surveys on the status of submerged plant species in South Africa were conducted to find out the distribution and diversity of the species present, imported to, and traded in South Africa. Numerous submerged indigenous and invasive macrophyte locality records were collected during field surveys, of which many were first time records. Pet stores and aquarist trading activities were identified as potential vectors for the spread of submerged macrophytes through online surveys and personal interviews. These results highlighted the potential these species have for continuing to enter, and spread within South African water bodies. Maximum Entropy (MAXENT) is a general-purpose method used to predict or infer distributions from incomplete information, and was used here to predict areas suitable for the establishment of five of these invasive macrophytes. Many systems throughout South Africa, particularly those in the subtropical coastal regions, were found to be climatically suitable for the establishment of Elodea canadensis Michx., Egeria densa Planch., Hydrilla verticillata (L.f.) Royle (all Hydrocharitaceae), Myriophyllum spicatum L. (Haloragaceae), and Cabomba caroliniana Gray (Cabombaceae). Despite the high probability of invasion, facilitated by vectors and suitable climate, South Africa’s rich indigenous submerged aquatic flora may be preventing the establishment of these submerged invasive species. Studies on the competitive interactions between a common indigenous submerged macrophytes, Lagarosiphon major (Roxb.) (Hydrocharitaceae) and M.spicatum, an invasive native to Eurasia, were conducted to ascertain which conditions influence competitive superiority. High sediment nutrient conditions significantly increased the growth rate and competitive ability of both species, while clay sediments significantly increased the competitive ability of L. major over M. spicatum, but sandy sediments improved the competitive ability of M. spicatum. These results highlighted the dynamic changes in competition between submerged species driven by abiotic factors, but did not take into consideration the effect that herbivory, a biotic factor, could have on competition between the two species. The effect of herbivory by phytophagous insects of submerged plant species has been regarded as negligible. To find out what this effect is, multiple field surveys were undertaken throughout South Africa to find natural enemies of indigenous Lagarosiphon species with the aim of identifying such species, and quantifying their influence on plant growth dynamics. Several new phytophagous species were recorded for the first time. An ephydrid fly, Hydrellia lagarosiphon Deeming (Diptera: Ephydridae) was ascertained to be the most ubiquitous and abundant species associated with L. major in South Africa. The influence of herbivory by this fly on the competitive ability of L. major in the presence of M. spicatum was investigated using an inverse linear model, which showed that herbivory by H. lagarosiphon reduced the competitive ability of L. major by approximately five times in favour of M. spicatum. This study served to highlight the importance of herbivory as a driver of submerged aquatic plant dynamics. Current ecological theory emphasises the importance of investigating beyond plant-herbivore interactions, by including multitrophic interactions in community dynamics. Therefore, the potential of parasitism by a parasitoid wasp, Chaenusa luteostigma sp. n. Achterberg (Hymenoptera: Braconidae: Alysiinae) on H. lagarosiphon to shift the competitive interactions between the two plant species was also examined. The addition of the parasitoid reduced the effect of herbivory by the fly on L. major by half, thereby shifting the competitive balance in favour of L. major over M. spicatum. This study provides valuable insight into a selection of drivers of submerged macrophyte assemblages of South Africa. It highlights the precarious position of South African freshwater systems with regard to the potential invasion by damaging submerged invasive species. It also provides interesting insights into the effect of competition, herbivory and parasitism on the establishment and spread of species within submerged freshwater systems. Understanding the different influences could assist managers and policy makers to make validated decisions ensuring the integrity of South African freshwater systems.
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Abbott, Kirsten L. "Alien ant invasion on Christmas Island, Indian Ocean : the role of ant-scale associations in the dynamics of supercolonies of the yellow crazy ant, Anoplolepis gracilipes." Monash University, School of Biological Sciences, 2004. http://arrow.monash.edu.au/hdl/1959.1/5141.
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Hepburn, Colleen. "The phenologies of macadamia (Proteaceae) and thrips (Insecta: Thysanoptera) communities in Mpumalanga Province, South Africa." Thesis, Rhodes University, 2017. http://hdl.handle.net/10962/6817.
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Macadamia (Proteaceae) is indigenous to Australia; four of the nine species have been used in plant breeding for cultivation and the production of a rapidly growing product. First introduced to Hawaii in the 1880s, macadamias’ potential as a crop was only really considered in 1910. It is due to the early Hawaiian pioneers’ research and the development of Hawaiian cultivars upon which most of the current world’s production is based today. Prior to the 1980s, cultivation in Australia was based mainly on Hawaiian cultivars. Extensive research has been conducted on cultivar development, performance, best practice, production, crop protection and processing. South Africa has become one of the world’s leading producers and exporters of macadamias. The cultivation of macadamia in South Africa began 80 years ago, but the phenology of macadamia has not been rigorously studied under local conditions, and neither has the thrips communities in macadamia. Data collected during this study on the macadamia phenological stages can be used as a foundation on which seasonal data of all insect pests can be plotted, as a basis on which an extensive Integrated Pest Management (IPM) programme can be developed for the macadamia industry in South Africa. Extensive sampling of thrips communities present in macadamias was undertaken over two years, with more than 142,000 individuals collected. The most basic, common trait into which specimens could be sorted were colour groups. Specimens from each colour group were identified through slide-mounting individuals. Fifteen species of thrips were identified to species-level, excluding specimens from the Panchaetothripinae, Haplothrips and Scolothrips which occurred only periodically. The presence of larvae indicated that macadamia is a host plant for some species. Due to their size and morphology, identification i of the total collection could not be processed to species level using a dissection microscope, although Scirtothrips aurantii Faure were distinguishable from other species and their distribution over the seasons observed. Due to logistical constraints and events beyond the author’s control, the results are mainly qualitative. There seems to be phenological variation within and between cultivars. The date of anthesis and duration of immature nut-drop was estimated; some cultivars set out- of-season flowers and nuts; this “secondary crop” could have far-reaching effects on the implementation of an IPM programme. Comparisons of the phenological data of macadamia and thrips showed the highest abundances and diversity of thrips species occurred when flowers were present. An extensive study of abscised nuts showed no significant difference between most cultivars or at the sites where management practices were implemented and those sites where these practices were not. There was however a consistent difference between the two seasons. There was no difference in maturity of abscised nuts, regardless of whether thrips damage to the husk was present or not. Excessive Bathycoelia distincta (Hemiptera: Pentatomidae) damage was found on the kernels of the abscised nuts processed for maturity testing, which is more likely to have been the primary cause of abscission. The Author’s opinion is that thrips damage to the outer husk does not lead to abscission of maturing nuts. Ascertaining the cause of abscission at nut-set and immature nut-drop is more problematic as there are numerous other potential causes. Damage to new flush, especially the late summer flush essential for the build-up of carbohydrates and resources for the following yield, should be carefully monitored and controlled when necessary.
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Wood, Diane L. "The influence of abiotic factors on lotic insect communities of submerged rootmats and temporary pools /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9964013.
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Burk, Rosemary A. "Ecology and Recolonization of Benthic Macroinvertebrates in a Groundwater-dependent Stream in North Central Texas During a Supra-seasonal Drought." Thesis, University of North Texas, 2012. https://digital.library.unt.edu/ark:/67531/metadc115054/.
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Extreme climatic events such as droughts are known to eliminate aquatic biota and alter community structure and function. Perennial headwater springs provide important drought refugia to benthic macroinvertebrates and an important source of colonists via drift or aerial adults to intermittent streams post-drought. During a supra-seasonal drought in North-central Texas summer and fall 2006, benthic macroinvertebrates from persistent groundwater-dependent macrohabitats of varying hydrological connectivity and riparian shading were studied: perennial riffles, connected pools, shaded disconnected pools, and full sun disconnected pools. Riffles were a distinct habitat with significantly higher taxa richness, proportion of lotic taxa, diversity and evenness than other macrohabitats. Macrohabitats were found to be important refugia for 106 benthic macroinvertebrates and 4 microcrustacean taxa. Throughout the extreme drought, perennially flowing habitats were refugia to 19 taxa (17.9% total taxa) not collected in disconnected pools. Shaded disconnected pools contained lotic taxa not previously known to be able to complete their lifecycles in lentic habitats, emphasizing the importance of groundwater effluent and shading. With the resumption of flow at a downstream intermittent site of Ash Creek in mid-October 2006, an annual recolonization study was conducted comparing the perennial headwaters’ benthic macroinvertebrate taxa richness, densities and community ecology with the downstream intermittent site. The headwaters supported higher mean taxa richness than the intermittent site over the duration of the study (ANOVA P < 0.001). However, the unexpected result of overall decreasing taxa richness at the perennial headwater site from August 2006 to April 2008 appears to reflect lag effects of the supra-seasonal drought combined with effects of multiple spates of 2007, which are factors confounding the point of recovery for taxa richness. Recovery of taxa richness at the intermittent site took 9 months compared to 1 to 2 months reported in other arid and semi-arid streams in the United States recovering from seasonal drying and floods. Sustainable use of groundwater resources and conservation of riparian corridors is vital to protecting groundwater-dependent ecosystems that play a vital role in maintaining regional biodiversity by serving as biotic refugia during catastrophic disturbance.
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Doka, Margaret E. "Impact of silvicultural practices on insect communities and herbivory on young jack pine in northern Ontario." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ46003.pdf.
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Gonthier, David Jonathan. "Influence of Soil-Quality on Coffee-Plant Quality and a Complex Tropical Insect Food Web." University of Toledo / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1271380868.
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Heads, P. A. "The influence of predators on the behaviour and feeding ecology of prey species in two insect communities." Thesis, University of York, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.370733.
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Kuria, Simon Kamande. "The role of ants in structuring insect communities on the canopies of senegalia drepanolobium near Laikipia, Kenya." Thesis, Rhodes University, 2007. http://hdl.handle.net/10962/d1005446.
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In the black cotton ecosystem of Laikipia, Kenya, four symbiotic ants coexist at a fine spatial scale on canopies of Senegalia drepanolobium. They exhibit different aggressive behaviours and modify their tree canopies differently. These diverse behaviours were expected to affect the associated canopy arthropod communities. At the Kenya long-term exclosure experiment (KLEE) and its immediate environs at Mpala Research Centre, Laikipia, the insect communities coexisting with each of the four ant species were characterized, and their response to different vertebrate herbivory. Other ant species inhabiting the tree canopies or the ground were surveyed too. Pitfall trapping was used in sampling terrestrial ants, while beating and mist-blowing were used in collecting arboreal insects. Different sampling methods had varying efficacies, revealing the importance of using several methods. There are at least sixteen ant species in this ecosystem, all occurring on the ground, but only ten species on the trees. Terrestrial ant communities in this ecosystem cannot be used as indicators of grazing pressure for range management. A total of 10,145 individual insects were collected from the tree canopies, comprising of 117 species from seven orders and 25 families, forming a complex community of species interacting at different levels. Symbiotic ant species had a significant effect on insect community structure and composition. Crematogaster sjostedti was associated with a community that was significantly different from the other ant species. There was no significant effect of vertebrate feeding pressure on the canopy insect community, but there was an interaction effect between ant species and treatments. Significant differences between ant species mostly occurred on treatment plots where only cows were allowed to graze. One or more of the ant species may be a keystone species in this ecosystem even though experimental manipulations failed to confirm earlier findings. It was concluded that the one-year period during which experimental manipulations were carried out was not long enough to reflect takeover effects on the insect community. The four symbiotic ant species colonizing S. drepanolobium comprises of two guilds, the hemipteran-tending ants (C. sjostedti and Crematogaster mimosae) and non-tending ants (Crematogaster nigriceps and Tetraponera penzigi). Communities associated with these guilds were found to be significantly different in all four diversity indices. The black cotton ecosystem is species-poor compared to other ecosystem such as forests. The number of insect species that colonizes S. drepanolobium and coexists with acacia-ants forms a large proportion of the invertebrate community. Therefore, this ecosystem should be conserved to safeguard this invertebrate community. This will also give scientists a chance to establish how the various insect species coexist with symbiotic ants on tree canopies.
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Viegas, Gustavo Vinícius. "Respostas dos besouros (INSECTA: COLEOPTERA) a pressões pastoris em campos naturais no sul do Brasil." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/187235.
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O crescimento populacional humano e o consumismo exacerbado têm elevado as demandas na produção de alimentos e gerado uma intensificação rural, se tornando um dos principais direcionadores do declínio da biodiversidade. O manejo de gado está se intensificando e expandindo, muitas vezes às custas da derrubada de áreas florestais. Mas manejar o gado em campos naturais pode ser uma estratégia para a conservação desses ecossistemas. Os métodos de manejo determinam as comunidades de campos, de forma que baixa pressão de pastejo parece promissor para a conservação. De modo geral, direcionadores ambientais tendem a gerar padrões na diversidade em grande escala, enquanto a competição contribui para determinar a coexistência local. Contudo, os processos de montagem das comunidades podem diferir entre regiões. Assim, especialmente filtros ambientais e interações bióticas atuam dinamicamente e direcionam o padrão da comunidade. As espécies que persistem se diferenciam especialmente em grupos alimentares conforme os recursos disponíveis, e competem dentro desses grupos conforme os nichos dos consumidores se sobrepõem. Além disso, as características morfológicas individuais podem facilitar ou restringir sua habilidade em persistir em um ambiente, ao passo que mediam os processos ecossistêmicos. Os insetos representam o maior componente da biodiversidade em ecossistemas terrestres, e são considerados sensíveis às condições ambientais. Coleoptera é a ordem de insetos com maior riqueza em espécies, que abrange uma larga extensão de grupos funcionais, e são sensíveis às variações ambientais. O objetivo desta Tese foi testar se as comunidades de Coleoptera refletem diferenças nas pressões pastoris exercidas pelo gado. Essa Tese revela resultados inéditos para cada uma das abordagens empregadas, especialmente considerando a escala regional do experimento. A diversidade de besouros residentes do solo mostrou um padrão geral com relação positiva ao pastejo enquanto os residentes da vegetação demonstraram uma relação negativa ao pastejo. Os herbívoros residentes da vegetação são bastante sensíveis ao pastejo do gado, e declinam com o aumento da intensidade, enquanto que os predadores residentes da vegetação parecem responder positivamente a uma vegetação mais arbustiva do que de gramíneas. Além disso, parece que, potencialmente, os besouros também respondem com seus atributos morfológicos às diferenças na estrutura da vegetação conforme a intensidade de pastejo. O pastejo de baixa intensidade parece uma boa opção para beneficiar a conservação da biodiversidade. Contudo, manejar campos naturais com apenas uma técnica não permite conservar igualmente os besouros campestres.<br>Human population growth and exacerbated consumerism have raised the demands on food production and generated rural intensification, becoming one of the main drivers of biodiversity decline. Livestock management is intensifying and expanding, often at the cost of clearing forested areas. However, managing livestock in natural grasslands may be a strategy for the conservation of these ecosystems. Management methods determines the communities in grasslands, so that low pressure grazing seems promising for conservation. In general, environmental drivers tend to generate diversity patterns at large scales, while competition contributes to determining local coexistence. However, the assembly processes of communities may differ between regions. Thus, environmental filters and biotic interactions, especially, act dynamically and direct the community pattern. Species may persist when different, especially according to feeding groups, and compete within these groups when consumer niches overlap. In addition, individual morphological traits may facilitate or restrict a species ability to persist in an environment, while at the same time mediating ecosystem processes. Insects represent the largest component of biodiversity in terrestrial ecosystems, and have been considered sensitive to environmental conditions. Coleoptera is the insect order with the largest species richness, covering a wide range of functional groups, and are sensitive to environmental variations. The aim of this thesis was to test whether Coleoptera assemblages reflect differences in the pastoral pressures exerted by livestock. Ground-dwelling beetle diversity showed a general pattern of positive relationship with grazing while grass-dwellers showed a negative relationship with grazing. Grass-dweller herbivores are quite sensitive to livestock effects, and decline with increasing grazing intensity, while grass-dweller predators appear to respond positively to scrubs rather than to grass vegetation. In addition, it seems that, potentially, beetles also respond with their morphological traits to differences in vegetation structure according to grazing intensity. Some of these results are unprecedented, especially considering the regional scale of the experiment. Low intensity grazing seems to be a good option to benefit biodiversity conservation. However, managing grasslands with a single technique would not provide grassland beetles conservation equally.
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Georgitis, Kathryn M. "Evaluating Shade Bias in Insect Trap Catch and Assessing the Short- and Long-term Impacts of Herbicide Application in Regenerating Clearcuts on Flowering Plant Communities." Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/GeorgitisKM2001.pdf.
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Netshifhefhe, Shandukani Rudolf. "The compilation of indigenous knowledge regarding insect pests in small-scale farming communities in North Eastern South Africa." Pretoria: [s.n.], 2005. http://upetd.up.ac.za/thesis/available/etd-06302005-113354.
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Clark, Maxwell Maitland. "Insect herbivore communities colonising the flower-heads of Berkheya in South Africa and Carduoideae in Europe and California." Doctoral thesis, University of Cape Town, 1989. http://hdl.handle.net/11427/8416.
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Bibliography: leaves 231-233.<br>One of the main purposes of this study was to determine whether general conclusions can be made about the association of insect herbivores with Berkheya and thistles and whether there are any 'rules' that have influenced the evolution of these associations. It is shown repeatedly that there are significant and interesting correlations between characteristics of the plants and their herbivore communities, but these are not universal.