Includes bibliographical references

In the past 10 years we have witnessed the beginnings of the study of soil ecology as a unified science, and the general realization by soil scientists, farmers, and land managers that many of the most important economic aspects of soil health are controlled by biological factors. This research focuses on alterations in a tropical soil microarthropod community under differing intensive agricultural protocols: native vegetation, pastures and cropland, during June, July and August 1998. The effect of pesticides in potato cultivation was also studied. In the Ecuadorean montane forest, 361 morphospecies of soil arthropods, were classified during the three sampling months. August was the month with highest abundance and diversity. Acari, Coleoptera, Collembola, Diptera and Homoptera were the most abundant orders present in all the three types of land management. The native vegetation had the most abundant and diverse representation of all soil arthropod taxa compared to the pastures and croplands. Coleoptera, Diptera, Diplopoda, Diplura and Hemiptera were significantly more diverse in native vegetation than in pastures and croplands. The most abundant functional groups were the fungivores, herbivores and predators. The abundance of functional groups was significantly higher in the native vegetation for predators, herbivores and detritivores. 115 morphospecies of soil arthropods were identified in the study of arthropod response to pesticides in a complete randomized potato plot. Seasonal effects were documented for Acari, Collembola, Diptera, and Homoptera. Predators were most abundant in July and fungivores decreased in September. Neither arthropod orders nor functional groups showed a significant change in abundance between different treatments. Only Homoptera showed an increase in its abundance in the third sampling date and only in the Antracol plots. The potato plants in the whole block showed poor productivity, suggesting that the whole system was stressed by the fungal pest. / Graduation date: 2000

Thesis (Ph. D.)--Ohio State University, 2007. / Originally issued in print. "Publications [by Jih-Pai Lin]": p. ix-x. Includes bibliographical references (p. 342-392). Full text release at OhioLINK's ETD Center delayed at author's request

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Orientador: Raphael de Campos Castilho / Banca: Odair Aparecido Fernandes / Banca: Wesley Augusto Conde Godoy / Resumo: Estudos para avaliar o impacto de cultivos Bt em artrópodes não alvo, inclusive com a diminuição do uso de inseticidas, são necessários ao longo de safras consecutivas e nas diferentes regiões produtores do Brasil. Assim, foi feita análise da comunidade e uma análise da curva de resposta principal da abundância dos artrópodes não alvo em diferentes áreas produtoras para comparar o efeito do plantio de milho geneticamente modificado MON810 contendo a proteína Cry1Ab e do milho convencional. Essa comparação foi realizada em seis áreas produtoras de milho no Brasil (Araguari-MG, Campo Verde-MT, Dourados-MS, Luis Eduardo Magalhães-BA, Passo Fundo-RS), em amostragens com armadilha Pitfall (para os artrópodes da camada epígea), bandeja amarela (artrópodes da parte aérea) e com coletas de solo (artrópodes a 15 cm da superfície). As amostragens foram realizadas aos 30, 45 e 60 dias após a emergência em 3 safras consecutivas, 2010-2012. Os experimentos foram desenhados com delineamento em delineamento de blocos inteiramente casualizados, com 3 repetições. Os artrópodes coletados foram agrupados em grupos representativos e/ou importantes ecologicamente, sendo que a análise de distribuição do peso dos grupos mostrou que Araneae, Cicadellidae, Coccinellidae, Collembola, Doru luteipes, Dorymyrmex sp., Drosophilidae, Hemerobius sp., Mesostigamata, Mycetophilidae, Pheidole spp., Phoridae, Scarabaeidae, Solenopsis spp., Staphylinidae e Syrphidae foram mais abundantes no mil... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Studies to assess the impact of Bt crops on non-target arthropods, including decrease in the use of insecticides are necessary over consecutive seasons and in different producing regions of Brazil. Therefore, it was was performed a community and principal response curve analysis of the non target arthropods abundance in different producing areas to compare genetically modified MON810 expressing Cry1Ab protein and conventional maize. This comparison werecarried out in six maize producing sites in Brazil (Araguari-MG, Campo Verde-MT, Dourados-MS, Luis Eduardo Magalhães-BA, Passo Fundo-RS and Rolândia-PR) including assessments as Pitfall (to the epigean arthropods), yellow tray (to the flying arthropods) and soil samples (15 cm from surface arthropods). Samples were taken in 30, 45 e 60 days from emergence in the consecutive seasons, from 2010 to 2012. Experiments was design by completely ramdomized blocks with 3 repetitions. Arthropods collected was grouped in typical groups and/or ecologically important and the group distribution weight exibits that Araneae, Cicadellidae, Coccinellidae, Collembola, Doru luteipes, Dorymyrmex sp., Drosophilidae, Hemerobius sp., Mesostigamata, Mycetophilidae, Pheidole spp., Phoridae, Scarabaeidae, Solenopsis spp., Staphylinidae e Syrphidae were more abundant in MON810 maize over assessment while Aphididae, Apidae, Astylus variegatus, Carabidae, Chloropidae, Chrysomelidae, Coreidae, Diplopoda, Dolichopodidae, Euxesta spp., Ichneumonoidea, Nitiduli... (Complete abstract click electronic access below) / Mestre

The abundance and diversity of arthropods present in the surface soil layers at various forest sites in northern California were investigated, primarily at two old-growth redwood forest sites in Prairie Creek Redwoods State Park and Jedediah Smith Redwoods State Park. A wide variety of arthropods were found, including representatives of Araneae, Pseudoscorpiones, Opiliones, Acarina, Isopoda, Diplopoda, Chilopoda, Symphyla, Pauropoda, Protura, Diplura, Collembola, Thysanoptera, Hemiptera, Coleoptera, Diptera, and Hymenoptera. Arthropod densities were significantly higher in the wet than in the dry period, indicating seasonal variation in surface densities of soil arthropods. The densities of arthropods in soils collected from beneath coast redwood (Sequoia sempervirens) and western hemlock (Tsuga heterophylla) trees were not significantly different.

In this study, I addressed how a large-scale wildfire affected a prairie arthropod community in southern Alberta, Canada. First, I looked at the general effects of disturbance on the arthropod community. Second, I addressed how processes such as competition and secondary succession may have affected diversity in this arthropod community. Third, I determined how the arthropod community trophic structure was regulated. Results showed that the effect of disturbance on arthropods varies greatly by taxa. Factors, such as site, year, distance from disturbance edge, as well as the disturbance itself, were important in determing the abudance, biomass, richness, and diversity of the arthropod community. There were strong year-to-year differences hat exceeded the disturbance effects. Results showed that the processess behind the intermediate disturbance hypothesis, succession and competition are not detectable in this arthropod community. This arthropod community was likely regulated in a bottom-up manner, in which herbivores ultimately control the abundance of predators and parasitoids. / x, 97 leaves : ill. ; 28 cm.

Diese Arbeit befasst sich mit der Entwicklung der Asselspinne Pseudopallene sp. (Arthropoda, Pycnogonida). Die Morphogenese und Nervensystementwicklung werden mithilfe von Rasterelektronenmikroskopie, Histologie, Immunhistochemie und Genexpressionsstudien untersucht. Während der Proboscisbildung lassen sich keine Anzeichen für ein Labrum erkennen. Aufgrund des Fehlens von Palpen- und Ovigeranlagen und der frühen Entwicklung der Laufbeinsegmente ist kein embryonales Protonymphon-Stadium identifizierbar. Die Evolution verschiedener Larvenformen der Pycnogoniden wird im Hinblick auf phylogenetische Studien diskutiert. Die frühen Prozesse im Neuroektoderm zeigen Ähnlichkeiten zu Eucheliceraten und Myriapoden. Hierzu zählen das Fehlen morphologisch distinkter Zelltypen, die Bildung von Zellinternalisierungszentren, die Immigration vorwiegend post-mitotischer Ganglionzellen mit erhöhter Delta-Genexpression und fast ausschließlich tangentiale Zellteilungen. Anschließend bilden sich pro Neuromer ein Paar Invaginationen, was durch Vergrößerung der apikalen Zellen begleitet wird. Letztere sind aufgrund ihrer hohen Mitoseaktivität, ihres asymmetrischen Teilungsmodus und des anhaltenden Zuwachses der basalen Ganglionzellen als stammzellartige neuronale Vorläuferzellen identifizierbar. Hierauf basierend wird die Validität von stammzellartigen neuronalen Vorläuferzellen als Synapomorphie der Krebse und Insekten diskutiert. Zwei evolutionäre Szenarien zur Arthropoden-Neurogenese werden erörtert. In der post-embryonalen Phase lösen sich die invaginierten Zellregionen vom Ektoderm ab. Sie bilden apikal auf den Ganglien paarige Zellcluster und bleiben mit deren Somacortex über fibrilläre ‚cell streams‘ verbunden. Der weitere Zuwachs an Ganglionzellen und die exklusive Zellproliferation in den cluster-stream-Systemen weisen letztere als post-embryonale neurogenetische Nischen aus. Ähnlichkeiten zu der neurogenetischen Nische im Deutocerebrum der decapoden Krebse werden aufgezeigt. / This study addresses aspects of the development of the sea spider Pseudopallene sp. (Arthropoda, Pycnogonida). In order to investigate morphogenesis and nervous system development, a combination of scanning electron microscopy, histology, immunohistochemistry and gene expression studies is used. Embryonic proboscis development shows no signs of a labrum. The lack of palpal and ovigeral limbs and the early anlagen of the walking leg segments lead to the rejection of an embryonized protonymphon stage during Pseudopallene development. The evolution of pycnogonid hatching stages is evaluated in light of recent phylogenetic analyses. Early neurogenesis shares similarities with euchelicerates and myriapods, including the lack of morphologically distinct neuroectodermal cell types, formation of transient cell internalization sites, immigration of mostly post-mitotic ganglion cells with elevated levels of Delta gene expression and predominantly tangentially oriented cell divisions in the neuroectoderm. Subsequently, paired invaginations form in each neuromere, being accompanied by marked enlargement of the apical cells. Due to their high mitotic activity, their asymmetric division mode and a marked cell number increase in the ganglia, the big cells are identified as stem cell-like neuronal precursors. Based on this, the validity of stem cell-like neuronal precursors as synapomorphy of crustaceans and hexapods is discussed. Two scenarios on the evolution of arthropod neurogenesis are presented. During the post-embryonic phase, the invaginating cell regions detach internally and form paired cell clusters at the apical ganglion sides. Each cluster remains connected to the ganglion soma cortex via fibrous cell streams. Increasing ganglion cell numbers and exclusive occurrence of mitoses within the cluster-stream-systems characterize the latter as post-embryonic neurogenic niches. Similarities to the neurogenic niche in the deutocerebrum of decapod crustaceans are discussed.

Arthropods typically show two types of segmentation: the embryonic parasegments and the adult segments that lie out of register with each other. Such a dual nature of body segmentation has not been described from Onychophora, one of the closest arthropod relatives. Hence, it is unclear whether onychophorans have segments, parasegments, or both, and which of these features was present in the last common ancestor of Onychophora and Arthropoda. To address this issue, we analysed the expression patterns of the "segment polarity genes" engrailed, cubitus interruptus, wingless and hedgehog in embryos of the onychophoran Euperipatoides rowelli. Our data revealed that these genes are expressed in repeated sets with a specific anterior-to-posterior order along the body in embryos of E. rowelli. In contrast to arthropods, the expression occurs after the segmental boundaries have formed. Moreover, the initial segmental furrow retains its position within the engrailed domain throughout development, whereas no new furrow is formed posterior to this domain. This suggests that no re-segmentation of the embryo occurs in E. rowelli. Irrespective of whether or not there is a morphological or genetic manifestation of parasegments in Onychophora, our data clearly show that parasegments, even if present, cannot be regarded as the initial metameric units of the onychophoran embryo, because the expression of key genes that define the parasegmental boundaries in arthropods occurs after the segmental boundaries have formed. This is in contrast to arthropods, in which parasegments rather than segments are the initial metameric units of the embryo. Our data further revealed that the expression patterns of "segment polarity genes" correspond to organogenesis rather than segment formation. This is in line with the concept of segmentation as a result of concerted evolution of individual periodic structures rather than with the interpretation of \"segments\" as holistic units.

Thesis (MSc)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Five new species of ophiostomatoid fungi, colon ising the infructescences of serotinous Protea species, have recently been discovered in South Africa. Prior to this, ophostomatoid fungi were thought to be restricted to the Northern Hemisphere. The discovery of these five species thus extensively expanded the known geographical range of these fungi, now also to include the Southern Hemisphere. Since this discovery, few studies have focused on the interesting ecology of this group, which is uniquely adapted for spore dispersal by arthropods. Studies focussed on ophiostomatoid fungi provide an unique opportunity to study inter-organism interactions between fungi, their host plants and the arthropods responsible for their spore dispersal. Very few similar studies have been undertaken, particularly in the Fynbos Biome, to which most of our economically important Protea species are confined. The current study provides insight into some ecological aspects of these complex interactions. The seasonal distribution of the ophiostomatoid fungi associated with the infructescences of members of the Proteaceae was investigated. Definite seasonal patterns were observed, with peak fungal colonisation occurring during the wetter winter months. While determining the host specificity of these fungi, a new Protea host for Ophiostoma splendens was identified, and a new species of Rhyncomeliola was discovered. All ophiostomatoid species native to Fynbos in the Stellenbosch region are exclusively associated with the infructescences of species in the plant genus Protea. By employing a multiplex Polymerase Chain Reaction (PCR), a set of group specific primers was developed for the identification of South African Ophiostoma and Gondwanamyces fungal DNA. This newly developed method was used to scan arthropods collected from the infructescences of P. repens for the presence of 0. splendens and G. proteae spores. By using these group-specific primers, three insects possibly responsible for long range dispersal of fungal spores were identified. Three further insect species, possibly contributing to the short-range dispersal of ophiostomatoid spores, were also implicated through this method. All arthropods associated with the fruiting structures of selected members of the Proteaceae were also investigated. A total of 62 pseudospecies (ca. 7500 individuals), belonging to 45 different arthropod families, were collected. Proteaceae species with larger fruiting structures housed more arthropod species and higher numbers of individuals than Proteaceae taxa with smaller fruiting structures. Some plant species housed similar arthropod communities, while others housed unique suites of arthropods. Seasonal patterns in arthropod numbers were observed, and it was found that, in most instances, arthropod numbers peaked during the autumn and winter months. Twenty-five fungal taxa were isolated from various Proteaceae arthropods, many of which are genera known to include Proteaceae pathogenic species. Ophiostomatoid fungi have a saprophytic relationship with their Protea hosts, and may deter some of these potentially harmful fungi from colon ising the infrutescences. Some fungi showed a high degree of specificity towards potential vectors, while others were found on a diverse range of arthropods. This study highlights the existence of complex inter-organismal interactions within the Fynbos Biome, a study area where the interactions between plants, fungi and insects have been grossly neglected. The few studies that have been conducted in this field have mostly focussed on a limited number of organisms, and no wide-scale attempts, such as presented here, have been published. It is important to obtain a holistic view in any ecological study that focuses on interactions between different suites of organisms. Ultimately this will aid in the development of better conservation strategies. This study thus provides a muchneeded start in studies on multi-organismal interactions in the Fynbos Biome. / AFRIKAANSE OPSOMMING: Vyf nuwe ophiostoma-agtige fungus spesies is onlangs in die vrug-liggame van Suid Afrikaanse Protea plante ontdek. Voor hierdie ontdekking, was die algemene opvatting dat ophiostoma-agtige fungi beperk is tot die Noordelike Halfrond. Die ontdekking van hierdie vyf spesies het dus die bekende geografiese verspreiding van hierdie tipe fungi vergroot om nou ook die Suidelike Halfrond in te sluit. Sederdien het min studies gefokus op die interesante ekologie van hierdie groep, wat aangepas is vir spoorverspreiding deur geleedpotiges. Studies wat fokus op die ophiostoma-agtige fungi voorsien 'n unieke geleentheid om die inter-organismiese-interaksies tussen fungi, hul gasheer plante en die geleedpotiges wat hul spore versprei, te bestudeer. Baie min soortgelyke studies is al voorheen in die Fynbos Bioom, waar die meeste van ons ekonomies-belangrike Protea spesies voorkom, onderneem. Die huidige studie verleen meer inligting oor sommige ekologiese aspekte van hierdie komplekse interaksies. Seisoenale verspreidingspatrone van ophiostoma-agtige fungi geassosieer met die vrug-liggame van lede van die Proteaceae, is ondersoek. Daar is defnitiewe seisoenale patrone in die aanwesigheid van fungi gevind, met 'n piek in fungi kolonisasie-getalle gedurende die vogtiger wintermaande. 'n Nuwe Protea gasheer vir Ophiostoma splendens en 'n nuwe fungus spesie (Rhyncomeliola sp.), is ontdek. Alle Fynbos ophiostoma-agtige spesies in die Stellenbosch area, is beperk tot Protea spesies. 'n Multipleks Polimerase Ketting Reaksie is ontwikkel om die spesifieke DNS van ophiostoma-agtige fungi te herken. Hierdie metode is gebruik om te toets vir die aanwesigheid van spore van hierdie fungi op die liggame van geleedpotiges (geassosieerd met P. repens). Hierdeur is drie insekte wat waarskynlik verantwoordelik is vir die langafstand verspreiding van spore geidentifiseer. Drie verdere insekte wat moontlik verantwoordelik is vir die kortafstand verspreiding van ophiostoma-agtige fungi is ook aangewys. Alle geleedpotiges geassosieer met die vrugstrukture van geselekteerde lede van die Proteaceae is ondersoek. 'n Totaal van 62 pseudo-spesies (omtrent 7500 individue), wat tot 45 families behoort, is versamel. Proteaceae spesies met groter vrugstrukture het meer geleedpotige spesies en individue gehuisves as taksa met kleiner vrugstrukture. Sommige plant spesies het soortgelyke geleedpotige gemeenskappe gehuisves, terwyl unieke groepe geleedpotiges in ander plante voorgekom het. Alhoewel die geleedpotiges seisonale variasies in getalle geopenbaar het, het die meeste groepe 'n piek in getalle getoon gedurende die herfs- en wintermaande. Vyf-en-twintig fungi taksa is geïsoleer vanaf verskeie Proteaceae geleedpotiges. Sommige van hierdie is genera wat Proteaceae patogeniese spesies insluit. Sommige fungi het 'n hoë graad van spesifisiteit teenoor potensiële vektore getoon, terwyl ander weer algemeen op verskeie geleedpotige spesies gevind is. Hierdie studie dui op die bestaan van komplekse inter-organismiese-interaksies in die Fynbos Bioom, in 'n area waar die studie van interaksies tussen plante, fungi en insekte nog baie min aandag geniet het. Die beperkte aantal studies wat tot dusver in hierdie veld onderneem is, fokus gewoonlik slegs op 'n paar organismes. Geen grootskaalse studies, soos die een hier voorgelê, is al gepubliseer nie. In enige ekologiese studie wat fokus op interaksies tussen verskeie organismes, is dit belangrik om 'n holistiese siening te probeer verkry. Uiteindelik sal dit bydra tot die ontwikkeling van beter bewarings-strategië. Hierdie studie verleen dus 'n noodsaaklike begin tot studies op multiorganismiese- interaksies.