Thèse de doctorat : Université de Neuchâtel, 2011 ; 2235.
Cooperation in larger group is often more difficult to explain then cooperation in pairs. For humans it has been proposed that punishment plays a major role in stabilising individual contributions to group success (‘public goods’) but that claim remains contentious. The aim of this thesis was to gain understanding of a system in which both punishment and public goods may exist, and which can...
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Thèse de doctorat : Université de Neuchâtel, 2009 ; Th. 2110.
Changes in tectonic conformation and orbital parameters of the Earth (eccentricity, obliquity and axial wobble) caused drastic climatic oscillations during the Quaternary. These oscillations strongly influenced the genetic landscape of the contemporary European flora and fauna. During cold periods the extending ice sheets and permafrost forced many temperate species to migrate into southern...
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Thèse de doctorat : Université de Neuchâtel, 2008 ; Th. 2041.
One of the most widely discussed ecological effects of genetically engineered (GE) crops is their impact on non-target organisms including natural enemies that are important for pest regulation and thus of economic value. Prior to commercialization of a GE crop a detailed risk assessment for potential adverse effects on non-target organisms has to be conducted. Finding surrogate species is...
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Thèse de doctorat : Université de Neuchâtel, 2004 ; 2015.
The alpine leaf beetle Oreina gloriosa (Coleoptera: Chrysomelidae) is highly specialized on the umbelliferous plant Peucedanum ostruthium (Apiaceae). Adults and larvae feed on leaves and clearly discriminate between individual plants in nature. Preliminary studies suggested that the larvae are active at night. Like many other apiaceous plants, P. ostruthium produces several linear...
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Thèse de doctorat : Université de Neuchâtel, 2007 ; 1947.
Independently, both fungal disease and herbivorous insects are considered to have major impacts on plant populations, affecting growth, survival, and reproduction, as well as modifying their interactions with other species. By providing habitats, protection, and food for numerous species, plants form an essential component of terrestrial ecosystems and constitute the convergent point for...
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Thèse de doctorat : Université de Neuchâtel, 2006 ; 1888.
Insect-resistant genetically modified (GM) crops could harm organisms other than the pests targeted by the toxin. These so-called non-target organisms include parasitoids and predators that are important for natural pest regulation, which could be exposed to the expressed insecticidal proteins through feeding on transgenic plant tissue or through feeding on target or non-target herbivores...
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Thèse de doctorat : Université de Neuchâtel, 2000 ; 1568.
Evidence for the use of defensive compounds for sexual purpose is scarce. However sexual selection might have some importance in the evolution of defense-related traits. The present study reports a parallel analysis of defense-related traits and mate choice in two sister species of leafbeetles differing in their type of chemical defense. Oreina gloriosa produces autogenous cardenolides, whereas...
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Thèse de doctorat : Université de Neuchâtel, 2001 ; 1536.
Many parasitoids that attack phytophageous insects make use of plant odours to locate the habitat of their host. In maize large amount of these odours are specifically emitted by a plant after it has been damaged by a herbivore, but not after mechanical damage. The odour emissions occur systematically throughout the plant. Factors in the oral secretion of the herbivores are the main elicitors of...
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Thèse de doctorat : Université de Neuchâtel, 2000 ; 1506.
The alpine leaf beetle Oreina cacaliae was observed to overwinter either in the ground close to their main host plant Adenostyles alliariae or, after flight, at distinct overwintering sites away from that host. In spring, beetles flew from overwintering sites to flowering Petasites paradoxus on which they fed until the emergence of their main host. This host, A. alliariae, contains pyrrolizidine...
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Thèse de doctorat : Université de Neuchâtel, 2003 ; 1713.
Local adaptation and host specialization is often seen as the result of the balance between three major forces: natural selection, genetic drift and gene flow. In phytophagous insects, the relationship between the insect and its host plant is so intimate that the selective pressures leading to local adaptation are often seen as being related to host plant use only. In this study, we investigate...
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