@phdthesis{Heisswolf2006,
  abstract = {Herbivorous insects are the major link between primary producers and a multitude of animals at higher trophic levels. Elucidating the causes and consequences of their distribution patterns in the "green world" is thus essential for our understanding of numerous ecological processes on multiple spatial scales. We can ask where and why a certain herbivore can be found in the landscape, within the habitat, on which plant within the habitat and finally, where on that plant. Depending on spatial scale the distribution of herbivores is shaped by different processes (fitness considerations, physiological abilities, population dynamics, dispersal behavior, history of the landscape etc.).
Scaling down from fragmented landscapes to individual host plants this thesis analyzes the distribution patterns of the strictly monophagous herbivore Cassida canaliculata Laich. (Coleoptera: Chrysomelidae), which feeds and oviposits exclusively on meadow sage, Salvia pratensis L. (Lamiales: Lamiaceae), and compares it to those of the polyphagous tansy leaf beetle Galeruca tanaceti L. (Coleoptera: Chrysomelidae), which does not oviposit on its host plants, but on dry non-host structures.
The specialist Cassida canaliculata depended on all spatial scales (fragmented landscape, microhabitat and host plant individual) mainly on the distribution and quality of its single host plant species Salvia pratensis, whereas enemy-free-space - i.e. avoidance of parasitism and predation of egg clutches, larvae, and pupae - seemed to influence oviposition site choice only on the scale of the host plant individual. On this spatial scale, offspring of Cassida canaliculata had a higher chance of survival on large host plant individuals, which were also preferred for oviposition by the females.
In contrast, the distribution patterns of the generalist Galeruca tanaceti was shaped by the interaction with its parasitoid regarding both microhabitat choice and egg distribution within individual host plants. On the microhabitat scale, beetles could escape from their parasitoids by ovipositing into high and dense vegetation. Regarding oviposition site choice within a host plant individual, females oviposited as high as possible in the vegetation and could thus reduce both the risk of parasitism and the probability of winter mortality.
The results of my thesis show that the degree of specificity of a herbivore is of central importance for the resulting egg distribution pattern on all spatial scales.},
  author = {Heisswolf, Annette},
  interhash = {e9949d27b88b1b3dc0327cd142ba5b68},
  intrahash = {eb26daad871d45604ea1bec36a35643b},
  language = {eng},
  school = {Universität Würzburg},
  title = {The distribution of leaf beetles on multiple spatial scales:
causes and consequences},
  url = {http://www.opus-bayern.de/uni-wuerzburg/volltexte/2006/1894/},
  year = 2006
}

@article{Obermaier2006,
  abstract = {Oviposition site selection in insects is essential in terms of low egg mortality, high offspring survival and therefore a high reproductive output. Although oviposition height could be a crucial factor for the fitness of overwintering eggs, it has rarely been investigated. In this study the oviposition height of a polyphagous leaf beetle, Galeruca tanaceti Linnaeus in different habitats and at different times of the season was examined and its effect on egg clutch mortality was recorded. The leaf beetle occurs as an occasional pest on several agricultural plants. It deposits its eggs within herbaceous vegetation in autumn. Eggs are exposed to numerous biotic and abiotic mortality factors summarized as egg parasitism and winter mortality. Oviposition height of the leaf beetle was not uniform, but changed significantly with the structure of the habitat and during the season. Mean oviposition height per site (70.2±4.9 cm) was significantly higher than mean vegetation height (28.4±2.4 cm). Height of plants with egg clutches attached and oviposition height were significantly positively correlated. The results suggest that females try to oviposit as high as possible in the vegetation and on the plants selected. In accordance with this, the probability of egg parasitism and of winter egg clutch mortality significantly declined with increasing oviposition height. A preference of G. tanaceti for oviposition sites high up in the vegetation might therefore have evolved due to selection pressures by parasitoids and winter mortality.},
  author = {Obermaier, Elisabeth and Heisswolf, Annette and Randlkofer, Barbara and Meiners, Torsten},
  interhash = {c6ac78ae8a06d6a81ff728463804d902},
  intrahash = {4a4ce2759f0507dd5fcee829fbc622d1},
  journal = {Bulletin of Entomological Research},
  number = 04,
  pages = {337-343},
  title = {Enemies in low places? Insects avoid winter mortality and egg parasitism by modulating oviposition height},
  url = {http://dx.doi.org/10.1079/BER2006431},
  volume = 96,
  year = 2006
}