@article{HeisswolfUlmannObermaieretal.2007,
  author    = {Heisswolf, Annette and Ulmann, Sandra and Obermaier, Elisabeth and Mitesser, Oliver and Poethke, Hans J.},
  title     = {Host plant finding in the specialised leaf beetle Cassida canaliculata: an analysis of small-scale movement behaviour},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49485},
  year      = {2007},
  abstract  = {1. Host plant finding in walking herbivorous beetles is still poorly understood. Analysis of small-scale movement patterns under semi-natural conditions can be a useful tool to detect behavioural responses towards host plant cues. 2. In this study, the small-scale movement behaviour of the monophagous leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) was studied in a semi-natural arena (r = 1 m). In three different settings, a host (Salvia pratensis L., Lamiales: Lamiaceae), a non-host (Rumex conglomeratus Murr., Caryophyllales: Polygonaceae), or no plant was presented in the centre of the arena. 3. The beetles showed no differences in the absolute movement variables, straightness and mean walking speed, between the three settings. However, the relative movement variables, mean distance to the centre and mean angular deviation from walking straight to the centre, were significantly smaller when a host plant was offered. Likewise, the angular deviation from walking straight to the centre tended to decline with decreasing distance from the centre. Finally, significantly more beetles were found on the host than on the non-host at the end of all the trials. 4. It is concluded that C. canaliculata is able to recognise its host plant from a distance. Whether olfactory or visual cues (or a combination of both) are used to find the host plant remains to be elucidated by further studies.},
  subject      = {K{\"a}fer},
  language  = {en}
}
@article{HeisswolfGablerObermaieretal.2007,
  author    = {Heisswolf, Annette and Gabler, Dirk and Obermaier, Elisabeth and M{\"u}ller, Caroline},
  title     = {Olfactory versus contact cues in host plant recognition of a monophagous chrysomelid beetle},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-49475},
  year      = {2007},
  abstract  = {The importance of olfactory versus contact cues for host plant recognition was investigated in the tortoise beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae), which is strictly monophagous on meadow sage. The reaction of adult beetles to olfactory and contact host cues was tested using three bioassays (locomotion compensator, six-chamber-olfactometer, stem arena') to account for different behavioral contexts. Bioassay-guided fractionation of plant extracts was elaborated to characterize the nature of contact stimuli. The beetles were only slightly attracted to odors from small amounts of leaf material. However, when contact cues were provided additionally, the beetles showed strong preferences for samples of their host plant over controls. Bioassay-guided fractionation led to isolation of at least two non-polar contact stimuli acting in concert that are sufficient for host plant identification in C. canaliculata.},
  subject      = {Insekt},
  language  = {en}
}
@article{ObermaierHeisswolfRandlkoferetal.2006,
  author    = {Obermaier, Elisabeth and Heisswolf, Annette and Randlkofer, B. and Meiners, T.},
  title     = {Enemies in low places - insects avoid winter mortality and egg parasitism by modulating oviposition height},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-48200},
  year      = {2006},
  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.},
  language  = {en}
}
@article{HeisswolfObermaierPoethke2005,
  author    = {Heisswolf, Annette and Obermaier, Elisabeth and Poethke, Hans-Joachim},
  title     = {Selection of large host plants for oviposition by a monophagous leaf beetle: nutritional quality or enemy-free space?},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47728},
  year      = {2005},
  abstract  = {1. Oviposition site selection is crucial for the reproductive success of herbivorous insects. According to the preference-performance hypothesis, females should oviposit on host plants that enhance the performance of their offspring. More specifically, the plant vigour hypothesis predicts that females should prefer large and vigorously growing host plants for oviposition and that larvae should perform best on these plants. 2. The present study examined whether females of the monophagous leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) prefer to oviposit on large host plant individuals of the meadow clary and whether large host plants are of higher nutritional quality than small host plants. Subsequently, it was tested whether the female preference correlates with offspring performance and survival. 3. In the field, females preferred large host plant individuals for oviposition and host plant quality, i.e. leaf nitrogen content, was significantly higher in leaves of large than of small host plants. 4. In the laboratory, larval development time was shorter on leaves of large host plant individuals than on small host plant individuals, but this could not be shown in the field. 5. However, a predator-exclusion experiment in the field resulted in a higher survival of larvae on large host plants than on small host plants when all predators had free access to the plants. On caged host plants there was no difference in survival of larvae between plant size categories. 6. It is concluded that females of C. canaliculata select oviposition sites that enhance both performance and survival of their offspring, which meets the predictions of the plant vigour hypothesis.},
  subject      = {Insekten},
  language  = {en}
}
@article{HeisswolfPoethkeObermaier2006,
  author    = {Heisswolf, Annette and Poethke, Hans-Joachim and Obermaier, Elisabeth},
  title     = {Multitrophic influences on oviposition site selection in a specialized leaf beetle at multiple spatial scales},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47738},
  year      = {2006},
  abstract  = {Egg distribution in herbivorous beetles can be affected by bottom-up (host plant), and by top-down factors (parasitoids and predators), as well as by other habitat parameters. The importance of bottom-up and top-down effects may change with spatial scale. In this study, we investigated the influence of host plant factors and habitat structure on egg distribution in the leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae), a monophagous herbivore on Salvia pratensis L. (Lamiales: Lamiaceae), on four spatial scales: individual host plant, microhabitat, macrohabitat, and landscape. At the individual host plant scale we studied the correlation between egg clutch incidence and plant size and quality. On all other scales we analyzed the relationship between the egg clutch incidence of C. canaliculata and host plant percentage cover, host plant density, and the surrounding vegetation structure. Vegetation structure was examined as herbivores might escape egg parasitism by depositing their eggs on sites with vegetation factors unfavorable for host searching parasitoids. The probability that egg clutches of C. canaliculata were present increased with an increasing size, percentage cover, and density of the host plant on three of the four spatial scales: individual host plant, microhabitat, and macrohabitat. There was no correlation between vegetation structure and egg clutch occurrence or parasitism on any spatial scale. A high percentage of egg clutches (38-56\%) was parasitized by Foersterella reptans Nees (Hymenoptera: Tetracampidae), the only egg parasitoid, but there was no relationship between egg parasitism and the spatial distribution of egg clutches of C. canaliculata on any of the spatial scales investigated. However, we also discuss results from a further study, which revealed top-down effects on the larval stage.},
  subject      = {Eiablage},
  language  = {en}
}
@article{HeisswolfReichmannPoethkeetal.2009,
  author    = {Heisswolf, Annette and Reichmann, Stefanie and Poethke, Hans-Joachim and Schr{\"o}der, Boris and Obermaier, Elisabeth},
  title     = {Habitat quality matters for the distribution of an endangered leaf beetle and its egg parasitoid in a fragmented landscape},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-47740},
  year      = {2009},
  abstract  = {Fragmentation, deterioration, and loss of habitat patches threaten the survival of many insect species. Depending on their trophic level, species may be differently affected by these factors. However, studies investigating more than one trophic level on a landscape scale are still rare. In the present study we analyzed the effects of habitat size, isolation, and quality for the occurrence and population density of the endangered leaf beetle Cassida canaliculata Laich. (Coleoptera: Chrysomelidae) and its egg parasitoid, the hymenopteran wasp Foersterella reptans Nees (Hymenoptera: Tetracampidae). C. canaliculata is strictly monophagous on meadow sage (Salvia pratensis), while F. reptans can also parasitize other hosts. Both size and isolation of habitat patches strongly determined the occurrence of the beetle. However, population density increased to a much greater extent with increasing host plant density ( = habitat quality) than with habitat size. The occurrence probability of the egg parasitoid increased with increasing population density of C. canaliculata. In conclusion, although maintaining large, well-connected patches with high host plant density is surely the major conservation goal for the specialized herbivore C. canaliculata, also small patches with high host plant densities can support viable populations and should thus be conserved. The less specialized parasitoid F. reptans is more likely to be found on patches with high beetle density, while patch size and isolation seem to be less important.},
  subject      = {Fragmentierung},
  language  = {en}
}
@phdthesis{Heisswolf2006,
  author    = {Heisswolf, Annette},
  title     = {The distribution of leaf beetles on multiple spatial scales : causes and consequences},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-18945},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2006},
  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.},
  subject      = {Blattk{\"a}fer},
  language  = {en}
}