Time filter

Source Type

Brau M.,Buro fur okologische Gutachten M. Brau | Bonelli S.,University of Turin | Cerrato C.,University of Turin | Balletto E.,University of Turin | And 2 more authors.
Journal of Insect Conservation | Year: 2015

The knowledge on species’ habitat preferences at local scales across its range is an essential condition for defining the most appropriate habitat management for the conservation of any species. In this study, we combined field observations from three European countries with breeding experiments under field conditions to identify oviposition and larval preferences of Coenonympha oedippus at the micro-scale level across contrasting habitat types (wet vs. dry). Despite the wide geographical range and the different habitats we found some common features: (1) vegetation structure of the herb layer is an essential factor for oviposition site electivity and successful development of premature stages; (2) high cover of litter and/or dwarf shrubs in the microhabitat (larval 45–70 %, oviposition 40–50 %) creates a herb layer rich in gaps; at their edges eggs are deposited and the caterpillars are adequately sun-exposed; (3) egg-laying females are not selective regarding oviposition substratum; (4) oviposition height is adjusted to positions with direct sunlight or warm substratum; (5) the host-plants coverage in oviposition sites was high: between 45 and 50 % in wet habitats, and between 18 and 41 % in dry habitats (depending on whether only plants observed as hosts in this study are counted, or whether all potential host species are included); (6) the most important host-plant is Carex panicea (wet) and Carex humilis (dry), but Molinia caerulea (wet) and Festuca rupicola (dry) are also used regularly; (7) the availability of winter-green host-plants in the vicinity of hibernated larvae plays a substantial role in their survival. As regular mowing or grazing would remove the litter and destroy the gaps, the management should be restricted to selective reed cutting or manual shrub removal. Only selective mowing during winter (December–February) can be recommended for keeping the habitat open where the reduction of bushes is not sufficient. © 2014, Springer International Publishing Switzerland.

Dolek M.,Okologische Forschung und Planung | Freese-Hager A.,Okologische Forschung und Planung | Geyer A.,Okologische Forschung und Planung
Journal of Insect Conservation | Year: 2013

Globally, Euphydryas maturna is a polyphagous butterfly species. At our study sites in Italy and Germany however, the plant used for egg-laying was almost exclusively Fraxinus excelsior. Nevertheless, in Germany, two egg-batches were found on Ligustrum vulgare and one on Viburnum opulus. Females lay their egg-batches at low heights and mostly on small trees (but not <1 m). At the end of the flight season, small egg-batches are laid and we conclude that these are late batches laid by "old females". Egg-batches and pre-diapause larval webs are often clustered on certain trees and even leaves. This was shown to be a result of female behaviour and not of habitat quality, since the trees chosen were different in subsequent years. Individual females may return for laying further egg-batches to the place of the first egg-deposition and other females follow, since the survival of pre-diapause larvae is higher when more larval webs are on one tree. A further possible advantage during hibernation is discussed. In Italy, post-hibernation larvae form two distinct cohorts: larvae feeding on herbaceous plants (Plantago major, P. minor, Veronica hederifolia), and larvae feeding on Fraxinus excelsior. Although the latter group starts feeding later and pupates later, it reaches the same pupation weight. At our German site, post-hibernation larvae were found almost exclusively on F. excelsior. In fact, we observed larvae searching for food on F. excelsior while the buds of this tree were still closed. We also found larvae searching for food in the herbal layer without finding suitable plants. In some areas, larvae have to wait for the buds of the ash tree to open. Our data suggest that conservation strategies for E. maturna must be site specific according to food plant use of pre- and post-hibernation larvae and habitat type. © 2012 Springer Science+Business Media B.V.

Schmeller D.S.,French National Center for Scientific Research | Dolek M.,Okologische Forschung und Planung | Geyer A.,Okologische Forschung und Planung | Settele J.,Helmholtz Center for Environmental Research | Brandl R.,University of Marburg
Journal for Nature Conservation | Year: 2011

There are many biological factors that influence the developmental stability and therewith the morphological symmetry of species, such as the environment, stress during development, hybridisation between species, inbreeding and loss of genetic variability. Here, we analysed the developmental stability of wing traits of the butterfly Parnassius apollo, a threatened species with small local populations. We assessed the historical trajectory of developmental stability as measured by fluctuating asymmetry (FA) to evaluate the effect of protection and management actions on an Apollo population in Germany. We analysed 89 individuals collected from 1906 to 2004 at six morphological wing traits, four of which were FA traits. Our results show that legal protection (= listed on a red list) alone did not have any effect on FA and hence did not improve the population fitness. However, FA showed a clear response to management actions, but only after several generations. In 2004, 13 years after population management actions were implemented, the variance of population wide FA was comparable to the FA-variance from the beginning of the 20th century. Our study supports the utilisation of FA as an assessment tool of effects of population management. © 2010 Elsevier GmbH.

Loading Okologische Forschung und Planung collaborators
Loading Okologische Forschung und Planung collaborators