Schultner Eva. 2008. The biology and ecology of a rare specialist : Arcyptera brevipennis vicheti Brunner, 1861 (Acrididae, Orthoptera). s.l. : Freie Universitaet Berlin, 77 p. Thèse de doctorat : Freie Universitaet Berlin
Encadrement : Lecoq, Michel ; Vassal, Jean-Michel
Résumé : Species conservation is an important step in maintaining the biodiversity of ecosystems and detailed knowledge of species' biology and ecology is essential for understanding the mechanisms that regulate species' survival. Arcyptera brevipennis vicheti BRUNNER, 1861 (Acrididae, Orthoptera) is a rare grasshopper native of Mediterranean grassland habitats in the Languedoc-Roussillon in southern France. Modifications in land use are destroying these unique habitats and endangering the survival of A. b. vicheti, whose dispersion capacities are limited due to very short wings. In this study, we describe aspects of this species' life-cycle for the first time. Morphology and development were studied by rearing hoppers in the laboratory and recording various characteristics of growth and development. Population ecology and dynamics were studied by effectuating bi-weekly population counts on two experimental sites on the Causse d'Aumelas in the Hérault department during the spring season 2008. We recorded abiotic factors and the temporal evolution of vegetation and habitat structure in order to establish relationships between environmental factors and the species' life-cycle. Feeding preferences were studied by analysing the faecal contents of 20 male and female imagos. Finally, the reproductive capacity of females was studied using two different methods: examination of egg-pods and dissection of female reproductive organs. The development of A. b. vicheti passes through five stages and is closely associated with the Mediterranean spring season. The species shows a prominent sexual dimorphism but the larger females develop in the same number of instars as males. Hatchings are prompted by the rise in temperature and humidity mid-April and continue until mid-May. By mid-June, all individuals in the field are adult, resulting in a mean development time of 42 days. Successive instars differ in their habitat preferences, with young hoppers more often found on patches of bare earth and rock, while older hoppers and imagos are found in grass. Grass not only offers shelter, but is also the main food source for imagos: 93% of faecal content consists of debris from grasses. Females lay 16 eggs on average and deposit two clutches in their lifetime; resulting population fecundity lies at approx. 7 eggs per imago. Our results reveal that A. b. vicheti is a true ecological specialist whose survival depends on the conservation of grassland habitats. Further field studies will help validate our findings and establish the conservation status of A. b. vicheti.
Mots-clés Agrovoc : Acrididae
Mots-clés géographiques Agrovoc : Languedoc-Roussillon, France
Mots-clés complémentaires : Arcyptera brevipennis
Classification Agris : L50 - Physiologie et biochimie animales
L20 - Écologie animale
Champ stratégique Cirad : Axe 6 (2005-2013) - Agriculture, environnement, nature et sociétés
Auteurs et affiliations
- Schultner Eva, Freie Universitaet Berlin (DEU)
Autres liens de la publication
Source : Cirad - Agritrop (https://agritrop.cirad.fr/547735/)
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