Le choix des plantes nourricières et la spécialisation trophique chez les Acridoidea (Orthoptères)

Les études récentes ont montré la diversité des régimes alimentaires et des relations acridiens-plantes. Toutes les étapes de la spécialisation trophique, de la monophagie à la polyphagie sont observées. Les différents facteurs susceptibles de réduire le spectre de plantes consommables par une population acridienne sont envisagés à travers les exemples pris dans la faune ouest-africaine et la littérature. La taxonomie des plantes intervient seulement dans la définition de trois grands types de régime : graminivore, non-graminivore et mixte. La constitution biochimique, la distribution spatiale, le cycle annuel des végétaux doivent être considérés ensemble pour tenter d'expliquer les situations décrites. La structure du tapis végétal est un élément fondamental dans la description de la niche écologique des criquets. Enfin, les Orthoptères sont l'objet d'une importante prédation. Les mécanismes d'échappement au prédateur créent des contraintes essentielles dans la mise en place des relations criquets-plantes. La plante est non seulement la source nutritive, mais aussi l'habitat du criquet. Les deux composantes peuvent être ou non confondues dans la même espèce végétale. (Résumé d'auteur

On the Connectivity of Unions of Random Graphs

Graph-theoretic tools and techniques have seen wide use in the multi-agent systems literature, and the unpredictable nature of some multi-agent communications has been successfully modeled using random communication graphs. Across both network control and network optimization, a common assumption is that the union of agents' communication graphs is connected across any finite interval of some prescribed length, and some convergence results explicitly depend upon this length. Despite the prevalence of this assumption and the prevalence of random graphs in studying multi-agent systems, to the best of our knowledge, there has not been a study dedicated to determining how many random graphs must be in a union before it is connected. To address this point, this paper solves two related problems. The first bounds the number of random graphs required in a union before its expected algebraic connectivity exceeds the minimum needed for connectedness. The second bounds the probability that a union of random graphs is connected. The random graph model used is the Erd\H{o}s-R\'enyi model, and, in solving these problems, we also bound the expectation and variance of the algebraic connectivity of unions of such graphs. Numerical results for several use cases are given to supplement the theoretical developments made.Comment: 16 pages, 3 tables; accepted to 2017 IEEE Conference on Decision and Control (CDC

Contribution to the knowledge of the Cicindelidae of Benin with collecting notes (Coleoptera Cicindelidae)

A checklist of Coleoptera Cicindelidae presently known from Benin is given. Nine taxa are recorded for the first time from this country. Collecting data, habitat and behaviour observations of adults made by the first author during two expeditions are given along with collecting data provided by the second author

A crispy dedicacy : Augosoma beetle as alternative source of protein in East Cameroon

Despite the fact that the exoskeleton of the Augosoma centaurus (Dynastinae) is hard and difficult to chew, this insect is often gathered in Eastern Cameroon for food in periods of availability. Nine ethnic groups in Eastern Cameroon were surveyed to understand the role of this insect in assuring food security, using quantitative and qualitative social science approaches. Both the larvae and adult stages of this beetle are habitually consumed in the areas studied. In total, about 65% of consumers prefer consuming the adults, while 35% prefer consuming the larvae. About 24% of consumers derive the same satisfaction from the consumption of Augosoma or other edible insects. Close to 39% of consumers prefer other edible insects to Augosoma, while 37% prefer the consumption of Augosoma to other edible insects. This beetle usually occurs at a period when other edible insects are not available, therefore constituting a good source of alternative protein in this region where poverty, poaching, and biodiversity erosion are still a major problem. Furthermore, the gathering of this beetle for food is equally a means of biological pest control of raffia plants and a tool to enhance community-based conservation of the areas global biodiversity