Taphonomic signature of Eurasian eagle owl (Bubo bubo) on fish remains

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Gymnocranius oblongus, a new large-eye bream species from New Caledonia (Teleostei: Lethrinidae)

Gymnocranius oblongus is described as a new species of the subfamily Monotaxinae (Sparoidea: Lethrinidae), a group of commercially important fishes distributed throughout the Indo-West Pacific, from six specimens collected in New Caledonia. It is characterized by an oblong, fusiform body, slightly rounded snout, elongate tail with rounded tips and sub-horizontal, wavy blue lines or dashes on snout and cheeks. It is distinct from sympatric G. grandoculis by a more slender body which is also more symmetrical dorsoventrally and a more elongated caudal fin. Both mitochondrial-DNA and nuclear-DNA markers provide a genetic basis to the distinction of G. oblongus from G. grandoculis

Les poissons rapportés au Muséum par Alcide dˈOrbigny : statut actuel et anecdotes

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Phytophagous arthropods and a pathogen sharing a host plant: evidence for indirect plant-mediated interactions.

In ecological systems, indirect interactions between plant pathogens and phytophagous arthropods can arise when infestation by a first attacker alters the common host plant so that although a second attacker could be spatially or temporally separated from the first one, the former could be affected. The induction of plant defense reactions leading to the production of secondary metabolites is thought to have an important role since it involves antagonistic and/or synergistic cross-talks that may determine the outcome of such interactions. We carried out experiments under controlled conditions on young rose plants in order to assess the impact of these indirect interactions on life history traits of three pests: the necrotrophic fungus Botrytis cinerea Pers.: Fr. (Helotiales: Sclerotiniaceae), the aphid Rhodobium porosum Sanderson (Hemiptera: Aphididae) and the thrips Frankliniella occidentalis Pergande (Thysanoptera: Thripidae). Our results indicated (i) a bi-directional negative interaction between B. cinerea and R. porosum, which is conveyed by decreased aphid growth rate and reduced fungal lesion area, as well as (ii) an indirect negative effect of B. cinerea on insect behavior. No indirect effect was observed between thrips and aphids. This research highlights several complex interactions that may be involved in structuring herbivore and plant pathogen communities within natural and managed ecosystems

Sharing a predator: can an invasive alien pest affect the predation on a local pest?

International audienceInvasive species can strongly affect biotic interactions in ecosystems, interacting both directly and indirectly with local species. In European tomato greenhouses , the invasive alien pest Tuta absoluta may impact the population dynamics of other pests like whiteflies. Besides inducing damages to the host plant and competing for resources with local pests, this alien species may exert a predator-mediated interaction on local pests sharing common natural enemies. Biocontrol agents usually used against whiteflies may also prey upon T. absoluta and this could alter the dynamics of local pest populations. We evaluated possible resource competition and predator-mediated interactions in a system involving one mirid predator Macrolophus pygmaeus and two pests, T. absoluta and a local whitefly, Bemisia tabaci, on greenhouse tomatoes. Results showed that both resource competition and predator-mediated interactions occurred simultaneously. In the presence of the shared predator, there was a short-term positive effect of T. absoluta on B. tabaci [up to 5.9-fold increase of B. tabaci juveniles (egg ? larvae) after four weeks]. However, in the long-term there was a negative predator-mediated interaction of T. absoluta on B. tabaci, i.e., after ten weeks the density of B. tabaci was 7.3-fold lower in the presence of the invasive pest. We emphasize the critical role of generalist predators in managing both local and invasive alien pest populations and that the strength and direction of predator-mediated indirect interactions can depend on the time scale considered

Survival of a specialist natural enemy experiencing resource competition with an omnivorous predator when sharing the invasive prey Tuta absoluta

International audienceCan specialist natural enemies persist in ecosystems when competing with omnivorous natural enemies for their shared prey? The consequences of omnivory have been studied theoretically, but empirical studies are still lacking. Omnivory is nevertheless common in nature and omnivorous predators coexist with specialists in many ecosystems, even when they are intraguild predators. This type of association is also common in agroecosystems in which biological control strategies are used. Our study provides an example of the outcome of such an association in the context of biological control of the invasive pest Tuta absoluta (Lepidoptera) in a tomato agroecosystem. The two natural enemies involved, that is, a specialist (Stenomesius japonicus (Hymenoptera) parasitoid) and an omnivore (Macrolophus pygmaeus (Hemiptera) predator), were able to coexist for 3months in our experimental cages in the absence of metacommunity mechanisms (i.e., emigration and recolonization), contrary to theoretical expectations. However, they negatively affected each other's population dynamics. We found that spatial resource segregation was not a mechanism that promoted their coexistence. Regarding pest control, the specialist and omnivorous natural enemies were found to exhibit complementary functional traits, leading to the best control when together. Mechanisms that may have promoted the coexistence of the two species as well as consequences with regard to the inoculative biological control program are discussed

Analyses sclérochronologiques d’écailles archéologiques d’ombres commun Thymallus thymallus et inférences sur la pêche paléolithique au Taillis des Coteaux (Vienne, France)

Lors des fouilles archéologiques du Taillis des Coteaux, plus de 791 écailles ont été mises au jour dans une zone attribuée chronologiquement au Magdalénien inférieur. L’origine (animale ou anthropique) des accumulations de poissons dans les sites archéologiques est souvent méconnue. L’application de la sclérochronologie à l’étude de ces restes nous permet non seulement d’avoir une estimation de l’âge du poisson, mais aussi de préciser la période de capture. La connaissance de la saison de mort des individus est un bon indicateur des activités humaines et/ou d’autres prédateurs (carnivores, oiseaux). La majorité des écailles est attribuable aux salmonidae. Parmi les espèces identifiées, seul l’ombre commun Thymallus thymallus (L., 1758) est bien représenté. Ses écailles sont les mieux préservées et ont permis de tester sur un échantillon (n=50) l’interprétation des marques de croissance de périodicité annuelle. Une collection de référence actuelle (France, Suisse, Finlande) a été créée afin d’estimer le rythme de croissance de cette espèce et d’établir un modèle de référence pour comparer la croissance globale des ombres archéologiques. Notre protocole repose sur une série de mesures standardisées allant du foyer (ou focus) au bord externe de l’écaille, en passant par les différents annulii. L’estimation des âges de nos individus archéologiques a aussi été réalisée. Les résultats de l’étude nous ont permis de comparer la croissance des spécimens archéologiques avec celles de nos spécimens actuels et de mettre en évidence que la croissance des poissons du Magdalénien inférieur est très comparable à celle des poissons actuels peuplant la France et la Suisse. De plus, la période « estivale » constitue une saison préférentielle de capture pour les ombres communs au Magdalénien inférieur

Gymnocranius superciliosus and Gymnocranius satoi, two new large-eye breams (Sparoidea : Lethrinidae) from the Coral Sea and adjacent regions

Two related perciform fish species of the subfamily Monotaxinae (Sparoidea: Lethrinidae) Gymnocranius superciliosus sp. nov. and Gymnocranius satoi sp. nov. are described from specimens and tissue samples from the Coral Sea and adjacent regions. G. superciliosus sp. nov. is distinct from all other known Gymnocranius spp. by the following combination of characters: body elongated (depth 2.7-3.1 in standard length), caudal fin moderately forked with a subtle middle notch, its lobes slightly convex inside, distinctive blackish eyebrow, snout and cheek with blue speckles, and dorsal, pectoral, anal and caudal fins reddish. G. satoi sp. nov. is the red-finned 'Gymnocranius sp.' depicted in previous taxonomic revisions. While colour patterns are similar between the two species, G. satoi sp. nov. is distinct from G. superciliosus sp. nov. by the ratio of standard length to body depth (2.4-2.5 vs. 2.7-3.1) and by the shape of the caudal fin, which is more shallowly forked, its lobes convex inside and their extremities rounded. The two species are genetically distinct from each other and they are genetically distinct from G. elongatus, G. euanus, G. grandoculis, and G. oblongus sampled from the Coral Sea and adjacent regions

A downward way of cutting roses : the Schuss method

National audienc