Changes in structure and function in response to changing diversity within Mediterranean grassland communities

The effects of species richness, functional group richness and functional composition upon structural traits of vegetation (cover, canopy height, LAI and PAR) and ecosystem processes (above-and belowground biomass production and short-and long-term decomposition) have been monitored in constructed Mediterranean mixed grasslands. The experiment is part of the european-wide BIODEPTH project. The main findings are : 1. Ecosystem processes and structural traits of constructed grasslands showed different responses to the variation of the various community diversity components. For instance, biomass production varied in a nonsignificant way across manipulated diversity levels. On the contrary, short-term decomposition has showed a strong curvi¬ linear response to species richness. Strong significance was also obser¬ ved for plant cover and leaf area index. 2. Since the various descriptors of productivity (plant cover, Leaf Area Index, and standing biomass) can respond differently to the variation of diversity, a direct measurement of productivity would offer a more robust evidence on the diversity-productivity relationship in these ecosystems. 3. Species composition has significant effects on above-and belowground biomass production, plant cover, canopy height and decom¬ position. Identity of species is of primary importance in determining the overall performance of ecosystem processes in grasslands.Cet article présente les résultats d'une étude expérimentale concernant les effets de la richesse spécifique et fonctionnelle ainsi que de la composition fonctionnelle sur les traits structurels et les processus écosystémiques de pelouses méditerranéennes synthétiques. L'étude fait partie du projet multinational BIODEPTH. 1. Les processus écosystémiques et les traits structuraux de la végétation des pelouses manipulées répondent de manière différente à la variation des composantes de la diversité de ces communautés. La production de biomasse ne répond pas de façon significative à la variation de la diversité. Au contraire, la décomposition rapide, le pourcentage de recouvrement végétal et l'index de surface foliaire (LAI) montrent une réponse puissante et curvilinéaire aux variations de la richesse spécifique. 2. Les différents descripteurs de la productivité (pourcentage de recouvrement végétal, LAI et biomasse) répondent de façon différente aux variations de la diversité. Ainsi, des mesures directes de la productivité semblent plus appropriées afin d'acquérir des données robustes sur la relation diversité-productivité dans ces écosystèmes. 3. La composition spécifique engendre des effets importants sur la variation de la production épigée et souterraine de biomasse, la hauteur de la végétation et la décomposition. L'identité des espèces semble ainsi avoir une importance significative dans la détermination de la performance globale des processus écosystémiques de ces pelouses.Memtsas Dimitri, Dimitrakopoulos Panayiotis G., Siamantziouras Akis Stavros D., Troumbis Andreas Y. Changes in structure and function in response to changing diversity within Mediterranean grassland communities. In: Ecologia mediterranea, tome 28 n°1, 2002. pp. 5-18

Revisiting the distribution of Thaumetopoea pityocampa (Lepidoptera: Notodontidae) and T. pityocampa ENA Clade in Greece

In the present work, we sampled individuals of the processionary pine moth, Thaumetopoea pityocampa (Denis and Schiffermüller; Lepidoptera: Notodontidae) from different areas of Greece between 2014 and 2016. These samples were sequenced for a 760-bp long mtDNA COI locus and the haplotypes retrieved clearly showed that the occurrence of T. pityocampa in Greece is being considerably restricted, with only 8 individuals out of the 221 exhibiting T. pityocampa haplotypes and the rest being identified as T. pityocampa ENA clade haplotypes. To that, one haplotype in particular exhibited the highest abundance and broadest geographic distribution, occurring both in mainland and on islands. Our data suggest a rather recent and rapid population expansion of the ENA clade in Greece and a concomitant recent displacement of T. pityocampa. It thus seems that the relation between T. pityocampa and T. pityocampa ENA clade needs to be further and thorough analyzed before the taxonomic status of T. pityocampa ENA clade can be concluded with confidence. © The Author(s) 2018. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved

New data on the range expansion of the Thaumetopoea pityocampa (Lepidoptera: Notodontidae) ‘ENA clade’ in Greece:The role of bacterial endosymbionts

The pine processionary moth, Thaumetopoea pityocampa (Denis and Schiffermüller), is an important insect in the Mediterranean region, as it defoliates pines and its urticating hairs can cause allergic reactions in humans and animals. Moreover, this species exhibits an interesting genetic structure as recently a distinct East-North African mtDNA lineage (‘ENA clade’) has been described.This clade has been recently detected in Greek populations where it has currently expanded its range by replacing the ‘endemic’ T. pityocampa lineages. Here, we report new data on the rapid spread of ‘ENA clade’ in the Greek island Evoia in only a few years. As the underlying mechanisms of the ‘ENA clade’ range expansion has not been studied so far, we screened T. pityocampa for an infection with the heritable bacterial endosymbionts Wolbachia (Bacteria: Anaplasmataceae), Cardinium (Bacteria: Bacteroidaceae), Rickettsia (Bacteria: Rickettsiaceae) and Spiroplasma (Bacteria: Spiroplasmataceae). These bacteria can manipulate the reproduction of infected hosts, something that could potentially explain the rapid spread of ‘ENA clade’ lineage. Therefore, we screened 28 individuals that exhibited T. pityocampa ‘ENA clade’ and ‘endemic’ T. pityocampa haplotypes from nine populations scattered all over Greece. None of them was infected with any of the four endosymbionts, suggesting that these bacteria do not cause reproductive manipulations in T. pityocampa lineages and, thus, other factors should be explored in future research efforts. © The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved

Exposure to ethanol during neurodevelopment modifies crucial offspring rat brain enzyme activities in a region-specific manner

The experimental simulation of conditions falling within “the fetal alcohol spectrum disorder” (FASD) requires the maternal exposure to ethanol (EtOH) during crucial neurodevelopmental periods; EtOH has been linked to a number of neurotoxic effects on the fetus, which are dependent upon the extent and the magnitude of the maternal exposure to EtOH and for which very little is known with regard to the exact mechanism(s) involved. The current study has examined the effects of moderate maternal exposure to EtOH (10 % v/v in the drinking water) throughout gestation, or gestation and lactation, on crucial 21-day-old offspring Wistar rat brain parameters, such as the activities of acetylcholinesterase (AChE) and two adenosine triphosphatases (Na+,K+-ATPase and Mg2+-ATPase), in major offspring CNS regions (frontal cortex, hippocampus, hypothalamus, cerebellum and pons). The implemented experimental setting has provided a comparative view of the neurotoxic effects of maternal exposure to EtOH between gestation alone and a wider exposure timeframe that better covers the human third trimester-matching CNS neurodevelopment period (gestation and lactation), and has revealed a CNS region-specific susceptibility of the examined crucial neurochemical parameters to the EtOH exposure schemes attempted. Amongst these parameters, of particular importance is the recorded extensive stimulation of Na+,K+-ATPase in the frontal cortex of the EtOH-exposed offspring that seems to be a result of the deleterious effect of EtOH during gestation. Although this stimulation could be inversely related to the observed inhibition of AChE in the same CNS region, its dependency upon the EtOH-induced modulation of other systems of neurotransmission cannot be excluded and must be further clarified in future experimental attempts aiming to simulate and to shed more light on the milder forms of the FASD-related pathophysiology. © 2015, Springer Science+Business Media New York