Genetic and Environmental Sources of Variation in the Autogenous Chemical Defense of a Leaf Beetle

Chemical defense plays a central role for many herbivorous insects in their interactions with predators and host plants. The leaf beetle genus Oreina (Coleoptera, Chrysomelidae) includes species able to both sequester pyrrolizidine alkaloids and autogenously produce cardenolides. Sequestered compounds are clearly related to patterns of host-plant use, but variation in de novo synthesized cardenolides is less obviously linked to the environment. In this study, intraspecific variation in cardenolide composition was examined by HPLC-MS analysis in 18 populations of Oreina speciosa spanning Europe from the Massif Central to the Balkans. This revealed the defense secretion to be a complex blend of up to 42 compounds per population. There was considerable geographical variation in the total sample of 50 compounds detected, with only 14 found in all sites. The environmental and genetic influences on defense chemistry were investigated by correlation with distance matrices based on habitat factors, host-plant use, and genetics (sequence data from COI, COII, and 16s rRNA). This demonstrated an influence of both genetics and host-plant use on the overall blend of cardenolides and on the presence of some of the individual compounds. The implications of this result are discussed for the evolution of defense chemistry and for the use of cardenolide compounds as markers of the evolutionary history of the specie

Ecological niche overlap in sister species: how do oil-collecting bees Macropis europaea and M. fulvipes (Hymenoptera: Melittidae) avoid competition and hybridization?

Oil-collecting bees are found worldwide and always in association with particular oil-producing flowers. In the Western Palearctic, three oil-collecting bee species within the genus Macropis (Hymenoptera, Melittidae) interact in a tight pollination mutualism with species of the only European oil-producing plant genus Lysimachia L. (Myrsinaceae). Two of these oil-collecting bees (Macropis europaea and Macropis fulvipes) show overlapping geographic distributions, comparable morphologies, and similar ecological characteristics (e.g., habitat type, floral preferences). In view of these similarities, we presume that hybridization should occur between the two species unless potential variation among the species' ecological niches prevents it, simultaneously decreasing competition for resources. Using modern genetic analyses and ecological niche modeling on a large bee sampling throughout Europe, we discuss new perspectives on the ecology and evolutionary history of this mutualism

Decoupled post-glacial history in mutualistic plant-insect interactions: insights from the yellow loosestrife (Lysimachia vulgaris) and its associated oil-collecting bees (Macropis europaea and M-fulvipes)

AimWe take a comparative phylogeographical approach to assess whether three species involved in a specialized oil-rewarding pollination system (i.e. Lysimachia vulgaris and two oil-collecting bees within the genus Macropis) show congruent phylogeographical trajectories during post-glacial colonization processes. Our working hypothesis is that within specialized mutualistic interactions, where each species relies on the co-occurrence of the other for survival and/or reproduction, partners are expected to show congruent evolutionary trajectories, because they are likely to have followed parallel migration routes and to have shared glacial refugia. LocationWestern Palaearctic. MethodsOur analysis relies on the extensive sampling of 104 Western Palaearctic populations (totalling 434, 159 and 74 specimens of Lysimachiavulgaris, Macropiseuropaea and Macropisfulvipes, respectively), genotyped with amplified fragment length polymorphism. Based on this, we evaluated the regional genetic diversity (Shannon diversity and allele rarity index) and genetic structure (assessed using structure, population networks, isolation-by-distance and spatial autocorrelation metrics) of each species. Finally, we compared the general phylogeographical patterns obtained. ResultsContrary to our expectations, the analyses revealed phylogeographical signals suggesting that the investigated organisms demonstrate independent post-glacial trajectories as well as distinct contemporaneous demographic parameters, despite their mutualistic interaction. Main conclusionsThe mutualistic partners investigated here are likely to be experiencing distinct and independent evolutionary dynamics because of their contrasting life-history traits (e.g. dispersal abilities), as well as distinct hubs and migration routes. Such conditions would prevent and/or erase any signature of co-structuring of lineages in space and time. As a result, the lack of phylogeographical congruence driven by differences in life-history traits might have arisen irrespective of the three species having shared similar Pleistocene glacial refugia

Outcome of parapneumonic empyema managed surgically or by fibrinolysis: a multicenter study

Background: Parapneumonic empyema (PPE) management remains debated. Here we present the outcome of a comparable population with PPE treated over a 4-year period in two Thoracic Surgery University Centers with different approaches: one with an early "surgical" and the other with a "fibrinolytic" approach. Methods: All operable patients with PPE managed in both centers between January 2014 and January 2018 were reviewed. Patients with persistent pleural effusion/loculations following drainage were managed by a "surgical" approach in one center and by "fibrinolytic" approach in the other. For each patient, we recorded the age, sex, hospital stay, morbidity/mortality and change in pleural opacity on chest X-ray before and at the end of the treatment. Results: During the study period, 66 and 93 patients underwent PPE management in the "surgical" and "fibrinolytic" centers respectively. The population characteristics were comparable. Infection was controlled in all patients. In the "fibrinolytic" group, 20 patients (21.5%) underwent an additional drain placement while 12 patients (12.9%) required surgery to correct PPE. In the "surgical" group, 4 patients (6.1%) developed postoperative arrhythmia while 2 patients (3%) underwent a second surgery to evacuate a hemothorax. Median drainage {3 [2-4] vs. 5 [4-7] days} and hospital {7 [5-10] vs. 11 [7-19] days} durations were significantly lower in the "surgical" compared to the "fibrinolytic" center. Pleural opacity regression with therapy was significantly more important in the "surgical" compared to the "fibrinolytic" group (-22%±18% vs. -16%±17%, P=0.035). Conclusions: Surgical management of PPE was associated with shorter chest tube and hospital duration and better pleural space control. Prospective randomized studies are mandatory