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Rhynchophorus ferrugineus, also known as the red palm weevil, is regarded as the major pest of palm trees. Although studies of the microbiota associated with this species have been performed in recent years, little attention has been dedicated to the influence of the diet in shaping the host bacterial community. Here, we investigated the influence of food sources (i.e. palm tissues vs apple based substrate) on the microbial diversity associated with RPW, which was compared with the microbiota associated with wild individuals of the sister species Rhynchophorus vulneratus. The bacterial characterization was performed using a culture independent approach, i.e. the 16S rRNA pyrotag, and a culture dependent approach for a subset of the samples, in order to obtain bacterial isolates from RPW tissues. The bacterial community appeared significantly influenced by diet. Proteobacteria resulted to be the most abundant clade and was present in all the specimens of the three examined weevil groups. Within Proteobacteria, Enterobacteriaceae were identified in all the organs analysed, including hemolymph and reproductive organs. The apple-fed RPWs and the wild R. vulneratus showed a second dominant taxon within Firmicutes that was scarcely present in the microbiota associated with palm-fed RPWs. A comparative analysis on the bacteria associated with the palm tissues highlighted that 12 bacterial genera out of the 13 identified in the plant tissues were also present in weevils, thus indicating that palm tissues may present a source for bacterial acquisition.

A molecular analysis was carried out on the European hermit beetles (the Osmoderma eremita species complex) to explore their genetic diversification and the robustness of previous morphologically based taxonomic arrangements. Complete sequences of mtDNA cytochrome C oxidase I gene were obtained from 26 individuals. Mean levels of interspecific sequence divergence ranged from 0.044 to 0.186. The results indicate a clear-cut distinction between two clades. The first one includes the W-European O. eremita Scopoli 1763; and the two Italian endemic taxa Osmoderma italicum Sparacio, 2000 and Osmoderma cristinae Sparacio, 1994; from southern peninsular Italy and Sicily, respectively. The second one includes the widespread E-European Osmoderma barnabita; and the southern Balcanic Osmoderma lassallei Baraud and Tauzin, 1991 from Greece and European Turkey. Within the two clades, molecular and morphological data well support a specific rank for O. lassallei and O. barnabita on one side, and for O. eremita and O. cristinae on the other side, while the taxonomic position of O. italicum, more closely related to O. eremita, is still uncertain. Current geographical distribution, interspecific genetic diversification, and very low levels of intraspecific genetic divergence in western European populations of O. eremita sensu stricto are hypothesized to be the result of multiple speciation events (mainly occurred in refugial forest areas of the Italian and Balkan peninsulas and Sicily before and during the Pleistocene glacial peaks), followed by fast post-glacial northward and westward expansion of some species.

No abstract

Results of a molecular analysis on the European hermit beetles (the <em>Osmoderma</em> <em>eremita</em> species-complex), recently published in a companion paper, are shortly dis- cussed and commented. These results indicate a clear-cut distinction between two clades. The first one includes the W-European <em>O. eremita</em> Scopoli, 1763, and the two Italian endemic taxa <em>O. italicum</em> Sparacio, 2000 and <em>O. cristinae</em> Sparacio, 1994, from southern peninsular Italy and Sicily, respectively. The second one includes the widespread E-European<em> O. barnabita</em> Motschulsky, 1845 (<strong>nom. resurr</strong>.), and the southern Balcanic <em>O. lassallei</em> Baraud &amp; Tauzin, 1991 from Greece and European Turkey. Within the two clades, molecular data well support a specific rank for <em>O. lassallei</em> and <em>O. barn­abita</em> on one side, and of <em>O.</em> <em>eremita</em> and <em>O. cristinae</em> on the other side, while the taxonomic position of <em>O. italicum</em>, more closely related with <em>O. eremita</em>, is still uncertain, waiting for analysis of additional specimens of this very rare taxon. Current geographical distribution, interspecific genetic diversification, and relatively low levels of intraspecific genetic divergence in <em>O. eremita</em> sensu stricto, are hypothesized to be the result of multiple speciation events (mainly occurred in refugial forest areas of the Italian and Balkan peninsulas and Sicily before and during the Pleistocene glacial peaks), followed by fast post-glacial northward and westward expansion of some species. The need of further genetic data on the rare and threatened hermit beetle species and the importance of more detailed information on their distribution ranges are emphasized and discussed, in order to plan conservation strategies in the near future. An updated worldwide checklist of the species of the genus <em>Osmoderma</em> is finally presented.