New agent of wood alteration in poplar (populus nigra)

Megaplatypus mutatus Chapuis (Coleoptera: Platypodidae) (Fig.1), an exotic insect introduced from the neotropical region, is an emerging pest in Southern Italy (Tremblay et al., 2000; Allegro & Griffo, 2008). The platypodid beetle is a primary and polyphagous pest infesting only healthy standing trees of several botanical species (Corylus, Prunus, Juglans, Pyrus, Malus, Populus, etc.); cut wood or “sick” trees are not colonized. M. mutatus is a xylomicetophagous species (=Ambrosia beetle). In Campania it may cause dramatic damages, especially in commercial plantations of Populus nigra. Male platypodid infest new trees primarily in late spring: coarse boring dust can be observed on attacked trees, which usually exude sap through the entrance holes. Females join the males soon after a successful attack and complete most of the typical galleries, excavated on a transversal plane through the xylem, as they lay eggs. The young larvae feed on symbiontic fungus and the last instant also on wood, boring each a vertical pupal chamber. Economic losses in poplar woods are due to stem fracture caused by the presence of parental gallery systems, the massive diffusion of the fungi in the xylem and wood alteration (Fig. 2). From a poplar wood infested by M. mutatus in Campania (Fig. 3), a fungus responsible of a chromatic wood alteration has been identified. Wall tissues from M. mutatus galleries coated with a firm mycelium were sampled (Fig. 4,5). Several fungal colonies with a red mycelium and a strong coloration on PDA have been isolated. All the red strains belong to the genus Verticillium spp. (Fig. 6). The fungus establish a physical contamination with the platypodid and are massively present in the brood galleries. To our knowledge, this is a new association and up to now the possible role of this relationship is unknown. A typical symbiontic species recorded for M. mutatus in Argentina is an ascomycota of the genus Raffaelea (Jones & Blackwell, 1998; Gebhardt & Oberwinkler, 2005). Differences in environmental conditions and in ecological interactions may explain the presence of Verticillium spp. in the galleries of M. mutatus on poplar in Campania. Biological investigations in order to characterize the beetle-fungus association are in progress

Both lactoferrin and iron influence aggregation and biofilm formation in Streptococcus mutans

Streptococcus mutans, a gram-positive immobile bacterium, is an oral pathogen considered to be the principal etiologic agent of dental caries. Although some researches suggest that trace metals, including iron, can be associated with dental caries, the function of salivary iron and lactoferrin in the human oral cavity remains unclear. The data reported in this study indicates that iron-deprived saliva (Fe3+ 1 microM) inhibits both phenomena. Our findings are consistent with the hypothesis that S. mutans aggregation and biofilm formation are negatively iron-modulated as confirmed by the different effect of bovine lactoferrin (bLf), added to saliva at physiological concentration (20 microg/ml) in the apo- or iron-saturated form. Even if saliva itself induces bacterial aggregation, iron binding capability of apo-bLf is responsible for the noticeable increase of bacterial aggregation and biofilm development in the fluid and adherent phases. On the contrary, iron-saturated bLf decreases aggregation and biofilm development by supplying iron to S. mutans. Therefore, the iron-withholding capability of apo-Lf or native Lf is an important signal to which S. mutans counteracts by leaving the planktonic state and entering into a new lifestyle, biofilm, to colonize and persist in the human oral cavity. In addition, another function of bLf, unrelated to its iron binding capability, is responsible for the inhibition of the adhesion of S. mutans free, aggregated or biofilm on abiotic surfaces. Both these activities of lactoferrin, related and unrelated to the iron binding capability, could have a key role in protecting the human oral cavity from S. mutans pathogenicity

Protecting one, protecting both? Scale-dependent ecological differences in two species using dead trees, the rosalia longicorn beetle and the barbastelle bat

Organisms sharing the same habitats may differ in small-scale microhabitat requirements or benefit from different management. In this study, set in Italy, we focused on two species of high conservation value, the cerambycid beetle Rosalia alpina and the bat Barbastella barbastellus, which often share the same forest areas and in several cases the same individual trees. We compared the potential distribution and, at two spatial scales, the niches between such species. The predicted distributions largely overlapped between the beetle and the bat. The niches proved to be similar on a broad scale, yet not on the plot one. Compared with B.barbastellus, R.alpina tends to occur at lower altitude in more irradiated sites with lower canopy closure and uses shorter trees with wider diameters. B.barbastellus occurred more often in trees within forest or along its edges, whereas R.alpina lays eggs in trees found in clearings. B.barbastellus plots were more frequent in forest, R.alpina plots in forested pasture and open-shredded forest. Overall, exposure to sun influenced more critically site and tree selection by R.alpina, as a warm microclimate is essential for larval development. Although B.barbastellus reproduction may be favored by warmer roosting conditions, bats may also find such conditions in dense forest and in strongly irradiated cavities high up in tall trees that project above the canopy. We emphasize that subtle differences in the ecological requirements of syntopic taxa could be missed at broad scales, so multiple-scale assessment is always advisable.

Severe outbreak of Fusarium solani on Quercus ilex vectored by Xylosandrus compactus

The first European record of an outbreak of Fusarium solani on Quercus ilex following a massive attack by Xylosandrus compactus from southern Italy is reported