Associates Of Bark Beetles Research Articles

Geosmithia associated with hardwood-infesting bark and ambrosia beetles, with the description of three new species from Poland.

Geosmithia species (Hypocreales, Ascomycota) are associates of bark beetles and other arthropods. One species, Geosmithia morbida, is a virulent tree pathogen of Juglans nigra. To date, 10 Geosmithia spp. from conifer-infesting, and at least 23 species from hardwood associated bark beetles have been reported from Europe. The aim of this study was to survey Geosmithia spp. associated with 18 bark and ambrosia beetle species in hardwood ecosystems in Poland. In addition, we evaluated the pathogenicity of the six Geosmithia species by inoculating Acer, Fagus, Quercus, Tilia and Ulmus seedlings. Our surveys yielded a total of 1060 isolates from 2915 beetles and 1887 galleries. We identified isolates using morphology and ITS, β-tubulin and TEF1-α sequences. Altogether we identified 11 species including nine previously known and two new species described here as Geosmithia fagi sp. nov. and G. pazoutovae sp. nov. In addition, a sister species G. longistipitata sp. nov., associated with Picea trees, is described here. Bark beetles from hardwoods, with exeption of Dryocoetes alni, D. villosus, Scolytus ratzeburgi and ambrosia beetles, appear to be regular vectors of Geosmithia spp. Like in other parts of the world, most Geosmithia taxa exhibited a distinct level of vector/host specificity. None of Geosmithia isolates induced any disease symptoms under the conditions of our experiment. This study highlights the need for more intensive surveys across additional areas of Central and Northern Europe, insect vectors and host tree species in order to elucidate the Geosmithia species diversity in this region.

Mites Trichouropoda and Uroobovella spp. (Uropodoidea) phoretic on bark beetles (Scolytinae): a comparison from a declining mountain spruce forest in Central Europe

ABSTRACTMites of the genera Trichouropoda and Uroobovella are characteristic associates of bark beetles which act as agents of their dispersal in many types of forest ecosystems worldwide. We compared the phoretic assemblages of Trichouropoda and Uroobovella mites on six species of bark beetle associated with Norway spruce (Picea abies (L.) Karsten), namely: Dryocoetes autographus Ratzeburg, Hylastes cunicularius Erichson, Hylurgops palliatus (Gyllenhal), Ips typographus (Linnaeus), Pityogenes chalcographus (Linnaeus) and Polygraphus poligraphus (Linnaeus). Bark beetles were caught at random in non-baited flight-interception traps set in the shrub layer of a declining mountain spruce forest in the Tatra Mountains, West Carpathians, Central Europe. Over four years of a bark beetle outbreak, a total of six species of mites and 12 phoretic associations between mites and beetles were recorded. A newly documented host association includes that of Trichouropoda pecinai Hirschmann & Wiśniewski with H. palliatus. The most frequently recorded mite-beetle associations were: T. pecinai with H. cunicularius, Trichouropoda obscura (Koch) with H. palliatus, Trichouropoda polytricha (Vitzthum) with P. chalcographus and I. typographus and Uroobovella vinicolora (Vitzthum) with D. autographus. The results suggest that most of the recorded mite species have distinct bark beetle dispersants and that niche partitioning in these dispersants may be reflected by the observed mite–host associations.

Beetles (Coleoptera) caught with pheromones of Gnathotrichus retusus and G. sulcatus (Col., Scolytidae) in southern Finland

AbstractThe ambrosia beetle Gnathotrichus materiarius, which originally came from North America, was discovered in southern Finland in 1996. In 1997, using Norwegian drainpipe traps baited with pheromones of Gnathotrichus retusus and G. sulcatus, we collected beetles in the region where the first specimen had been caught in order to determine whether this potential pest species had become established in the area. Samples from a total of 16 traps included 79 species of beetles and 719 individuals, but no specimens of G. materiarius. The most abundant species in the samples were the ambrosia beetles Xyleborus dispar and Trypodendron lineatum. Several predators and other associates of bark beetles were also captured. The majority of the beetles caught were saproxylic species.

REVIEW OF THE GENUS HETEROTARSONEMUS (ACARINA: TARSONEMIDAE)

AbstractThe generic concept of Heterotarsonemus Smiley is reviewed and redefined. The type-species, H. lindquisti Smiley, is redescribed and illustrated along with a new species, H. bicornis; the only described European species, H. coleopterorum Schaarschmidt new combination, is compared with the above two nearctic species. The known species of this genus are associates of bark beetles in conifers.