The pine bark beetle, Dendroctonus armandi, is a native pest restricted to forests in the Qinling Mountains in China. There was an outbreak of this species there that affected over 0.36 million hectares of pine forest. We hypothesized that there are differences between the numbers of beetles captured by traps baited with various combinations of candidate semiochemicals extracted from the hindguts of D. armandi. In order to determine whether a better operational lure could be developed for D. armandi, we analyzed the volatiles in extracts of the hindgut of D. armandi and tested various combinations of candidate semiochemicals. The GC-MS and GC-FID analyses of volatiles in the extracts of the hindguts of D. armandi collected at different stages of the attack revealed that they are mainly a-pinene, b-caryophyllene and (+)-3-carene with minor amounts of myrcene, limonene, verbenol and verbenone. We tested various combinations of these candidate semiochemicals in order to determine an optimal blend. Our results suggest that the addition of b-caryophyllene to either a-pinene, or blends of a-pinene and other candidate semiochemicals, significantly enhanced the attractiveness of the lures for D. armandi. Field trapping experiments indicated that the blends that included b-caryophyllene, myrcene and other candidate semiochemicals resulted in significantly higher trap catches (161–243% higher) than a-pinene alone. Therefore, a simple lure consisting of a-pinene and b-caryophyllene would be an optimal blend for D. armandi. We conclude that this blend of semiochemicals may provide a better method of reducing the numbers of D. armandi in forest ecosystem., Shou-An Xie, Shu-Jie LV., and Obsahuje seznam literatury
Předmětem výzkumu je pár náramků z Nového Knína, okr. Příbram, z nichž první se objevil v roce 1965, druhý v roce 2014. První náramek byl v minulosti charakterizován jako stříbrný, s analogiemi v skandinávském kruhovém šperku 10.–11. století. V roce 2008 byl podroben prvkové analýze RFA. Ukázalo se, že je složen ze slitiny mosazi s příměsí stříbra. Po překvapivém objevu druhého náramku byla realizována série přírodovědných a archeologicko-kulturně antropologických analýz, které v souhrnu přinesly chronologické a materiálové přehodnocení dosud publikovaných údajů, včetně jejich „nálezových“ okolností. Z výsledků analýz plyne, že oba šperky jsou téměř identické. Analýzy dále přinesly zjištění, že je nelze považovat za raně středověké, nýbrž za novověké až recentní výrobky patrně mimoevropského původu (Afrika?), nejspíš turistické suvenýry. and The subject of the investigation is a pair of bracelets from Nový Knín in the Příbram district, the first of which appeared in 1965, the second in 2014. In the past, the first bracelet was characterised as silver, with analogies in Scandinavian ring ornaments of the 10th–11th century AD. But when this bracelet was subjected to an elemental analysis XRF in 2008, it was found to be composed of an alloy of brass with an admixture of silver. Following the surprising discovery of the second bracelet, a series of scientific and archaeological-culturally anthropological analyses were conducted, the results of which led to a chronological and material re-evaluation of previously published data, including their ‘find’ contexts. The analyses indicate that the two ornaments are virtually identical and also reveal that they cannot be regarded as early medieval artefacts but rather as Modern to recent products that were likely made outside of Europe (Africa?), probably of a tourist souvenir