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41.
42.
B. WERMELINGER A. RIGLING D. SCHNEIDER MATHIS M. DOBBERTIN 《Ecological Entomology》2008,33(2):239-249
Abstract. 1. In several dry inner Alpine valleys higher mortality levels of pine have been observed in recent years. This paper evaluates the role of xylophagous insects in the current pine decline and the influence of climate change on the infestation dynamics.
2. More than 200 trees of different levels of crown transparency (needle loss) were felled between 2001 and 2005 and sections of them incubated in insect emergence traps. Colonisation densities were related to the transparency level of each host tree at the time of attack.
3. Trees with more than 80% needle loss were colonised most frequently, but the breeding density was highest in trees with 65–80% needle loss.
4. The scolytine Ips acuminatus and the buprestid Phaenops cyanea colonised trees with 30–90% needle loss in high densities. The bark beetle Tomicus minor was less aggressive, preferring trees with 60–85% needle loss. The hymenopteran Sirex noctilio and the cerambycid Acanthocinus aedilis were restricted to greatly weakened trees with 50–85% needle loss. Most species colonised trees that had experienced a decline in vigour, that is an increase in crown transparency shortly before attack.
5. The infestation dynamics of P. cyanea covaried with the drought index as well as with temperature.
6. Increased temperatures not only trigger a drought stress rendering the host trees susceptible to insect attack, but also accelerate insect development. As more frequent drought periods are likely as a result of climate change, even trees only slightly or temporarily weakened will be more subject to attack by aggressive species such as I. acuminatus and P. cyanea . 相似文献
2. More than 200 trees of different levels of crown transparency (needle loss) were felled between 2001 and 2005 and sections of them incubated in insect emergence traps. Colonisation densities were related to the transparency level of each host tree at the time of attack.
3. Trees with more than 80% needle loss were colonised most frequently, but the breeding density was highest in trees with 65–80% needle loss.
4. The scolytine Ips acuminatus and the buprestid Phaenops cyanea colonised trees with 30–90% needle loss in high densities. The bark beetle Tomicus minor was less aggressive, preferring trees with 60–85% needle loss. The hymenopteran Sirex noctilio and the cerambycid Acanthocinus aedilis were restricted to greatly weakened trees with 50–85% needle loss. Most species colonised trees that had experienced a decline in vigour, that is an increase in crown transparency shortly before attack.
5. The infestation dynamics of P. cyanea covaried with the drought index as well as with temperature.
6. Increased temperatures not only trigger a drought stress rendering the host trees susceptible to insect attack, but also accelerate insect development. As more frequent drought periods are likely as a result of climate change, even trees only slightly or temporarily weakened will be more subject to attack by aggressive species such as I. acuminatus and P. cyanea . 相似文献
43.
Jung JA Jhang E. John Staba Jung Yun Kim 《In vitro cellular & developmental biology. Plant》1974,9(4):253-259
Summary Roots, stems, or leaves of American (Panax quinquefolium) and Korean (Panax ginsing) ginseng were grown as callus or supension tissue cultures. Tissue cultures ofP. ginseng would occasionally form plantlets. The fundamental chemical composition, inorganic analysis, and saponin (panaquilin) content
of American and Korean ginseng plants and tissue cultures were determined. The crude saponin content is very similar to, but
approximately one-half (1.3%, fresh weight) of that present in ginseng roots. Two-dimensional thin layer chromatographic analysis
revealed minor differences in the panaquilins present in American and Korean ginseng tissue cultures. The sapogenin, panaxadiol,
was isolated from Korean ginseng callus. 相似文献
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45.
HOCHACHKA PETER W.; SCHNEIDER DAVID E.; MOON THOMAS W. 《Integrative and comparative biology》1971,11(3):479-490
SYNOPSIS. At low temperature (3°C), in the absence of substrateand cofactor, trout liver fructose diphosphatase (FDPase) isinactivated by exposures to relatively low pressures. FDP andMg2+ protect against this inactivation; hence, maximum catalysisat pH 7.5 is pressure insensitive, while at more alkaline pH,it is markedly accelerated by pressure. The volume change ofactivation, V*, at saturating FDP and Mg2+ concentrations isabout 40 cm3/mole. The apparent Km for FDP and the Kafor Mg2+ are markedly increased by pressure. At low FDP or Mg2+levels these kinetic properties outweigh V* in determining thereaction rate; hence, under these conditions, piessure retardscatalysis. Similarly, the K4 for AMP is notably pressure sensitive.Comparable effects of pressure on the kinetic constants forliver FDPase from benthic Corypliaenoides are much less pronounced,suggesting that in these off-shore species enzyme-substrate,enzyme-cofactor, and enzyme-modulator interactions have beentailored through evolution for pressure independent catalyticfunction. 相似文献
46.
JA Nboyine S Boyer D Saville MJ Smith SD Wratten 《New Zealand journal of zoology.》2016,43(4):336-350
The endemic New Zealand ground wētā (Hemiandrus sp. ‘promontorius’) has a Naturally Uncommon conservation status. This is because of the paucity of information on its density and distribution. Here, the biology, density and distribution of a population of this wētā found in and around vineyards in the Awatere Valley, Marlborough was studied. Wētā density was assessed in vineyards, paddocks and shrublands in this valley. Soil moisture, penetration resistance, pH and organic matter were recorded at locations with and without wētā. Wētā density in vineyards was significantly higher than in either paddocks or shrub habitats. In vineyards, the density of this insect was significantly higher under-vines than in the inter-rows. Higher numbers of this wētā were found in moist soils that required lower force to burrow. Females laid an average of 55 eggs between March and April, which hatched in September. These findings highlight the intersection between agriculture and conservation. 相似文献
47.
Distinguishing morphologically cryptic taxa, by definition, requires genetic data such as DNA sequences. However, DNA sequences may not be obtained easily for taxa from remote sites. Here we provide the details of a high-resolution melt-curve-based method using taxon-specific primers that can distinguish two taxa of Adélie penguins, and that will be usable in Antarctica when combined with some of the newly developed field-deployable thermal cyclers. We suggest that the wider adoption of field-deployable polymerase-chain-reaction-based techniques will enable faster assignation of haplotype to individuals in situ, and so allow the targeting of observations and sample collection to specimens relevant to the research question. Targeting individuals will also reduce the need to repeatedly handle animals and reduce the time and travel required to complete field work. 相似文献
48.
SEM studies on vessels in ferns. 11. Ophioglossum 总被引:4,自引:0,他引:4
EDWARD L. SCHNEIDER SHERWIN CARLQUIST FLS 《Botanical journal of the Linnean Society. Linnean Society of London》1999,129(2):105-114
With scanning electron microscopy (SEM), the nature of metaxylem vessel elements and tracheids was examined in Ophioglossum crotalophomides, 0. pendulum subsp. falcatum , and 0. vulgatum roots and rhizomes. Vessels were identified in all species. End walls of vessel elements, which bear perforations, are like lateral wall pitting of those elements in the secondary wall framework and differ only in absence of pit membranes or presence of pit membrane remnants. Some of the perforations contain pit membrane remnants that have large pores, small porosities, or are threadlike or weblike in structure. Dimorphic perforations were found in some vessel elements of rhizomes of 0. pendulum subsp. falcatum. Tracheids are very likely present in addition to vessels in all three species. The secondary wall framework of both tracheids and vessels is basically scalariform, although deviations in pattern are present. Vessel elements of Ophiglossum are entirely comparable to those of leptosporangiate ferns. 相似文献
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