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71.
The palm weevil, Rhynchophorus palmarum (L.), was collected in cocoons from red ring-diseased coconut palms (Cocos nucifera L.) in Trinidad and Tobago. Juveniles of five species of nematodes were extracted from the genitalia and macerated bodies of newly emerged adults of the palm weevil: Rhadinaphelenchus cocophilus (Cobb) Goodey (the red ring nematode), Teratorhabditis sp., Diplogasteritus sp., Mononchoides sp., and Bursaphelenchus sp. Over 90% of newly emerged weevil females and males were infested internally with red ring nematode juveniles, and over 47% of the weevils contained more than 1,000 red ring nematodes each. There was no significant correlation between weevil body length and the number of red ring nematodes carried internally by each weevil. Teratorhabditis sp. and Diplogasteritus sp. were extracted from over 50% of the palm weevils, and Monochoides sp. and Bursaphelenchus sp. were found in a small proportion of the weevils. Field-collected adult weevils were also internally and externally infested with a Rhabditis sp., which was not observed in or on weevils allowed to emerge from field-collected cocoons. 相似文献
72.
Spontaneous bleeding of sugar-rich sap from cambial-deep incisions in the bark of trunks was demonstrated for Eucalyptus globulus and other eucalypts across a range of localities and seasonal conditions in south-west Australia. High levels of sucrose
and raffinose (up to 31% w/v total sugars) were present in the exudates, and upward and downward gradients in exudate sugar
concentrations were recorded between samples obtained at different heights up trunks of E. globulus. The data indicated a phloem origin for the exudates, with source:sink pressure gradients driving translocation. Concentration
ratios of sugars to amino acids were consistently lower in exudate from upper (distal) than basal regions of trunks, suggesting
preferential partitioning of nitrogen upwards towards the trunk apex. A comparison of phloem and xylem sap composition from
one plantation over a season showed nitrate in xylem but not phloem and substantial amounts of sodium, and high concentrations
of chloride and sulphate relative to phosphate in xylem and phloem. Phloem sap sampled across a range of 29 contrasting plantations
of E. globulus at peak stress (autumn) showed great inter-site variability in concentrations of amino acids, sulphur, sodium and certain
trace elements and in C:N and Na:K ratios of sap. Carbon isotope ratios (δ13C) were strongly correlated with sugar concentrations of the sap samples from these and other plantations. Use of sap compositional
attributes of phloem and δ13C values of translocated carbon is suggested for assessing the current nutritional condition and water status of E. globulus plantings.
Received: 9 April 1998 / Accepted: 20 August 1998 相似文献
73.
Natural regeneration of Eucalyptus is a major problem for the restoration and preservation of temperate woodlands. South‐eastern Australia experienced a period of above average rainfall from mid‐2010 to early 2011, creating favourable conditions for localised Eucalyptus regeneration. We conducted a case–control study comparing sites where natural regeneration from seed was present and absent. Vegetation cover, soil condition and hydrophobicity, as well as shelter objects and landscape position, were recorded to identify what influences natural regeneration from seed. Using conditional logistic regression, we found the odds of regeneration occurring increased with uphill slope angle and herbaceous cover. Our results suggest that, during periods of high rainfall, stable microsites that capture seed and resources are most likely to support Eucalyptus regeneration. 相似文献
74.
Summary Micropropagation has the potential to quickly introduce selected genotypes of adult Eucalyptus globulus clones and it is now widely used in Portugal as a part of genetic improvement programs. Several clones have been established
and multiplied in vitro. The different clones have individual requirements for successful rooting. Rejuvenation was achieved at different periods
after culture initiation for the different clones. Subculturing preceding rooting in multiplication medium supplemented with
riboflavin and cholene chloride allowed the increase of rooting ability for several clones tested. Removal of boron from the
rooting medium increased rooting by 10%. Indolebutyric acid (IBA) dipping before transfer to the rooting medium resulted in
a rooting percentage of 80–95% for the best clones tested. Acclimatization was performed without difficulties (90–95% success)
and the rooted plants were either planted directly or used as mother plants for further cutting production, depending on the
needs. The results described in this paper increase the commercial feasibility of the micropropagation system for E. globulus. 相似文献
75.
Revisiting the link between breeding effort and oxidative balance through field evaluation of two sympatric sibling insect species 下载免费PDF全文
Benjamin Rey Pierre‐François Pélisson Marie‐Claude Bel‐Venner Yann Voituron Samuel Venner 《Evolution; international journal of organic evolution》2015,69(3):815-822
The idea that oxidative stress could be a major force governing evolutionary trade‐offs has recently been challenged by experimental approaches in laboratory conditions, triggering extensive debates centered on theoretical and methodological issues. Here, we revisited the link between oxidative stress and reproduction by measuring multiple antioxidant and oxidative damages in wild‐caught females of two sibling weevil species (Curculio elephas, C. glandium). The strength of our study arised from (1) studied species that were sympatric and exploited similar resource, but displayed contrasting reproductive strategies and (2) individuals were sampled throughout adult life so as to relate oxidative status to breeding effort. We found that the short‐lived C. elephas sacrifices red‐ox homeostasis for immediate reproduction upon emergence as characterized by low antioxidant defenses and elevated oxidative damage. Comparatively, C. glandium massively invests in antioxidant and maintains low oxidative damage, which may contribute to their extended prereproductive period. Intriguingly, we also reveal, for the first time in a field study, an unexpected reactivation of antioxidant defenses with the onset of reproduction. Our results thus support the existence of a strong, but complex relationship between oxidative stress and life‐history evolution and highlight the need for a finer‐scale picture of antioxidant strategies. 相似文献
76.
A novel genome‐wide microsatellite resource for species of Eucalyptus with linkage‐to‐physical correspondence on the reference genome sequence 下载免费PDF全文
Dario Grattapaglia Eva M. C. Mamani Orzenil B. Silva‐Junior Danielle A. Faria 《Molecular ecology resources》2015,15(2):437-448
Keystone species in their native ranges, eucalypts, are ecologically and genetically very diverse, growing naturally along extensive latitudinal and altitudinal ranges and variable environments. Besides their ecological importance, eucalypts are also the most widely planted trees for sustainable forestry in the world. We report the development of a novel collection of 535 microsatellites for species of Eucalyptus, 494 designed from ESTs and 41 from genomic libraries. A selected subset of 223 was evaluated for individual identification, parentage testing, and ancestral information content in the two most extensively studied species, Eucalyptus grandis and Eucalyptus globulus. Microsatellites showed high transferability and overlapping allele size range, suggesting they have arisen still in their common ancestor and confirming the extensive genome conservation between these two species. A consensus linkage map with 437 microsatellites, the most comprehensive microsatellite‐only genetic map for Eucalyptus, was built by assembling segregation data from three mapping populations and anchored to the Eucalyptus genome. An overall colinearity between recombination‐based and physical positioning of 84% of the mapped microsatellites was observed, with some ordering discrepancies and sporadic locus duplications, consistent with the recently described whole genome duplication events in Eucalyptus. The linkage map covered 95.2% of the 605.8‐Mbp assembled genome sequence, placing one microsatellite every 1.55 Mbp on average, and an overall estimate of physical to recombination distance of 618 kbp/cM. The genetic parameters estimates together with linkage and physical position data for this large set of microsatellites should assist marker choice for genome‐wide population genetics and comparative mapping in Eucalyptus. 相似文献
77.
The importance of litter to nutrient and organic matter storage and the possible influence of species selection on soil fertility
in ten stands each consisting of a separate tree species were examined in this study. The plantations had been grown under
similar conditions in an arboretum in the Luquillo Experimental Forest, Puerto Rico. The species involved were: Anthocephalus chinensis, Eucalyptus × patentinervis, E. saligna, Hernandia sonora, Hibiscus elatus, Khaya nyasica, Pinus caribaea var. hondurensis, P. elliottii var. densa, Swietenia macrophylla, and Terminalia ivorensis. After 26 yr, litter mass ranged from 5 mg ha-1 in the H. sonora stand to 27.2 Mg ha-1 in the P. caribaea stand. Nutrients in the litter (N, P, K, Ca, and Mg) also varied widely, but stands were ranked in different order when ranked
by nutrients in the litter than then ranked according to accumulation of mass. Only E. saligna and A. chinensis stands were ranked similarly in accumulation of both nutrients and mass, and the stand of H. elatus was ranked higher with respect to nutrient accumulation than to accumulation of mass. The nutrient concentration in standing
leaf litter generally increased in the order of recently fallen <old intact< fragmented. Nutrient concentration of standing
leaf litter appears to increase with age and depth in the litter layer. The amount of nutrients stored in the litter compartment
of these plantations was in the same order of magnitude as the quantity of available nutrients in the top 10-cm of mineral
soil. Total litter mass was negatively correlated with the mass-weighted concentration of N, K, and Mg. The same relationship
was found for Ca in the leaf litter and N in the fine wood litter compartments. In some stands (notably P. caribaea, P. elliottii, and E. saligna), leaf litter derived from species other than the species planted in that particular stand had higher nutrient concentration
than leaf litter from the planted species. Soils of the 10 stands were classified in the same soil series and had similar
texture (clay soils). However, significantly different chemical characteristics were found. Results obtained by analysis of
covariance and by limiting comparisons to adjacent stands with similar soil texture, indicate that different species have
had different influences on the concentration of available nutrients in soil. 相似文献
78.
1. The loss of input of leaf litter through clearing of riparian vegetation may result in significant changes to aquatic ecosystems. River red gums (Eucalyptus camaldulensis) surrounding floodplain wetlands in the Murray–Darling Basin, Australia, contribute large quantities of leaf litter, but the quality of this resource may change depending on the timing of inundation. 2. We used experimental mesocosms to test the hypotheses that zooplankton would have a greater abundance with an input of leaf litter and that fewer zooplankton would emerge from egg banks in cleared than forested wetlands. The experiment was carried out in summer/autumn and in spring to test a third hypothesis that zooplankton would respond to changes in the timing of wetland inundation as a result of river regulation. 3. In summer/autumn, leaf litter reduced zooplankton abundance by 89% at the beginning of the experiment through its influence on water quality. Only a few taxa (Polyarthra spp., Colurella spp. and the cladoceran Family Moinidae) responded positively to leaf litter when water quality improved later in the experiment, indicating a switch in the role of leaf litter from a non‐trophic to a trophic pathway. 4. In spring, microcrustaceans emerged in smaller numbers from sediment sourced from cleared compared to forested wetlands, reflecting different communities in these two wetland types and/or disturbances to the sediment that interfere with emergence. 5. Although leaf litter appears not to be an important resource for zooplankton in floodplain wetlands, riparian clearing may have lasting effects on future emerging zooplankton communities. Additionally, river regulation may have considerable impacts on the influence of leaf litter on zooplankton, which has implications for the management of floodplain river systems. 相似文献
79.